Heat-induced growth inhibition and apoptosis in transplanted human head and neck squamous cell carcinomas with different status of p53

To examine p53-dependency in hyperthermic cancer therapy, heat-induced growth inhibition and apoptosis in transplanted human head and neck squamous cell carcinoma (HNSCC) tumours were analysed with different status of p53 into nude mice. The tumour tissue from HNSCC cell line (SAS) transfected with mutant p53 gene (SAS/mp53) or control vector containing neo gene (SAS/neo) was transplanted into the subcutaneous tissue of the thigh of nude mice using a trocar. Hyperthermia was performed at 42 degrees C when the mean diameter of tumour was 5-6mm. The diameter of tumours was measured using vernier calipers and tumour weight (TW) and the relative tumour weight (RW) was calculated. Tumour regrowth delay was evaluated when the RW reached 5-fold against the control group. The accumulation of p53 and Bax proteins was examined by an immunohistochemical technique. Apoptotic cells in the sections were detected by staining of DNA ends using an immunohistochemical technique. SAS/mp53 tumours showed more heat-resistance than SAS/neo tumours. The p53-positively staining cells were observed in untreated SAS/mp53 tumours, but not in untreated SAS/neo tumours. After heat treatment, the accumulation of p53 and Bax proteins was observed in SAS/neo tumours, but little in SAS/mp53 tumours. The incidence of apoptotic cells induced by heat treatment was very low in SAS/mp53 tumours compared with SAS/neo tumours. In conclusion, the heat-induced growth inhibition of a transplanted HNSCC may be correlated with the induction of p53-dependent Bax-mediated apoptosis. Thus, p53 status appears to be one of the useful parameters for the predictive assays in hyperthermic cancer therapy.

Present characteristics of symptomatic Entamoeba histolytica infection in the big cities of Japan

Medical records, for 2000 and 2001, of symptomatic amoebic patients who were treated at our hospitals in Tokyo, Yokohama and Osaka were studied retrospectively for the purpose of gathering epidemiological data on symptomatic Entamoeba histolytica infection. A total of 58 patients were treated. Fifty-five of them were male, and 96% of the male patients were Japanese. The mean age of patients was 44.9 years old, and 91% of patients contracted the disease in Japan. Fifty-six per cent of the male patients indicated that they were practising homosexuals, and 44% of the male patients denied these practices or left the question unanswered. The serum Treponema pallidum haemagglutination test was positive in 45% of the patients, and antibody to human immunodeficiency virus (HIV) was positive in 45%. Our study revealed that recent symptomatic E. histolytica infection almost exclusively afflicted middle-aged males in the big cities of Japan, that a majority of the patients were probably exposed to the causative organism during homosexual activity, and that an increasing number of patients will be co-infected with HIV.

Purification and characterization of the flagellar basal body of Rhodobacter sphaeroides

Flagellar hook-basal body (HBB) complexes were purified from Rhodobacter sphaeroides. The HBB was more acid labile but more heat stable than that of Salmonella species, and protein identification revealed that HBB components were expressed only from one of the two sets of flagellar gene clusters on the R. sphaeroides genome, under the heterotrophic growth conditions tested here.

Treatment of acute promyelocytic leukemia: strategy toward further increase of cure rate

Acute promyelocytic leukemia (APL) has become a curable disease by all-trans retinoic acid (ATRA)-based induction therapy followed by two or three courses of consolidation chemotherapy. Currently around 90% of newly diagnosed patients with APL achieve complete remission (CR) and over 70% of patients are curable. To further increase the CR and cure rates, detection and diagnosis of this disease at its early stage is very important, hopefully before the appearance of APL-associated coagulopathy. In induction therapy, concomitant chemotherapy is indispensable, except for patients with low initial leukocyte counts. Prophylactic use of intrathecal methotrexate and cytarabine should be done, particularly for patients with hyperleukocytosis. If patients relapse hematologically or even molecularly, arsenic trioxide will be the treatment of choice under careful electrocardiogram monitoring. Am80, liposomal ATRA, gemtuzumab ozogamicin or ATRA in combination with cytotoxic drugs may be used at this stage or later. Allogeneic SCT will be the treatment of choice after patients of age <50 years have relapsed, provided that they have HLA-identical family donors or DNA-identical unrelated donors.

p53-dependent hyperthermic enhancement of tumour growth inhibition by X-ray or carbon-ion beam irradiation

To elucidate p53-dependency on combined treatment with radiation and hyperthermia, growth inhibition and apoptosis were analysed using transplantable human tumour. Human head and neck squamous cell carcinoma (HNSCC) cells carrying different p53 genes were transplanted into the thigh of nude mice. When the mean diameter of tumour reached 5-6 mm, the tumours were exposed to X-rays (2 Gy) or Carbon-ion (C-) beams (1 Gy) followed by heating at 42 degrees C for 20 min. Tumour growth inhibition was evaluated by measuring the diameters of tumour. The induction of apoptosis and accumulation of apoptosis-related proteins were also analysed by immunohistochemical staining. Synergistic enhancement of tumour growth inhibition by hyperthermia was observed in wild-type p53 tumours treated with X-rays or C-beams but not in mutant p53 tumours. The incidence of apoptotic cells and activated-caspase-3-positive cells after combined treatment with them were significantly high in wild-type p53 tumours compared with that in mutant p53 tumours. The hyperthermic enhancement of tumour growth inhibition by X-ray- or C-beam-irradiation was p53-dependent, suggesting that it might be highly correlated with p53-dependent apoptosis.

