Swelling of Doubly Magic

Interaction cross sections for ^{42-51}Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number N=28. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and mean field calculations point out that this anomalous enhancement of the nuclear size beyond N=28 results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ^{48}Ca core in Ca isotopes beyond N=28.

Direct observation of long-lived isomers in 212Bi.

Long-lived isomers in (212)Bi have been studied following (238)U projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of (212)Bi was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30 min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies.

Magnetic dipole moment of the doubly-closed-shell plus one proton nucleus 49Sc.

The nucleus 49Sc, having a single f(7/2) proton outside doubly magic 48Ca (Z=20, N=28), is one of the very few isotopes which makes possible testing of the fundamental theory of nuclear magnetism. The magnetic moment has been measured by online ß NMR of nuclei oriented at milli-Kelvin temperatures to be (+)5.616(25) µ(N). The result is discussed in terms of a detailed theory of the structure of the magnetic moment operator, showing excellent agreement with calculated departure from the f(7/2) Schmidt limit extreme single-particle value. The measurement completes the sequence of moments of Sc isotopes with even numbers of f(7/2) neutrons: the first such isotopic chain between two major shells for which a full set of moment measurements exists. The result further completes the isotonic sequence of ground-state moments of nuclei with an odd number of f(7/2) protons coupled to a closed subshell of f(7/2) neutrons. Comparison with a recent shell-model calculation of the latter sequence is made.

Observation of a large reaction cross section in the drip-line nucleus 22C.

Reaction cross sections (sigma(R)) for 19C, 20C and the drip-line nucleus 22C on a liquid hydrogen target have been measured at around 40A MeV by a transmission method. A large enhancement of sigma(R) for 22C compared to those for neighboring C isotopes was observed. Using a finite-range Glauber calculation under an optical-limit approximation the rms matter radius of 22C was deduced to be 5.4+/-0.9 fm. It does not follow the systematic behavior of radii in carbon isotopes with N < or = 14, suggesting a neutron halo. It was found by an analysis based on a few-body Glauber calculation that the two-valence neutrons in 22C preferentially occupy the 1s(1/2) orbital.

Expression and differential intracellular localization of two major forms of human 8-oxoguanine DNA glycosylase encoded by alternatively spliced OGG1 mRNAs.

We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types 1a and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1-1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1-1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1-2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1-2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1-2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1-1a depends on the NLS at its C terminus.

Identification of human MutY homolog (hMYH) as a repair enzyme for 2-hydroxyadenine in DNA and detection of multiple forms of hMYH located in nuclei and mitochondria.

An enzyme activity introducing an alkali-labile site at 2-hydroxyadenine (2-OH-A) in double-stranded oligonucleotides was detected in nuclear extracts of Jurkat cells. This activity co-eluted with activities toward adenine paired with guanine and 8-oxo-7,8-dihydroguanine (8-oxoG) as a single peak corresponding to a 55 kDa molecular mass on gel filtration chromatography. Further co-purification was then done. Western blotting revealed that these activities also co-purified with a 52 kDa polypeptide which reacted with antibodies against human MYH (anti-hMYH). Recombinant hMYH has essentially similar activities to the partially purified enzyme. Thus, hMYH is likely to possess both adenine and 2-OH-A DNA glycosylase activities. In nuclear extracts from Jurkat cells, a 52 kDa polypeptide was detected with a small amount of 53 kDa polypeptide, while in mitochondrial extracts a 57 kDa polypeptide was detected using anti-hMYH. With amplification of the 5'-regions of the hMYH cDNA, 10 forms of hMYH transcripts were identified and subgrouped into three types, each with a unique 5' sequence. These hMYH transcripts are likely to encode multiple authentic hMYH polypeptides including the 52, 53 and 57 kDa polypeptides detected in Jurkat cells.

p53-dependent induction of WAF1 by a low-pH culture condition in human glioblastoma cells.

