Fast-ion-induced secondary ion emission from submicron droplet surfaces studied using a new coincidence technique with forward-scattered projectiles.

A mass spectrometric study of secondary ions emitted from droplet surfaces by MeV-energy heavy ion impact was performed to investigate fast-ion-induced molecular reaction processes on liquid surfaces. Herein, a new coincidence technique was developed between secondary ions and scattered projectile ions at a small forward angle. The advantages of this technique were demonstrated by measurement of the collision between 4-MeV C3+ and ethanol droplets. Secondary ion emission probabilities were obtained directly from the coincidence data. Notably, this technique enabled positive fragment ions that had not been identified in previous measurements to be observed by suppressing the strong background originating from gas-phase molecules more than 104-fold. H+, H3O+, C2H5 +, and C2H5O+ were found to be produced as major positive fragment ions, in addition to minor fragments H2 +, C2H3 +, and CH2OH+. Production of these ions suggests that competition between rapid hydrogen ion emission from multiply ionized states and intermolecular proton transfer accompanied by fragmentation through protonated ethanol occurs after fast heavy-ion collisions. Clarification of the positive fragment ions also revealed the characteristic features of negative ions. Negative ions were realized to exhibit higher degrees of fragmentation and reactivity compared with positive ions. Furthermore, the energy loss by forward-scattered ions during droplet penetration was used to evaluate the target thickness at a submicron level. Variations in secondary ion yield, mass distribution, and kinetic energies depending on the penetration length were observed below 1 µm. These results highlight the unknown mechanism of these "submicron effects" observed in secondary ion emission processes as a new phenomenon.

The clinical value of PERCIST to predict tumour response and prognosis of patients with oesophageal cancer treated by neoadjuvant chemoradiotherapy.

AIM: To examine whether Positron Emission Tomography Response Criteria in Solid Tumours (PERCIST) is useful to predict tumour response and prognosis of patients with oesophageal cancer who received neoadjuvant chemoradiotherapy (NACRT) followed by surgery. MATERIALS AND METHODS: This multicentre retrospective study included 60 patients with oesophageal cancer who underwent 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (18F-FDG-PET/CT) before and after NACRT prior to surgery from January 2007 and June 2016. The correlation between pathological response and PERCIST was assessed by χ2 test. The prognostic significance was assessed by the Kaplan-Meier method and Cox regression analysis. RESULTS: There were 30 responders and 30 non-responders pathologically. The complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD) were seen in 22, 29, seven, and two patients, respectively. There was a significant correlation between pathological response and PERCIST (p<0.001). Forty patients showed eventual progression, and 20 patients were alive without progression between the start of NACRT and last clinical follow-up (median follow-up period; 27 months [range, 3-107]). Pathological stage and PERCIST were significant for progression-free survival (PFS; p=0.044 and 0.006, respectively) and also significant for overall survival (OS; p=0.009 and 0.001, respectively) at univariate analysis. Pathological lymph node staging was also significant for OS at univariate analysis (p=0.018). At multivariate analysis, PERCIST remained significant and independent for PFS (hazard ratio [HR]: 1.59, p=0.046) and OS (HR: 1.82, p=0.008). CONCLUSION: PERCIST may be useful for predicting tumour response and prognosis of patients with oesophageal cancer who received NACRT.

Follow-up rates of living kidney donor in Japan: A single center study.

