N-methyl-D-aspartate receptors play important roles in acquisition and expression of the eyeblink conditioned response in glutamate receptor subunit delta2 mutant mice.

Classical eyeblink conditioning has been known to depend critically on the cerebellum. Apparently consistent with this, glutamate receptor subunit delta2 null mutant mice, which have serious morphological and functional deficiencies in the cerebellar cortex, are severely impaired in delay paradigm. However, these mutant mice successfully learn in trace paradigm, even in '0-trace paradigm,' in which the unconditioned stimulus starts just after the conditioned stimulus terminates. Our previous studies revealed that the hippocampus and the muscarinic acetylcholine receptors play crucial roles in 0-trace paradigm in glutamate receptor subunit delta2 null mutant mice unlike in wild-type mice, suggesting a large contribution of the forebrain to 0-trace conditioning in this type of mutant mice. In the present study, we investigated the role of N-methyl-D-aspartate receptors in 0-trace eyeblink conditioning in glutamate receptor subunit delta2 null mutant mice. Mice were injected intraperitoneally with the noncompetitive N-methyl-d-aspartate receptor antagonist (+)MK-801 (0.1mg/kg) or saline, and conditioned with 350-ms tone conditioned stimulus followed by 100-ms periorbital shock unconditioned stimulus. Glutamate receptor subunit delta2 null mutant mice that received (+)MK-801 injection exhibited a severe impairment in acquisition of the conditioned response, compared with the saline-injected glutamate receptor subunit delta2 null mutant mice. In contrast, wild-type mice were not impaired in acquisition of 0-trace conditioned response by (+)MK-801 injection. After the injection solution was changed from (+)MK-801 to saline, glutamate receptor subunit delta2 null mutant mice showed a rapid and partial recovery of performance of the conditioned response. On the other hand, when the injection solution was changed from saline to (+)MK-801, glutamate receptor subunit delta2 null mutant mice showed a marked impairment in expression of the pre-acquired conditioned response, whereas impairment of the expression was small in wild-type mice. Injection of (+)MK-801 had no significant effects on spontaneous eyeblink frequency or startle eyeblink frequency to the tone conditioned stimulus in either glutamate receptor subunit delta2 null mutant mice or wild-type mice. These results suggest that N-methyl-D-aspartate receptors play critical roles both in acquisition and expression of the conditioned response in 0-trace eyeblink conditioning in glutamate receptor subunit delta2 null mutant mice.

Hippocampal Damage Disrupts Eyeblink Conditioning in Mice Lacking Glutamate Receptor Subunit δ2.

Cerebellar long-term depression (LTD) at the parallel fiber-Purkinje cell synapses has been proposed to be a neural substrate for classical eyeblink conditioning. Mutant mice lacking the glutamate receptor subunit δ2 (GluRδ2), in which the cerebellar LTD is disrupted, exhibited a severe impairment in the delay eyeblink conditioning with a temporal overlap of CS and US. However, they learned normally trace and delay conditioning without CS-US overlap, suggesting a learning mechanism which does not require the cerebellar LTD.In the present study, we tested possible involvement of the hippocampus in this cerebellar LTD-independent learning. We examined effects of scopolamine and hippocampal lesion on the delay conditioning without CS-US overlap. TheGluRδ2 mutant mice that received scopolamine or aspiration of the dorsalhippocampus together with its overlying cortex exhibited a severe impairment in learning, while the control mutant mice that received saline or aspiration of the overlying cortex learned normally. In contrast, wild-type mice that received either treatment learned as normally as the control wild-type mice. These results suggest that the hippocampus is essential in the cerebellar LTD-independent learning in the GluRδ2 mutant mice, indicating a newrole of hippocampus in the paradigm with a short trace interval.

Effects of the noncompetitive NMDA receptor antagonist MK-801 on classical eyeblink conditioning in mice.

