Plate reduction in southern Japanese freshwater populations of threespine stickleback (Gasterosteus aculeatus).

Adaptation to similar environments can lead to the evolution of similar phenotypes in phylogenetically independent lineages. However, the extent of parallel evolution often varies. Because such variations can be due to environmental heterogeneity among seemingly similar habitats, identification of the environmental factors that cause non-parallel patterns can provide valuable insight into the ecological factors associated with phenotypic diversification. Armor plate reduction in replicate freshwater populations of the threespine stickleback (Gasterosteus aculeatus) represents a well-known example of parallel evolution. Many freshwater populations in multiple regions of the Northern Hemisphere have reduced plate numbers, but not all freshwater populations exhibit plate reduction. In this study, we characterized plate number variation in Japanese freshwater populations and investigated the association between plate number and several abiotic environmental factors. We found that most freshwater populations have not reduced plate numbers in Japan. Plate reduction tends to occur in habitats with warmer winter temperatures at lower latitudes in Japan. In contrast, low dissolved calcium levels or water turbidity had no significant effects on plate reduction, although these were reported to be associated with plate reduction in Europe. Although our data are consistent with the hypothesis that winter temperatures are associated with plate reduction, further studies on the relationship between temperatures and fitness using sticklebacks with varying plate numbers are necessary to confirm this hypothesis and understand the factors causing variations in the extent of parallel evolution.

Multiple waves of freshwater colonization of the three-spined stickleback in the Japanese Archipelago.

BACKGROUND: The three-spined stickleback (Gasterosteus aculeatus) is a remarkable system to study the genetic mechanisms underlying parallel evolution during the transition from marine to freshwater habitats. Although the majority of previous studies on the parallel evolution of sticklebacks have mainly focused on postglacial freshwater populations in the Pacific Northwest of North America and northern Europe, we recently use Japanese stickleback populations for investigating shared and unique features of adaptation and speciation between geographically distant populations. However, we currently lack a comprehensive phylogeny of the Japanese three-spined sticklebacks, despite the fact that a good phylogeny is essential for any evolutionary and ecological studies. Here, we conducted a phylogenomic analysis of the three-spined stickleback in the Japanese Archipelago. RESULTS: We found that freshwater colonization occurred in multiple waves, each of which may reflect different interglacial isolations. Some of the oldest freshwater populations from the central regions of the mainland of Japan (hariyo populations) were estimated to colonize freshwater approximately 170,000 years ago. The next wave of colonization likely occurred approximately 100,000 years ago. The inferred origins of several human-introduced populations showed that introduction occurred mainly from nearby habitats. We also found a new habitat of the three-spined stickleback sympatric with the Japan Sea stickleback (Gasterosteus nipponicus). CONCLUSIONS: These Japanese stickleback systems differ from those in the Pacific Northwest of North America and northern Europe in terms of divergence time and history. Stickleback populations in the Japanese Archipelago offer valuable opportunities to study diverse evolutionary processes in historical and contemporary timescales.

Usefulness of dual-phase 18F-FDG PET/CT for diagnosing small pancreatic tumors.

OBJECTIVES: The usefulness of dual-phase F-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) for pancreatic tumors was investigated including numerous small tumors. METHODS: Consecutive 116 patients with solid pancreatic tumors were subjected. Maximum standard uptake values (SUVmax) at 1 and 2 hours after FDG injection were defined as early and delayed SUVmax, respectively. Receiver operating characteristic curve was used to determine the optimal cutoff value of early SUVmax. Diagnostic accuracy of dual-phase FDG PET/CT was compared with that of single phase. RESULTS: The mean ± SD tumor size was 25 ±12 mm in diameter. The level of early SUVmax and proportion of elevated SUVmax in delayed phase were significantly higher in malignancy than those in benignancy for less than 25 mm tumors (4.1 ± 2.6 vs 1.9 ± 0.5, P < 0.001; 89% vs 17%, P < 0.0001) although they did not reach statistical significance for greater than or equal to 25 mm tumors. When diagnostic criteria of dual-phase FDG PET/CT for less than 25 mm tumors were determined as (1) early SUVmax greater than or equal to 2.1 and/or (2) delayed SUVmax greater than early SUVmax, sensitivity, specificity, and over all accuracy of dual-phase FDG PET/CT were better than that of single phase for less than 25 mm tumor (93%, 83%, and 91% vs 79%, 83%, and 80%, respectively). CONCLUSIONS: Dual-phase FDG PET/CT might be useful for diagnosing small pancreatic tumors.

Alteration of strain ratio evaluated by transabdominal ultrasound elastography may predict the efficacy of preoperative chemoradiation performed for pancreatic ductal carcinoma: preliminary results.

