Energy increase in multi-MeV ion acceleration in the interaction of a short pulse laser with a cluster-gas target

An approach for accelerating ions, with the use of a cluster-gas target and an ultrashort pulse laser of 150-mJ energy and 40-fs duration, is presented. Ions with energy 10-20 MeV per nucleon having a small divergence (full angle) of 3.4 degrees are generated in the forward direction, corresponding to approximately tenfold increase in the ion energies compared to previous experiments using solid targets. It is inferred from a particle-in-cell simulation that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in subcritical density plasmas.

Spontaneous complete regression of a rectal cancer

We report a unique case of a biopsy-proven rectal cancer exhibiting spontaneous complete regression in an extremely short period of 3 months. An 80-year-old man visited our hospital because of a positive fecal occult blood test. Colonoscopy showed a sessile polyp, about 25 mm in diameter, in the middle part of the rectum. Instead of endoscopic resection, two endoscopic biopsies were taken for histological evaluation, as an invasive cancer was endoscopically suspected.Well-differentiated invasive adenocarcinoma was revealed, and thus surgical resection was planned. At the second colonoscopy for endoscopic tattooing before surgery, the polyp was found to have unexpectedly developed into a flat lesion. Furthermore, the surgically removed specimen showed that the flat lesion had transformed to a depressed lesion, and surprisingly, no cancerous tissue was detected histologically.

Ion spectrometer composed of time-of-flight and Thomson parabola spectrometers for simultaneous characterization of laser-driven ions

An ion spectrometer, composed of a time-of-flight spectrometer (TOFS) and a Thomson parabola spectrometer (TPS), has been developed to measure energy spectra and to analyze species of laser-driven ions. Two spectrometers can be operated simultaneously, thereby facilitate to compare the independently measured data and to combine advantages of each spectrometer. Real-time and shot-to-shot characterizations have been possible with the TOFS, and species of ions can be analyzed with the TPS. The two spectrometers show very good agreement of maximum proton energy even for a single laser shot. The composite ion spectrometer can provide two complementary spectra measured by TOFS with a large solid angle and TPS with a small one for the same ion source, which are useful to estimate precise total ion number and to investigate fine structure of energy spectrum at high energy depending on the detection position and solid angle. Advantage and comparison to other online measurement system, such as the TPS equipped with microchannel plate, are discussed in terms of overlay of ion species, high-repetition rate operation, detection solid angle, and detector characteristics of imaging plate.

Efficacy and safety of endoscopic submucosal dissection for gastric cancer in patients with liver cirrhosis

Endoscopic submucosal dissection (ESD) has become a widely accepted method for treating gastrointestinal cancer. The aim of this study was to evaluate the efficacy and safety of ESD for gastric cancer in patients with liver cirrhosis. A total of 18 gastric cancers were treated by ESD in 15 patients with cirrhosis. The rate of en bloc resection was 88.9% (16/18). En bloc resection with tumor-free lateral/basal margins (R0 resection) was 77.8% (14/18). Three patients had postoperative bleeding and underwent emergency gastroscopy for hemostasis. No recurrence was observed during the median follow-up of 21.4 months, excluding three patients in whom additional endoscopic resection or surgery was carried out. ESD can be safely performed for gastric cancer in patients with cirrhosis, resulting in a high en bloc resection rate.

Laser ion acceleration via control of the near-critical density target

Duration-controlled amplified spontaneous emission with an intensity of 10(13) W/cm(2) is used to convert a 7.5-microm -thick polyimide foil into a near-critical plasma, in which the p -polarized, 45-fs , 10(19) -Wcm (2) laser pulse generates 3.8-MeV protons, emitted at some angle between the target normal and the laser propagation direction of 45 degrees . Particle-in-cell simulations reveal that the efficient proton acceleration is due to the generation of a quasistatic magnetic field on the target rear side with magnetic pressure inducing and sustaining a charge separation electrostatic field.

Demonstration of laser-frequency upshift by electron-density modulations in a plasma wakefield

In a plasma wake wave generated by a high power laser, modulations of the electron density take the shape of paraboloidal dense shells, moving almost at the speed of light. A counterpropagating laser pulse is partially reflected from the shells, acting as relativistic flying mirrors, producing a time-compressed frequency-multiplied pulse due to the double Doppler effect. The counterpropagating laser pulse reflection from the plasma wake wave accompanied by its frequency multiplication (with a factor from 50 to 114) was detected in our experiment.