N-methyl-D-aspartate (NMDA) receptors are involved in synaptic plasticity and play a critical role in learning and memory. We investigated the effects of the noncompetitive NMDA receptor antagonist (+)MK-801 on classical eyeblink conditioning of mice, using various interstimulus intervals between the conditioned stimulus (CS) and unconditioned stimulus (US). A tone was used for the CS and a periorbital shock was used for the US. In the delay paradigm, in which the US coterminated with the CS or started immediately after CS offset, the effect of (+)MK-801 (0.1mg/kg, i.p.) was a slight impairment in the acquisition of the conditioned response (CR). During subsequent CS-alone trials, the responses of (+)MK-801-injected mice were extinguished as easily as those of saline-injected mice. In the trace paradigm, (+)MK-801 impaired acquisition of the CR with a trace interval of 250 ms more than it did with a trace interval of 100 ms, and more than in the delay paradigm. (+)MK-801 injected after acquisition of 250-ms trace conditioning did not impair expression or extinction of the CR. These results suggest that NMDA receptors are involved in acquisition of the CR during longer trace interval conditioning more than during shorter trace interval conditioning or delay conditioning, and that their contribution to extinction is much smaller than their contribution to acquisition in mouse eyeblink conditioning.

A new G-CSF-supported combination chemotherapy, LSG15, for adult T-cell leukaemia-lymphoma: Japan Clinical Oncology Group Study 9303.

This phase II trial was performed to evaluate the efficacy of a new granulocyte colony-stimulating factor (G-CSF)-supported multi-agent chemotherapy protocol, LSG15, for aggressive adult T-cell leukaemia-lymphoma (ATL). Ninety-six previously untreated patients with aggressive ATL were enrolled and grouped as: acute type (58), lymphoma type (28) and unfavourable chronic type (10). Therapy consisted of seven cycles of VCAP (vincristine, cyclophosphamide, doxorubicin and prednisone), AMP (doxorubicin, ranimustine and prednisone) and VECP (vindesine, etoposide, carboplatin and prednisone). G-CSF was administered during the intervals between chemotherapy until neutrophil reconstitution was achieved. Eighty-one per cent of the 93 eligible patients responded [95% confidence interval (CI), 71.1-88.1%], with 33 patients obtaining complete response (35.5%) and 42 obtaining partial response (45.2%). The median survival time (MST) after registration was 13 months and the median follow-up duration of the 20 surviving patients was 4.2 years (range 2.8-5.6). Overall survival at 2 years was estimated to be 31.3% (95% CI, 22.0-40.5%). Grade 4 haematological toxicity of neutropenia and thrombocytopenia were observed in 65.3% and 52.6% of the patients respectively, but grade 4 non-haematological toxicity was observed in only one patient. LSG15 is feasible with mild non-haematological toxicity and improved the clinical outcome of ATL patients. MST and overall survival at 2 years were superior to those obtained by our previous trials.

[Ovalbumin sensitization affects nonadrenergic noncholinergic relaxation response on guinea-pig tracheal smooth muscle].

We investigated the effects of anaphylactic challenge on nonadrenergic noncholinergic (NANC) relaxation response to electrical field stimulation (EFS) or to aminophylline in sensitized guinea pig tracheal smooth muscles. An anaphylactic challenge with ovalbumin (OA) reduced the relaxation response to EFS (20 V. 5 Hz. 300 pulse. duration 1 msec.), but the relaxation response to aminophylline was not affected by OA exposure. NG-monomethyl L-arginine, a nitric oxide (NO) synthesis inhibitor, reduced the relaxation response to EFS in the OA sensitized guinea pig. While the relaxation response to EFS on the sensitized guinea pig tracheal smooth muscle was significantly attenuated compared with that on the non-sensitized guinea-pig, there was no significant difference between the tracheal strip of OA challenge group and that of control group in sensitized guinea-pig under the existence of NO synthesis inhibitor. These results suggest that the attenuation of NANC relaxation response associated with sensitization plays an important role in airway hyperreactivity and is responsible for the decrease in NO amount.

A novel natural killer cell line (KHYG-1) from a patient with aggressive natural killer cell leukemia carrying a p53 point mutation.

