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K F Wong

Publications and source records attributed to K F Wong.

At least 55 records · Page 3Linked to original sources
PubMed2001

Spontaneous entrapment of polynucleotides upon electrostatic interaction with ethanol-destabilized cationic liposomes.

This study describes the effect of ethanol and the presence of poly(ethylene) glycol (PEG) lipids on the interaction of nucleotide-based polyelectrolytes with cationic liposomes. It is shown that preformed large unilamellar vesicles (LUVs) containing a cationic lipid and a PEG coating can be induced to entrap polynucleotides such as antisense oligonucleotides and plasmid DNA in the presence of ethanol. The interaction of the cationic liposomes with the polynucleotides leads to the formation of multilamellar liposomes ranging in size from 70 to 120 nm, only slightly bigger than the parent LUVs from which they originated. The degree of lamellarity as well as the size and polydispersity of the liposomes formed increases with increasing polynucleotide-to-lipid ratio. A direct correlation between the entrapment efficiency and the membrane-destabilizing effect of ethanol was observed. Although the morphology of the liposomes is still preserved at the ethanol concentrations used for entrapment (25-40%, v/v), entrapped low-molecular-weight solutes leak rapidly. In addition, lipids can flip-flop across the membrane and exchange rapidly between liposomes. Furthermore, there are indications that the interaction of the polynucleotides with the cationic liposomes in ethanol leads to formation of polynucleotide-cationic lipid domains, which act as adhesion points between liposomes. It is suggested that the spreading of this contact area leads to expulsion of PEG-ceramide and triggers processes that result in the formation of multilamellar systems with internalized polynucleotides. The high entrapment efficiencies achieved at high polyelectrolyte-to-lipid ratios and the small size and neutral character of these novel liposomal systems are of utility for liposomal delivery of macromolecular drugs.

Cations↗
PubMed2001

Acute myeloid leukemia with concomitant trisomies 4 and 10: a distinctive form of myeloid leukemia?

The occurrence of trisomy 4 or trisomy 10 as the sole chromosomal abnormality in acute myeloid leukemia (AML) is very rare, the reported frequency being less than 1%. We describe two cases of AML-M2 with concomitant trisomy 4 and trisomy 10, a hitherto undescribed phenomenon. They showed two unusual features, including immunoreactivity for CD56 and a short-lived but rapidly progressive myelodysplastic phase preceding the appearance of frank leukemia. These findings raise the possibility that AML with concommitant trisomy 4 and trisomy 10 may constitute a distinctive subtype of AML.

Acute Disease↗
PubMed2001

Sinonasal angiosarcoma with marrow involvement at presentation mimicking malignant lymphoma: cytogenetic analysis using multiple techniques.

Angiosarcoma of the head and neck most commonly involves the skin of the scalp or face; primary involvement of the sinonasal region is exceedingly rate. We report a patient with sinonasal angiosarcoma who showed marrow involvement at presentation. Marrow aspiration smears showed many large, often segregated blast-like cells, mimicking malignant lymphoma. However, trephine biopsy revealed formation of anastomosing vascular spaces by the tumor cells and immunoreactivity for CD31, supporting a diagnosis of angiosarcoma. DNA ploidy analysis showed an apparent diploidy. Nevertheless, conventional cytogenetics demonstrated very complex chromosomal abnormalities with the presence of multiple hypodiploid clones, together with several near-triploid to near-tetraploid clones showing structural abnormalities involving chromosomes 1, 3, 4, 9, 14, 16, 17, 18, and 22. The identification of these karyotypic changes has been facilitated by the application of comparative genomic hybridization and spectral karyotyping.

Adult↗
PubMed2001

Bone marrow involvement by nasal NK cell lymphoma at diagnosis is uncommon.

