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Aileen Wee

Publications and source records attributed to Aileen Wee.

13 recordsLinked to original sources
PubMed2006

Impact of new legislation on presumed consent on organ donation on liver transplant in Singapore: a preliminary analysis.

Demand for the liver organ for transplantation vastly exceeded the availability of deceased donor organs. A new law, the revised Human Organ Transplant Act (HOTA), was implemented in Singapore in July 2004, which allowed for recovering four organs, including liver, for transplant unless the deceased give objection prior to their demise. We set to study the impact of the revised legislation by comparing the number of potential suitable donors, liver recovery surgery, and liver transplants two years before and one year after the implementation. There was no change in the number of suitable donors, but there was an increase in the number of liver recovery surgeries and liver transplantation, and a lower refusal rate among suitable donors. Although the revised legislation helped improve the availability of deceased donor organs moderately, other nonlegislative, supplementary measures are needed to further improve the low organ donation rate.

Female↗
PubMed2006

Diagnostic utility of immunohistochemistry in hepatocellular carcinoma, its variants and their mimics.

Hepatocellular carcinoma (HCC) is known for its histomorphologic heterogeneity. Immunohistochemistry (IHC) can help in the comparative morphologic evaluation of HCC, its variants and their mimics. Some of these diagnostic challenges can be attributed to (i) the variety of neoplasms that can arise from the hepatic stem cell lineage; (ii) the spectrum of well-differentiated hepatocellular nodular lesions; (iii) the liver being a target for metastases with some of these histologic entities mimicking variants of HCC or actually arising in the liver; and (iv) the limitations of serum alpha-fetoprotein (AFP). The role of IHC is in the distinction of benign hepatocellular nodules from reactive hepatocytes; WD-HCC from benign hepatocellular nodules; poorly differentiated HCC from cholangiocarcinoma and metastases; and determination of histogenesis of malignant tumor; and of primary site of origin of malignant tumor. A panel of antibodies has more discriminant value. AFP expression usually indicates malignancy in a hepatocellular nodule and hepatocytic histogenesis of a malignancy. Polyclonal carcinoembryonic antigen (pCEA) and CD10 stain bile canaliculi in better-differentiated HCC. HepPar1 is generally accepted as a hepatocytic marker. However, not all HCC stain uniformly and not all HepPar1-positive tumors are of hepatocytic origin or arise in the liver. Mature hepatocytes and hepatocellular nodules stain with CAM 5.2, CK 8, and 18 but not with CK 7, 19, 20, or AE1/AE3. Biliary epithelium expresses CK 7 and 19. CD 34 highlights sinusoidal capillarization. AFP, pCEA/CD10, and CD34 are useful for ascertainment of malignancy in hepatocellular nodules; HepPar1 and cytokeratins to be included if histogenesis is the issue. IHC results should be interpreted in the larger context of the case.

Biomarkers, Tumor↗
PubMed2006

Non-invasive models for predicting histology in patients with chronic hepatitis B.

BACKGROUND AND AIM: In contrast to chronic hepatitis C (CHC), few studies had been performed in assessing non-invasive models for predicting significant fibrosis or cirrhosis in chronic hepatitis B (CHB) patients. We aimed to evaluate non-invasive markers for diagnosing significant fibrosis/cirrhosis in patients with CHB, and to evaluate accuracy of models from CHC in CHB patients. PATIENTS AND METHODS: Liver biopsies from consecutive treatment-naïve CHB patients were evaluated histologically by a pathologist blindly, using the Ishak score. Patients were divided randomly into a training (65%) and a validation sets (35%). Markers of fibrosis were evaluated by univariate followed by multivariate analysis in the training set. Area under receiver operating characteristics curve (AUROC) was assessed and validated in the training set. AUROC of aspartate aminotransferase (AST), AST/alanine aminotransferase (ALT) ratio, and AST-platelets ratio index (APRI) (derived from studies from CHC) in diagnosing significant fibrosis/cirrhosis were also assessed. RESULTS: Two-hundred and eighteen CHB patients were evaluated: 83% male, 86% Chinese, 47% having significant fibrosis, 19% having cirrhosis. Platelets were the only factor significantly associated with significant fibrosis and cirrhosis at multivariate analysis but the AUROC was only modest at 0.63 and 0.73, respectively. Models derived from studies from CHC were even less accurate. CONCLUSION: Models with non-invasive markers in predicting histology from CHC patients were unsuitable for CHB patients. No variables consisting of simple and readily available markers were able to predict cirrhosis accurately in patients with CHB.