Possible dominant-negative mutation of the SHIP gene in acute myeloid leukemia

The SH2 domain-containing inositol 5'-phosphatase (SHIP) is crucial in hematopoietic development. To evaluate the possible tumor suppressor role of the SHIP gene in myeloid leukemogenesis, we examined primary leukemia cells from 30 acute myeloid leukemia (AML) patients, together with eight myeloid leukemia cell lines. A somatic mutation at codon 684, replacing Val with Glu, was detected in one patient, lying within the signature motif 2, which is the phosphatase active site. The results of an in vitro inositol 5'-phosphatase assay revealed that the mutation reduced catalytic activity of SHIP. Leukemia cells with the mutation showed enhanced Akt phosphorylation following IL-3 stimulation. K562 cells transfected with the mutated SHIP-V684E cDNA showed a growth advantage even at lower serum concentrations and resistance to apoptosis induced by serum deprivation and exposure to etoposide. These results suggest a possible role of the mutated SHIP gene in the development of acute leukemia and chemotherapy resistance through the deregulation of the phosphatidylinositol-3,4,5-triphosphate (PI(3,4,5)P3)/Akt signaling pathway. This is the first report of a mutation in the SHIP gene in any given human cancer, and indicates the need for more attention to be paid to this gene with respect to cancer pathogenesis.

Radiation-induced apoptosis in scid mice spleen after low dose irradiation

To assess the radioadaptive response of the whole body system in mice, we examined the temporal effect of low dose priming as an indicator of challenging irradiation-induced apoptosis through a p53 tumor suppressor protein- mediated signal transduction pathway. The p53 protein also plays an important role both in cell cycle control and DNA repair through cellular signal transduction. Using severe combined immunodeficiency mice defective in DNA-dependent protein kinase catalytic subunit, we examined the role of DNA-dependent protein kinase activity in radioadaptation induced by low dose irradiation. Specific pathogen free 5-week-old female severe combined immunodeficiency mice and the parental mice (CB- 17 Icr +/+) were irradiated with X-ray at 3.0 Gy at 1, 2, 3 or 4 weeks after the conditioning irradiation at 0.15, 0.30, 0.45 or 0.60 Gy. The mice spleens were fixed for immunohistochemistry 12 h after the challenging irradiation. The p53-dependent apoptosis related Bax proteins on formalin-fixed paraffin-embedded sections were stained by the avidin-biotin peroxidase complex method. The apoptosis incidence in the sections was measured by hematoxylin-eosin staining. The frequency of Bax- and apoptosis-positive cells increased up to 12 h after the challenging irradiation in the spleen of both mice. However, these cells were not observed after a low dose irradiation at 0.15-0.60 Gy. When pre-irradiation at 0.45 Gy 2 weeks before the challenging irradiation at 3.0 Gy was performed, Bax accumulation and apoptosis induced by challenging irradiation were depressed in the spleens of CB-17 Icr +/+ mice, but not in severe combined immunodeficiency mice. These data suggest that DNA-dependent protein kinase might play a major role in radioadaptation induced by pre-irradiation with a low dose in mice spleen. We expect that the present findings will provide useful information in the health care of space crews.

Prognosis and prognostic factors for patients with chronic myeloid leukemia: nontransplant therapy

Reliable knowledge about an individual's prognosis is needed to select the appropriate treatment for patients with chronic myeloid leukemia (CML). The New CML score using age, spleen size, blast cell count, eosinophil count, basophil count, and platelet count shows good discrimination for survival (96, 65, or 42 months, P </=.0001) and has been thoroughly validated. Careful analyses indicate that the New CML score is considerably more precise in identifying high-risk patients than the Sokal score. Achievement of complete hematologic response (CHR) up to 9 months shows a distinct impact on survival, which, however, depends on the baseline prognosis. Ten-year survival probabilities for low- and intermediate-risk patients with a CHR were 0.51 (95% confidence interval [CI], 0.42 to 0.60) and 0.23 (95% CI, 0.15 to 0.31) and without a CHR were 0.26 (95% CI, 0.16 to 0.37) and 0.12 (95% CI, 0.04 to 0.20). In high-risk patients CHR had no impact on prognosis. Therapeutic options were widened by the approval of imatinib for the treatment of CML. However, it will still take 2 or more years to know whether the high rates of CHR and cytogenetic complete remission (CCR) achieved with imatinib translate into a clinically relevant survival advantage for all patients.

Circulating D-dimer and thrombomodulin levels in acute febrile phase of measles

OBJECTIVES

Circulating D-dimer and thrombomodulin (TM) levels are now routinely measured in clinical laboratories. Plasma levels of D-dimer are used as a marker of fibrin formation and degradation, and serum TM is used to assess the state of endothelial cell injuries. While the levels of circulating D-dimer and TM have been investigated in many diseases, to our knowledge they have not been studied in patients with measles. We measured circulating levels of D-dimer in patients with measles to discuss whether fibrin formation and degradation occur and TM whether endothelial injury occur.

METHODS

The plasma levels of D-dimer and serum levels of alanine aminotransferase (ALT) and creatinine were measured of 14 adolescent and adult Japanese patients with measles, and the serum or plasma levels of TM of 10 of these 14 patients were measured in the acute febrile phase and convalescent afebrile phase with commercially available kits.

RESULTS

Plasma D-dimer levels were significantly higher in the acute febrile phase than in the convalescent afebrile phase in patients with measles, and no significant difference was shown in serum and plasma TM levels between the two phases. Plasma D-dimer levels were not correlated with serum or plasma TM levels in either phase. No significant differences were identified in the serum ALT and creatinine levels between the acute febrile and convalescent afebrile phases, and the levels of plasma D-dimer were not significantly correlated with the serum ALT levels.

CONCLUSIONS

Our results indicate that while clot formation and fibrinolysis may tend to occur in patients with the acute febrile phase of measles, there may be little risk that such patients will suffer endothelial injury.

Radiation-induced apoptosis in the scid mouse spleen after low dose-rate irradiation

PURPOSE

To elucidate the process of radioadaptation, the role of DNA-PK activity was examined using the scid mouse defective in DNA-PKcs.

MATERIALS AND METHODS

The induction of apoptosis in the spleens of the C.B-17 Icr scid mouse and the parental mouse was studied after chronic irradiation with gamma-rays at 1.5 Gy (0.001 Gy min(-1) for 25 h) followed by challenge irradiation with X-rays at 3.0 Gy (1.0 Gy min(-1) for 3 min).

RESULTS

When the wild-type mouse was previously exposed to chronic irradiation (1.5 Gy) at a low dose-rate (0.001 Gy min(-1)), apoptosis induced by acute irradiation (3.0 Gy, 1.0 Gy min(-1)) was significantly suppressed, especially in the splenic white pulp. There was no change by acute irradiation after chronic irradiation in the scid mouse, although an effect was detected in the spleen after acute irradiation alone.

