Differential Cross Section and Photon-Beam Asymmetry for the γ[over →]p → π

Differential cross sections and photon-beam asymmetries for the γ[over →]p→π^{-}Δ^{++}(1232) reaction have been measured for 0.7

Tooth shape reconstruction from dental CT images with the region-growing method.

OBJECTIVES: The three-dimensional shape information of teeth provides useful information. However, obtaining accurate three-dimensional shapes of teeth is difficult without extracting them physically. In this study, we aimed to develop a method for automatically extracting accurate three-dimensional shapes of teeth from dental CT images. METHODS: The proposed method includes pre-processing and region extraction. Pre-processing is a combination of image-processing techniques that enhances tooth regions. In the region-extraction process, the region-growing method is introduced for extracting a region of each tooth. Constraint conditions determined by considering the characteristics of the structure of teeth are introduced for accurate extraction. Finally, morphological image processing is applied for eliminating discontinuous points. RESULTS: We carried out an experiment in which the three-dimensional shapes of teeth were reconstructed from dental CT images. Quantitative evaluation was performed by measuring the three-dimensional spatial accordance rates between the region obtained by the proposed method and the manually extracted region. The proposed method was significantly more accurate than an existing method at the 5% level. CONCLUSIONS: The experimental results showed that the proposed method reconstructs the shapes of teeth with high precision. However, an unextracted region remained at the surface of the enamel. Solving this problem and improving the extraction accuracy are important topics for future work.

Spin-density matrix elements for γp→K*0Σ+ at Eγ=1.85-3.0 GeV with evidence for the κ(800) meson exchange.

The exclusive reaction γp→K(+)π(-)Σ(+) was measured for the first time using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. Angular distributions in the rest frame of the K(+)π(-) system were fitted to extract spin-density matrix elements of the K(*0) decay. The measured parity spin asymmetry shows that natural-parity exchange is dominant in this reaction. This result clearly indicates the need for t-channel exchange of the κ(800) scalar meson.

Near-threshold Lambda(1520) production by the gamma(p)-->K{+}Lambda(1520) reaction at forward K+ angles.

Differential cross sections and photon-beam asymmetries for the gamma(p)-->K{+}Lambda(1520) reaction have been measured with linearly polarized photon beams at energies from the threshold to 2.4 GeV at 0.6or=5/2 or by a new reaction process, for example, an interference effect with the phi photoproduction having a similar bump structure in the cross sections.

Near-threshold photoproduction of Lambda(1520) from protons and deuterons.

Photoproduction of Lambda(1520) with liquid hydrogen and deuterium targets was examined at photon energies below 2.4 GeV in the SPring-8 LEPS experiment. For the first time, the differential cross sections were measured at low energies and with a deuterium target. A large asymmetry of the production cross sections from protons and neutrons was observed at backward K+/0 angles. This suggests the importance of the contact term, which coexists with t-channel K exchange under gauge invariance. This interpretation was compatible with the differential cross sections, decay asymmetry, and photon beam asymmetry measured in the production from protons at forward K+ angles.

Cross sections and beam asymmetry for K;{+}Sigma;{*-} photoproduction from the deuteron at E_{gamma}=1.5-2.4 GeV.

The Sigma(1385) resonance, or Sigma;{*}, is well known as part of the standard baryon decuplet with spin J=3/2. Measurements of the reaction gammap-->K;{+}Sigma;{*0} are difficult to extract due to overlap with the nearby Lambda(1405) resonance. However, the reaction gamman-->K;{+}Sigma;{*-} has no overlap with the Lambda(1405) due to its charge. Here we report the first measurement of cross sections and beam asymmetries for photoproduction of the Sigma;{*-} from a deuteron target. The cross sections at forward angles range from 0.4 to 1.2 mub, with a broad maximum near E_{gamma} approximately 1.8 GeV. The beam asymmetries are negative, in contrast with positive values for the gamman-->K;{+}Sigma;{-} reaction.

Search for a light pseudoscalar particle in the decay K_{L};{0}-->pi;{0}pi;{0}X.