Adolescent↗
PubMed2006

A randomized, placebo-controlled trial of thymosin-alpha1 and lymphoblastoid interferon for HBeAg-positive chronic hepatitis B.

Combination therapy between two immunomodulators used for treatment of chronic hepatitis B was explored based on reported therapeutic efficacy of interferon-alpha, and thymosin-alpha1 as monotherapeutic agents to determine if combination therapy was superior to interferon alone. This double-blinded, randomized, placebo-controlled trial compares the addition of thymosin-alpha1, 1.6 microg taken three times per week (combination therapy) or thymosin placebo (monotherapy) to lymphoblastoid interferon (Wellferon), 5 million international units (MIU) taken three times per week, for 24 weeks. Entry criteria included positive hepatitis B e antigen (HBeAg); alanine aminotransferease (ALT) > or = 1.5 x upper normal limit, but < or = 10 x upper normal limit; positive HBV DNA; absence of cirrhosis; treatment naivety and no co-morbid factors. A total of 98 HBeAg-positive patients were recruited, of which 48 were randomized to combination therapy and 50 to monotherapy. The primary endpoint was the loss of HBeAg at 72 weeks. The secondary endpoints were HBeAg seroconversion, normalization of ALT, loss of HBV DNA and improvement in histology. The HBeAg loss was 45.8% and 28.0% for combination therapy and monotherapy, respectively (difference, 17.8%; 95% CI -1.2%-35.3%, P = 0.067). There was a trend towards HBeAg loss when using combination therapy. There were also no statistically significant differences between the different therapies with respect to the secondary endpoints of HBeAg seroconversion, changes in histology, normalization of ALT or loss of HBV DNA. In conclusion, this trial showed a 17.8% improvement in HBeAg loss rates using combination therapy over interferon monotherapy. This could clinically indicate a potential important difference that would need confirmation in subsequent trials.

Adult↗
PubMed2005

CCAAT/enhancer binding protein alpha knock-in mice exhibit early liver glycogen storage and reduced susceptibility to hepatocellular carcinoma.

The CCAAT/enhancer binding protein alpha (C/EBPalpha) is vital for establishing normal hepatic energy homeostasis and moderating hepatocellular growth. CEBPA loss-of-function mutations identified in acute myeloid leukemia patients support a tumor suppressor role for C/EBPalpha. Recent work showed reductions of C/EBPalpha levels in human hepatocellular carcinoma with the reductions correlating to tumor size and progression. We investigated the potential of reactivating c/ebpalpha expression during hepatic carcinogenesis to prevent tumor cell growth. We have developed a c/ebpalpha knock-in mouse in which a single-copy c/ebpalpha is regulated by one allele of the alpha-fetoprotein (AFP) gene promoter. The knock-in mice are physically indistinguishable from wild-type (WT) controls. However, knock-in animals were found to deposit fetal hepatic glycogen earlier than WT animals. Quantitative real-time PCR confirmed early c/ebpalpha expression and early glycogen synthase gene activation in knock-in fetuses. We then used diethylnitrosamine to induce hepatocellular carcinoma in our animals. Diethylnitrosamine produced half the number of hepatocellular nodules in knock-in mice as in WT mice. Immunohistochemistry showed reduced C/EBPalpha content in WT nodules whereas knock-in nodules stained strongly for C/EBPalpha. The p21 protein was examined because it mediates a C/EBPalpha growth arrest pathway. Nuclear p21 was absent in WT nodules whereas cytoplasmic p21 was abundant; knock-in nodules were positive for nuclear p21. Interestingly, only C/EBPalpha-positive nodules were positive for nuclear p21, suggesting that C/EBPalpha may be required to direct p21 to the cell nucleus to inhibit growth. Our data establish that controlled C/EBPalpha production can inhibit liver tumor growth in vivo.

Alleles↗
PubMed2005

Fine needle aspiration biopsy of the liver: Algorithmic approach and current issues in the diagnosis of hepatocellular carcinoma.