We present the establishment of a natural killer (NK) leukemia cell line, designated KHYG-1, from the blood of a patient with aggressive NK leukemia, which both possessed the same p53 point mutation. The immunophenotype of the primary leukemia cells was CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16+, CD56+, CD57+ and HLA-DR+. A new cell line (KHYG-1) was established by culturing peripheral leukemia cells with 100 units of recombinant interleukin (IL)-2. The KHYG-1 cells showed LGL morphology with a large nucleus, coarse chromatin, conspicuous nucleoli, and abundant basophilic cytoplasm with many azurophilic granules. The immunophenotype of KHYG-1 cells was CD1-, CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16-, CD25-, CD33+, CD34-, CD56+, CD57-, CD122+, CD132+, and TdT-. Southern blot analysis of these cells revealed a normal germline configuration for the beta, delta, and gamma chains of the T cell receptor and the immunoglobulin heavy-chain genes. Moreover, the KHYG-1 cells displayed NK cell activity and IL-2-dependent proliferation in vitro, suggesting that they are of NK cell origin. Epstein-Barr virus (EBV) DNA was not detected in KHYG-1 cells by Southern blot analysis with a terminal repeat probe from an EBV genome. A point mutation in exon 7 of the p53 gene was detected in the KHYG-1 cells by PCR/SSCP analysis, and direct sequencing revealed the conversion of C to T at nucleotide 877 in codon 248. The primary leukemia cells also carried the same point mutation. Although the precise role of the p53 point mutation in leukemogenesis remains to be clarified, the establishment of an NK leukemia cell line with a p53 point mutation could be valuable in the study of leukemogenesis.

[Intravascular large B-cell lymphoma associated with hypoalbuminemia and hypoxemia].

A 67-year-old man was referred to our hospital for treatment of hemophagocytic syndrome. Hypotension, hypoxemia, pleural effusion, severe anasarca, and splenomegaly were noticed at the time of admission. Laboratory findings showed anemia (7.7 g/dl), thrombocytopenia (4.5 x 10(4)/microliter), an increase of serum LDH (1,466 IU/L) and severe hypoalbuminemia (1.9 g/dl). Bone marrow aspiration revealed an increase of reticulum cells with active hemophagocytosis and the presence of immature lymphocytes (6.0%). Lymphoma was suspected, but effective chemotherapy could not be performed because of progressive hypoxemia and severe hypoalbuminemia, and the patient died of the disease 2 weeks after admission. Autopsy revealed large lymphoid cells packed within systemic vessels as well as invasion into organs such as the liver, lungs, and spleen. The postmortem diagnosis was intravascular large B-cell lymphoma. Hypoalbuminemia and hypoxemia appear to be important clinical features of intravascular large B-cell lymphoma.

Long-term remission in an elderly patient with mantle cell leukemia treated with low-dose cyclophosphamide.

We present an elderly patient with mantle cell leukemia who was successfully treated with low-dose cyclophosphamide (CY). A 76-year-old female was diagnosed as mantle cell leukemia based on abnormal lymphocytosis and splenomegaly without lymphadenopathy. She was orally treated with 50 mg of CY daily and had continuous remission over 4 years. Rearrangements of BCL1 and immunoglobulin heavy chain genes in the peripheral blood lymphocytes were detected at diagnosis, but not 1 or 4 years later. Further studies are required to confirm the role of low-dose CY therapy for patients with mantle cell leukemia and lymphoma.

Detection of inducible nitric oxide synthase (iNOS) mRNA by RT-PCR in ATL patients and HTLV-I infected cell lines: clinical features and apoptosis by NOS inhibitor.

Various tumors have been reported to express an inducible form of nitric oxide synthase (iNOS), and nitric oxide (NO) may affect the clinicopathological features of these tumors. Previously, Burkitt's lymphoma and Epstein-Barr virus (EBV)-infected cells were shown to express iNOS constitutively at a low level. We analyzed iNOS expression by the reverse transcriptase-polymerase reaction method (RT-PCR) in eight HTLV-I-infected cell lines (five were ATL-derived lines and there were in vitro transformed lines), nine ATL patients (three were chronic, two were acute, and four were lymphoma type), and an HTLV-I-negative T cell line (CEM). In four ATL derived and in all three in vitro transformed cell lines, iNOS was expressed constitutively, but it was not expressed in CEM cells. Four out of nine ATL patients also showed iNOS expression. The expression of iNOS was found in all subtypes of ATL. Three of four iNOS-positive patients had infiltration of ATL cells to organs such as skin, lung, or liver. In NOS inhibitor (NG-monomethyl-L-arginine: L-NMMA)-containing medium, an iNOS-positive ATL cell line (K3T) showed growth inhibition and DNA ladder. Although only a limited number of patients was analyzed, our results suggest that NO may be involved in the invasive character of ATL cells. The NOS inhibitor can induce apoptosis in an ATL cell line, as it does in EBV-infected cell lines.

Rapid quantification of HTLV-I provirus load: detection of monoclonal proliferation of HTLV-I-infected cells among blood donors.