To look for subtle evidence of marrow involvement in nasal NK cell lymphoma at diagnosis, we retrospectively studied trephine biopsy specimens from 25 consecutive patients by 2 sensitive techniques: CD56 immunohistochemistry and Epstein-Barr virus-encoded RNA in situ hybridization (EBER ISH). Only 2 patients had marrow involvement by NK cell lymphoma at diagnosis. In 3 additional patients, marrow involvement developed during or after systemic recurrence. All 5 positive cases were revealed by EBER ISH, but only 3 cases showed CD56 immunoreactivity. Among the 5 cases, only 2 were recognized by morphologic assessment. All 5 patients died, often within a short period, compared with a mortality of 50% for patients without demonstrable marrow involvement. Marrow involvement is distinctly uncommon in nasal NK cell lymphoma at diagnosis, and EBER ISH is the most sensitive technique for the demonstration of occult NK cell lymphoma. Despite the low frequency of marrow involvement in nasal NK cell lymphoma, EBER ISH is worthwhile to identify the minor subgroup of patients with a high likelihood of early death due to disease and when autologous bone marrow or peripheral blood stem cell transplantation is contemplated.

Adult↗
PubMed2001

Rearrangement of the myeloid-lymphoid leukaemia gene in Hong Kong Chinese children with acute leukaemia.

OBJECTIVE: To determine the frequency of rearrangement of the myeloid-lymphoid leukaemia gene in acute leukaemia in Hong Kong Chinese children. DESIGN: Immunophenotyping, cytogenetic, and molecular analysis. SETTING: Regional hospital, Hong Kong. PARTICIPANTS: Bone marrow or peripheral blood samples were taken from 27 children aged 16 years or younger with acute leukaemia, from September 1995 through February 1998. MAIN OUTCOME MEASURES: Gene rearrangement was analysed by Southern blotting of HindIII digestion products of mononuclear cell DNA, followed by hybridisation with the myeloid-lymphoid leukaemia P/S4 probe. Nested reverse transcription-polymerase chain reaction analysis was performed to detect and characterise duplication of the myeloid-lymphoid leukaemia gene. RESULTS: Only one (4%) of 23 children whose marrow or peripheral blood samples contained adequate material for genetic study showed rearrangement in the myeloid-lymphoid leukaemia gene. No children were positive for partial tandem duplication of the myeloid-lymphoid leukaemia gene. CONCLUSION: Myeloid-lymphoid leukaemia gene rearrangement is rare in Hong Kong Chinese children with acute leukaemia.

Adolescent↗
PubMed2000

Deletion of Xq23 is a recurrent karyotypic abnormality in acute myeloid leukemia.

Deletion of chromosome Xq23 has been reported in a number of solid tumors, including soft tissue sarcoma, malignant melanoma, astrocytoma, and adenocarcinoma. The deleted Xq often occurs in a setting of very complex karyotypic changes. A similar abnormality has also been described in rare cases of acute myeloid leukemia (AML) but in no other hematologic malignancies. In this study, we report the occurrence of del(X)(q23) in two cases of AML.

Acute Disease↗
PubMed2000

Cytogenetic triclonality in T-cell acute lymphoblastic leukemia: a conventional and molecular cytogenetic study.

Cytogenetically-unrelated clones are infrequently seen in hematologic malignancies, and are particularly uncommon in acute lymphoblastic leukemia. We report a case of T-cell acute lymphoblastic leukemia with L2 morphology which demonstrated three cytogenetically distinct clones: 46,XY,t(2;9)(p21;q34)/46,XY,del(6)(q21q23)/47,XX,+8. Interphase cytogenetic analysis by fluorescence in situ hybridization (FISH) confirmed the presence of trisomy 8 in a significant proportion of lymphoblasts, while reverse transcription-polymerase chain reaction (RT-PCR) did not show the presence of BCR/ABL fusion. This is the first report describing the occurrence of cytogenetic triclonality in de novo T-cell acute lymphoblastic leukemia.

Child↗
PubMed2000

A 3-cM commonly deleted region in 6q21 in leukemias and lymphomas delineated by fluorescence in situ hybridization.