We performed a search for a light pseudoscalar particle X in the decay K_{L};{0}-->pi;{0}pi;{0}X, X-->gammagamma with the E391a detector at KEK. Such a particle with a mass of 214.3 MeV/c;{2} was suggested by the HyperCP experiment. We found no evidence for X and set an upper limit on the product branching ratio for K_{L};{0}-->pi;{0}pi;{0}X, X-->gammagamma of 2.4x10;{-7} at the 90% confidence level. Upper limits on the branching ratios in the mass region of X from 194.3 to 219.3 MeV/c;{2} are also presented.

Search for the Decay K L0-->pi0nu nu[over].

We performed a search for the K L0-->pi0nu nu[over] decay at the KEK 12-GeV proton synchrotron. No candidate events were observed. An upper limit on the branching ratio for the decay was set to be 6.7 x 10(-8) at the 90% confidence level.

Differential cross section and photon-beam asymmetry for the gamma n --> K+ Sigma- reaction at E gamma = 1.5-2.4 GeV.

Differential cross sections and photon-beam asymmetries have been measured for the gamma n --> K+ Sigma- and gamma p --> K+Sigma0 reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of E gamma = 1.5-2.4 GeV at 0.6 < cos ThetacmK< 1. The cross section ratio of sigma K+ Sigma-/sigma K+ Sigma0, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K+ Sigma- reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K+ Sigma- and K+ Sigma0 reactions cannot be explained by simple theoretical considerations based on Regge model calculations.

Near-threshold diffractive psi-meson photoproduction from the proton.

Photoproduction of a phi meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections at t = -|t|min do not increase smoothly as Egamma increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that phi mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

Beam-polarization asymmetries for the p(gamma-->, K+)Lambda and p(gamma-->, K+)Sigma(0) reactions for E(gamma)=1.5-2.4 GeV.

Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6

Evidence for a narrow S = +1 baryon resonance in photoproduction from the neutron.

The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.

Chromatographic probing of electrostatic potential.

Electrostatic potential in the vicinity of the surface of a cation-exchange resin has been evaluated by modeling chromatographic retention. Binary mixtures of K+ and its crown ether complex in methanol are used as mobile phases, and two types of solutes, that is, cationic and crown ether probes, have been examined. The cationic probes show the sigmoidal retention changes with increasing concentration of a crown ether incorporated into the mobile phase, whereas crown ether probes give retention maximums. The model derived from the Poisson-Boltzmann theory well explains these specific changes in probe retention and gives the electrostatic potential at the closest approach of each probe molecule. The closest approaches for probe molecules correlate well with their molecular sizes. In addition, changes in retention of cationic probes also correlate well with the electrostatic potential changes at the closest approaches of probe molecules, indicating that simple sensing of the electrostatic potential is feasible using probe retention. The reduction of crown ether complexation occurs in the vicinity of the cation-exchange resin surface and causes the specific retention behaviors of crown ether probes in the mobile-phase systems composed of K+ and its complex with a modifier crown ether.

Lower ureteral replacement using a tubularized gastric segment.

OBJECTIVES: To review our early experience with the use of a gastric segment for lower ureteral replacement in patients with bilateral ureteral stenosis after pelvic radiotherapy. METHODS: Four adult patients (three women and one man) underwent bilateral ureteral substitution using stomach. All patients received whole pelvic irradiation for malignant disease and had undergone bilateral nephrostomy because of severe bilateral ureteral stenosis. The postoperative follow-up period was 11 to 50 months. RESULTS: No major complication was recognized, and the bilateral nephrostomy tubes were removed in all patients. Three female patients could void urethrally without incontinence, and the male patient needed regular self-catheterization. The three women were alive with normal renal function at a follow-up of 11 to 50 months. The man had a vesicorectal fistula 8 months postoperatively, and colostomy was performed. He died of a cause unrelated to the operation 11 months after surgery. CONCLUSIONS: Stomach has not been used commonly for ureteral replacement. In patients with bilateral severe ureteral stenosis after pelvic radiotherapy, ureteral substitution with a gastric segment can be safely performed and will increase the patient's quality of life.

