Tsuyoshi Muta

Human herpesvirus-6 encephalitis in hematopoietic SCT recipients in Japan: a retrospective multicenter study.

Human herpesvirus-6 encephalitis in hematopoietic SCT recipients in Japan: a retrospective multicenter study

Semi-quantitative analysis of telomerase in pancreatic ductal adenocarcinoma

Using a polymerase chain reaction-based amplification assay, we measured telomerase activity in surgically resected pancreatic ductal carcinomas (n=16 cases) and normal ducts (n=6), comparing findings with the telomerase activity of a human pancreatic cancer cell line, MIA PaCa-2, as a standard, i.e., relative telomerase activity was determined. Telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of MIA PaCa-2 per μg protein of tissue samples. The median value for telomerase activity in normal pancreatic ducts was 0.13 and the 25th and 75th percentile were 0.01 and 0.76. The median value for telomerase activity in pancreatic ductal adenocarcinoma was 34.7 (25th percentile, 4.98; and 75th percentile, 296), significantly higher than that of normal ducts (P<0.001). When the cut-off value was set at 1.0 and 3.0, the telomerase positivity rate of pancreatic ductal adenocarcinomas was 100% and 81.3%, respectively. Telomerase may be a specific marker for pancreatic ductal carcinomas.

MITOCHONDRIAL DNA REPLICATION IN HUMAN T LYMPHOCYTES IS REGULATED PRIMARILY AT THE H-STRAND TERMINATION SITE

The most unique feature in the replication of mitochondrial DNA (mtDNA) is that most of the newly synthesized heavy strands (H-strands) terminate prematurely, resulting in the formation of displacement loop (D-loop) strands. Only the H-strand which proceeds past the termination site is a true nascent H-strand leading to the overall replication on a circular mtDNA molecule. The physiological significance of the D-loop formation has long been unclear. To examine the role of premature termination in mtDNA replication, we therefore developed a method for selectively measuring both the total amount of nascent H-strands and the amount of true nascent H-strands using ligation-mediated polymerase chain reaction, which, for the first time, enabled us to estimate the frequency of premature termination. The stimulation of cell proliferation with interleukin 2 and phytohemagglutinin in human peripheral T lymphocytes caused an increase in the net replication rate of mtDNA. In stimulated cells, in comparison to resting ones, the amount of true nascent H-strands increased approx. 2.6-fold while the total amount of nascent H-strands remained unchanged, indicating that premature termination decreased while the initiation of replication remained the same. Our findings thus demonstrate the first clear example that premature termination plays a primary role in the up-regulation of the net rate of mtDNA replication in human cells.

Apoptosis in perforated cornea of a patient with graft-versus-host disease

CASE REPORT Although ocular complications associated with graft-versus-host disease (GVHD) can include corneal dysfunction, corneal perforation is not common. We report the presence of apoptotic cells in a perforated cornea of a patient with GVHD. A 72-year-old man with the angioimmunoblastic type of malignant lymphoma developed chronic GVHD after allogeneic peripheral blood stem cell transplantation. Despite systemic and topical treatment, both corneas perforated, and penetrating keratoplasty with cataract extraction and intraocular lens implantation was performed on both eyes. COMMENTS The corneal button excised from the right eye was examined histologically and stained for apoptotic cells by TdT-mediated dUTP nick end labeling (TUNEL). This revealed thinning of the epithelial cell layer and stroma, with cells, including lymphocytes, infiltrating to the site of the perforation. Some of the epithelial cells and keratocytes were TUNEL positive. The presence of apoptotic cells in our case suggests that apoptosis may be involved in the perforation of the cornea in patients with GVHD.

Inhibitory effect of coenzyme Q1 on eukaryotic DNA polymerase γ and DNA topoisomerase II activities on the growth of a human cancer cell line

Coenzyme Q (CoQ) is an isoprenoid quinine that functions as an electron carrier in the mitochondrial respiratory chain in eukaryotes. CoQ having shorter isoprenoid chains, especially CoQ1 and CoQ2, selectively inhibited the in vitro activity of eukaryotic DNA polymerase (pol) γ, which is a mitochondrial pol. These compounds did not influence the activities of nuclear DNA replicative pols such as α, δ and ɛ, and nuclear DNA repair‐related pols such as β, η, ι, κ and λ. CoQ also inhibited DNA topoisomerase II (topo II) activity, although the enzymatic characteristics, including modes of action, amino acid sequences and three‐dimensional structures, were markedly different from those of pol γ. These compounds did not inhibit the activities of procaryotic pols such as Escherichia coli pol I, and other DNA metabolic enzymes such as human immunodeficiency virus reverse transcriptase, T7 RNA polymerase and bovine deoxyribonuclease I. CoQ1, which has the shortest isoprenoid chains, had the strongest inhibitory effect on pol γ and topo II activities among CoQ1–CoQ10, with 50% inhibitory concentration (IC50) values of 12.2 and 15.5 µM, respectively. CoQ1 could prevent the growth of human promyelocytic leukemia cells, HL‐60, and the 50% lethal dose (LD50) value was 14.0 µM. The cells were halted at S phase and G1 phase in the cell cycle, and suppressed mitochondrial proliferation. From these results, the relationship between the inhibition of pol γ/topo II and cancer cell growth by CoQ is discussed. (Cancer Sci 2006; 97: 716–723)