Deletions of the long arm of chromosome 6 (6q) are frequent chromosome aberrations in non-Hodgkin lymphomas (NHLs) and acute lymphoblastic leukemias (ALLs). It is presumed that one or more tumor suppressor genes are localized on 6q. By means of fluorescence in situ hybridization (FISH), we attempted to detect and delineate deletions of 6q in leukemias and lymphomas. We performed FISH on 148 cases of lymphoma and acute leukemia using a panel of 36 YAC probes distributed from 6q12 to 6q27 and a centromeric probe of chromosome 6 as internal control. Deletions of 6q that included a 7-cM commonly deleted region in 6q21 were detected in 59 patients who had B- and T-cell low-grade and high-grade NHL and ALL. FISH with two YAC probes flanking this region was performed on an additional 97 cases of NHL and leukemia. Deletions in 6q21 were detected in an additional 21 cases. In five cases of high-grade B- and T-cell NHL and ALL, the deletion breakpoints were located within the commonly deleted region. To define the deletion breakpoints exactly and to narrow this region further, FISH was performed with six additional YAC probes that have been physically localized within this region. A 3-cM (4-5 Mb) commonly deleted region in 6q21 was delineated. Our study suggests that this commonly deleted region harbors a putative tumor suppressor gene involved in the pathogenesis of both low-grade and high-grade NHL and ALL. Genes Chromosomes Cancer 27:52-58, 2000.

Chromosome Deletion↗
PubMed2000

Hairy cell leukemia in Hong Kong Chinese: a 12-year retrospective survey.

BACKGROUND: Hairy cell leukemia (HCL) is a unique chronic B cell lymphoproliferative disease (B-LPD), with distinct clinical and pathological features, and excellent treatment response to 2-chlorodeoxyadenosine (2-CDA) and pentostatin. There have been few reports of HCL from oriental countries. PATIENTS AND METHODS: A retrospective survey of HCL in six major hematology units in Hong Kong over a 12-year period. RESULTS: There were 18 cases of HCL identified. Most patients presented with fever, splenomegaly and monocytopenia. Lymphadenopathy was present in three patients, and open biopsy revealed tuberculosis infection in two cases. Seven cases received interferon and 12 cases received 2-CDA. Four patients died from bronchogenic carcinoma, cerebral vascular accident, fulminant hepatitis B virus reactivation and malignant melanoma. The remaining 14 patients are in clinical remission at a median of 6 years' follow-up; two are also surviving from second malignancies (thyroid papillary carcinoma and renal cell carcinoma). CONCLUSIONS: Parallel to the low incidence of B-LPD in Chinese, the incidence of HCL (0.035/100000 population per year) is much lower than in Western series. Other clinical features such as male dominance, clinical presentation, response to 2-CDA treatment, and association with second malignancy are similar to Western reports. However, two common complications in the Chinese population are the fulminant reactivation of hepatitis B infection and disseminated tuberculosis infection.

Adult↗
PubMed2000

Consistent patterns of allelic loss in natural killer cell lymphoma.

Natural killer (NK) cell lymphomas are a group of rare but highly aggressive malignancies. Clinically, they can be divided into nasal NK cell lymphomas, nonnasal NK cell lymphomas, and aggressive NK cell lymphoma/leukemia. To determine the patterns of genetic deletions in these tumors, we performed loss of heterozygosity (LOH) analysis on 15 cases (11 nasal and four nonnasal), and fluorescence in situ hybridization on three cases of aggressive lymphoma/leukemia. A panel of 41 microsatellite loci on chromosomes 6q, 11q, 13q, and 17p were investigated. LOH at chromosomes 6q and 13q was frequently detected in NK cell lymphomas, being found in 80 and 66.7% of cases, respectively. LOH at chromosomes 11q and 17p was less common, being found in 28.6 and 30.8% of cases, respectively. Most tumors showed multiple loci deletions at different chromosomal regions, but several patterns of LOH could be defined. LOH at chromosome 6q was found in 90.9% of nasal NK cell lymphomas, but only in 50% of nonnasal NK cell lymphomas. LOH at chromosome 13q was found in 63.6% of nasal NK cell lymphomas and 75% of nonnasal NK cell lymphomas. For nasal NK cell lymphomas, LOH at 13q was found in 33.3% of cases at presentation, but 100% of cases at relapse. Five tumors showed LOH in only one chromosomal region, involving 6q in three cases (two nasal and one nonnasal), and 13q in two cases (both nonnasal). For the three cases of aggressive NK cell lymphoma/leukemia studied by fluorescence in situ hybridization, DNA loss at 13q14 and 17p13 regions were demonstrated. 17p13 seemed to be more commonly involved in aggressive than nasal and nonnasal NK cell lymphomas. Our results suggested that consistent patterns of LOH could be defined in NK cell malignancies. These deleted loci may contain genes important in the initiation and progression of this lymphoma.

