Regulation of hematopoietic stem cells using protein transduction domain-fused Polycomb

The Polycomb-group complex is a chromatin regulatory factor that is classified into two different complexes: Polycomb repressive complex 1 and 2. Components of Polycomb repressive complex 1 are involved in the self-renewal of hematopoietic stem cells. Bmi1, one of these components, maintains the immaturity of neural and cancer stem cells as well as that of hematopoietic stem cells. We constructed recombinant protein transduction domain (PTD)-Polycomb proteins and transduced them into murine bone marrow (BM) cells. We designed and fused the PTD-protein transduction domain to three proteins (i.e., green fluorescent protein, Bmi1, and Mel18). Murine BM cells were incubated for 48 h and each PTD-Polycomb protein was added. Then, we analyzed the function of hematopoiesis using the colony assay and transplantation. BM cells exposed to PTD-Bmi1 showed an increased number of colonies. In contrast, BM cells exposed to PTD-Mel18 or to both proteins showed a decreased number of colonies. Hematopoietic cells derived from PTD-Bmi1-transduced BM cells were significantly increased in the peripheral blood at 6 weeks after transplantation. Moreover, 80% of mice transplanted with PTD-Bmi1-transduced BM cells died at 8 to 24 weeks after transplantation. However, only a few early deaths were observed in the mice transplanted with BM cells exposed to both PTD-Bmi1 and PTD-Mel18. We expect that hematopoietic stem cells could proliferate after transduction with PTD-Bmi1, but this may generate undesirable effects, e.g., tumorigenesis. Thus, Bmi1 and Mel18 have opposing functions and are present in distinct complexes.     

The efficacy and safety of piperacillin-tazobactam for febrile neutropenic patients in Japan

The IDSA guideline for management of febrile neutropenic patients updated in 2010 recommends monotherapy with anti-pseudomonal-lactam agents, including piperacillin-tazobactam (PIPC/TAZ) for high-risk patients. However, clinical studies of PIPC/TAZ are limited in Japanese patients. In this study, we conducted an open-labeled non-randomized prospective trial to examine the efficacy and safety of PIPC/TAZ as an empirical treatment for Japanese patients with febrile neutropenia. Forty-nine febrile episodes in neutropenic patients excluding those undergoing allogeneic stem cell transplantation (high risk 36, low risk 13) were analyzed. The overall response rate was 71%, and no significant differences between the high-risk and the low-risk group were observed (high risk 72%, low risk 69%). Neither PS nor usage of G-CSF affected the response rate. No major side effects were observed in the study. The efficacy and the safety profile of PIPC/TAZ treatment were comparable to those in other previous Western studies. In conclusion, this study suggests PIPC/TAZ is effective and well tolerated as an initial empirical treatment for febrile neutropenic Japanese patients.     

Clinicopathological features of serrated lesions of the colorectum

We reviewed 428 subjects with colorectal serrated lesions resected endoscopically or surgically at our institution. Colorectal serrated lesions were pathologically divided into 3 groups: hyperplastic polyp (HP), sessile serrated adenoma/polyp (SSA/P), and traditional serrated adenoma (TSA). SSA/P was detected frequently in the right colon and SSA/P was mainly flat-elevated. Cancers occurring in SSA/P were found more frequently than HP or TSA. The incidence of cancer in SSA/P was equivalent to that of cancer in traditional adenoma. Further studies are warranted to clarify clinicopathological features of serrated lesions of the colorectum.     

Successful treatment with low-dose etoposide for hemophagocytic syndrome following reduced-intensity conditioning for cord blood transplantation in a patient with acute myelgenous leukemia

A 56-year-old man was diagnosed with acute myeloid leukemia with myelodysplasia-related changes. Chromosomal analysis showed a complex karyotype. Complete remission could not be achieved even after several induction chemotherapy regimens, and the patient suffered from invasive pulmonary aspergillosis. He was transferred to our hospital and underwent reduced-intensity conditioning cord blood transplantation (RIC-CBT) in a non-remission state. The conditioning regimen involved fludarabine 125 mg/m2 combined with melphalan 140 mg/m2 and total body irradiation (4 Gy). GVHD prophylaxis was tacrolimus alone at relatively low concentrations (app. 5 ng/ml). On days 6 and 9 after CBT, he experienced a pre-engraftment immune reaction and hemophagocytic syndrome (HPS). We started steroid pulse therapy, but this failed to resolve the symptoms. We then administered low-dose etoposide (50 mg/m2). The symptoms gradually resolved after three administrations of etoposide and engraftment was achieved on day 35. Satisfactory hematological recovery was noted on day 300 after CBT and the patient has maintained complete remission to date. HPS is one of the most serious complications following CBT and often results in engraftment failure. This case suggests that repeated administration of etoposide may safely and effectively overcome this serious complication in some cases.     

Suppression of Complex Visual Hallucinatory Experiences by Occipital Transcranial Magnetic Stimulation: A Case Report

We report a patient with visual hallucinations and illusions along with an associated visual field defect after bilateral ischemic damage to his occipital visual cortex. These hallucinations were long-standing and of both simple and complex (well-formed) type. Application of low frequency (1 Hz) repetitive Transcranial Magnetic Stimulation (rTMS) to the occipital cortex led to a complete cessation of visual hallucinatory symptoms. The use of TMS to probe the neurophysiology, and possibly alleviate, visual hallucinatory experiences is discussed.