Radiological and histological features of tumoral calcinosis of the dorsum of the foot

Tumoral calcinosis is a rare condition characterized by large calcific masses occurring predominantly in the juxta-articular regions of the extremities. To our knowledge, occurrences in the foot, particularly in association with bone erosion, have been very rare. A 52-year-old Japanese man presented with a mass in the foot, the size of which increased over a period of 27 years. CT scan and MRI demonstrated a 6 cm x 3 cm x 2.5 cm sized mass. There was bone erosion of the dorsal side of the third metatarsal head. Marginal excision was made. Histopathologically, the mass was composed of amorphous calcification with inflammatory cell infiltration. X-ray diffraction method revealed that the pattern of the mass coincided with hydroxyapatite. The patients had no local recurrence at 5 years after operation.

CagA protein secreted by the intact type IV secretion system leads to gastric epithelial inflammation in the Mongolian gerbil model

Helicobacter pylori causes various gastro-duodenal diseases, including gastric cancer. The CagA protein, an H. pylori virulence factor, induces morphological changes in host cells and may be associated with the development of peptic ulcer and gastric carcinoma. The present study has analysed the role of CagA protein in the pathogenesis of H. pylori infection in the Mongolian gerbil model. Mongolian gerbils were challenged with wild-type H. pylori strain TN2, which has a functional cag pathogenicity island or isogenic mutants with disrupted cagA (DeltacagA) or cagE (DeltacagE) genes. They were sacrificed at 7, 13, and 25 weeks after inoculation. Pathological changes of the gastric mucosa were determined and apoptosis was assessed by the TUNEL assay. Immunohistochemistry for PCNA, phospho-IkappaBalpha, and phospho-Erk was also performed. All of the bacterial strains colonized the gerbil stomach at similar densities; however, the DeltacagA mutant induced milder gastritis than did the wild type. The extent of apoptosis and lymphoid follicle formation in the epithelium appeared to depend on intact cagA. The DeltacagA mutant induced less phosphorylation of IkappaBalpha and Erk, and less expression of interferon-gamma and interleukin-1beta mRNA in the epithelium than did the wild type. It is concluded that CagA protein may be essential for the induction of severe gastritis in the Mongolian gerbil model.

Successful nonsurgical management of perforation complicating endoscopic submucosal dissection of gastrointestinal epithelial neoplasms

BACKGROUND AND STUDY AIMS

Endoscopic submucosal dissection (ESD) is a novel technique used for the treatment of gastrointestinal neoplasia. One of its major limitations, however, is the complication of perforation.

PATIENTS AND METHODS

We included in our study all the cases of perforation that occurred during ESD procedures for gastrointestinal epithelial neoplasia between February 2000 and February 2005. Clinical outcomes after perforation were investigated.

RESULTS

Perforation was experienced at 27 lesions in 27 patients (four in the esophagus, fourteen in the stomach, seven in the colon, and two in the rectum). Fibrosis under the lesions was confirmed histologically in seven patients (26 %). Immediate closure using endoclips was performed in all patients except for three asymptomatic patients in whom a stomach perforation was first noticed when free air was noticed on a radiograph the morning after the ESD procedure. Air accumulation was detected radiographically in 21 patients (78 %). The mean duration of antibiotic treatment was 6.7 days and the patients were fasted for a mean period of 5.3 days. The mean maximum body temperature was 37.3 degrees C, the mean white blood cell count was 9733/mm3, and the mean C-reactive protein level was 5.0 mg/dl. All the patients were discharged well from the ward after a mean time of 12.1 days after ESD, and no recurrence caused by tumor spread from the perforation occurred in any patient after a median follow-up period of 36 months (range 9 - 52 months).

CONCLUSION

Successful nonsurgical management after ESD complicated by perforation is a highly feasible option if intensive conservative treatments are used following immediate endoscopic closure of the perforation.

New microsurgical technique for intraparenchymal lesions of the brain: transcylinder approach

BACKGROUND

Although various minimally invasive approaches, including endoscopic, stereotaxic, and ultrasound-guided surgery, have been introduced to minimize damage to healthy brain tissue, the microsurgical technique has retained a significant role in contemporary neurosurgery. A new microsurgical approach to intraparenchymal brain lesions, namely, the transcylinder approach, was developed to realize both minimal surgical access and sufficient microsurgical technique.

METHOD

A 0.1-mm transparent polyester film was used to create a cylindrical surgical route. The film was rolled into a thin stick and used to penetrate the brain, and a computer-aided navigation system was used from inside the stick to access the lesion accurately. After the stick gained access to the lesion, it was dilated to 2 cm, and this diameter was maintained during surgery.