Long-term follow-up of kidney donors is needed not only for the individual donor's benefit but also to establish analyzable databases to improve the selection criteria for future donors. We collected data including the date of transplantation, the date of the last follow-up, donor's age, sex, their relationship to the recipient, renal function, proteinuria, and the prevalence of hypertension. Of 124 donors, 52 donors were not being followed up. The mean duration of follow-up was 4.3 ± 3.6 years. Follow-up rates were 83.9%, 74.6%, and 59.2% at 1 year, 2 years, and 5 years postdonation, respectively. Of those not being followed up, 75% dropped out. Follow-up rates did not differ between parent and spouse donors 5 years (57.1% vs. 71.4%; P = 0.4) postdonation. Similarly, follow-up rates at 5 years did not differ between donors aged 60 years or older and those younger than 60 (57.5% vs. 61.3%; P = 0.6). Of 72 donors being followed up, 75.0% had estimated glomerular filtration rate of <60 mL/min/1.73 m2, 8.3% had proteinuria, and 41.7% had hypertension requiring medication. There is a limitation to the endeavor of each transplant center to follow-up all their donors. Long-term donor follow-up in Japan requires a national registration system and mandates transplant center participation.

Carbon and sulfur isotopic signatures of ancient life and environment at the microbial scale: Neoarchean shales and carbonates.

An approach to coordinated, spatially resolved, in situ carbon isotope analysis of organic matter and carbonate minerals, and sulfur three- and four-isotope analysis of pyrite with an unprecedented combination of spatial resolution, precision, and accuracy is described. Organic matter and pyrite from eleven rock samples of Neoarchean drill core express nearly the entire range of δ(13) C, δ(34) S, Δ(33) S, and Δ(36) S known from the geologic record, commonly in correlation with morphology, mineralogy, and elemental composition. A new analytical approach (including a set of organic calibration standards) to account for a strong correlation between H/C and instrumental bias in SIMS δ(13) C measurement of organic matter is identified. Small (2-3 µm) organic domains in carbonate matrices are analyzed with sub-permil accuracy and precision. Separate 20- to 50-µm domains of kerogen in a single ~0.5 cm(3) sample of the ~2.7 Ga Tumbiana Formation have δ(13) C = -52.3 ± 0.1‰ and -34.4 ± 0.1‰, likely preserving distinct signatures of methanotrophy and photoautotrophy. Pyrobitumen in the ~2.6 Ga Jeerinah Formation and the ~2.5 Ga Mount McRae Shale is systematically (13) C-enriched relative to co-occurring kerogen, and associations with uraniferous mineral grains suggest radiolytic alteration. A large range in sulfur isotopic compositions (including higher Δ(33) S and more extreme spatial gradients in Δ(33) S and Δ(36) S than any previously reported) are observed in correlation with morphology and associated mineralogy. Changing systematics of δ(34) S, Δ(33) S, and Δ(36) S, previously investigated at the millimeter to centimeter scale using bulk analysis, are shown to occur at the micrometer scale of individual pyrite grains. These results support the emerging view that the dampened signature of mass-independent sulfur isotope fractionation (S-MIF) associated with the Mesoarchean continued into the early Neoarchean, and that the connections between methane and sulfur metabolism affected the production and preservation of S-MIF during the first half of the planet's history.

Transplantation of Restored Kidneys From Unrelated Donors After Resection of Renal Cell Carcinoma: Results From 10 Patients.

PURPOSE: To relieve the chronic shortage of donor kidneys, we conducted a prospective kidney transplantation trial using kidneys removed from 10 unrelated patients (51 to 79 years of age) who had undergone nephrectomy for small renal cell carcinoma (1.5 to 3.9 cm) of low-to-moderate complexity based on RENAL (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, anterior/posterior location relative to polar lines) nephrometry (objective description helpful for operative indication and planning). METHODS: Donors were selected from among 15 patients who opted to undergo nephrectomy for small renal cell carcinoma. A total of 76 dialysis patients 34 to 85 years of age who agreed to undergo restored kidney transplantation were recruited as transplant candidates. RESULTS: In stage 1 (5 cases), high-risk patients were selected without human leukocyte antigen testing, and accelerated acute rejection occurred in 4 of 5 recipients. This trial was subsequently extended with human leukocyte antigen testing, and an additional 5 patients were enrolled in stage 2. Eight recipients, including 4 recipients with a history of renal transplantation, experienced rejection; 1 patient resumed dialysis 35 months after transplantation. The most recent serum creatinine levels ranged from 1.10 to 3.19 mg/dL in the 9 recipients with functioning grafts and from 0.84 to 4.68 mg/dL in the 10 donors. No tumor recurrence was noted at 32 to 58 months after surgery in either the recipients or the donors. CONCLUSIONS: Restored kidney transplantation using kidneys with a small renal tumor seems suitable for carefully selected high-risk recipients and, in particular, elderly kidneys can also function well. Avoiding cancer transmission, fair recipient selection, close follow-up, and a well-organized tracking system warrant further study.