The effects of an acidic condition (pH 6.5) on WAF1 gene expression and p53 accumulation was investigated in human glioblastoma cells with different p53 statuses. WAF1 and p53 accumulation after treatment in acidic conditions was observed in A-172 cells carrying the wild-type p53 gene but not in T98G cells carrying the mutant p53 gene. Northern blot analysis showed that WAF1 gene activation by acidic conditions only occurred in A-172 cells. Consistent with this, activation of the binding of p53 to its specific DNA sequence by acidic stress was detected by gel mobility shift assay using p53 consensus sequence as a probe. Moreover, the increased WAF1 protein and mRNA levels that were due to acidic treatment returned to normal levels upon the return of the cells to neutral conditions, 6 h after the cells had been cultured in acidic conditions for 6 or 12 h. These findings suggest that WAF1 gene activation is inducible by acidic conditions in human glioblastoma cells, which is probably due to activation of the p53-dependent signal transduction pathway.

Nitric oxide is an initiator of intercellular signal transduction for stress response after hyperthermia in mutant p53 cells of human glioblastoma.

Nitric oxide is known to be a multifunctional physiological substance. Recently, it was suggested that nitric oxide is involved in p53-dependent response to many kinds of stress, such as heat shock and changes in cellular metabolism. To verify this hypothesis, we examined the effect of nitric oxide produced endogenously by heat-shocked cells on nonstressed cells using a human glioblastoma cell line, A-172, and its mutant p53 (mp53) transfectant (A-172/mp53). The accumulation of inducible nitric oxide synthase was caused by heat treatment of the mtp53 cells but not of the wild-type p53 (wtp53) cells. The accumulation of heat shock protein 72 (hsp72) and p53 was observed in nontreated mtp53 cells cocultivated with heated mp53 cells, and the accumulation of these proteins was suppressed by the addition of a specific inducible nitric oxide synthase inhibitor, aminoguanidine, to the medium. Furthermore, the accumulation of these proteins was observed in the wtp53 cells after exposure to the conditioned medium by preculture of the heated mp53 cells, and the accumulation was completely blocked 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. In addition, the accumulation of hsp72 and p53 in the wtp53 cells was induced by the administration of an nitric oxide-generating agent, S-nitroso-N-acetylpenicillamine, to the medium. Finally, the thermosensitivity of the wtp53 cells was reduced in the conditioned medium by preculture of the heated mp53 cells as compared with conventional fresh growth medium. Our finding of the accumulation of hsp72 and p53 in nitric oxide-recipient cells cocultivated with heated nitric oxide-donor cells provides the first evidence for an intercellular signal transduction pathway via nitric oxide as intermediate without cell-to-cell interactions such as gap junctions.

Cell cycle progression and apoptosis after irradiation in an acidic environment.

We investigated the effect of an acidic environment on the radiation-induced G2/M arrest and apoptosis using RKO.C human colorectal cancer cells expressing wild-type p53 and RC10.1 cells, a subline of RKO.C cells deficient in p53 as well as p53+/+ MEFs and p53-/- MEFs (mouse embryonic fibroblasts). The cells were irradiated with 4 Gy or 12 Gy of gamma-rays in pH 7.5 medium or pH 6.6 medium. p53 accentuated the progression of cells from radiation-induced G2/M arrest to apoptosis and the pH 6.6 environment suppressed the progression of cells through G2/M-phase to apoptosis after irradiation. Further analysis indicated that the radiation-induced G2/M arrest was due mainly to G2 arrest in both pH 7.5 and pH 6.6. Therefore, it was concluded that p53 enhances, and an acidic environment suppresses, the exit of cells from radiation-induced G2 arrest by altering cyclin B1-Cdc2 kinase activity.

Identification of NRF2, a member of the NF-E2 family of transcription factors, as a substrate for caspase-3(-like) proteases.