CONCLUSIONS

These data suggest that DNA-PK activity might play a major role in the radioadaptive response following pre-irradiation at a low dose-rate.

Transfection of mutant p53 gene depresses X-ray- or CDDP-induced apoptosis in a human squamous cell carcinoma of the head and neck

The present study examined whether X-ray- and CDDP-sensitivities depend on p53 gene status in human squamous cell carcinoma of the head and neck (SAS cells) showing dominant negative nature of mutant p53 protein. SAS cells were transfected with a vector carrying a mutant p53 gene (SAS/Trp248 cells) or neomycin resistant gene control vector (SAS/neo cells). Sensitivities of the transfected cells to X-ray or CDDP were measured with colony formation assay. The incidence of apoptosis by X-ray or CDDP was analyzed with Hoechst staining or DNA ladder formation assay. The activation of caspase-3 was estimated as an indicator of apoptosis by the detection of fragmentation of caspase-3 or poly (ADP ribose) polymerase (PARP) with Western blot. SAS/Trp248 cells showed X-ray- and CDDP-resistance due to the dominant negative nature of mutant p53, compared with SAS/neo cells. The incidence of DNA ladders and apoptotic bodies increased markedly in SAS/neo cells after X-ray irradiation or CDDP treatment, but increased only slightly in SAS/Trp248 cells. Fragmentation of caspase-3 and PARP was observed in SAS/neo cells, but almost no such fragmentation was observed in SAS/Trp248 cells after X-ray irradiation or CDDP treatment. The present results strongly suggest that the X-ray- and CDDP-sensitivities of human squamous cell carcinomas are p53-dependent, and that the sensitivities are tightly correlated with the induction of apoptosis through caspase-3 activation. The p53-dependent X-ray- or CDDP-sensitivity was supported by results from p53-null human lung cancer H1299 cells which were transfected with wild-type or mutant p53 gene.

Tumor suppressor p53 response is blunted by low-dose radiation

To estimate the effects of space radiation on health of space crews, we aimed to clarify whether g-ray-irradiation at a low-dose-rate interferes in a p53 centered signal transduction pathway induced by radiation in human cultured cells and CB-17 Icr+/+ mice. In vitro experiments, the human cultured squamous cell carcinoma cells (SAS/neo) were examined for cellular levels of p53 and Bax, and the incidence of apoptosis after irradiation at a low-dose-rate (1 mGy/min) or a high-dose-rate (1 Gy/min). It was found that challenging irradiation-induced apoptosis was depressed by chronic irradiation at 1.5 Gy for 25 h with the depression of p53 and Bax accumulation. In vivo experiments, a significant suppression of Bax and apoptosis induced by challenging irradiation at 3.0 Gy was observed when the mice were pre-irradiated chronically at 1.5 Gy for 25 h in the spleen of CB-17 Icr+/+ mice. These findings suggest that chronic pre-irradiation suppressed p53 function through radiation-induced signaling and/or p53 stability.

Factors affecting toxicity, response and progression-free survival in relapsed patients with indolent B-cell lymphoma and mantle cell lymphoma treated with rituximab: a Japanese phase II study

BACKGROUND

The aim of the study was to determine factors affecting the toxicity and efficacy of rituximab monotherapy in relapsed patients with indolent B-cell lymphoma and mantle cell lymphoma (MCL).

PATIENTS AND METHODS

A total of 90 patients were enrolled and treated with rituximab infusions at 375 mg/m2 once weekly for 4 weeks. Central pathology review revealed that histologically, 81 patients had indolent B-cell lymphoma or MCL: 59 with follicular lymphoma, 17 with MCL, four with marginal zone lymphoma and one with lymphoplasmacytoid lymphoma. Of these, four were ineligible due to violation of other eligibility criteria. Pre-treatment variables affecting toxicities were analyzed for all 90 patients, and those affecting response and progression-free survival (PFS) were analyzed for 77 eligible patients with confirmed indolent B-cell lymphoma or MCL. The relationship between serum rituximab levels and efficacy was also analyzed for 66 eligible patients.

RESULTS

Hematological toxicities (grade > or =3) occurred more frequently in females (P <0.05), and thrombocytopenia and leukopenia were more frequent in patients with high lactate dehydrogenase (LDH) levels (P <0.05). Non-hematological toxicities (grade > or =2) were more frequent in patients with extranodal disease or bone marrow involvement. The overall response rate (ORR) in patients receiving one prior chemotherapy regimen was higher than those receiving two or more regimens (P <0.05). The median PFS was shorter in MCL patients, in those with extranodal disease, or in those receiving two or more prior chemotherapy regimens (P <0.01). The PFS intervals of patients with higher serum rituximab levels (> or =70 microg/ml) immediately before the third infusion were longer than in other patients (P <0.01).

CONCLUSIONS

Several prognostic factors and serum rituximab levels are useful for predicting the toxicity and efficacy of rituximab monotherapy.

[Subdiaphragmatic bronchogenic cyst in the left crus of diaphragm: report of a case]

A 39-year-old man who had a subdiaphragmatic bronchogenic cyst in the left crus of diaphragm received surgical treatment. The cyst was located in the retroperitoneum just below the diaphragm and was adhered to the left crus of diaphragm and unconnected with any other structures. The surgically resected cyst was 50 x 25 x 22 mm diameter and the wall was thin and contained white turbid mucus. Histologically, the cyst consisted of ciliated epithelium, mucus glands, smooth muscle, cartilage and this evidence established the final diagnosis of bronchogenic cyst. The post operative course was uneventful and the patient was discharged 10 days after operation. This is the 4th reported case of a subdiaphragmatic bronchogenic cyst in the Japanese literature.