Autoradiographic studies using L-[(14)C]DOPA and L-DOPA reveal regional Na(+)-dependent uptake of the neurotransmitter candidate L-DOPA in the CNS.

We previously proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter in the CNS. Receptor and transporter molecules for L-DOPA, however, have not been determined. In the present study, in order to localize the uptake sites of L-DOPA in the CNS, we performed autoradiographic uptake studies using L-[14C]DOPA and L-[3H]DOPA in the uptake study on rat brain slice preparations, and further analyzed the properties of L-DOPA uptake. Image analysis of the L-[14C]DOPA autoradiogram showed a unique heterogeneous distribution of uptake sites in the brain. The intensity was relatively high in the cerebral cortex, the hypothalamus, the cerebellum and the hippocampus, while the density was moderate or even low in the striatum and the substantia nigra. L-DOPA and phenylalanine, but not dopamine (10mM) were able to almost completely inhibit the uptake of L-[14C]DOPA to basal levels. Microautoradiographic studies using L-[3H]DOPA revealed accumulation of dense grains in the median eminence, the supraoptic nucleus of the hypothalamus, the cerebral cortex (layer I) and the hippocampus. In the cerebellum, grains formed in clusters surrounding the Purkinje cells. This grain accumulation was concluded to be in Bergmann glial cells, since the morphological pattern of grain accumulation was similar to that of the immunoreactivity of the glutamate aspartate transporter, a marker protein for Bergmann glial cells. In the hippocampus, the grain density significantly decreased under Na(+)-free conditions. In addition, grain density also decreased in the absence of Cl(-). In contrast, grains in the choroid plexus and the ependymal cell layer, were not affected by the absence of Na(+). These findings indicated that the uptake of L-DOPA occurs via various types of large neutral amino acid transport mechanisms. It appears that neuronal and/or glial cells, which take up L-DOPA in a Na(+)-dependent manner, exist in the CNS. Our finding further supports the concept that L-DOPA itself may act as a neurotransmitter or neuromodulator.

[A case of leiomyosarcoma of the renal vein].

A 54-year-old woman presented with a 6-month history of left back pain. She had undergone left mastectomy for breast cancer in 1993 and hysterectomy for cervical cancer in 1997. Excretory urography showed no abnormality in the left collecting system, but right hydronephrosis caused by a midureteral stone. She was treated by transurethral ureterolithotripsy first. Computerized tomography showed a 4 x 3 cm. mass enhanced slightly by contrast medium at the left renal hilus. The tumor was bordered laterally by the left kidney and posteriorly by the left renal vein which appeared normal on magnetic resonance imaging. Selective left renal angiography revealed no abnormality. Radical en bloc excision of the tumor with the left kidney and adrenal gland was performed. Pathological examination showed a well differentiated leiomyosarcoma arising from the renal vein; the tumor cells stained positive for alpha-smooth muscle actin, vimentin and desmin and negative for S 100-protein. She was free of symptoms and there was no evidence of local recurrence or distant metastases 22 months postoperatively.

[Intra-arterial infusion chemotherapy for superficial bladder cancer].

Intra-arterial infusion chemotherapy (AI) is widely used in the treatment of invasive bladder cancer, but few studies have been reported on its efficacy for superficial bladder cancer. We retrospectively examined the anti-tumor effect and prophylactic effect of AI in 18 cases which were either a case with multiple or extensive tumors which could not be controlled completely by transurethral resection (TUR), a case with grade 3 tumors or a recurrent case after TUR and/or intravesical chemotherapy. Fifty mg of adriamycin and 100 mg of cisplatin were administered into bilateral internal iliac arterys. This treatment was repeated 1-3 times every three weeks. Concerning the anti-tumor effect, 8 showed a complete response, 5 showed partial response and 5 showed no change; the overall response rate (CR + PR) was 72%. Concerning the prophylactic effect, 1-, 2- and 3-year recurrence-free rates were 58.8%, 41.1% and 32.9%, respectively. This study demonstrated the efficacy of AI in the anti-tumor treatment, but not in the prophylactic treatment of superficial bladder cancer.

