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S K Ma

Publications and source records attributed to S K Ma.

At least 19 recordsLinked to original sources
PubMed2006

Serial analysis of JAK2 mutation in a patient who developed essential thrombocythemia after orthotopic liver transplantation.

A 52-year-old man developed essential thrombocythemia (ET) with JAK2 V617F mutation after orthotopic liver transplantation (OLT). Retrospective analysis showed that, despite a low platelet count, the JAK2 mutation was already found at presentation 14 months before OLT. The high platelet count that would have been typical of ET might be masked by the cirrhosis-related hypersplenism. Thrombocythemia became obvious after OLT. The patient subsequently developed blastic transformation 12 months afterward, a process probably accelerated by the immunosuppression required for the OLT.

Amino Acid Substitution↗
PubMed2005

Hyperbilirubinemia and cholelithiasis in Chinese patients with hemoglobin H disease.

Hemoglobin H disease (HbH) is a hemoglobinopathy peculiar to parts of the world with high incidence alpha-thalassemia mutations. Among 90 HbH cases, 50 cases suffered from clinically significant jaundice (bilirubin >30 mmol/l), including 14 with severe jaundice (bilirubin >60 mmol/l). Cholelithiasis was found in 38 cases. The incidence is roughly eight times higher than that in background control population but 50% lower than that in beta-thalassemia. The risk of gallstones was related to higher bilirubin levels but not alpha-globin genotype, sex, ferritin, and hemoglobin levels. Homozygotes or double heterozygotes for Gilbert alleles (17.2%), but not heterozgyotes (42.2%), were found to have a significantly increased risk of gallstones and jaundice. However, common Chinese Gilbert syndrome alleles do not completely explain the variable risks.

Alleles↗
PubMed2005

Der(8)t(1;8) in myeloblastic transformation of ET with hydroxyurea as the sole prior treatment.

We described a patient with ET that evolved into MF and then subsequently developed myeloblastic transformation. A novel derivative chromosome der(8)t(1;8) was identified in the AML phase. The only prior treatment had been hydroxyurea. We hypothesized that AML in this case resulted from a complex pre-disposition by the natural progression of ET, prolonged use of HU, and the prior evolution into MF. The leukemogenic risk of HU is critically appraised.

Cell Transformation, Neoplastic↗
PubMed2005

The distribution of inhibitory and excitatory synapses on single, reconstructed jaw-opening motoneurons in the cat.

In a previous study, we reported that the distribution of inhibitory input, in contrast to excitatory input, decreased somatofugally along dendrites of cat jaw-closing alpha-motoneurons [J Comp Neurol 414 (1999) 454]. The present study examined the distribution of GABA, glycine, and glutamate immunopositive boutons covering horseradish peroxidase-labeled cat jaw-opening motoneurons. The motoneurons were divided into four compartments: the soma, and primary, intermediate, and distal dendrites. Ninety-seven percent of the total number of studied boutons had immunoreactivity for at least one of the three amino acids. The proportion of boutons immunoreactive for GABA and/or glycine was lower than the proportion of boutons immunoreactive for glutamate. Boutons immunoreactive to glycine alone were more numerous than boutons double-labeled for GABA and glycine, which, in turn, occurred more frequently than boutons immunoreactive to GABA alone. The percentage synaptic covering (proportion of membrane covered by synaptic boutons) of the putatively excitatory (glutamate containing) and putatively inhibitory (GABA and/or glycine containing) boutons decreased somatofugally along the dendrites. Such systematic variations were not seen in the packing density (number of boutons per 100 microm(2)); the packing density showed a distinct drop between the soma and primary dendrites but did not differ significantly among the three dendritic compartments. Overall, the packing density was slightly higher for the putatively excitatory boutons than for the inhibitory ones. When taken together with previous analyses of jaw-closing alpha-motoneurons the present data on jaw-opening alpha-motoneurons indicate that the two types of neuron differ in regard to the nature of synaptic integration in the dendritic tree.

Amino Acid Transport System X-AG↗
PubMed2005

Eosinophilic leukemic transformation in polycythemia rubra vera (PRV).

We report a rare case of eosinophilic leukemia transformation in a patient with polycythemia rubra vera on hydroxycarbamide (hydroxyurea) therapy only. Cytogenetic study showed complex abnormalities including -5, -7, +8, suggestive of a secondary leukemia. The leukemogenic risk of hydroxycarbamide, a ribonucleoside reductase, and the risk of natural leukemic transformation of polycythemia rubra vera is discussed in the context of previous PVSG studies.