Urinary tract reconstruction using uretero-ureteral end-to-side anastomosis in kidney transplant recipients.

BACKGROUND: In kidney transplant recipients, the most widely used method for the reconstruction of the urinary pathway is ureteroneocystostomy, which may be difficult in cases with disused atrophic bladder. In this study, we evaluated kidney transplant recipients who underwent uretero-ureteral end-to-side anastomosis (UUA) in urinary reconstruction due to disused atrophic bladder. METHODS: To clarify the effectiveness of this method, we retrospectively reviewed the clinical records of kidney transplant recipients in our hospital. RESULTS: A total of 9 recipients with urinary reconstruction using UUA were evaluated. All of these patients had a history of long-term hemodialysis before transplantation, accompanied by complete anuria and small capacity of the bladder. In 4 patients, cranial native ureter was ligated, whereas it was not ligated in the remaining 5 patients. In 2 of 4 patients with cranial ligation, hydronephrosis developed in the native kidney with no further treatment being required. No patients experienced urinary tract complications including hydronephrosis in the graft, urine extravasation, or urinary tract infection in the follow-up period (757.6 ± 491.3 days). Allograft function was maintained well in all patients (serum creatinine level, 1.08 ± 0.23 mg/dL). CONCLUSIONS: Although UUA is not a routine method of urinary reconstruction in kidney transplantation, it can be safely performed and should be a surgical option, especially for recipients with disused atrophic bladder. The ligation of cranial native ureter may lead to hydronephrosis of the native kidney, and it is tentatively concluded that UUA without native ureteral ligation is clinically feasible.

Computed diffusion-weighted MRI for prostate cancer detection: the influence of the combinations of b-values.

OBJECTIVE: To evaluate the influence of the combinations of b-values on computed diffusion-weighted images (cDWIs) for prostate cancer (PCa) detection at b = 2000 s mm(-2). METHODS: Diffusion-weighted imaging (DWIs) for 31 patients with PCa (65.2 ± 7.1 years) were obtained pre-operatively at different b-values (0, 100, 500, 1000 and 2000 s mm(-2)) on a 3-T MRI. cDWIs at b = 2000 were generated by using six b-value combinations: 0-100 s mm(-2) (cDWI0-100); 0-500 s mm(-2) (cDWI0-500); 100-500 s mm(-2) (cDWI100-500); 0-1000 s mm(-2) (cDWI0-1000); 100-1000 s mm(-2) (cDWI100-1000); and 500-1000 s mm(-2) (cDWI500-1000). These cDWIs and measured DWIs with b = 2000 s mm(-2) (mDWI2000) were evaluated in this setting. To assess image quality for each DWI, contrast ratios (CRs) of cancerous and non-cancerous lesions were evaluated. To compare the detectability of PCa for each DWI, receiver operating characteristic analysis was used. RESULTS: CRs of all cDWIs were significantly higher than those of mDWI2000 (p < 0.05). Areas under the curve of cDWI0-100 (0.62) and cDWI0-500 (0.65) were significantly smaller (p < 0.05) than those of others (cDWI100-500, 0.72; cDWI0-1000, 0.73; cDWI100-1000, 0.71; cDWI500-1000, 0.74; mDWI2000, 0.72). CONCLUSION: The combinations of b-values influenced image quality and diagnostic ability of cDWIs for PCa detection. The combinations of b ≥ 100 and b ≥ 500 s mm(-2), as well as b = 0 and b = 1000 s mm(-2), were optimal in this study. ADVANCES IN KNOWLEDGE: For generating the useful cDWI for PCa detection, radiologists should take care of the combination of b-values when including low b-values.

