Improvement of learning and increase in dopamine level in the frontal cortex by methylphenidate in mice lacking dopamine transporter.

The symptoms of attention-deficit/hyperactivity disorder (ADHD) are characterized by inattention and hyperactivity-impulsivity. It is a common childhood neurodevelopmental disorder that often persists into adulthood. Improvements in ADHD symptoms using psychostimulants have been recognized as a paradoxical calming effect. The psychostimulant methylphenidate (MPH) is currently used as the first-line medication for the management of ADHD. Recent studies have drawn attention to altered dopamine-mediated neurotransmission in ADHD, particularly reuptake by the dopamine transporter (DAT). This hypothesis is supported by the observation that DAT knockout mice exhibit marked hyperactivity that is responsive to acute MPH treatment. However, other behaviors relevant to ADHD have not been fully clarified. In the present study, we observed learning impairment in shuttle-box avoidance behavior together with hyperactivity in a novel environment in DAT knockout mice. Methylphenidate normalized these behaviors and enhanced escape activity in the tail suspension test. Interestingly, the effective dose of MPH increased extracellular dopamine in the prefrontal cortex but not striatum, suggesting an important role for changes in prefrontal dopamine in ADHD. Research that uses rodent models such as DAT knockout mice may be useful for elucidating the pathophysiology of ADHD.

Polyphenols from Eriobotrya japonica and their cytotoxicity against human oral tumor cell lines.

Three new flavonoid glycosides, together with 15 known flavonoids, have been isolated from the leaves of Eriobotrya japonica, and characterized as (2S)- and (2R)-naringenin 8-C-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosides, and cinchonain Id 7-O-beta-D-glucopyranoside, respectively, based on spectral analyses including two dimensional (2D) NMR techniques. Higher proanthocyanidin fraction in the water-soluble portion of the extract was characterized as a procyanidin oligomer mixture mainly composed of undecameric procyanidin. These polyphenols have also been assessed for cytotoxic activity against two human oral tumor (human squamous cell carcinoma and human salivary gland tumor) cell lines. Selective cytotoxicity of the procyanidin oligomer between tumor and normal gingival fibroblast cells, and its possible mechanism, were also described.

Successful second autologous blood stem cell transplantation after G-CSF-combined conditioning for the treatment of high-risk acute myelogenous leukemia.

We describe a patient with acute myelogenous leukemia (AML) who received his second autologous blood stem cell transplantation (ABSCT) following a G-CSF-combined pre-transplant conditioning regimen. The patient underwent ABSCT during first remission but suffered a relapse 8 months later. After achieving second remission, he was prepared for his second ABSCT; recombinant human granulocyte colony-stimulating factor (rhG-CSF) was administered in combination with Ara C, in addition to the same conditioning regimen as that used before the first ABSCT. There was no increase in regimen-related toxicity after this second G-CSF-combined conditioning regimen when compared with that observed after the first ABSCT. To date, the patient's second remission following the second ABSCT has lasted 26 months, which has exceeded that following the first ABSCT. The G-CSF-combined pretransplant conditioning regimen for ABSCT may be effective in the treatment of high-risk AML by increasing the chemosensitivity of the residual leukemic cells.

Identification of an alternative form of the Drosophila Ca2+/calmodulin-dependent protein kinase II that is maternally derived.

Four forms of the Drosophila Ca2+/calmodulin-dependent protein kinase II are generated from a single gene by alternative splicing (Ohsako et al. (1993) J. Biol. Chem. 268, 2052-2062). We identified a fifth form of the cDNA encoding the enzyme expressed in the ovary, unfertilized egg and early embryos by reverse transcription-polymerase chain reaction, which suggests that it is maternally derived. The fifth form was also generated from the gene by alternative splicing and was identical to the cDNA encoding the 530-amino-acid polypeptide, the longest of the four forms previously identified, except that it lacked exon 11. Three splicing derivatives which lost one amino acid from the 509- and 530-amino-acid polypeptides were also found in 4 to 10 h embryos.

Evaluation of leukaemic contamination in peripheral blood stem cell harvests by reverse transcriptase polymerase chain reaction.

A major issue in autologous blood stem cell transplantation (ABSCT) for leukaemia is whether peripheral blood stem cell (PBSC) harvests are less contaminated with leukaemic cells than bone marrow mononuclear cells (BMMNC). We compared leukaemic contamination in PBSC harvests and BMMNC, obtained simultaneously, by using reverse transcriptase polymerase chain reaction (RT-PCR) of leukaemia-specific chimaeric messenger RNA (mRNA), in three patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukaemia (ALL), one with Ph-positive acute myelogenous leukaemia (AML), and two with acute promyelocytic leukaemia (APL). Our two-step PCR method employed 'nested primers' in the second step and can detect one leukaemic blast diluted into 10(6) HL-60 cells. In three of four patients with Ph-positive ALL and AML we detected leukaemic contamination in both PBSC harvests and BMMNC. In the remaining patient with ALL, both PBSC harvests and BMMNC were PCR-negative. Both PBSC harvests and BMMNC from one patient with APL were PCR-positive. In contrast, PBSC harvests from another patient with APL, whose BMMNC could not be obtained because of bone marrow necrosis, were PCR-positive after the first course of consolidation chemotherapy, but became PCR-negative after the second course. The present study does not support the hypothesis that PBSC harvests are less contaminated by leukaemic cells than BMMNC, but suggests that PBSC harvests are contaminated when BMMNC are contaminated.