Reduced effect of gemtuzumab ozogamicin (CMA-676) on P-glycoprotein and/or CD34-positive leukemia cells and its restoration by multidrug resistance modifiers

Gemtuzumab ozogamicin (CMA-676), a calicheamicin-conjugated humanized anti-CD33 mouse monoclonal antibody, has recently been introduced clinically as a promising drug for the treatment of patients with acute myeloid leukemia (AML), more than 90% of which express CD33 antigen. However, our recent study suggested that CMA-676 was excreted by a multi- drug-resistance (MDR) mechanism in P-glycoprotein (P-gp)-expressing leukemia cell lines. We analyzed the in vitro effects of CMA-676 on leukemia cells from 27 AML patients in relation to the amount of P-gp, MDR-associated protein 1 (MRP1), CD33 and CD34, using a multi-laser-equipped flow cytometer. The cytocidal effect of CMA-676, estimated by the amount of hypodiploid portion on cell cycle, was inversely related to the amount of P-gp estimated by MRK16 monoclonal antibody (P = 0.004), and to the P-gp function assessed by intracellular rhodamine-123 accumulation in the presence of PSC833 or MS209 as a MDR modifier (P = 0.0004 and P = 0.002, respectively). In addition, these MDR modifiers reversed CMA-676 resistance in P-gp-expressing CD33(+) leukemia cells (P = 0.001 with PSC833 and P = 0.0007 with MS209). In CD33(+) AML cells from 13 patients, CMA-676 was less effective on CD33(+)CD34(+) than CD33(+)CD34(-) cells (P = 0.002). PSC833 partially restored the effect of CMA-676 in CD33(+)CD34(+) cells. These results suggest that the combined use of CMA-676 and a MDR modifier will be more effective on CD33(+) AML with P-gp-related MDR.

Arsenic trioxide therapy for relapsed or refractory Japanese patients with acute promyelocytic leukemia: need for careful electrocardiogram monitoring

Recent studies have shown that arsenic trioxide (As(2)O(3)) can induce complete remission in patients with acute promyelocytic leukemia (APL). We tested the efficacy and safety of As(2)O(3) for the treatment of patients with APL who had relapsed from or become refractory to all-trans retinoic acid (ATRA) and conventional chemotherapy in a prospective study. As(2)O(3) at a dose of 0.15 mg/kg was administered until the date of bone marrow remission to a maximum of 60 days. In patients who achieved complete remission (CR), one additional course of As(2)O(3) was administered using the same dose for 25 days. Of 14 patients, 11 (78%) achieved CR. Six of 10 patients who achieved CR showed disappearance of PML-RARalpha transcript by RT-PCR assay. The duration of As(2)O(3)-induced CR ranged from 4 to 22 months (median, 8 months) at a median follow-up of 17 months. Adverse events included 13 electrocardiogram abnormalities (13 QTc prolongation, eight ventricular premature contraction, four nonsustained ventricular tachycardia and two paroxysmal supraventricular tachycardia), seven nausea and vomiting, four pruritus, three peripheral neuropathy, three fluid retention and one APL differentiation syndrome. Four patients received antiarrhythmic agents. Hyperleukocytosis developed in five patients and in three cytotoxic drugs were necessary. Other adverse events were relatively mild. As(2)O(3) treatment is effective and relatively safe in relapsed or refectory patients with APL. Cardiac toxicities in patients with QTc prolongation should be carefully monitored.

Regeneration of canine peroneal nerve with the use of a polyglycolic acid-collagen tube filled with laminin-soaked collagen sponge: a comparative study of collagen sponge and collagen fibers as filling materials for nerve conduits

A novel artificial nerve conduit was developed and its efficiency was evaluated on the basis of promotion of peripheral nerve regeneration across an 80-mm gap in dogs. The nerve conduit was made of a polyglycolic acid-collagen tube filled with laminin-soaked collagen sponge. Conduits filled with either sponge- or fiber-form collagen were implanted into an 80-mm gap of the peroneal nerve (five dogs for each form). Twelve months postoperatively nerve regeneration was superior in the sponge group both morphometrically (percentage of neural tissue: fiber: 39.7 +/- 5.2, sponge: 43.0 +/- 4.5, n=3) and electrophysiologically (fiber: CMAP 1.06 +/- 0.077, SEP 1.32 +/- 0.127 sponge: CMAP 1.04 +/- 0.106, SEP 1.24 +/- 0.197, n=5), although these differences were not statistically significant. The observed regeneration was complementary to successful results reported previously in the same model, in which collagen fibers exclusively were used. The results indicate a possible superiority of collagen sponge over collagen fibers as filling materials. In addition, the mass-producibility, superior scaffolding potential, and capacity for gradual release of soluble factors of the sponge provide make it an attractive alternative to fine fibers, which are both technologically difficult and costly to produce. This newly developed nerve conduit has the potential to enhance peripheral nerve regeneration across longer gaps commonly encountered in clinical settings.

Role of P-glycoprotein in all-trans retinoic acid (ATRA) resistance in acute promyelocytic leukaemia cells: analysis of intracellular concentration of ATRA

We analysed the relationship between all-trans retinoic acid (ATRA) resistance and P-glycoprotein (P-gp)-associated multidrug resistance (MDR) in acute promyelocytic leukaemia (APL). There was no difference in the intracellular ATRA accumulation between NB4 cells and an MDR1 cDNA-transduced NB4 subline and between ATRA-resistant NB4 cells (NB4/RA) and an MDR1 cDNA-transduced NB4/RA subline. PSC833, a MDR modifier, did not increase the intracellular accumulation of ATRA or affect the expression of CD11b, the nitroblue tetrazolium (NBT) reduction activity, the proportion of apoptotic cells or the morphology of these four ATRA-treated cell lines. Similar results were obtained in the analysis of APL cells from five patients relapsed after ATRA-induced complete remission.

Influence of the angiotensin II receptor antagonist losartan on diuretic-induced metabolic effects in elderly hypertensive patients: comparison with a calcium channel blocker

OBJECTIVE

Diuretic therapy frequently induces undesirable biochemical changes and side effects. We compared metabolic effects of a low-dose diuretic (D) given in combination with an angiotensin II receptor antagonist, losartan (L), with those resulting from a diuretic given in combination with a calcium channel blocker, slow-release nifedipine (N).