Leiomyosarcoma of the broad ligament: a case report with CT and MRI images.

Primary leiomyosarcoma of the broad ligament is a very rare and highly malignant gynecological tumor. The authors report a 61-year-old postmenopausal woman with signs and symptoms of malignant ovarian tumor. Preoperative magnetic resonance imaging (MRI) was interpreted as being suspicious for malignant tumors, such as an ovarian cancer or a leiomyosarcoma of the broad ligament, so laparotomy was performed. Macroscopically, the tumor was revealed with a 18 x 13.7 x 9.5 cm degenerated, multiple cystic part and solid whitish part arising from broad ligament which on histopathology proved to be leiomyosarcoma. To the best of the authors' knowledge, primary leiomyosarcoma of the broad ligament has been documented in 21 reports or so, and no imaging findings are available. Here the authors present the MRI findings of primary leiomyosarcoma of the broad ligament.

Established, emerging and future applications of FDG-PET/CT in the uterine cancer.

Integrated positron emission tomography/computed tomography (PET/CT) with 2-[¹8F]fluoro-2-deoxy-D-glucose (FDG) is a useful technique to acquire both glucose metabolic and anatomic imaging data using a single device in a single diagnostic session and has opened a new field in clinical oncologic imaging. FDG-PET/CT has been used successfully for the staging, optimization of treatment, re-staging, therapy monitoring, and prognostic prediction of uterine cervical cancer and endometrial cancer as well as various malignant tumours. The present review discusses the current role of FDG-PET/CT in the management of uterine cancer, discussing its usefulness and limitations in the imaging of these patients.

FDG PET/CT features of ovarian metastasis.

AIM: To assess the characteristics of [(18)F]-fluoro-2-deoxy-d-glucose (FDG) uptake in cases of ovarian metastasis using positron-emission tomography/computed tomography (PET/CT). MATERIALS AND METHODS: Twelve patients with 16 ovarian metastases arising from colon cancer (n=6), breast cancer (n=4), gastric cancer (n=3), and pancreatic cancer (n=3) who underwent FDG-PET/CT examination were included in this study. The effect of lesion size and morphological pattern (predominantly solid or cystic) on FDG uptake was evaluated using the quantitative standardized uptake value (SUV). RESULTS: The mean maximum SUV for the 16 lesions was 4.6±2.4 (range 1.8∼9.9). The Pearson correlation coefficient test showed no significant correlation between maximum SUV and lesion size (r=0.21, p=0.42). The maximum SUV of solid (n=5) and cystic (n=11) lesions was 5.5±2.7 and 4.3±2.2, respectively, and the difference was not significant (p=0.43). Breast cancer showed the highest maximum SUV (6.4±3.6), followed by colon cancer (5.3±1.4), gastric cancer (3.3±0.5), and pancreatic cancer (2.2±0.6). CONCLUSION: Ovarian metastases show a variable maximum SUV with mild to intense FDG uptake.

Perioperative management of combined heart-liver transplantation in patients with cirrhosis, renal insufficiency, or pulmonary hypertension.

