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Raymond H S Liang

Publications and source records attributed to Raymond H S Liang.

6 recordsLinked to original sources
PubMed2004

Natural killer cell neoplasms.

Lymphoid neoplasms that are derived from natural killer (NK) cells are uncommon but distinct clinicopathologic disease entities. Three types have been recognized and categorized in the latest World Health Organization classification: extranodal NK cell lymphoma, nasal-type; aggressive NK cell leukemia; and blastic NK cell lymphoma. All NK tumor cells express the NK cell marker CD56, but they lack the expression of surface CD3 and the rearrangement of T-cell receptor genes, which distinguish them from T-lymphoid neoplasms. There is also a strong association with the Epstein-Barr virus, except in blastic NK cell lymphoma. Extranodal involvement by the NK cell tumor is common, especially in the nasal cavity, the skin, and the gastrointestinal tract. All 3 NK cell neoplasms are characterized by aggressive clinical course and poor response to treatment. Although the optimal treatment modality remains to be determined, good initial response to combined radiation therapy and chemotherapy has been observed in localized disease. Further studies in the basic biology of the NK cell and the pathology of NK cell neoplasms may shed light on the development of newer and more effective therapy.

Adult↗
PubMed2003

Role of liver biopsy in the management of liver dysfunction after hematopoietic stem-cell transplantation in a hepatitis B virus-prevalent patient population.

BACKGROUND: Derangement of liver function tests (LFT) is common after hematopoietic stem-cell transplantation (HSCT). The role of liver biopsy in such cases has not been defined in hepatitis B virus (HBV)-prevalent patients. The impact of liver biopsy in the management of LFT derangement after HSCT in an HBV-prevalent population was examined. METHODS: Seventy-five liver biopsies, performed for 323 patients with LFT derangement post-HSCT (263 allogeneic, 60 autologous), were analyzed. The HBV carrier rate was 13.6%. RESULTS: Significantly more LFT derangements and therefore liver biopsies occurred in allogeneic versus autologous HSCT. Before biopsy, graft-versus-host disease (GVHD) and HBV reactivation were clinically diagnosed in 70.6% and 25.3% of cases, respectively. A definite histopathologic diagnosis was obtained after biopsy in 53 cases, with GVHD, HBV hepatitis, and concomitant GVHD-HBV hepatitis found in 33%, 21%, and 8% of cases, respectively. The clinical and histopathologic diagnoses were concordant in 43 cases and discordant in 9 cases. Clinical management was altered in six of nine discordant cases, five of which were caused by HBV or hepatitis C virus (HCV) reactivation. Twenty-two biopsy specimens showed nondiagnostic histopathologic features. Twenty of these cases were successfully managed on the basis of clinical diagnoses. The clinical-biochemical features of patients clinically diagnosed to have GVHD did not differ significantly whether or not they were HBV-HCV carriers. However, liver biopsies in HBV-HCV carriers resulted in significantly more treatment alterations as compared with noncarriers. CONCLUSIONS: Clinical diagnoses of LFT derangements post-HSCT might be adequate for initiation of treatment, but liver biopsies in HBV-HCV carriers were needed, as this might impact on management.

Adolescent↗
PubMed2002

Frequent deletion of Fas gene sequences encoding death and transmembrane domains in nasal natural killer/T-cell lymphoma.

Nasal natural killer (NK)/T-cell lymphoma (NL) frequently co-expresses Fas (Apo-1/CD95) and Fas ligand (FasL), but the tumor cells seldom undergo apoptosis. To determine the reason for failure of apoptosis, we examined Fas mRNA expression in 23 NL cases by reverse transcriptase-polymerase chain reaction and sequenced the entire coding region of the Fas gene in 15 of these cases for which the full-length Fas cDNA could be amplified. The reverse transcriptase-polymerase chain reaction analysis revealed that all of the 23 cases expressed Fas mRNA and the sequencing results showed that in addition to the commonly expressed wild-type Fas mRNA and four alternative splice variants detected in 7 cases, mutant Fas transcripts were present in 9 of the 15 (60%) cases sequenced. With confirmation of some Fas mutations at the gene level, 12 deletions in nine cases and one insertion in one case were eventually identified. To rule out any potential polymerase chain reaction artifacts, the same protocol was used to examine 10 reactive tonsils as a control. No aberrant transcripts associated with deletions were detected in these tonsils except for three alternative splice variants. All of the deletion variants detected in NL contained N-terminal preligand assembly domain but not C-terminal death domain and/or transmembrane domain. Co-detection of the wild-type allele and the mutated Fas alleles without the death domain suggested that a dominant-negative mechanism could block the apoptosis signaling. Moreover, loss of the transmembrane domain could protect the tumor cells from apo-ptosis by producing a soluble form of the Fas receptor. The actuarial 3-year survivals leveled off at 15% for patients carrying the Fas mutations and/or splice variants in the lesions and 49% for those carrying the wild type only, but the difference did not reach statistical significance on the univariate analysis (P = 0.396). Taken together, the findings in this study suggest that frequent Fas gene mutations in NL can result in resistance to apoptosis and may contribute to the pathogenesis of NL by adding to the tumor immune privilege.

Adolescent↗