The role of fine needle aspiration biopsy (FNAB) in the evaluation of focal liver lesions has evolved. Guided FNAB is still useful to procure a tissue diagnosis if clinical, biochemical and radiologic findings are inconclusive. Major diagnostic issues include: (i) Distinction of benign hepatocellular nodular lesions from reactive hepatocytes, (ii) Distinction of well-differentiated hepatocellular carcinoma (WD-HCC) from benign hepatocellular nodular lesions, (iii) Distinction of poorly differentiated HCC from cholangiocarcinoma and metastatic carcinomas, (iv) Determination of histogenesis of malignant tumor, and (v) Determination of primary site of origin of malignant tumor. This review gives a general overview of hepatic FNAB; outlines an algorithmic approach to cytodiagnosis with emphasis on HCC, its variants and their mimics; and addresses current diagnostic issues. Close radiologic surveillance of high-risk cirrhotic patients has resulted in the increasing detection of smaller lesions with many subjected to biopsy for tissue characterization. The need for tissue confirmation in clinically obvious HCC is questioned due to risk of malignant seeding. When a biopsy is indicated, core needle biopsy is favored over FNAB. The inherent difficulty of distinguishing small/early HCC from benign hepatocellular nodular lesions has resulted in indeterminate reports. Changing concepts in the understanding of the biological behavior and morphologic evolution of HCC and its precursors; and the current lack of agreement on the morphologic criteria for distinguishing high-grade dysplastic lesions (with small cell change) from WD-HCC, have profound impact on nomenclature, cytohistologic interpretation and management. Optimization of hepatic FNAB to enhance the yield and accuracy of diagnoses requires close clinicopathologic correlation; combined cytohistologic approach; judicious use of ancillary tests; and skilled healthcare teams.

Journal Article↗
PubMed2004

Hydroxyapatite-chitin materials as potential tissue engineered bone substitutes.

Hydroxyapatite (HA) in 25%, 50% and 75% w/w fractions was incorporated into chitin solutions and processed into air- and freeze-dried materials. These HA-chitin materials were exposed to cell cultures and implanted into the intramusculature of a rat model. The HA-chitin materials were found to be non-cytotoxic and degraded in vivo. The presence of the HA filler enhanced calcification as well as accelerated degradation of the chitin matrix. The freeze-dried HA-chitin matrixes were selected for further cell seeding experiments because of their porous nature. Mesenchymal stem cells harvested from NZW rabbits were induced into osteoblasts in vitro using dexamethasone. These osteoblasts were cultured for 1 week, statically loaded onto the porous HA-chitin matrixes and implanted into bone defects of the rabbit femur for 2 months. Histology of explants showed bone regeneration with biodegradation of the HA-chitin matrix. Similarly, green fluorescence protein (GFP) transfected MSC-induced osteoblasts were also loaded onto porous HA-chitin matrixes and implanted into the rabbit femur. The results from GFP-transfected MSCs showed that loaded MSCs-induced osteoblasts did not only proliferate but also recruited surrounding tissue to grow in. This study demonstrates the potential of HA-chitin matrixes as a good substrate candidate for tissue engineered bone substitute.

Animals↗
PubMed2003

Flexible chitin films as potential wound-dressing materials: wound model studies.

Chitin films possessing increased flexibility, softness, transparency, and conformability have been prepared. These attributes enable the potential application of chitin films as occlusive, semipermeable film wound dressings similar to commercial products such as Opsite trade mark. The chitin films are generally nonabsorbent, exhibiting a total weight gain of only up to 120-160% in physiological fluid. Dry chitin films transpire water vapor at a rate of about 600 g/m(2)/24 h, similar to commercial polyurethane-based film dressings, but rises to 2400 g/m(2)/24 h, when wet, which is higher than the water vapor transmission rate of intact skin. The chitin films are nontoxic to human skin fibroblasts, maintaining 70-80% cell viability. Wound studies using a rat model showed no signs of allergenicity or the high inflammatory response associated with biodegradable biomaterials. The chitin films displayed accelerated wound-healing properties. Based on histological examination, wound sites dressed with the chitin films stabilized and healed faster, and appeared stronger than those dressed with Opsite trade mark and gauze dressings after 7 days of healing.

Animals↗
PubMed2003

Diffuse uterine adenomatoid tumor in an immunosuppressed renal transplant recipient.

A case of diffuse adenomatoid tumor of the uterus in an immunosuppressed renal transplant recipient is reported and compared with two previously reported, similar cases. The multinodular uterine lesion grossly resembled intramural leiomyomata except for a mucoid cut surface and a cystic serosal component. The predominant patterns of the tumor were adenoid and angiomatoid with less prominent solid and cystic patterns. Immunohistochemical and ultrastructural studies confirmed the mesothelial nature of the tumor cells. Additionally, there was strong diffuse immunoreactivity for proliferating cell nuclear antigen, a low expression of Ki-67, and weak nuclear p53 staining. The relationship between immunosuppression and diffuse adenomatoid tumors is discussed.

Adenocarcinoma↗
PubMed2002

Chitosan-alginate PEC membrane as a wound dressing: Assessment of incisional wound healing.