In this report, we quantified HTLV-I provirus load using the AmpliSensor system, which utilizes fluorescence to measure PCR products. With this method, provirus loads could be measured within 6 hr, and the results obtained correlated well with those obtained by other methods. Samples from 256 blood donors, who were positive for antibodies against HTLV-I, were analyzed, showing that provirus load ranged from less than 0.1% to 56% among carriers. We analyzed the association between provirus load and the biomarkers age and sex and found that it was not influenced by either. Provirus load was better correlated with soluble interleukin-2 receptor (sIL-2R) levels than with antibody titer against the virus. Among 18 blood donors with high provirus load (more than 10%), Southern blotting detected monoclonal integration of HTLV-I in infected cells in 2 cases, both of them showing high sIL-2R levels (more than 900 U/ml). Sequential analyses of provirus load showed stable levels of provirus in the same carriers, suggesting that some factors other than age or sex determined provirus load in infected individuals. Thus, this rapid method is a useful tool for the early detection of adult T-cell leukemia and other HTLV-I-associated diseases.

[Phase I clinical study of SH L573 (fludarabine phosphate) in patients with chronic lymphocytic leukemia and adult T-cell leukemia/lymphoma].

We have conducted a phase I clinical study of fludarabine phosphate, a new purine nucleoside derivative, in patients with chronic lymphocytic leukemia and adult T-cell leukemia/lymphoma. The patients were given intravenous administration at a dose of 15 mg/m2/day followed by 20 mg/m2/day and 25 mg/m2/day, each dose given consecutively for 5 days. The dose limiting factors were thrombocytopenia and neutropenia. The thrombocyte count and neutrocyte count dropped to their lowest value in week 1 to 2 after administration, but the changes were reversible, and these counts recovered in most patients. The maximum tolerated dose of the study drug was 25 mg/m2/day, and it was decided to administer 20 mg/m2/day as the recommended dose for the subsequent phase II clinical study.

Characterization of T-cell receptor beta chain mRNA expression in IFN-alpha-responsive chronic myelogenous leukaemia patients.

Interferon-alpha (IFN-alpha) has shown promise in the treatment of chronic phase of chronic myelogenous leukaemia (CML). IFN-alpha has also been found to indirectly up-regulate the expression of major histocompatibility (MHC) antigens, and to directly increase the activity of lymphocytes against tumour cells. To elucidate whether IFN-alpha induces anti-leukaemic activity of the autologous T cells in CML patients, we analysed the accumulation of T-cell receptor (TCR) in each Vbeta family using the reverse transcriptase-polymerase chain reaction (RT-PCR) followed by single-strand conformation (SSCP) analysis. We found the predominant expression of the Vbeta 10, 12, and 14 families in the peripheral blood (PB) of CML patients, in contrast to healthy donors. Especially, in IFN-alpha-responsive patients, we observed an enhancement of the accumulation of the Vbeta 9 and 20 families, suggesting that T cells enhanced by IFN-alpha may react with a discrete set of antigens on the surface of malignant cells. These findings may demonstrate that CML cells possess the heterogenous antigens and the clonal expansion of Vbeta 9+ and Vbeta 20+ T cells may be a prognostic indicator of the immune responsiveness to IFN-alpha.

Presentation of tumor antigens by phagocytic dendritic cell clusters generated from human CD34+ hematopoietic progenitor cells: induction of autologous cytotoxic T lymphocytes against leukemic cells in acute myelogenous leukemia patients.

The use of antigen-presenting dendritic cells (DCs) is currently proposed for tumor immunotherapy through generation of CTLs to tumor antigens in cancer patients. In this study, DCs were differentiated using granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha from CD34+ hematopoietic progenitor cells that had been mobilized into the peripheral blood. To use the phagocytic activity of DCs for processing and presentation of tumor antigens, we established DC clusters containing immature DCs by preserving proliferating cell clusters without mechanical disruption. After an 11-day culture, the developed clusters contained not only typical mature DCs but also immature DCs that showed active phagocytosis of latex particles, suggesting that the clusters consisted of DCs of different maturational stages. These heterogeneous clusters could present an exogenous protein antigen, keyhold limpet hemocyanin, to both CD4+ and CD8+ T lymphocytes. Furthermore, in three acute myelogeneous leukemia patients, clusters pulsed with autologous irradiated leukemic cells could also induce antileukemic CTLs. The mechanical disruption of clusters abrogated the induction of CTLs to leukemic cells as well as to hemocyanin. This observation gives an important information for the use of heterogeneous DC clusters derived from autologous peripheral blood CD34+ cells in the case of immunotherapy for leukemia.