Fulminant Hemophagocytic Syndrome with a High Interferon γ Level Diagnosed as Macrophage Activation Syndrome

A 26-year-old woman presented with general fatigue, persistent fever, nuchal lymphadenitis, thrombocytopenia, and liver damage. From the bone marrow finding, we diagnosed her condition as hemophagocytic syndrome. Steroid pulse therapy, cyclosporin A treatment, and combined chemotherapy generated no response. The patient showed severe mucosal bleeding, rapidly experienced multiple organ failure, and finally died of a brain hemorrhage on the 13th hospital day. Epstein-Barr virus, cytomegalovirus, human herpes virus type 6, human parvovirus B19, and herpes simplex virus were not detected. Autopsied samples of the spleen, bone marrow, and liver showed extreme proliferation of activated macrophages, so-called histiocytes, without lymphoid malignancy. The interferon γ level at presentation was prominently high. The continuously elevated levels of ferritin and soluble interleukin 2 receptor were correlated with the catastrophic outcome. The disease in our case mimicked infantile hemophagocytic lymphohistiocytosis. However, there was neither a family history of the disease nor a mutation in the perforin gene. So, it is reasonable to categorize our case as macrophage activation syndrome. Although our patient lacked arthritis or eruption, we cannot deny the possibility that an oligoarthritis type of systemiconset juvenile rheumatoid arthritis or, considering the patient’s age, adult-onset Still disease lies at the base of our case.

Acute myelogenous leukemia concurrent with untreated chronic lymphocytic leukemia.

We report a case of acute myelogenous leukemia (AML) concurrent with untreated chronic lymphocytic leukemia (CLL). An 84-year-old Japanese man was admitted to the Chihaya Hospital with persistent high-grade fever. Morphologic observation of peripheral blood and bone marrow smears revealed a proliferation of blasts and lymphocytosis with small and mature phenotypes. Immunophenotyping of the blast cells revealed CD13+, CD33+, CD34+, and HLA-DR+, and that of the lymphocytes revealed CD5+, CD19+, CD20+, and λ+ on the cell surface. The peripheral lymphocytes revealed an IgH gene rearrangement. Chromosome analysis of 20 metaphase cells from bone marrow showed numerous abnormalities, containing +8,+11,+21. The patient’s disease was diagnosed as AML with trilineage dysplasia concurrent with CLL. The simultaneous occurrence of AML and CLL is extremely rare but should not be overlooked as a possible underlying cause of lymphocyte abnormalities in AML patients.

Comparative analysis of pulmonary hypertension in patients treated with imatinib, nilotinib and dasatinib

Pulmonary hypertension (PH) is a rare, but life‐threatening, adverse event in patients treated with tyrosine kinase inhibitors (TKIs), such as dasatinib, but has not been fully evaluated in patients treated with imatinib or nilotinib. We used echocardiography to noninvasively assess the incidence of PH in 105 patients with chronic myeloid leukaemia (CML) treated with imatinib (n = 37), nilotinib (n = 30) or dasatinib (n = 38). The mean triscupid regurgitation peak gradient (TRPG), which reflects pulmonary arterial pressure, was 22·7 mmHg in the imatinib group, 23·1 mmHg in the nilotinib group and 23·4 mmHg for dasatinib group. These values were not significantly different, but higher than those (19·0 mmHg) in newly diagnosed CML patients. A TRPG > 31 mmHg, marking possible PH onset, was detected in 9 of 105 patients: one (2·7%) treated with imatinib, three (10·0%) with nilotinib and five (13·2%) with dasatinib. Only three patients complained of dyspnoea, whereas the other six were asymptomatic. In addition, there was a tendency toward correlation of TRPG value and age or TKI treatment duration. These results suggested that treatment with not only dasatinib, but also imatinib and nilotinib, can be associated with subclinical PH. Noninvasive echocardiography is useful for screening, especially in older patients with long‐term TKI treatment.

Efficacy and safety of aprepitant in allogeneic hematopoietic stem cell transplantation.

To evaluate the efficacy and safety of aprepitant added to standard antiemetic regimens used in high‐dose chemotherapy for allogeneic hematopoietic stem cell transplantation (allo‐HSCT).

Successful therapy with argatroban for superior mesenteric vein thrombosis in a patient with congenital antithrombin deficiency

Abstract:  A 38‐year‐old woman was admitted with superior mesenteric vein (SMV) thrombosis, which was refractory to anticoagulation therapy. The plasma antithrombin activity was decreased and hardly compensated by concentrated antithrombin preparation due to high consumption rate. However, successful anticoagulation was achieved by administration of direct thrombin inhibitor, argatroban. Family studies of antithrombin activity revealed that she had type I congenital antithrombin deficiency. A novel heterozygous mutation in the gene for antithrombin (single nucleotide T insertion at 7916 and 7917, Glu 272 to stop in exon 4) was identified. Argatroban administration would be effective in the treatment of congenital antithrombin deficiency with SMV thrombosis.