Flexible, thin, transparent, novel chitosan-alginate polyelectrolyte complex (PEC) membranes, cast from aqueous suspensions of chitosan-alginate coacervates with CaCl(2), were evaluated as potential wound-dressing materials. MTT and NR assays suggested that the chitosan-alginate PEC membranes and their aqueous extracts were nontoxic towards mouse and human fibroblast cells. Cell growth was also not hindered by co-incubation with the membranes. Compared to conventional gauze dressing, the PEC membranes caused an accelerated healing of incision wounds in a rat model. Wounds closed at 14 days postoperatively, and histological observations showed mature epidermal architecture with keratinized surface of normal thickness and a subsided inflammation in the dermis. This was followed by an excellent remodeling phase with organized thicker collagen bundles and mature fibroblasts at 21 days postoperative. Control wounds continued to show signs of an active inflammatory phase under scab on Day 21. Closure rate and appearance of PEC membrane-treated wounds were comparable with Opsite(R)-treated wounds. On the basis of its biocompatibility and wound-healing efficacy, the chitosan-alginate PEC membrane can be considered for wound-dressing applications.

Alginates↗
PubMedDate not supplied

Highly well differentiated hepatocellular carcinoma and benign hepatocellular lesions. Can they be distinguished on fine needle aspiration biopsy?

OBJECTIVE: To determine whether highly well differentiated hepatocellular carcinoma can be distinguished from benign hepatocellular lesions on fine needle aspiration biopsy (FNAB). STUDY DESIGN: Ninety-five FNABs from 88 patients with hepatic masses/diffuse conditions were reviewed according to new cytologic criteria established by Takenaka et al. They were classified into well-, moderately and poorly differentiated hepatocellular carcinomas (W-, M- and P-HCC) and benign aspirates and histologically verified. RESULTS: There were 21 W-HCC, 39 M-HCC, 10 P-HCC, 3 problematic and 22 benign aspirates. The most useful criteria for diagnosing highly W-HCC were architectural features on the smears/cell block sections, including hypercellularity; arborescent, cohesive clusters; broad trabeculae; transgressing and peripheral endothelium; and cytologic details of small, monotonous hepatocytes with nuclear crowding, decreased cytoplasm, increased nuclear/cytoplasmic ratio, atypical naked nuclei and tumor giant cells. Well-defined cytoplasmic borders, abundant thick and monotonous cytoplasm, eccentric nuclei, thick nuclear membranes, irregular nuclear contours, increased chromatin density, irregular chromatin distribution and macronucleoli were not always detectable in highly W-HCC. In fact, some of them were seen in dysplastic hepatocytes. Deficient reticulin patterns and diffuse sinusoidal CD34 reactivity were helpful. CONCLUSION: Experience, attention to architectural and cytologic details in smears/cell blocks and clinicopathologic correlation should reduce the number of indeterminate reports. However, there will always remain some cytohistologically challenging cases.

Adolescent↗
PubMedDate not supplied

alpha-Fetoprotein-producing liver carcinomas of primary extrahepatic origin.

BACKGROUND: alpha-Fetoprotein (AFP)-producing carcinomas, hepatoid or otherwise, are increasingly being recognized at extrahepatic sites. Some of them not only mimic hepatocellular carcinomas (HCCs) in having a proclivity for vascular permeation and distant metastases but also exhibit identical morphology and immunoreactivity for alpha-1-antitrypsin and HepPar1. beta-Human chorionic gonadotropin (hCG) is also detected. This would create diagnostic problems in hepatic fine needle aspiration biopsies (FNABs) from patients with elevated serum AFP. Apart from HCC, its variants and germ cell tumors, one must consider metastatic AFP-producing carcinomas. CASES: A man with gastric adenocarcinoma had a liver mass. Hepatic FNAB revealed an AFP-producing adenocarcinoma. The gastric tumor was positive for AFP, polyclonal carcinoembryonic antigen, HepPar1, CK19, hCG and synaptophysin. A woman with endocervical adenocarcinoma had multiple liver nodules. FNAB revealed an AFP-producing, undifferentiated carcinoma. The cervix showed a large cell neuroendocrine carcinoma coexisting with an adenocarcinoma in situ. The large cells were positive for synaptophysin, AFP, hCG and AE1/3. The glands showed diffuse HepPar1 and focal synaptophysin expression. CONCLUSION: A wide histologic spectrum of extrahepatic carcinomas can produce AFP and other peptide hormones. The true AFP status probably is not recognized at the first presentation. Such carcinomas, whether hepatoid or not, behave aggressively. Their recognition at the initial presentation is crucial to early and appropriate therapy. These entities add a new dimension to the challenges of FNAB diagnosis.

Adenocarcinoma↗