MATERIAL AND METHODS

Thirty-seven elderly patients with mild to moderate hypertension (mean age: 71 +/- 3 years) were treated with either L+D (n = 18) or N+D (n = 19) for 1 year. Diuretic therapy included low-dose trichlormethiazide or low-dose furosemide in numbers of patients that were similar between L+D and N+D groups. Blood pressure, serum electrolytes, uric acid, blood glucose, renal function and lipid parameters were measured at baseline, 6 months and 1 year.

RESULTS

Effective blood pressure control was observed in both groups at 6 months, and with further improvement at 1 year. Serum potassium was significantly decreased from baseline at 6 months (p < 0.01) and 1 year (p < 0.01) in the N+D group, but not in the L+D group. Serum uric acid was significantly increased from baseline at 6 months (p < 0.01) and 1 year (p < 0.01) in the N+D group, but had minimally decreased at 1 year in the L+D group (p < 0.1). Blood glucose, renal function and lipid parameters did not change in either group.

CONCLUSION

The combination of losartan and low-dose diuretics effectively treated hypertension in elderly patients while minimizing the metabolic consequences of diuretic therapy. Larger trials will be necessary to confirm this finding.

Biological effects of space radiation

To determine the effects of space radiation on human health for long-term stays in space, we performed 21 space experiments on radiation biology. Two main characteristics of space are microgravity and space radiation that consists of low dose, chronic exposure at low dose-rates, and heavy particles. Through space experiments, we demonstrated the formation of DNA strand breaks, induced mutations, abnormal cell differentiation and the inducible gene expression of a tumor suppressor gene product, p53, in various kinds of organisms. In addition, we investigated the influence of microgravity on radiation-induced biological effects in in vitro biochemical reaction systems and in vivo cell culture systems of bacteria and lower eukaryotes. We review here the importance of radiation biology studies on space radiation from the viewpoints of human health and biological evolution, from the beginning of life until today, in the context of environmental genotoxic radiation.

p53-dependent thermal enhancement of cellular sensitivity in human squamous cell carcinomas in relation to LET

PURPOSE

To investigate the dependence on p53 gene status of the thermal enhancement of cellular sensitivity against different levels of linear energy transfer (LET) from X-rays or carbon-ion (C-) beams.

MATERIALS AND METHODS

Two kinds of human squamous cell carcinoma cell lines were used with an identical genotype except for the p53 gene. SAS/mp53 cells were established by transfection with mutated p53 (mp53) gene to SAS cells having functional wild-type p53 (wtp53). As the control, a neo vector was transfected to the SAS cells (SAS/neo cells). Both cells were exposed to X-rays or accelerated C-beams (30-150 KeV microm(-1)) followed by heating at 44 degrees C. Cellular sensitivity was determined by colony-forming activity. Induction of apoptosis was analysed by Hoechst 33342 staining of apoptotic bodies and agarose-gel electrophoresis for the formation of DNA ladders.

RESULTS

It was found that (1) there was no significant difference in cellular sensitivity between SAS/neo and SAS/mp53 cells to LET radiation of >30 KeV microm(-1), although the radiosensitivity of SAS/neo cells to X-rays was higher (1.2-fold) than that of SAS/mp53 cells; (2) there was an interactive thermal enhancement of radiosensitivity below an LET of 70 KeV microm(-1) in SAS/neo cells, although only additive thermal enhancement was observed in SAS/mp53 cells through all LET levels examined; (3) low-LET radiation induced apoptosis only in SAS/neo cells; (4) high-LET radiation at an isosurvival dose-induced apoptosis of SAS/neo cells at a higher frequency compared with that with low-LET radiation; (5) high-LET radiation-induced p53-independent apoptosis in SAS/mp53 cells; and (6) thermal enhancement of cellular sensitivity to X-rays was due to induction of p53-dependent apoptosis.

CONCLUSIONS

The findings suggest that thermal enhancement of radiosensitivity may result from p53-dependent apoptosis induced by inhibition of p53-dependent cell survival system(s) through either regulation of the cell cycle or induction of DNA repair. It is also suggested that the analysis of p53 gene status of cancer cells may predict response to combined therapies with low-LET radiation and hyperthermia.

Long-lasting memory of sounds combined with reward in rats

We investigated the effects of sound stimuli combined with reward on the subsequent sound discrimination. Water-deprived rats were exposed to one of two sounds (S+ or S-) in a trial, and licking a spout only during the presentation of S+ was rewarded with water. The percentage of trials in which licking occurred was calculated separately for S+ and S-, and sound discrimination was estimated from the difference in the percentage. S+ and S- were significantly discriminated during an 8 h period. In the second test after 1-2 weeks, sound discrimination for the same S+ and S- was significantly better than that for the S+ of the previous S- and S- of the previous S+. These findings indicate that the memory of the sounds combined with reward in the first test was maintained for 1-2 weeks.

Role of Rab3 GDP/GTP exchange protein in synaptic vesicle trafficking at the mouse neuromuscular junction

The Rab3 small G protein family consists of four members, Rab3A, -3B, -3C, and -3D. Of these members, Rab3A regulates Ca(2+)-dependent neurotransmitter release. These small G proteins are activated by Rab3 GDP/GTP exchange protein (Rab3 GEP). To determine the function of Rab3 GEP during neurotransmitter release, we have knocked out Rab3 GEP in mice. Rab3 GEP-/- mice developed normally but died immediately after birth. Embryos at E18.5 showed no evoked action potentials of the diaphragm and gastrocnemius muscles in response to electrical stimulation of the phrenic and sciatic nerves, respectively. In contrast, axonal conduction of the spinal cord and the phrenic nerve was not impaired. Total numbers of synaptic vesicles, especially those docked at the presynaptic plasma membrane, were reduced at the neuromuscular junction approximately 10-fold compared with controls, whereas postsynaptic structures and functions appeared normal. Thus, Rab3 GEP is essential for neurotransmitter release and probably for formation and trafficking of the synaptic vesicles.