[A case of pulmonary metastasis from renal cell carcinoma with complete response to interferon-alpha and tegafur/uracil (UFT) but possibly UFT-induced liver dysfunction and leukoencephalopathy-like symptoms].

A 61-year-old man presented with gross hematuria. He underwent left radical nephrectomy under a diagnosis of left renal cell carcinoma without distant metastasis, but bilateral multiple pulmonary metastases appeared 2.5 months after the operation. Though the metastases responded well to combination therapy of interferon-alpha and a 1:4 mixture of tegafur and uracil (UFT), the side effects of liver dysfunction and leukoencephalopathy-like symptoms due to UFT appeared 7 months after the beginning of the chemotherapy. These side effects were improved after the cessation of UFT administration.

MRI findings and clinical manifestations in Rathke's cleft cyst.

We retrospectively analysed patients with histologically proven Rathke's cleft cyst (RCC) in relation to the clinical manifestations and MRI findings, in particular, of cyst size and intensity in order to obtain an insight into their growing mechanisms, clinical presentations and their management. Eleven patients with RCC were divided into two groups based on T1 weighted images(WI). The A group consisted of 4 patients with cyst of low intensity in T1 WI. The age averaged 64.5 years. Their initial complaints were visual field defects(VFD). Their complaints were rather insidious. The maximum cyst size averaged 27.8+/-2.4 mm. The B group consisted of 7 patients with cyst of iso- or high-intensity in T1 WI. Two patients in the B group showed mixture of low and high and iso- and high-intensity, suggesting the presence of bleeding at the onset of symptoms or growing mechanism of the cysts. In the B group the age averaged 39.9 years, being lower than that in the A group. (P=0.0140 with Mann-Whitney's U test) The 5 patients out of 7 showed headache of insidious type or acute onset and the 3 showed a fluctuation of the VFD. The average size was 21.7+/-3.5 mm and smaller than that of the A group. (P=0.0298 with Mann-Whitney's U test) Our study has shown that the cyst with iso-to high intensity on T1 WI may cause clinical symptoms with a smaller size than cysts of the low intensity. In the former cyst pattern the onset and growing mechanism may be related to bleeding. The patients with this pattern are more likely to have acute and/or fluctuation of clinical presentations. Knowing these various clinical manifestations based on MRI pattern will be of help in following and managing patients with RCC.

Strand asymmetry of +1 frameshift mutagenesis at a homopolymeric run by DNA polymerase III holoenzyme of Escherichia coli.

We have recently shown that single-base frameshifts were predominant among mutations induced within the rpsL target sequence upon oriC plasmid DNA replication in vitro. We found that the occurrence of +1 frameshifts at a run of 6 residues of dA/dT could be increased proportionally by increasing the concentration of dATP present in the in vitro replication. Using single-stranded circular DNA containing either the coding sequence of the rpsL gene or its complementary sequence, the +1 frameshift mutagenesis by DNA polymerase III holoenzyme of Escherichia coli was extensively examined. A(6) --> A(7) frameshifts occurred 30 to 90 times more frequently during DNA synthesis with the noncoding sequence (dT tract) template than with the coding sequence (dA tract). Excess dATP enhanced the occurrence of +1 frameshifts during DNA synthesis with the dT tract template, but no other dNTPs showed such an effect. In the presence of 0.1 mM dATP, the A(6) --> A(7) mutagenesis with the dT tract template was not inhibited by 1.5 mM dCTP, which is complementary to the residue immediately upstream of the dT tract. These results strongly suggested that the A(6) --> A(7) frameshift mutagenesis possesses an asymmetric strand nature and that slippage errors leading to the +1 frameshift are made during chain elongation within the tract rather than by misincorporation of nucleotides opposite residues next to the tract.