•We develop a general oligopolistic equilibrium model.•The effects of trade and FDI liberalization are examined.•Trade liberalization alone may be welfare-reducing.•FDI liberalization is necessarily ...welfare-improving.•Simultaneous liberalization of trade and FDI is welfare-improving.
Incorporating recent evidence that FDI firms are more efficient than exporters into a general oligopolistic equilibrium model, this paper examines the welfare effects of trade and FDI liberalization. We find that trade liberalization alone is beneficial if the difference in marginal cost between the exporting and FDI industries is small enough while FDI liberalization unambiguously improves welfare. Combining these results, we further show that simultaneous liberalization of trade and FDI necessarily turns out welfare-improving.
Background
Gallbladder polyps are relatively common. Although most gallbladder polyps are benign, some are malignant. Current guidelines state that malignancy should be suspected for polyps ≥ 10 mm ...in diameter. We clarified the cancer detection rates in accordance with the size distribution of gallbladder polyps, and evaluated the effectiveness of the reported risk factors in predicting malignancy.
Methods
In this retrospective case–control study, our institutional database was searched to identify patients who underwent laparoscopic cholecystectomy for benign or malignant gallbladder polyps at Sada Hospital, Japan. The chi-squared test was used to analyze the risk factors for malignancy.
Results
There were 227 protruding gallbladder lesions. The 206 benign polyps had a diameter of 2–21 mm, while the 21 malignant polyps were 7–60 mm. The cancer detection rates were 16.4% for lesions ≥ 10 mm, 55.9% for lesions ≥ 15 mm, and 94.1% for lesions ≥ 20 mm. Of the benign lesions, cholesterol polyps were the most frequent (50–100%) in all size ranges, even in large lesions (≥ 15 mm). The sessile lesion morphology was significantly more frequent in malignant (60%) than benign lesions (3.4%,
p
< 0.00001). Multiple polyps were frequently diagnosed not only as cholesterol polyps (81.1%), but also as adenomas (60%); adenomas were found as a single adenoma within other types of polyps. There were two cases of malignant small gallbladder polyps (< 10 mm); these lesions met the surgical indications of a size increase during observation or a sessile morphology.
Conclusions
The cancer detection rate increased significantly with an increase in the lesion size. Risk factors such as a sessile polyp morphology or an increase in lesion size were effective in predicting malignancy for small gallbladder polyps. It might be difficult to accurately predict the pathologic diagnoses of gallbladder polyps preoperatively, as cholesterol polyps were most frequent, even in the large size range.
Taking into account non‐constant marginal costs, this paper considers the effects of a tariff cut combined with a consumption tax increase on welfare, government revenue, and market access. We show ...that welfare, government revenue, and market access can all improve with this policy reform under decreasing marginal costs. This result may provide a theoretical rationale for the above policy reform, which is guided by the International Monetary Fund and the World Bank.
Pancreatic stellate cells (PSC), which are implicated in desmoplasia in pancreatic cancer, enhance the malignancy of cancer cells and confer resistance to established treatments. We investigated ...whether the antifibrotic agent pirfenidone can suppress desmoplasia and exert antitumor effects against pancreatic cancer. Primary PSCs were established from pancreatic cancer tissue obtained during surgery. In vitro, pirfenidone inhibited the proliferation, invasiveness, and migration of PSCs in a dose-dependent manner. Although supernatants of untreated PSCs increased the proliferation, invasiveness, and migration of pancreatic cancer cells (PCC), supernatants of pirfenidone-treated PSCs decreased these effects. Exposure to PCC supernatant increased the production of platelet-derived growth factor-A, hepatic growth factor, collagen type I, fibronectin, and periostin in PSCs, which was significantly reduced by pirfenidone. Mice were subcutaneously implanted with PCCs (SUIT-2 cells) and PSCs into the right flank and PCCs alone into the left flank. Oral administration of pirfenidone to these mice significantly reduced tumor growth of co-implanted PCCs and PSCs, but not of PCCs alone. Pirfenidone also decreased the proliferation of PSCs and the deposition of collagen type I and periostin in tumors. In mice with orthotopic tumors consisting of PCCs co-implanted with PSCs, pirfenidone suppressed tumor growth, reduced the number of peritoneal disseminated nodules, and reduced the incidence of liver metastasis. Pirfenidone in combination with gemcitabine more effectively suppressed orthotopic tumor growth compared with pirfenidone or gemcitabine alone. In conclusion, our findings indicate that pirfenidone is a promising antitumor agent for pancreatic cancer, owing to its suppression of desmoplasia through regulating PSCs.
Background The preoperative distinction between uncomplicated and complicated appendicitis is important to determine the appropriate treatments, such as antibiotics, surgery, or interval ...appendectomy. Computed tomography (CT) plays an important role; however, combining clinical and imaging factors may make preoperative evaluation more reliable. This study evaluated and analyzed cases and the usefulness of several preoperative factors and clinical scoring models to detect complicated appendicitis. Methods A total of 203 patients preoperatively diagnosed with acute appendicitis at our facility were included. Complicated appendicitis was defined as appendicitis with gangrene, perforated appendix, and/or abscess formation. Preoperative factors were collected from published clinical scoring models; patient information, symptoms, signs, results of laboratory tests, and findings of CT. Factors were analyzed using a chi-squared test and the Mann-Whitney U test. Results The preoperative factors were compared between 151 uncomplicated and 52 complicated appendicitis patients. The significant factors were age greater than or equal to40, duration of symptoms >24 hours, body temperature greater than or equal to37.3°C, high levels of CRP, findings in CT scan (appendix diameter greater than or equal to10 mm, stranding of the adjacent fat, presence of fluid collection, and suspicion of abscess or perforation). We also evaluated the usefulness of clinical scoring models for the detection of complicated appendicitis and found the Appendicitis Inflammatory Response score and two prediction models (Atema score and Imaoka score) showed significance (p < 0.05). High serum CRP level was significantly associated with complicated appendicitis (p < 0.001), and the predicted existence rates of complicated appendicitis were 52.7% for serum CRP level greater than or equal to50mg/L, 74.4% for greater than or equal to100mg/L, and 82.6% for greater than or equal to150mg/L. Conclusion The results demonstrated several preoperative factors and clinical scoring models to increase suspicion of complicated appendicitis. Specifically, high serum levels of CRP may be a useful factor in predicting complicated appendicitis prior to surgery when supported by clinical findings and imaging; however, further research is needed.