UNLABELLED: STATING THE MAIN PROBLEM: Only few reports have detailed perioperative management and outcome of combined heart and liver transplantation (CHLT), and none describe the long-term renal function. METHODS: Three patients presented clinical signs of cardiomyopathy with reduced ejection fraction and proven cirrhosis with evidence of portal hypertension. Two of them presented renal failure, and the other pulmonary hypertension. After cardiac transplantation and closure of the sternum, liver transplantation was performed using systematically venovenous double-limb (portal and caval) bypass. RESULTS: Mean cold ischemic time for heart and liver was 2 h 46 min and 12 h 47 min, respectively. Intraoperative hemodynamics remained grossly stable during surgery. Mean transfusions were 12 red blood cell packs. All three patients received anti-R-Il2 antibodies at post-operative day 1 and 4. Mean plasma creatinine concentration was 90 ± 8 µmol/L one yr post-CHLT, vs 160 ± 62 µmol/L pre-CHLT. All three patients are alive with functional grafts after a mean follow-up of 26 months (12-38). CONCLUSION: CHLT could be performed safely through two consecutive and independent usual procedures. Perioperative hemodynamic stability, minimal blood loss, and routine splanchnic decompression are probably major determinants of a favorable outcome and good long-term renal function.

The use of frequency scale for the symptoms of GERD in assessment of gastro-oesophageal reflex symptoms in asthma.

In adult asthmatics the incidence of gastro-oesophageal reflux disease (GERD) reportedly ranges from 34% to 89%. Oesophageal pH monitoring and endoscopy are not required in the patient with typical GERD symptoms before the initiation of a therapeutic trial. Diagnosis of GERD on the basis of history is the simplest and quickest method, placing no demand on patients. Recently, a new questionnaire (FSSG; Frequency Scale for the Symptoms of GERD) was produced to evaluate the severity and the therapeutic response of GERD. The FSSG (F-scale) was used to assess the GERD in subjects with persistent moderate to severe asthma treated with anti-inflammatory asthma medication. In the present study, 27.4% of the patients with asthma had symptoms suggestive of GERD. There is significant correlation between GERD symptom (F-scale score) and severity of cough and sputum. The observations suggested that reflux symptoms, not gastric dysmotility symptoms, significantly associated with severity of cough, not of sputum. It is the first such study to use a FSSG as incidence of GERD symptoms in asthmatics and examine the relationship between F-scale score and asthmatic symptoms.

ABO blood type incompatible kidney transplantation without splenectomy prepared with plasma exchange and rituximab.

We have designed a protocol for ABO-incompatible kidney transplantations based on preoperative plasmapheresis with a tacrolimus/mycophenolate mofetil/methylprednisolone/basiliximab protocol using low-dose rituximab (200 mg/body) instead of splenectomy to prevent antibody-mediated acute rejection. Eight patients successfully received transplants with this protocol. The titers of anti-A and -B antibodies as well as the number of CD20(+) cells were readily maintained at a low level posttransplantation. There were no side effects. All patients have renal transplant function with a follow-up of 1-34 months.

Autologous blood transfusion for kidney transplant recipients.

Autologous blood transfusion (ABT) is rarely employed in patients with end-stage renal disease (ESRD); these patients are usually anemic. Since 1998, we have attempted ABT for ESRD patients undergoing living-related kidney transplantation. Among 20 patients enrolled in this study the preoperative hemoglobin and hematocrit levels were 10.0 +/- 1.2 mg/dL (range, 8.1-11.7) and 30.0 +/- 3.7% (range, 24.7-34.3), respectively. Blood volume collected on each occasion was 235.7 +/- 57.7 mL (range, 200-400), and the number of blood collections was 2.45 +/- 0.9 (range, 1-4). Total collected volume was 567.5 +/- 157.5 mL (range, 400-800). Symptomatic hypotension was seen in two patients, but vital signs recovered spontaneously. No other problems related to blood collection were observed. Allogeneic transfusion was need in only one patient (5%). ABT was safe and efficacious in ESRD patients scheduled for living-related kidney transplantation.

Sonographic preoperative assessment of liver volume before major liver resection.