Aged↗
PubMed2004

Bone marrow transplantation for therapy-related acute myeloid leukemia in congenital retinoblastoma associated with 13q deletion syndrome.

Children with constitutional deletion of the long arm of chromosome 13 are at risk for retinoblastoma (RB) due to loss of the RB tumor suppressor gene. The prognosis is poor since the tumors are often bilateral, aggressive, and recurrent and the patients often harbor other congenital abnormalities. One further complication is that of therapy-related malignancies later in life. We report a case of allogeneic stem cell transplantation for therapy-related acute myeloid leukemia in an 8-year-old girl after multimodality treatment for refractory bilateral relapsing RB, with excellent outcome in both the ophthalmic and marrow disease.

Acute Disease↗
PubMed2004

Potential role for platelet apheresis for post-liver transplant thrombocytosis complicating portal vein thrombosis.

Except for patients with underlying myeloproliferative diseases (MPD), thrombocytosis is rarely encountered in cirrhotic patients after liver transplantation. Although the long-term control of primary thrombocytosis is important for the prevention of graft thrombosis in MPD patients, the threshold for intervention and best mode for the control of persistent reactive thrombocytosis after liver transplantation is unclear. We present two patients with extreme reactive thrombocytosis (over 1,000 x 10(9)/l) due to intra-abdominal sepsis after liver transplantation. Furthermore, both patients suffered from bleeding problems as well as ongoing venous thrombosis of the graft. Rapid control of the platelet count was achieved using platelet apheresis. The use of cell separation procedures may be a relatively rapid, reversible, and reasonably safe way to control platelet counts peri-operatively in liver transplant recipients.

Adult↗
PubMed2004

Transformation of diffuse large B-cell lymphoma into pre-B acute lymphoblastic leukemia: clinicopathologic features and clonal relationship.

A patient with fibrosing alveolitis developed a diffuse large B-cell (DLBC) lymphoma that expressed CD20 and CD30. After an initial response, the lymphoma relapsed and was salvaged with further chemotherapy. After another remission of 3 years, a pre-B-cell acute lymphoblastic leukemia (ALL), which expressed CD10, CD19, CD22, CD79a, CD34 and terminal deoxyribonucleotidyl transferase, developed and led to death. Molecular analysis of the immunoglobulin heavy-chain gene showed that the initial lymphoma and its relapse were clonally related. At leukemic relapse, 2 clones related to the initial and relapsed lymphoma clones were present. DLBC lymphomas arise from post-follicle center B cells, whereas ALL arises from pregerminal B cells. Therefore, a direct transformation of DLBC lymphoma to ALL appears unlikely. The overall features suggest instead separate lymphoma and leukemic evolution from a common mutated B-cell precursor rather than transformation of DLBC lymphoma to ALL.

Aged↗
PubMed2004

Pathogenesis of jumping translocations: a molecular cytogenetics study.

BACKGROUND/AIMS: Jumping translocations are rare cytogenetic aberrations in haematological malignancies, the pathogenesis of which remains to be fully characterised. We investigated the mechanism of formation of jumping translocations in a case of adult common acute lymphoblastic leukaemia (ALL) positive for the Ph translocation. METHODS: Interphase and metaphase fluorescence in situ hybridisation (FISH) was performed using several probe systems. Results were correlated with findings on conventional cytogenetics. Granulocytes, T-cells and leukaemic B-cells in peripheral blood were sorted by immunomagnetic method and the terminal restriction fragment (TRF) length of these cellular populations was determined by Southern blot analysis. RESULTS: Duplicated BCR-ABL fusion signals were found on a dic(14;22)der(22)t(9;22) chromosome. Clonal jumping translocations, existing as evolutionary changes, involved the donor chromosomal segment distal to 1q12 jumping onto the telomere ends of 11q, 15p, 19p and 20p. Telomere length was decreased in the neoplastic B-cell population and contributed to the formation of the dicentric chromosome that showed absence of telomere repeats at fusion ends. Subsequent pericentromeric heterochromatin decondensation of chromosome 1q occurred, and this donor segment was randomly fused to the shortened telomere ends of non-homologous chromosomes. CONCLUSIONS: Both telomere shortening and pericentromeric heterochromatin decondensation contribute to the formation of jumping translocations, which is most probably a multi-stage process.

Antigens, CD↗
PubMed2004

Chronic myeloid leukemia in an adolescent with Ollier's disease after intensive X-ray exposure.