Salmonella excretion after cessation of tosufloxacin therapy in acute nontyphoid salmonella enterocolitis

Symptomatic nontyphoid salmonella enterocolitis patients were treated with tosufloxacin (TFLX) at oral doses of 150 mg three times a day for 5 to 7 days, but bacterial relapse without symptoms occurred in 85% of the patients within 15 days after the cessation of therapy. Our study indicates that TFLX may not be an ideal drug against symptomatic salmonella enterocolitis from a bacteriological point of view.

Radiation response of apoptosis in C57BL/6N mouse spleen after whole-body irradiation

PURPOSE

Primary conditioning low dose irradiation suppresses the molecular responses against secondary challenge high dose irradiation; this phenomenon has been termed the radioadaptive response. The mechanism of the radioadaptive response is not yet clear. This study was undertaken to elucidate the radiation response of apoptosis in mouse spleen after whole-body irradiation.

MATERIALS AND METHODS

The induction of apoptosis was analysed in the spleens of C57BL/6N mice after chronic irradiation with gamma-rays at 1.5 Gy (0.001 Gy/min for 25 h) followed by challenge irradiation with X-rays at 3.0Gy (1 Gy/min).

RESULTS

Accumulation of p53 and Bax, and the induction of apoptosis were observed dose-dependently in mouse spleen 12 h after acute irradiation at a high dose-rate. However, it was found that there was significant suppression of the accumulation of p53 and Bax, and induction of apoptosis 12 h after challenge irradiation at 3.0Gy at a high dose-rate following chronic preirradiation at 1.5Gy at a low dose-rate. In addition, the combination of pre-irradiation at 1.5Gy at a high dose-rate and challenge irradiation at 3.0Gy at a high dose-rate could not suppress the accumulation of p53 and Bax or the induction of apoptosis.

CONCLUSIONS

Chronic pre-irradiation at a low dose-rate suppressed Bax-mediated apoptosis. These findings suggest that the radioadaptive response in mouse spleen may be due to a suppression of p53-mediated apoptosis.

[Chronic myelogenous leukemia]

STI571, a BCA-ABL tyrosine kinase inhibitor, has appeared in molecular targeted therapy as a new treatment option for patients with chronic myelogenous leukemia (CML) through rational drug development. In a phase I study in the USA, adverse effects were minimal. Complete hematologic response was observed in 98% of patients with chronic phase CML treated with a daily dose of 300 mg or more, and cytogenetic response was seen in 31% of patients. STI571 has substantial activity in the blast crisis of CML and Ph + ALL. Stem cell transplantation (SCT) may be compared with interferon-alpha (IFN-alpha) therapy from three analyses reported according to risk assessment. These studies indicated that SCT increased survival only in patients who were younger and at intermediate or high risk; however, survival with SCT in older patients at higher risk was no better than with IFN-alpha therapy in a Japanese prospective study. An individualized risk assessment-based approach is useful in prioritizing SCT and IFN-alpha in patients with chronic phase CML.

Interstitial pneumonia accompanying ulcerative colitis

We report a patient with ulcerative colitis complicated with idiopatic interstitial pneumonia, in whom the etiology of interstitial pneumonia was unknown, but immunological disturbance might have been involved. There are many complications with ulcerative colitis, but interstitial pneumonia is quite rare and its prognosis is quite poor. Antibiotic and steroid treatment were given under respiration supported therapy, but no response could be obtained. In the treatment of patients with ulcerative colitis, we must be mindful of interstitial pneumonia because the prognosis is quite poor.

Heat-induced p53-dependent signal transduction and its role in hyperthermic cancer therapy

A tumour suppressor gene product, p53, is well known to be activated by genotoxic stress such as radiation and DNA damaging agents. Recently, it has been found that non-genotoxic physiological stresses such as heat, cold and low pH also activate p53, which regulates the expression of downstream genes. p53 was found to contribute to heat sensitivity through Bax-mediated apoptosis via activation of caspase-3 in the human cancer cells. This study reviews heat-induced p53-dependent signal transduction and heat sensitivity via a p53-regulated pathway for apoptosis in human cancer cells with identical genetic backgrounds except for p53 status. Furthermore, based on recent reports, it is proposed that p53 status could be a useful indicator in predictive assays for hyperthermic cancer therapy. Hyperthermia treatment based on such predictive assays might improve the outcome and efficiency of cancer therapy in the future. It is further proposed that manipulation of mp53 by glycerol as a chemical chaperone may provide a new cancer therapy for patients with mp53-tumours.

All-trans retinoic acid (ATRA) differentiates acute promyelocytic leukemia cells independently of P-glycoprotein (P-gp) related multidrug resistance

Here the relationship between all-trans retinoic acid (ATRA)-resistance and P-glycoprotein (P-gp)-associated multidrug resistance (MDR) is discussed in acute promyelocytic leukemia (APL). First, the remission rates of ATRA therapy are similar in relapsed/refractory APL to the preceding chemotherapy given and in newly diagnosed APL. Second, MDR1 cDNA-transduced NB4 (NB4/MDR) cells accumulate less Rhodamine-123 (Rh123) than NB4 cells, but there is no difference in the intracellular ATRA concentration between them. PSC833 or MS209. MDR modifiers, increases the intracellular accumulation of Rh123 in NB4/MDR and APL cells expressing P-gp, but not of ATRA. Third, the expression of CD11b, the NBT reduction activity, the proportion of apoptotic cells and the morphology are not different between NB4/MDR and NB4 cells, and between APL cells expressing P-gp and not. APL cells express little P-gp, and mainly express CD33 but no CD34. Despite previous reports that ATRA-resistant APL cells express more P-gp than ATRA-sensitive ones, P-gp and ATRA-resistance seems to exist independently.