Adult↗
PubMed2000

Dissociative prime-probe contextual similarity effects on negative priming and repetition priming: a challenge to episodic retrieval as a unified account of negative priming.

This study examined the dependence of repetition priming (RP) and negative priming (NP) as a function of prime-probe contextual similarity in a paradigm in which participants were required to respond to a letter flanked by incompatible distractor letters (e.g., ABA). Experiment 1 used prime and probe displays containing a pair of "+" symbols that were presented horizontally or vertically. Experiments 2 and 3 manipulated whether the letter triplets contained the "!" symbol. In all experiments, regardless of whether the RP trials were intermixed with the NP trials (Experiment 2) or not (Experiment 3), RP was stronger in the prime-probe similar conditions than in the prime-probe dissimilar conditions, but NP was independent of prime-probe contextual similarity. These findings suggest that NP is not necessarily stronger in conditions in which episodic retrieval of the prime is more likely.

Adolescent↗
PubMed2000

Alloimmunization in Chinese with warm autoimmune haemolytic anaemia - incidence and characteristics.

We perform a retrospective study to determine the incidence and characteristics of alloimmunization in Chinese patients with warm autoimmune haemolytic anaemia. Among 67 patients studied, clinically significant alloantibodies were found in only eight patients, giving a rate of alloimmunization of 11.3%. The latter contrasts with the much higher rate reported in the Western population. This probably reflects the genetic homogeneity in Chinese with respect to the red cell phenotype. The alloimmunization rate, however, is still significant and therefore comprehensive pretransfusion testing is required for Chinese patients with warm autoantibodies so as to safeguard patient's safety.

Adult↗
PubMed2000

Chromosomal translocations are common in natural killer-cell lymphoma/leukemia as shown by spectral karyotyping.

Natural killer (NK)-cell lymphoma/leukemia is a group of rare but highly aggressive neoplasms. The associated genetic aberrations, as defined by conventional cytogenetics, include 6q deletion and chromosome X copy gain, while translocations have been suggested to be uncommon. In this study, three cases of NK cell lymphoma/ leukemia were investigated by spectral karyotyping (SKY). SKY permitted reinterpretation of the chromosomal alterations defined by G-banding and identified several cryptic translocations. In agreement with G-band, 6q deletion was detected in all 3 cases. Structural rearrangement involving chromosome X was observed in 2 cases, and fluorescence in situ hybridization (FISH) analysis indicated that both translocations involved Xp21-pter. Chromosome 8 translocation was also identified in 2 cases and shared a common breakpoint, 8p23. The present study shows the value of SKY in providing additional information on karyotypic abnormalities. The novel findings of recurring Xp21-pter rearrangements and 8p23 translocation should provide basis for further investigations into the tumorigenesis of NK cell lymphoma/leukemia.

Chromosome Banding↗
PubMed2000

Large cell transformation of Sézary syndrome. A conventional and molecular cytogenetic study.

Hyperdiploidy sometimes is found in mycosis fungoides-Sézary syndrome, but its diagnostic significance remains undefined. We report an unusual case of Sézary syndrome manifesting with leukemic large cell transformation. Conventional karyotypic analysis showed the presence of a near-tetraploid neoplastic clone. With dual-color cytometric analysis, we showed that the large Sézary cells were near-tetraploid with a DNA index of 1.86, thereby demonstrating a direct relationship between cell size and ploidy. Comparative genomic hybridization further showed chromosomal imbalances that were not revealed on conventional karyotyping. Our findings suggest that hyperdiploidy may be a marker of large cell transformation, so that when this karyotypic abnormality is found in mycosis fungoides-Sézary syndrome, a search for such a complication is indicated.

Aged↗