OBJECTIVE: The use of ultrasonography is widespread for both the diagnosis and treatment of liver tumors. However, the measurement of liver volume by ultrasonography is not commonly done. We report an original method of liver volumetry using ultrasonography and an investigation into the usefulness of ultrasonography in this context. METHODS: The data for 50 patients undergoing various types of major hepatectomy were collected. We preoperatively measured liver volume using ultrasonography, dividing the liver into three main compartments according to precise anatomical landmarks, and then made comparisons with the volume of the actual specimen after hepatectomy, for all of the study participants. RESULTS: Total volume correlation between the two groups was good (r = 0.916, P < 0.001). However, the correlation was weaker in cases of right hepatectomy compared with other types of hepatectomy. CONCLUSION: This study demonstrates the possibility of doing liver volumetry using an ultrasound device. Further investigation to establish the reliability of this easily available and noninvasive approach is needed.

Shedding of porcine circovirus into colostrum of sows.

The purpose of the present study was to investigate porcine circovirus (PCV) shedding into the milk of sows. Colostrum was collected from 33 sows. PCV1 was isolated from four of 33 milk whey samples. PCV1 DNA was detected by polymerase chain reaction in three of these samples and in three of 10 milk cell samples. PCV2 was also isolated and detected from every single milk whey sample. These results showed that PCV1 and PCV2 were shed into the milk of sows and suggest that PCV can be transmitted to offspring by an oral route through milk.

Methylation of the oestrogen receptor gene in non-neoplastic epithelium as a marker of colorectal neoplasia risk in longstanding and extensive ulcerative colitis.

BACKGROUND: Surveillance colonoscopy is widely recommended in patients with longstanding and extensive ulcerative colitis (UC) in order to detect colorectal neoplasia at an early stage. However, it still remains questionable whether surveillance colonoscopy effectively enables early detection of UC associated neoplasia. There is a great need for sensitive markers to identify individuals at increased risk of neoplasia. The oestrogen receptor (OR) gene shows age related methylation in the colorectal epithelium and is methylated frequently in sporadic colorectal neoplasia, suggesting that OR methylation may predispose to colorectal neoplasia. AIM: To clarify whether analysis of methylation of the OR gene in non-neoplastic epithelium can contribute to prediction of increased neoplasia risk in UC patients. MATERIALS AND METHODS: A total of 165 non-neoplastic colorectal epithelia from 30 patients with longstanding and extensive UC, including 13 UC patients with neoplasia and 17 patients without, were evaluated. Methylation specific polymerase chain reaction was performed to determine the methylation status of the OR gene. RESULTS: Methylation of the OR gene was detected in 54 of 70 (77.1%) non-neoplastic colorectal epithelia in UC with neoplasia but in only 23 of 95 (24.2%) without neoplasia. Methylation of the OR gene was significantly more frequent in non-neoplastic epithelium from UC with neoplasia than in chronic colitic epithelium from UC without neoplasia. Furthermore, in UC with neoplasia, the OR gene was extensively methylated in non-neoplastic epithelia throughout the colorectum compared with those in UC without neoplasia. CONCLUSION: These results suggest that analysis of OR gene methylation may have potential as a useful marker for identifying individuals at increased risk of neoplasia among those with longstanding and extensive UC.

Ethnic differences in the formation of small LDL particles in Asians: a comparison of Koreans, Japanese and Mongolians.

BACKGROUND: The presence of small, dense LDL particles has been recognized as an independent risk factor for coronary heart disease (CHD) but is not directly representative of CHD mortality rate beyond any given population. We investigated whether such inconsistency between three Asian ethnic groups might have arisen from anthropometric and metabolic factors. DESIGN: We conducted a cross-sectional survey among adult Koreans (412), Japanese (453) and Mongolians (253). RESULTS: The prevalence of small LDL particles was 36% in the Koreans, 21% in the Japanese and 7% in the Mongolians. Multiple logistic regression analysis revealed plasma triglyceride (TG) levels to be the strongest determinant of small LDL particle size in all three groups, with sex, HDL-cholesterol and non-HDL-C being other ethnic-specific significant determinants. Body mass index (BMI), FFA and insulin resistance were not significant factors in the regression analysis. Of the subjects with low TG levels (< 133 mg dL(-1)), 25% of the Koreans and 10% of the Japanese, but no Mongolians, had small LDL particles. CONCLUSIONS: Results of the present study suggest that traditionally, high-carbohydrate diets in Korea and Japan possibly contribute to higher TG-levels compared with BMI-matched Mongolians, and to the formation of small LDL particles, even in instances of low TG levels.