Multicenter prospective study of interferon-alpha versus bone marrow transplantation for newly diagnosed patients with chronic myelogenous leukemia: a preliminary analysis

Interferon-alpha (IFN-alpha) therapy was compared with bone marrow transplantation (BMT) in patients with chronic myelogenous leukemia (CML) in a multicenter, prospective study. Of 254 evaluable patients, 175 received IFN-alpha and 79 received allogeneic BMT, 50 of whom received transplants from human leukocyte antigen (HLA)-identical related donors and 29 from HLA-matched unrelated donors. Complete hematologic response was achieved by 148 patients (89%) in the IFN-alpha group and 53 (78%) in the BMT group. In the IFN-alpha group, a complete cytogenetic response was induced in 25 patients (15%), a partial cytogenetic response in 37 (23%), and a minor cytogenetic response in 41 (25%). At a median follow-up of 38 months, in the IFN-alpha group the predicted 5-year survival rate was 79%, and the predicted 5-year rate of remaining in chronic phase was 66%. In the BMT group the predicted 5-year survival rate was 72% for related-donor BMT and 67% for unrelated-donor BMT. Among low Sokal-risk patients, 5-year survival did not differ between IFN-alpha therapy and BMT, irrespective of age. In higher Sokal-risk patients, survival for related-donor BMT and unrelated-donor BMT tended to be better than that with IFN-alpha therapy in younger patients. On the other hand, in older patients, survival in the BMT group, especially for those receiving unrelated-donor BMT, appeared to be inferior to that in the IFN-alpha group. Unrelated-donor BMT can be recommended for high-risk younger patients. However, for older patients, it should be performed after careful consideration of prognostic factors such as age, Sokal score, and response to IFN-alpha.

[Successful treatment using iron depletion phlebotomy combined with recombinant erythropoietin after allogeneic bone marrow transplantation for myelodysplastic syndrome complicated by secondary hemochromatosis]

A 33 year-old female patient presented with apparent skin pigmentation, sustained liver dysfunction and impaired glucose tolerance. She had received blood transfusions totalling more than 40,000 ml for myelodysplastic syndrome and an allogeneic bone marrow transplant from her HLA-matched sister at the age of 31. Ferrokinetic data showed a significant iron overload. Magnetic resonance imaging suggested excessive iron deposition in the liver. The patient was diagnosed as having secondary hemochromatosis. She was given subcutaneous injections of 6,000 units of recombinant human erythropoietin initially twice a week and then weekly, and phlebotomies were performed to maintain her hemoglobin level above 10 g/dl. Three years later, the total volume of phlebotomized blood reached 24,000 ml, and her ferrokinetic data, serum transaminase levels, glucose tolerance and skin color were significantly improved.

5-Aminolaevulinic acid-mediated photodynamic therapy in multidrug resistant leukemia cells

To verify if photodynamic therapy (PDT) could overcome multidrug resistance (MDR) when it it applied to eradicate minimal residual disease in patients with leukemia, we investigated the fluorescence kinetics of 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) and the effect of subsequent photodynamic therapy on MDR leukemia cells, which express P-glycoprotein (P-gp), as well as on their parent cells. Evaluation of PpIX accumulation by flow cytometry showed that PpIX accumulated at higher levels in mdr-1 gene-transduced MDR cells (NB4/MDR) and at lower levels in doxorubicin-induced MDR cells (NOMO-1/ADR) than in their parent cells. A P-gp inhibitor could not increase PpIX accumulation. Measurement of extracellular PpIX concentration by fluorescence spectrometry showed that P-gp did not mediate the fluorescence kinetics of ALA-induced PpIX production. Assessment of ferrochelatase activity using high-performance liquid chromatography indicated that PpIX accumulation in drug-induced MDR cells was probably regulated by this enzyme. Assessment of phototoxicity of PDT using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that PDT was effective in NB4, NB4/MDR, NOMO-1 and NOMO-1/ADR cells, which accumulated high levels of PpIX, but not effective in K562 and K562/ADR cell lines, which accumulated relatively low levels of PpIX. These findings demonstrate that P-gp does not mediate the ALA-fluorescence kinetics, and multidrug resistant leukemia cells do not have cross-resistance to ALA-PDT.

Deterioration in learning and memory of fear conditioning in response to context in aged SAMP8 mice 1 1Abbreviations: SAM, senescence-accelerated mouse; SAMP, senescence-accelerated mouse prone; SAMR, senescence-accelerated mouse resistant; GABA, gamma-aminobutyric acid; MGRF, magnocelluar reticular formation; RSA, hippocampal rhythmic slow activity; CS, conditioned stimulus

This study examined age-dependent deficits in the learning and memory of fear conditioning, using a newly developed senescence-accelerated mouse (SAMP8) model of age-related brain dysfunction and its genetically related inbred strain (SAMR1). The mice were classically conditioned to tone by giving aversive foot shocks in a distinct experimental box (context). After conditioning, fear in response to the original context without the tone and to the tone in a different context were tested with no shocks. Freezing behavior was used as a reliable index of fear. At 4 and 8 months, contextual fear was weaker in the accelerated senescence-prone SAMP8 mice than in the accelerated senescence-resistant SAMR1 mice. However, at 1 and 2 months, both SAMP8 and SAMR1 mice showed significant contextual fear to equivalent levels. Aging did not affect the fear response to tone. These results indicate that SAMP8 mice have age-related learning and memory deficits in their fear response evoked by contextual but not explicit tone stimuli. Age-related hippocampal dysfunction is suggested to be the cause of these age-related deficits in contextual fear conditioning in SAMP8 mice.

Decreased amount of mpl and reduced expression of glycoprotein IIb/IIIa and glycoprotein Ib on platelets from patients with refractory anemia: analysis by a non-isotopic quantitative ligand binding assay and immunofluorescence

Using a non-isotopic ligand binding assay and immunofluorescence, we examined the amount of mpl, glycoprotein IIb/IIIa (gpIIb/IIIa) and glycoprotein Ib (gpIb) on platelets from healthy volunteers and patients with refractory anemia (RA). For the analysis of mpl expression, we applied both a non-isotopic ligand binding assay and immunofluorescence using anti-mpl monoclonal antibody, and compared the results from both methods. The non-isotopic ligand binding assay has been developed in our laboratory and is suitable for the quantitative analysis of a small amount of cytokine receptors such as mpl on platelets. In platelets from patients with RA, the amount of mpl expressed by the D value was 0.05+/-0.03 (mean+/-standard deviation), and was significantly lower than that in healthy volunteers (0.15+/-0.05, p<0.0001). The mean fluorescence intensities (MFI) of gpIIb/IIIa and gpIb on platelets from RA patients were 28.8+/-8.8 and 20.8+/-7.7, respectively, and were significantly lower than those on normal subjects (93.2+/-22.6 and 67.4+/-9.1, p<0.0001 and p<0.0001, respectively). There was a good correlation between the amount of mpl and the MFI of gpIIb/IIIa (p=0.794, p<0.0001) or gpIb (p=0.774, p<0.0001), and between those of gpIIb/IIIa and gpIb (p=0.728, p<0.0001). We demonstrated a decreased amount of mpl as well as a reduced expression of gpIIb/IIIa and gpIb on platelets from RA patients.