Apoptosis is mediated by members of the interleukin-1beta converting enzyme (ICE) family of proteases (caspases), which are activated by diverse stimuli, although the downstream molecular targets of caspases are still poorly understood. Using the modified yeast two-hybrid system, which we recently established to clone genes for caspase substrates, we identified NRF2 as a novel caspase substrate. NRF2 is a member of the NF-E2 family of basic region leucine-zipper transcription factors and has been shown to induce phase II detoxifying enzymes through anti-oxidant response elements. NRF2 was cleaved at two sites by recombinant caspase-3 in vitro as well as in HeLa cells during TNFalpha-mediated apoptosis. Overexpression of the C-terminal cleavage fragment containing the DNA binding and leucine-zipper domains induced apoptosis in HeLa cells. These observations suggest that NRF2 might have some role in the induction of apoptosis after cleavage by caspases.

Suppression of heat-induced HSF activation by CDDP in human glioblastoma cells.

PURPOSE: The kinetics of the accumulation of inducible 72-kD heat shock protein (hsp72) and the activation of heat shock transcriptional factor (HSF) after hyperthermia and/or CDDP treatment in two human glioblastoma cell lines, A-172 having the wild-type p53 gene and T98G having the mutated p53 gene were evaluated. METHODS AND MATERIALS: Western blot analysis of hsp72, gel-mobility shift assay of HSF, cell survival, and development of thermotolerance were examined. RESULTS: The prominent suppression of heat-induced hsp72 accumulation by CDDP was seen in A-172 cells, but not in T98G cells. This was due to the p53-dependent inhibition of heat-induced HSF activation by CDDP. The interactive hyperthermic enhancement of CDDP cytotoxicity was observed in A-172 cells, but not in T98G cells. In addition, the heat-induced thermotolerance was suppressed by the presence of CDDP in the pretreatment. CONCLUSION: Suppression of heat-induced hsp72 accumulation by CDDP contributes to an interactive hyperthermic enhancement of CDDP cytotoxicity in the cells bearing the wild-type p53 gene.

Acidic environment modifies heat- or radiation-induced apoptosis in human maxillary cancer cells.

PURPOSE: The effects of hyperthermia or irradiation on cell killing and induction of apoptosis were evaluated using human maxillary carcinoma IMC-3 cells and low pH (pH 6.8) adapted cells (IMC-3-pH). METHODS AND MATERIALS: Cellular heat-sensitivity or radiosensitivity was determined using the clonogenic assay. Apoptosis was assessed on the basis of a flow cytometric determination of the DNA content, DNA fragmentation, and poly(ADP-ribose)polymerase cleavage. RESULTS: When IMC-3 cells or IMC-3-pH cells were exposed to heat at 44 degrees C in pH 6.8 medium, an increase in thermosensitivity was observed compared with when the IMC-3 cells were exposed to heat at 44 degrees C in pH 7.4 medium. However, the selective reduction in survival was not observed after irradiation. In IMC-3 cells, apoptosis after heating at 44 degrees C for 60 min in pH 7.4 medium occurred earlier than that after 8 Gy irradiation, although both thermal and irradiated doses decreased the cell count to 10%. The degree of apoptosis after heating at pH 6.8 in IMC-3 cells or IMC-3-pH cells was greater than that at pH 7.4 in IMC-3 cells. However, the degree of apoptosis after 8 Gy irradiation at pH 6.8 in IMC-3 cells or IMC-3-pH cells was smaller than that at pH 7.4 in IMC-3 cells. CONCLUSION: Hyperthermia treatment is more effective at inducing apoptosis than radiation is in tumors that contain a population of low pH adapted cells.

Fluorine-18-fluorodeoxyglucose PET versus thallium-201 scintigraphy evaluation of thyroid tumors.