FINDINGS

The transcylinder approach was used in 11 cases, including intraparenchymal tumours and haematomas, and the usual microsurgical procedure was performed without difficulty. The film avoided unnecessary enlargement of the surgical field and minimized injury to the brain. Intra-operative ultrasonography also can be used to identify the lesion through the cylinder because the polyester film does not reflect the ultrasound beam. The surgical route was observed to recover to almost the same size as the initial cortical incision after removal of the cylinder.

CONCLUSIONS

The transcylinder approach could be advantageous for removing tumours or haematomas in the intraventricular or intraparenchymal regions. By avoiding unnecessary retraction, it significantly reduces the risk of injury to surrounding brain tissue while facilitating precise microsurgical technique. The accuracy of this minimally invasive technique can be enhanced when used in conjunction with frameless stereotaxy and intra-operative ultrasound guidance.

Endoscopic submucosal dissection for rectal epithelial neoplasia

BACKGROUND AND STUDY AIMS

The technique of endoscopic submucosal dissection (ESD) has recently been developed for en-bloc resection of gastric tumors. For oncological reasons and in order to improve the patients' quality of life, it may be desirable to use the same technique for rectal neoplasia.

PATIENTS AND METHODS

Thirty-five consecutive patients with rectal neoplasia who had a preoperative diagnosis of large intraepithelial neoplasias with submucosal fibrosis or located on the rectal folds were enrolled. ESD was carried out with the same technique previously described for the stomach, with some modifications. The efficacy, complications, and follow-up results of the treatment were assessed.

RESULTS

The rates of en-bloc resection and en-bloc plus R0 resection were 88.6 % (31 of 35) and 62.9 % (22 of 35), respectively. Hemoglobin levels did not drop by more than 2 g/dl in any of the patients after ESD. None of the patients had to receive blood transfusions or undergo emergency colonoscopy due to bleeding during ESD or hematochezia after ESD. Perforation during ESD occurred in two patients (5.7 %), who were managed with conservative medical treatment after endoscopic closure of the perforation. Excluding three patients in whom additional surgery was carried out, all but one of 32 patients were free of recurrence during a mean follow-up period of 36 months (range 12 - 60 months). The exception was a patient in whom a multiple-piece resection was required; the recurrent (residual) tumor, found 2 months after ESD, was a small adenoma that was again treated endoscopically.

CONCLUSIONS

ESD is applicable in the rectum with promising results, but the technique is still at a developmental stage and patients should be informed of the potential risks.

Clinical significance of immunohistochemically detectable lymph node metastasis in adenocarcinoma of the ampulla of Vater

BACKGROUND

The aim of this study was to assess the impact of immunohistochemically identified lymph node metastasis on survival in patients with carcinoma of the ampulla of Vater.

METHODS

Three hundred and twenty-six regional lymph nodes dissected from pancreatoduodenectomy specimens from 25 patients with ampulla of Vater carcinoma were immunostained with anticytokeratin antibody (CAM 5.2). The clinicopathological significance of immunohistochemically detectable lymph node metastasis was evaluated and compared with that of other potential prognostic factors.

RESULTS

The frequency of lymph node involvement in relation to the total number of dissected lymph nodes increased from 5.5 per cent (18 of 326) using haematoxylin and eosin staining to 9.5 per cent (31 of 326) using cytokeratin immunostaining (P < 0.001). Lymph node involvement was revealed by haematoxylin and eosin staining in eight of 25 patients and by cytokeratin immunostaining in 11 of 25 patients (P = 0.006). Absence of immunohistochemically detectable lymph node metastasis was identified as an independent predictor of improved postoperative survival.

CONCLUSION

Immunostaining of dissected lymph nodes adds additional information to data obtained by conventional haematoxylin and eosin staining when determining the prognosis of patients with carcinoma of the ampulla of Vater.

Estimation of photon dose generated by a short pulse high power laser

The authors obtain a new equation to estimate the forward component of a photon dose generated through the interaction between a target and a short pulse high power laser. As the equation is quite simple, it is useful for calculating the photon dose. The equation shows that the photon dose is proportional to the electron temperature in the range>3 MeV and proportional to the square of the electron temperature in the range<3 MeV. The dose estimated with this method is roughly consistent with the result of Monte Carlo simulation. With some assumptions and corrections, it can reproduce experimental results obtained and the dose result calculated at other laboratories.