BACKGROUND/AIM: We evaluated the usefulness of ultrasound-elastography (US-elastography) for prediction of therapy effect by measuring strain ratio (SR). METHODOLOGY: Consecutive patients with resectable pancreatic ductal carcinoma who underwent US-elastography before and after neoadjuvant chemoradiation were included. Patients were classified into either response group or non-response group according to the histological evaluation of resected specimens. Serum carbohydrate antigen 19-9 (CA19-9), SR, and maximum standard uptake value (SUVmax) obtained from 18F-fuluoro-deoxy-D-glucose positron emission tomography and computerized tomography were measured before and after chemoradiation. Alteration rate of each parameter was compared between response group and non-response group. RESULTS: Seven patients met the inclusion criteria. One patient was excluded from pancreatectomy because liver metastasis was found by laparotomy. Serum CA19-9 was not elevated for 2 patients throughout the chemoradiation. Three patients were classified into response group and the remaining three into non-response group. Alteration rate of CA19-9 and SR was shown to be grater in response group (26.83 +/- 19.69 vs. 4.87 +/- 4.25, and 3.61 +/- 2.40 vs. 1.39 +/- 0.20, respectively), whereas that of SUVmax was not (1.56 +/- 0.43 vs. 2.11 +/- 0.10). CONCLUSIONS: Increase rate of SR may predict the therapy effect of neoadjuvant chemoradiation for patients with pancreatic ductal carcinoma, especially for patients without elevation of tumor markers.

Differentiation of lung neoplasms with lepidic growth and good prognosis from those with poor prognosis using computer-aided 3D volumetric CT analysis and FDG-PET.

BACKGROUND: Many studies have reported that transverse computed tomography (CT) imaging findings correlate with prognosis of patients with small peripheral lung neoplasm with lepidic growth. However, no studies have examined this correlation with the aid of three-dimensional (3D) CT data. PURPOSE: To determine the most efficacious imaging factor for differentiation of lepidic growth type lung neoplasms with good prognosis from those with poor prognosis. MATERIAL AND METHODS: We evaluated CT findings, nodule patterns, SUVmax on FDG-PET/CT, as well as nodule volume and ratios of solid parts to nodule volume that were semi-automatically measured on CT images of 64 pulmonary nodules of ≤ 2 cm in 60 consecutive patients (24 men and 36 women; mean age, 65 years). For logistic modeling, we used all of the significant factors observed between the neoplasms with good and with poor prognosis as independent variables to estimate the statistically significant factors for discriminating invasive adenocarcinomas with lepidic growth (lesions with poor prognosis, n=42) from the other neoplasms, including preinvasive lesions (lesions with good prognosis, n=22), resulting in a recommendation for the optimal criterion for predicting lesions with poor prognosis. RESULTS: The logistic regression model identified the ratio of the solid part to the whole volume of a pulmonary nodule as the only significant factor (P=0.04) for differentiating lepidic growth type lung neoplasms with good prognosis from those with poor prognosis. A ratio of 0.238 or more showed the highest discriminatory accuracy of 84% with 91% sensitivity and 76% specificity. CONCLUSION: Computer-aided analyses of pulmonary nodules proved most useful for establishing the optimal criterion for differentiation of lepidic growth type lung neoplasms with good prognosis from those with poor prognosis.

F18-FDG PET-CT analyses of small peripheral adenocarcinoma of the lung.

BACKGROUND: Radiological discrimination of histologic subtypes of small peripheral adenocarcinoma of the lung is clinically important. Although there are many articles in which CT findings were used for this purpose, there are only a few reports on the capability of FDG PET-CT findings for histologic classification of this tumor. PURPOSE: To investigate the correlation between visual assessment or maximum standard uptake values (SUVmax) on F18-FDG PET-CT and histology grading of small peripheral adenocarcinoma of the lung. MATERIAL AND METHODS: Proportions of positive PET-CT diagnoses and SUVmax were retrospectively reviewed on 96 solitary pulmonary nodules of ≤2 cm in 90 consecutive patients. Tumors were classified into four groups according to Noguchi's classification (group 1 [n = 10], atypical adenomatous hyperplasia and type A tumors; group 2 [n = 12], type B tumors; group 3 [n = 42], type C tumors; group 4 [n = 32], types D, E, and F tumors). Proportions of positive PET-CT diagnoses and mean SUVmax of lesions among four groups were compared using trend tests to examine if there is a significant linear correlation with the progression of the histology grading of tumors. Then, an optimal threshold of SUVmax was proposed to best discriminate tumors of poor (groups 3 and 4) from good (groups 1 and 2) prognosis. RESULTS: There was a significant linear trend for both visual assessment (P < 0.01) and SUVmax (P < 0.01). A SUVmax of 0.42 showed the highest accuracy of 84% with 95% sensitivity and 50% specificity for predicting tumors of poor prognosis. A SUVmax of 2.05 showed 100% specificity with 49% sensitivity, and 60% accuracy. Positive visual diagnoses showed accuracy of 83% with 90% sensitivity and 59% specificity. CONCLUSION: Visual assessment and SUVmax on PET-CT correlated well with the histology grading of small peripheral adenocarcinoma of the lung.