Nucleotide sequence analysis of 5'-flanking region of salicylate hydroxylase gene, and identification and purification of a LysR-type regulator, SalR

The sal gene comprised of 1266 nucleotides encoding salicylate hydroxylase was cloned from the chromosomal DNA of Pseudomonas putida S-1 and sequenced [Suzuki, K., Mizuguchi, M., Ohnishi, K. and Itagaki, E. (1996) Biochim. Biophys. Acta 1275, 154-156]. Here, we describe the nucleotide sequences of the regulatory region of the sal gene and an ORF (salR gene) divergently oriented from the sal gene, which encodes the protein SalR. This gene product positively controls sal gene expression at the transcriptional level. The salR gene consists of 930 base pairs starting from a GTG codon and encodes a protein of 309 amino acids with a molecular mass of 34 542 Da. The amino-acid sequence is homologous to LysR-family regulatory proteins such as CatR of P. putida RB1 and has helix-turn-helix DNA binding motif near its N-terminal. Transcription start sites of sal and salR genes were determined to lie 30- and 24-bp upstream of the respective initiation codons and separated from each other by 78 nucleotides. A Shine-Dalgarno sequence and the putative promoter sequences containing -10 and -35 sequences were seen in the sal and salR genes. Expression of the salR gene on a plasmid in Escherichia coli cells was confirmed by DNA mobility shift assay. For the overexpression of the salR gene, it was cloned to pET28a (pSAHR) which was transferred to E. coli BL21 (E. coli BL21/pSAHR), and expressed by an inducer, isopropyl thio-beta-D-galactoside. SalR was further purified to homogeneity from the cell-free extracts in yields of approximately 3 mg.L-1 culture volume. The molecular mass was determined to be 33 kDa and the N-terminal amino-acid sequence was the same as that deduced from the nucleotide sequence of salR gene. Native SalR was also purified to homogeneity from P. putida S-1 with very low contents. The properties of the protein were similar to those of SalR expressed in E. coli.

Alginate, a bioresorbable material derived from brown seaweed, enhances elongation of amputated axons of spinal cord in infant rats

Freeze-dried alginate sponge crosslinked with covalent bonds was developed in our laboratory and has been demonstrated to enhance peripheral nerve regeneration. In this study, we examined spinal cord repair using alginate sponge in infant rats. On postnatal day 8-12, the spinal cord was transversely resected at Th7-Th8 to produce a 2-mm gap. The gap was filled with alginate sponge in the alginate group. For the control group, the gap was left empty. In the alginate group, the recovery of evoked electromyogram and sensory-evoked potentials 6 weeks after surgery indicated that elongation of axons could establish electrophysiologically functional projections through the gap. A histological study revealed that myelinated and unmyelinated axons, surrounded by a perineurial-like structure, had elongated across the gap. An immunohistochemical examination revealed that elongation of astrocytic processes and/or migration of astrocytes into the alginate sponge was induced, whereas astrocyte gliosis was reduced at the interface between the implanted alginate and the host spinal cord, compared with the control group. However, a horseradish peroxidase tracing study revealed ascending and descending fibers had also elongated into the gap and reentered the other stump of the transected spinal cord beyond the gap. These results suggest that alginate might provide a permissive microenvironment for elongation of spinal cord axons.

A new strategy for cancer therapy based on a predictive indicator

Tumor-associated genes have been analyzed at the molecular level in recent years, and using the analyses of these genes as a predictive indicator for cancer therapy has attracted attention. Among such genes, the actions of a tumor suppressor gene p53 are focused on the cancer therapy, and it is suggested that p53 genotypes can be used as a predictive indicator for radiotherapy, thermotherapy and chemotherapy. Transfection of wtp53 to p53-null cells increased radiation- or thermo-sensitivity and stimulated apoptosis induced by these therapies. Although therapy-induced apoptosis is suppressed in mp53 cells, apoptosis can be stimulated by glycerol treatment as a chemical chaperone. Therefore, a new strategy of combining p53-targeted gene therapy or chemical chaperone therapies is expected to improve the outcome and efficiency of cancer therapy in the future.

Induction of radioresistance by a nitric oxide-mediated bystander effect

To elucidate whether nitric oxide secreted from irradiated cells affects cellular radiosensitivity, we examined the accumulation of inducible nitric oxide synthase, TP53 and HSP72, the concentration of nitrite in the medium of cells after X irradiation, and cellular radiosensitivity using two human glioblastoma cell lines, A-172, which has a wild-type TP53 gene, and a transfectant of A-172 cells, A-172/mp53, bearing a mutated TP53 gene. Accumulation of inducible nitric oxide synthase was caused by X irradiation of the mutant TP53 cells but not of the wild-type TP53 cells. Accumulation of TP53 and HSP72 in the wild-type TP53 cells was observed by cocultivation with irradiated mutant TP53 cells, and the accumulation was abolished by the addition of an inhibitor for inducible nitric oxide synthase, aminoguanidine, to the medium. Likewise, accumulation of these proteins was observed in the wild-type TP53 cells after exposure to conditioned medium from irradiated mutant TP53 cells, and the accumulation was abolished by the addition of a specific nitric oxide scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, to the medium. The radiosensitivity of wild-type TP53 cells was reduced when the cells were cultured in conditioned medium from irradiated mutant TP53 cells compared to conventional fresh growth medium. Collectively, these findings indicate the potential importance of an intercellular signal transduction pathway initiated by nitric oxide in the cellular response to ionizing radiation.