Biallelic and heterozygous point mutations in the runt domain of the AML1/PEBP2alphaB gene associated with myeloblastic leukemias.

The AML1 gene encoding the DNA-binding alpha-subunit in the Runt domain family of heterodimeric transcription factors has been noted for its frequent involvement in chromosomal translocations associated with leukemia. Using reverse transcriptase-polymerase chain reaction (RT-PCR) combined with nonisotopic RNase cleavage assay (NIRCA), we found point mutations of the AML1 gene in 8 of 160 leukemia patients: silent mutations, heterozygous missense mutations, and biallelic nonsense or frameshift mutations in 2, 4, and 2 cases, respectively. The mutations were all clustered within the Runt domain. Missense mutations identified in 3 patients showed neither DNA binding nor transactivation, although being active in heterodimerization. These defective missense mutants may be relevant to the predisposition or progression of leukemia. On the other hand, the biallelic nonsense mutants encoding truncated AML1 proteins lost almost all functions examined and may play a role in leukemogenesis leading to acute myeloblastic leukemia.

Induction of antitumor cytotoxic activity using CD34+ cord blood cell-derived and irradiated tumor cell-primed dendritic cells.

Dendritic cells (DCs) are the most powerful antigen-presenting cells in the immune system. They can activate immunologically naive T cells and improve the efficacy of immunotherapy against tumors. In the present study we investigated whether CD34+ cord blood cell-derived DCs are capable of inducing antitumor cytotoxic cells, such as cytotoxic T lymphocytes (CTLs), NK cells, and monocytes. Cord blood T cells stimulated by DCs pulsed with irradiated K562 major histocompatibility complex (MHC) class I+ cells were highly effective in eliciting a selective killing response against K562 class I+ cells. This killing activity was almost completely abrogated by antibodies to CD8 or MHC class I, but not to CD4. This suggests that tumor cell-pulsed DCs generated from CD34+ cord blood cells are able to induce tumor specific CTLs against corresponding tumor cells from cord blood T cells, and that these CTLs are CD8+ T cells which may recognize tumor cells via MHC class I molecules. This observation has potentially important implications for the use of DCs in clinical immunotherapy in cord blood transplantation.

Acute myelomonoblastic leukemia carrying the PEBP2beta/MYH11 fusion gene.

As recurrent chromosome abnormalities in leukemia are highly associated with particular subtypes, the genetic events of specific chromosome alteration must be associated with leukemogenesis and characteristics of the disease. The chromosomal breakpoints involved in inv(16) and t(16;16) have been shown to generate the fusion gene PEBP2beta(CBFbeta)/MYH11. The PEBP2beta/MYH11 fusion transcripts in all 8 patients with M4Eo, 2 of 18 with M4, and one CML in the blastic phase were detected by using RT-PCR and Southern blotting. We demonstrated the marked expression of CD34 and c-KIT (CD117) antigens in myelomonoblastic leukemia cells from all patients carrying this fusion gene, which was in contrast to the patients with M4 but without the fusion gene. These results indicate that immunophenotypic analysis is useful for detection of leukemia with the fusion gene, and that the PEBP2beta/MYH11 fusion gene is involved in immature cells expressing CD34 and c-KIT antigens.

Mutation of CD95 (Fas/Apo-1) gene in adult T-cell leukemia cells.

CD95 antigen (also known as Fas or Apo-1) and Fas ligand play key roles in apoptosis of cells of the immune system, function as effector molecules of cytotoxic T lymphocytes, and function in the elimination of activated lymphocytes during the downregulation of the immune response. The critical roles of the Fas-Fas ligand system in apoptosis suggest that its inactivation may be involved in malignant transformation. We analyzed the expression of Fas antigen on adult T-cell leukemia (ATL) cells by flow cytometry and found that Fas antigen expression was absent in a case of ATL and markedly decreased in another case among 47 cases examined. Apoptosis could not be induced in the Fas-negative ATL cells by antibody against Fas antigen. Sequencing of reverse transcription-polymerase chain reaction products of the Fas genes in the Fas negative cells showed two types of aberrant transcripts: one had a 5-bp deletion and a 1-bp insertion in exon 2, and the other transcript lacked exon 4. These mutations caused the premature termination of both alleles, resulting in the loss of expression of surface Fas antigen. These aberrant transcripts were not detected in a nonleukemic B-cell line from the same patient. An RNase protection assay of the Fas gene showed mutations in 2 additional cases with Fas-positive ATL cells of 35 cases examined: 1 case lacked exon 4 and the other was a silent mutation. In the Fas antigen-negative case, leukemic cells were resistant to anticancer drugs in vivo, indicating that the loss of expression of Fas antigen may be associated with a poor response to anticancer drugs. Indeed, Fas-negative ATL cells were resistant to adriamycin-induced apoptosis in vitro, which is consistent with the finding that ATL in this case was resistant to chemotherapy. These findings indicate that mutation of the Fas gene may be associated with the progression of ATL and with resistance to anticancer drugs.