UNLABELLED: To determine whether PET could help differentiate malignant from benign thyroid tumors, 18F-fluorodeoxyglucose (FDG) accumulation and 201Tl scintigraphy were examined relative to histological diagnosis. METHODS: Nodular thyroid lesions in 11 patients were evaluated before surgical resection. Static PET scanning with 370 MBq FDG was done for 20 min (from 40 to 60 min postinjection) in all patients, and standardized uptake values (SUVs) in these lesions were calculated. In addition, eight patients were evaluated with dynamic PET scan up to 60 min postinjection, and the lesions were further evaluated using graphical analysis. Thallium-201 delayed images were visually evaluated in 10 patients. RESULTS: Four of 11 nodules were well-differentiated papillary carcinoma, another five were benign follicular adenomas, one was a multinodular goiter and another a case of chronic thyroiditis that was proved not to contain a nodule. Time-activity curves of FDG uptake showed different patterns in malignant and benign tumors. In the malignant tumors, FDG uptake increased with time after the tracer injection. By contrast, FDG uptake in benign tumors gradually decreased. With use of a cutoff value of 5.0 mg/ml for SUV and 10 microl x min(-1) x ml(-1) for Kc (K complex value determined using the linear fitting of the time-activity curve of FDG accumulation), all of the four malignant nodules and the six benign nodules were separated correctly. Chronic thyroiditis had high SUV in the malignant range. Of the four patients with thyroid carcinoma, the delayed 201Tl images revealed a slightly higher or equal uptake to background activity. In a patient with chronic thyroiditis, the delayed 201Tl images revealed diffuse accumulation higher than background activity. CONCLUSION: FDG-PET is superior to 201Tl in differentiating malignant from benign tumors. Both SUVs and Kc values were useful indexes for this discrimination. Although careful evaluation is needed for chronic inflammatory lesions, this technique appears to be useful in evaluating thyroid nodules.

Suppression of heat-induced hsp72 accumulation by cisplatin in human glioblastoma cells.

The accumulation of the inducible hsp72 (72-kDa heat shock protein) after hyperthermia and/or cisplatin treatment in human glioblastoma cell line (A-172) was studied by Western blot analysis. The level of hsp72 increased to eight-fold 10 h after hyperthermia alone (44 degrees C for 20 min, D50) and to three-fold 10 h after cisplatin treatment (5 microg/ml) at 37 degrees C for 15 min (D50). In contrast, when the cells were simultaneously heated with cisplatin, the accumulation of hsp72 was suppressed. The level of hsp72 increased to about six-fold and two-fold 10 h after hyperthermia (44 degrees C, 15 min) in the presence of 1 and 10 microg/ml (D50 or D10) of cisplatin, respectively. In addition, we found both the enhancement of thermosensitivity and the suppression of thermotolerance by the simultaneously combined treatment of hyperthermia and cisplatin. It has been reported that the enhancement of cisplatin cytotoxicity by hyperthermia is due to increase of both cisplatin uptake and DNA damage by hyperthermia. Our results suggest that the interactive cytotoxic enhancement by the combination of hyperthermia and cisplatin may be also due to the suppression of heat-induced hsp72 accumulation by cisplatin.

Enhancement of cisplatin sensitivity and platinum uptake by 40 degrees C hyperthermia in resistant cells.

We studied the cytotoxic and pharmacological properties of 40 degrees C hyperthermia and CDDP in CDDP-sensitive (IMC-3) and CDDP-resistant (IMC-3-DDP) human maxillary carcinoma cells. Heating at 40 degrees C alone caused almost no cell killing to IMC-3 and IMC-3-DDP cells. In both cell lines, the dose-dependent cytotoxicity of 2-h exposures to CDDP was increased at 40 degrees C in comparison to 37 degrees C. Heating at 40 degrees C also potentiated CDDP cytotoxicity in both IMC-3 and IMC-3-DDP cells with thermal chemoenhancement ratios (CER) of 1.48 and 1.94, respectively. The intracellular CDDP uptake level of IMC-3-DDP at 37 degrees C was significantly reduced compared with IMC-3 cells. At 40 degrees C, however, hyperthermia increased platinum accumulation by factors of 1.4 and 1.8 in IMC-3 and IMC-3-DDP cells, respectively. These findings indicated that CDDP sensitivity was hyperthermically chemopotentiated in CDDP-resistant variants rather than in the control clones. Thus, clinical cancer chemotherapy with CDDP may be improved by an appropriate combination with hyperthermia even at 40 degrees C.