Specificity of human trans-sialidase as probed with gangliosides.

It has been shown that human blood contains a soluble 67 kDa enzyme, belonging by its donor-acceptor properties to trans-sialidases. The enzyme is capable of both cleaving and synthesizing alpha2-3 and alpha2-6 sialosides [Atherosclerosis2001, 159, 103]. In this work the study of donor-acceptor specificity of the new enzyme was extended. It has been demonstrated in vitro that trans-sialidase possesses the ability of transferring Neu5Ac residue to acceptor (asialofetuin) both from alpha2-3- (GM1, GM3, GD1a), and alpha2-8-sialylated gangliosides (GD3 and GD1b, but not GT1b and GQ1b). Transfer of radiolabeled Neu5Ac from fetuin to glycosphingolipids demonstrated that Lac-Cer>mono- and disialogangliosides>GT1b>GQ1b were acceptors for this enzyme. Two methods were used to reveal whether alpha2-8 bond can be formed between Neu5Ac residues during trans-sialylation, that is immunochemical detection using monoclonal antibodies specific to alpha2-8 di- and oligosialic acids, and fluorometric C7/C9 analysis. Both methods demonstrated the formation of Neu5Acalpha2-8Neu5Ac termination by trans-sialidase, for example, in case of the use 3'SL as sialic acid donor and Neu5Ac-PAA or LDL as acceptor. Thus, human trans-sialidase in vitro displays wide substrate specificity: the enzyme is capable of digesting as well as synthesizing alpha2-3, alpha2-6, and alpha2-8 sialosides.

Development of colonic neoplasia in p53 deficient mice with experimental colitis induced by dextran sulphate sodium.

BACKGROUND: Several animal models for human ulcerative colitis (UC) associated neoplasia have been reported. However, most neoplasias developed in these models have morphological and genetic characteristics different from UC associated neoplasia. AIMS: To establish a new colitis associated neoplasia model in p53 deficient mice by treatment with dextran sulphate sodium (DSS). METHODS: DSS colitis was induced in homozygous p53 deficient mice (p53(-/-)-DSS), heterozygous p53 deficient mice (p53(+/-)-DSS) and wild-type mice (p53+/+-DSS) by treatment with 4% DSS. Numbers of developed neoplasias were compared among the experimental groups, and macroscopic and microscopic features of the neoplasias were analysed. Furthermore, K-ras mutation and beta-catenin expression were assessed. RESULTS: p53(-/-)-DSS mice showed 100% incidence of neoplasias whereas the incidences in p53(+/-)-DSS and p53+/+-DSS mice were 46.2% and 13.3%, respectively. No neoplasias were observed in the control groups. The mean numbers of total neoplasias per mouse were 5.0 (p53(-/-)-DSS), 0.62 (p53(+/-)-DSS), and 0.2 (p53+/+-DSS). The number of neoplasias per mouse in the p53(-/-)-DSS group was significantly higher than that in the other DSS groups. The incidences of superficial type neoplasias were 91.7% in p53(-/-)-DSS mice, 75.0% in p53(+/-)-DSS mice, and 33.3% in p53+/+-DSS mice. The K-ras mutation was not detected in any of the neoplasias tested. Translocation of beta-catenin from the cell membrane to the cytoplasm or nucleus was observed in 19 of 23 (82.6%) neoplasias. CONCLUSIONS: The p53(-/-)-DSS mice is an excellent animal model of UC associated neoplasia because the morphological features and molecular genetics are similar to those of UC associated neoplasia. Therefore, this model will contribute to the analysis of tumorigenesis related to human UC associated neoplasia and the development of chemopreventive agents.