Predicting the effects of chemoradiotherapy for squamous cell carcinoma of the esophagus by induction chemotherapy response assessed by positron emission tomography: toward PET-response-guided selection of chemoradiotherapy or esophagectomy.

BACKGROUND: We have developed a treatment protocol for esophageal cancer involving a single course of induction chemotherapy followed by chemoradiotherapy. This study aimed to determine if it was possible to predict the effects of chemoradiotherapy on the basis of the response to induction chemotherapy, assessed by positron emission tomography (PET). METHODS: Sixteen patients with Stage II-IVA esophageal cancer were treated using this protocol from April 2007 to July 2010. Chemotherapy involved a fluorouracil and platinum-based combination regimen. All patients received PET scans before and 12-24 days after the beginning of induction chemotherapy. Associations between the response to induction chemotherapy assessed by PET and the effects of chemoradiotherapy were evaluated. RESULTS: Induction chemotherapy followed by chemoradiotherapy resulted in complete response (CR) in 10 of the 16 patients. The reduction in maximum standardized uptake value (SUV(max)) was 58 ± 12% in patients with CR (n = 10), compared with 14 ± 16% in patients without CR (n = 6) (P < 0.0001). Using a cut-off value of 55% for SUV(max) reduction rate, eight of 10 cancers with CR and six of six cancers without CR were correctly identified, providing a sensitivity and specificity of 80 and 100%, respectively. The overall 1-year survival rates for patients with an SUV(max) reduction rate >55% (responders) were 100%, compared with 60% for patients with an SUV(max) reduction rate ≤55% (non-responders), respectively. CONCLUSIONS: The response to a single course of induction therapy assessed by PET was significantly associated with the effects of chemoradiotherapy.

Occult mediastinal lymph node metastasis in NSCLC patients diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT: Risk factors, pattern, and histopathological study.

BACKGROUND: Integrated F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is widely used for mediastinal lymph node (MLN) staging in patients with non-small cell lung cancer (NSCLC). However, FDG-PET/CT has certain limitations. Prediction of occult MLN metastasis could allow selection of candidates for preoperative cervical mediastinoscopy or endobronchial ultrasound-guided transbronchial needle aspiration. This study defined risk factors for occult MLN metastasis in patients with NSCLC patients who were diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT. METHODS: Consecutive patients with NSCLC who underwent staging using integrated FDG-PET/CT as an adjunct to CT prior to lung resection from October 2006 to September 2009 were evaluated retrospectively. The prevalence of MLN metastasis in patients diagnosed as clinical N0-1 was analyzed according to clinicopathological factors such as tumor location, tumor size, histology, and FDG uptake by the primary tumor. Risk factors for occult MLN metastasis were defined by multivariate analysis. Patterns of occult MLN metastasis were also analyzed and the involved MLNs were further examined histopathologically. RESULTS: The incidence of MLN metastasis was 11% (24 patients of 224). Multivariate analysis identified adenocarcinoma (P=0.04), tumors located in upper or middle lobe (P=0.02), tumor size >3 cm (P=0.01), and SUV(max) of primary tumor >4.0 g/ml (P=0.04) as significant risk factors for MLN metastasis. The pattern of occult MLN metastasis was typical for NSCLC cases. The size of metastatic foci were small, with 68% of foci smaller than 4.0mm. CONCLUSIONS: The present study demonstrated that adenocarcinoma, tumors located in the upper or middle lobe, tumor size >3 cm, and SUV(max) of primary tumor >4.0 g/ml are risk factors for occult MLN metastasis in patients with NSCLC who were diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT. Patients with tumors located in the right upper or middle lobe are considered candidates for cervical mediastinoscopy because the involved metastatic mediastinal lymph nodes are easily accessible by these modalities.

Clinical value of F18-fluorodeoxyglucose positron emission tomography-computed tomography in patients with non-small cell lung cancer after potentially curative surgery: experience with 241 patients.