[Psychiatric studies of chemotherapy and chemotherapy-induced nausea and vomiting of patients with lung or thymic cancer].

Psychiatric studies were made on 26 inoperable patients with lung cancer or thymic cancer to exam the possible correlation of chemotherapy and chemotherapy-induced nausea and vomiting. All patients were informed of their disease and how to undergo the therapy. Psychiatric tests of CMI (Cornell Medical, Index), MAS (Manifest Anxiety Scale), SDS (Self-Rating Depression Scale) and QOL questionnaire were performed just before the chemotherapy. SDS and QOL questionnaire were also done after chemotherapy. The patients were given chemotherapy including CDDP (80 mg/m2) and anti-emetic agents of 30 mg of azasetron, 750 mg of methylprednisolone and 1,800 mg of domperidone. The patients showing neurosis, anxiety or depression had significantly high nausea scores, so we concluded that psychiatric support was needed to improve these patients' QOL in chemotherapy.

Characterization of mRNA expression of IkappaB alpha and NF-kappaB subfamilies in primary adult T-cell leukemia cells.

Tax protein of HTLV-1 activates the transcriptional capacity of the NF-kappaB family, resulting in up-regulation of various genes, which are linked to phenotypic alterations of HTLV-1-infected T cells. To understand NF-kappaB regulation in HTLV-1-infected leukemic cells in vivo, we analyzed expression of NF-kappaB and IkappaB alpha in primary cells isolated from ATL patients. Using competitive polymerase chain reaction, we observed an elevated expression of IkappaB alpha mRNA in all four ATL cases tested. In contrast to the elevated mRNA levels, the levels of IkappaB alpha protein were remarkably reduced in some of these cases, suggesting destabilization of IkappaB alpha protein. On the other hand, mRNA expression of p50/p105 and p65, subfamilies of NF-kappaB, was enhanced in primary cells isolated from some ATL patients. Furthermore, the expression patterns of NF-kappaB subfamily were variable among patients and also different from those in T cells isolated from uninfected individuals. Although the number of cases analyzed was limited, we can conclude from these observations that activation of NF-kappaB is restricted to a few subfamilies in vivo. These findings in vivo are strikingly different from those in HTLV-1-infected T cell lines in vitro, in which Tax is responsible for NF-kappaB activation. It is therefore suggested that the elevation of NF-kappaB expression in leukemic cells of ATL patients might not be supported mainly by the viral protein Tax.

Multiple myeloma associated with serum amino acid disturbance and high output cardiac failure.

We experienced a plasma cell leukemia (PCL) patient complicated with high output cardiac failure (HOCF), proved as his elevated cardiac index and pulmonary artery wedge pressure and decreased systemic vascular resistance index in a hemodynamic study. We found no possible causes of HOCF. Interestingly, HOCF was improved as PCL responded to intensive chemotherapy. On the other hand, he showed consciousness disturbance, and had frequent attacks of generalized seizure. His electroencephalogram showed slow waves, and a spike and wave complex. Hyperammonemia and abnormal amino acid distribution were also found. This abnormal serum amino acid distribution, especially elevated glycine level, was different from that seen in chronic liver failure, and he had no hepatic disease. After intensive chemotherapy, the serum ammonia level and glycine level decreased. In this patient, PCL seemed to be responsible for HOCF, hyperammonemia, and abnormal amino acid distribution. We experienced two more cases of multiple myeloma (MM) with HOCF, hyperammonemia, abnormal serum amino acid distribution, and consciousness disturbance of unknown origin. Those two cases showed slow waves in the electroencephalogram. Improvement was seen in their HOCF, hyperammonemia, and abnormal amino acid levels after chemotherapy. The possibility of MM as a cause of HOCF is discussed.