Suppression of heat-induced p53 accumulation and activation by CDDP or x-rays in human glioblastoma cells.

We showed that the prominent suppressions of heat-induced accumulation and activation of p53 by CDDP or X-rays were observed in A-172 cells, but not in T98G cells. In addition, the interactive hyperthermic enhancement of CDDP or X-ray cytotoxicity was observed in A-172 cells, but not in T98G cells. Our findings indicate that suppressions of heat-induced accumulation and activation of p53 by CDDP or X-rays contribute positively to an interactive hyperthermic enhancement of CDDP- or X-ray cytotoxicity.

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.

Enhancement of cell killing by induction of apoptosis after treatment with mild hyperthermia at 42 degrees C and cisplatin.

Ohtsubo, T., Igawa, H., Saito, T., Matsumoto, H., Park, H. J., Song, C. W., Kano, E. and Saito, H. Enhancement of Cell Killing by Induction of Apoptosis after Treatment with Mild Hyperthermia at 42 degrees C and Cisplatin. Radiat. Res. 156, 103-109 (2001). We examined the interactive effects of cisplatin (1.0 microg/ml) combined with hyperthermia on cell killing and on the induction of apoptosis in IMC-3 human maxillary carcinoma cells. The cytotoxic effects of hyperthermia on IMC-3 cells at 44 degrees C were greater than at 42 degrees C, as has been reported for many other cells. The induction of apoptosis, DNA fragmentation and poly(ADP-ribose) polymerase cleavage were greater after hyperthermia at 44 degrees C for 30 min compared with treatment at 42 degrees C for 105 min, even though both of these heat doses were isoeffective in reducing cell survival to 50%. Treatment with cisplatin at 37 degrees C for up to 120 min did not result in cytotoxicity or the induction of apoptosis. The enhancement ratio for treatment with cisplatin at 42 degrees C was greater than that at 44 degrees C. More apoptosis was induced after the treatment with cisplatin at 42 degrees C compared to treatment with cisplatin at 44 degrees C. Taking these findings together, the combination of cisplatin and hyperthermia at 42 degrees C appeared to be more effective than cisplatin with hyperthermia at 44 degrees C for the induction of apoptosis in IMC-3 cells.

Effectiveness of systematized hepatectomy with Glisson's pedicle transection at the hepatic hilus for small nodular hepatocellular carcinoma: retrospective analysis.

BACKGROUND: The effectiveness of systematized hepatectomy with transection of Glisson's pedicle at the hepatic hilus in patients with small nodular hepatocellular carcinoma (HCC) has not been confirmed. METHODS: Surgical outcomes were reviewed in 204 patients with single nodular HCCs less than 5 cm in greatest diameter, including 68 patients with tumors that showed extranodular growth and 136 patients with tumors that did not, who had undergone curative hepatectomy (partial hepatic resection, n = 114; systematized hepatectomy, n = 90) from 1990 through 1994. RESULTS: The rates of microscopic vascular invasion and intrahepatic metastasis were significantly higher in patients who had single nodular HCCs with extranodular growth (34% and 49%) than in patients who had single nodular HCCs without extranodular growth (13%, P =.001, and 4%, P <.001). The 5-year survival rate in patients who had single nodular HCCs with extranodular growth was significantly greater after systematized hepatectomy (67%) than after partial hepatic resection (21%, P =.0002). Multivariate analysis showed that the type of operation was an independent prognostic factor in patients with single nodular HCCs with extranodular growth (P =.0008). CONCLUSIONS: Systematized hepatectomy with Glisson's pedicle transection at the hepatic hilus should be performed in patients who have single small nodular HCCs with extranodular growth because these tumors often invade within the liver sector containing the tumor.