OBJECTIVES: F18-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT), which allows differentiation between malignant and benign lesions based on difference in tissue glucose metabolism, has become increasingly important in lung cancer diagnosis. This study examined the clinical value of FDG-PET/CT in a large number of patients with non-small cell lung cancer (NSCLC) after potentially curative surgery. METHODS: Four hundred and ninety FDG-PET/CT of 241 patients (143 males and 98 females; age range 38-87 years; mean 68.0 years) between May 2006 and February 2008 were retrospectively evaluated. All the 241 patients had undergone potentially curative surgery for NSCLC >6 months before FDG-PET/CT and their pathologic stages were stage I and II according to the tumor-node-metastasis (TNM) classification. A final diagnosis of recurrence was confirmed by histologic or cytologic examination of the disease or by clinical and radiologic follow-up image analysis. Confirmation of recurrence-free status was based on a clinical and radiologic image analysis follow-up period of at least 12 months with no evidence of active malignancy. The diagnostic performance of FDG-PET/CT was evaluated. Details of false results and incidental detection of diseases other than recurrent lung cancer by FDG-PET/CT was also analyzed. RESULTS: Recurrences were confirmed in 35 (15%) patients, and 206 patients (85%) had no evidence of recurrence. FDG-PET/CT correctly diagnosed recurrence in 34 of 35 patients and provided true negative findings in 198 of 206 patients who had no evidence of recurrence (sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 97%, 96%, 96%, 81%, and 99%, respectively), indicating a high diagnostic performance. However, one patient had false negative studies and eight patients had false positive studies; misdiagnosis was more frequently in intrathoracic sites associated with postoperative changes. Malignancies other than recurrence were detected in nine of all 241 patients (4%) including five second primary lung cancers. CONCLUSIONS: The present study demonstrated the high diagnostic performance of FDG-PET/CT in detecting recurrences in a large group of patients with NSCLC after potentially curative surgery. FDG-PET/CT is useful not only for diagnosis of recurrence but also for detection of other diseases.

New ambulatory implant technique of high-dose-rate interstitial brachytherapy for prostate cancer.

PURPOSE: The aim of this study was to improve the performance status of prostate cancer patients during high-dose-rate interstitial brachytherapy (HDR-ISBT). To this end, we have developed a new ambulatory implant technique. MATERIALS AND METHODS: Ten prostate cancer patients were treated with HDR-ISBT as monotherapy from October 2003 until March 2004. We utilized a new removable template, a flexible applicator with a nonmetallic bead and button stopper, and an inner catheter connecting the applicator and the transfer tube of the brachytherapy unit. We shortened the connector end of the flexible applicator to enable the patient to sit down and walk freely during the treatment time. RESULTS: All 10 patients could walk without any support. No problem in the application was observed. CONCLUSION: Our new ambulatory implant technique for HDR-ISBT was able to improve the performance status of prostate cancer patients.

Quantitative evaluation of acute mucosal reaction to interstitial brachytherapy using color histograms.

PURPOSE: Color histograms of tongue photographs were used to make a quantitative evaluation of acute mucosal reaction to high-dose-rate fractionated interstitial brachytherapy. METHODS AND MATERIALS: Six patients with oral cavity cancer were analyzed with two methods (color histogram and vinyl plate). Using a photograph of the tongue, we calculated the histogram of each pixel of 1mm(2) of the tongue surface. The results were compared with the physician's inspection and the radiation dose. RESULTS: The histogram showed a difference between the reactive area (erythema and pseudomembranous mucositis [PM]) and the nonreactive area. The relationship between inspection and the histogram showed a good correlation, although the histogram tended to change earlier than the subjective judgment. The peak time was 12-13 days after delivery of the final fraction of brachytherapy. The minimum dose required to cause PM was 3.3-3.6Gy per fraction (total: 29.7-32.4Gy). CONCLUSIONS: Our new method of using color histograms for quantitative evaluation is helpful in the analysis of the relationship between mucosal reaction and radiation dose. The minimum dose causing PM was considered to be about 30Gy per nine fractions.

[Visualization of pancreaticobiliary reflux in patients with elevated amylase activity in bile with dynamic secretin-stimulated MR cholangiopancreatography].

Seven patients who had elevated amylase activity in the bile at cholecystectomy and seven normal volunteers were prospectively examined by secretin-stimulated dynamic MRCP. Thirty-five consecutive MR cholangiopancreatograms were acquired at intervals of approximately 10 sec after secretin injection; the acquisition time was 4 sec per image. In all normal volunteers, no apparent signal intensity (SI) changes were noted in the intra- and extrahepatic ducts. Of the 7 patients, the extrahepatic duct showed a sequential SI increase from downstream to upstream in 6; its caliber increased subsequent to pancreatic fluid secretion in 5; and duodenal filling grade tended to be lower in the patients (p < 0.01). These findings were thought to be suggestive of pancreaticobiliary reflux.