We report a 19-year-old man with Ollier's disease with multiple orthopedic procedures performed for leg length discrepancy; who developed chronic myeloid leukemia presenting with intramuscular hematoma. His symptoms resolved with cytoreductive treatment by hydroxyurea. Cytogenetic and molecular investigations showed a complex Philadelphia translocation t(9;22;13) (q34;q11.2;q12), with predominance of ela2 BCR/ABL splicing and deletion of reciprocal der(9) ABL/BCR locus, all suggesting poor prognosis. The cumulative X-ray exposure from repeated operations from the age of 7 to 12 years was estimated to be around 16 mSv, approximately the dose of 720 chest X rays. Literature review showed two other cases of leukemia occurring in patients with multiple enchondromatosis. Although the development of CML in this young patient might be related partly to genetic defects, the repeated radiation exposure, especially at young age and directly on the marrow tissue in the long bones, might also be an important pathogenetic factor.

Adult↗
PubMed2003

Poor engraftment after allogeneic bone marrow transplantation: role of chimerism analysis in treatment and outcome.

We analyzed the clinical course and risk factors of 18 patients with poor engraftment after allogeneic bone marrow transplantation (BMT), defined as absolute neutrophil count below 0.1 x 10(9)/l 28 days post-BMT. Significant risks associated with non-engraftment included HLA one antigen mismatch, BMT from matched unrelated donor, and a low dose of colony-forming units-granulocyte-macrophage (<10(4)/kg). Examined by a semiquantitative analysis of polymorphic microsatellite markers, donor DNA chimerism on day 28 was found to be predictive of treatment outcome. Seven patients had detectable donor DNA, varying from 43 to 100%. Five of them responded to granulocyte colony-stimulating factor (G-CSF) and achieved engraftment. Two were given further infusions of peripheral blood hematopoietic stem cells (PBSC) from the same donors, resulting in engraftment in one of them. Eleven patients had no detectable donor DNA, and none responded to G-CSF. Autologous regeneration occurred in six of these patients, four after infusion of backup marrow and two spontaneously. The remaining five patients died despite the administration of PBSC from the same or different donors. Regular monitoring of donor DNA chimerism is useful in the management of patients at high risk of poor engraftment.

Adolescent↗
PubMed2003

Trisomy 21 and other chromosomal abnormalities in acute promyelocytic leukemia.

We describe a case of acute promyelocytic leukemia (APL) with t(15;17)(q22;q12) and trisomy 21 as an additional change in a patient who died at relapse after achieving complete remission (CR) for the duration of 20 months. A survey of 42 cases of APL with cytogenetic study performed at our institutionover the past 10 years showed 12 cases (28.6%) having chromosomal changes in addition to t(15;17). Trisomy 8 and trisomy 21 as additional changes were noted in 4 and 2 cases, respectively, with one patient showing both trisomies simultaneously. Two cases showed t(15;17) in hyperdiploid clones. Among the 10 patients with follow-up data, all eventually relapsed and none achieved continuous complete remission 1. Survival analysis performed in APL patients with adequate follow-up data showed no significant difference in overall and disease free survival between those with and without additional cytogenetic changes. After excluding cases with one induction death, the overall survival was significantly in favor of the group without additional cytogenetic abnormalities (P = 0.022). Late relapses may therefore be significantly more common in APL patients with additional cytogenetic abnormalities, and may not be reflected by analysis focused at three-year survival only. As APL is now considered a curable disease, any confirmed long-term survival impact of additional cytogenetic changes is expected to have important management implications.

Adolescent↗
PubMed2003

Treatment of postrenal transplantation lymphoproliferative disease manifesting as plasmacytoma with nonmyeloablative hematopoietic stem cell transplantation from the same kidney donor.

Posttransplantation lymphoproliferative disease (PTLD) presenting as an Epstein-Barr-virus (EBV)-related nasal plasmacytoma developed in a renal-allograft recipient 13 years after transplantation. Systemic dissemination occurred despite immunosuppression withdrawal, surgery, irradiation, and chemotherapy. A nonmyeloablative hematopoietic-stem-cell-transplantation (HSCT) with peripheral blood HSC from the kidney donor was performed. With the onset of graft-versus-host disease, resolution of the systemic disease was demonstrated clinically and molecularly by serial quantification of plasma EBV-DNA. Isolated relapse occurred in the central nervous system (CNS), a known tumour sanctuary site, ultimately leading to death. Nonmyeloablative HSCT might be considered a cellular therapy for PTLD, but possible CNS relapse must be effectively tackled.

Aged↗