Background Unexpected gallbladder cancer (UGBC) is sometimes found in the resected gallbladder of patients during or after surgery. Some reports have indicated UGBC identification rates for all ...gallbladder surgeries, but scarce data are available for the UGBC identification rates for specific gallbladder diseases. The present study was performed to clarify UGBC rates and the factors suspicious for UGBC categorized according to preoperative diagnoses, in patients undergoing laparoscopic cholecystectomy (LSC). Methods We recorded data for all LSC surgeries performed in the Department of Surgery, Sada Hospital, Japan since 1991, and analyzed the 28-year data. We used the chi-square test and Kaplan-Meier analysis for this retrospective case-control study. Results The UGBC identification rate was 0.69% (63/9186 patients). The UGBC identification rates categorized according to the preoperative diagnoses were 1.3% (13/969) for acute cholecystitis, 2.4% (16/655) for benign tumor, 2.0% (28/1383) for chronic cholecystitis or cholecystitis, and 0.054% (3/5585) for cholecystolithiasis. The percentage of older patients (greater than or equal to 60 years) was significantly higher in UGBCs compared with cases finally diagnosed as benign in each group categorized according to the preoperative diagnoses (pless than or equal to0.0014), except for cholecystolithiasis. In cases pre-diagnosed as benign tumor, UGBCs were associated with higher rates of thickened gallbladder wall compared with benign tumor (69.2% vs. 27.9%, respectively; p = 0.0011). UGBCs pre-diagnosed as acute cholecystitis had higher T2-T4 rates (100% vs. 64.3%, respectively; p0.05) and lower survival rates (p = 0.0149) than UGBCs pre-diagnosed with chronic cholecystitis. Conclusions UGBC identification rates depend on the preoperative diagnosis and range from 0.054% to 2.4%. Older age (greater than or equal to 60 years) could be related to UGBC, and a pre-diagnosis of acute cholecystitis might indicate more advanced cancer compared with a pre-diagnosis of chronic cholecystitis.
How tumor-associated macrophages transit from a predominant antitumor M1-like phenotype to a protumoral M2-like phenotype during the development of pancreatic ductal adenocarcinoma (PDA) remains to ...be elucidated. We thus conducted a study by employing a PDA-macrophage co-culture system, an "orthotopic" PDA syngeneic mouse model, and human PDA specimens, together with macrophages derived from GARP knockout mice and multiple analytic tools including whole-genome RNA sequencing, DNA methylation arrays, multiplex immunohistochemistry, metabolism measurement, and invasion/metastasis assessment. Our study showed that PDA tumor cells, through direct cell-cell contact, induce DNA methylation and downregulation of a panel of glucose metabolism and OXPHOS genes selectively in M1-like macrophages, leading to a suppressed glucose metabolic status in M1-like but not in M2-like macrophages. Following the interaction with PDA tumor cells, M1-like macrophages are reprogrammed phenotypically to M2-like macrophages. The interaction between M1-like macrophages and PDA cells is mediated by GARP and integrin αV/β8, respectively. Blocking either GARP or integrin would suppress tumor-induced DNA methylation in Nqo-1 gene and the reprogramming of M1-like macrophages. Glucose-response genes such as Il-10 are subsequently activated in tumor-educated M1-like macrophages. Partly through Il-10 and its receptor Il-10R on tumor cells, M1-like macrophages functionally acquire a pro-cancerous capability. Both exogenous M1-like and M2-like macrophages promote metastasis in a mouse model of PDA while such a role of M1-like macrophages is dependent on DNA methylation. Our results suggest that PDA cells are able to reprogram M1-like macrophages metabolically and functionally through a GARP-dependent and DNA methylation-mediated mechanism to adopt a pro-cancerous fate.
A model of differentiated mixed oligopoly is developed to systematically discuss the welfare consequences of partial privatization of a public firm. We analytically derive the optimal degree of ...partial privatization not only in the short run with restricted entry but also in the long run with free entry. It is shown that the shortrun optimal policy is non-monotonic in the degree of love of variety, while the optimal degree of privatization is monotonically increasing in the consumer's preference for variety in the long run.
Constructing a duopoly model with non-constant marginal costs and a strict Pareto criterion, this paper examines welfare effects of world-price-fixing tariff reductions accompanied by adjustments of ...a domestic tax. If a destination-based consumption tax is used, this reform achieves a strict Pareto improvement under sufficiently decreasing marginal costs. If, in contrast, an origin-based production tax is employed, a strict Pareto improvement holds whether marginal cost is decreasing or not. Thus, we can conclude that tariff-tax reforms that improve the world welfare and are irrelevant of tax bases are possible if the targeted industry exhibits sufficiently decreasing marginal costs.
•This paper explores welfare effects of tariff-tax reforms in a duopoly.•Tariff reductions with consumption tax increases can improve welfare.•Tariff reductions with production tax decreases always improve welfare.
This article develops a dynamic game model of an asymmetric oligopoly with a renewable resource to reconsider welfare effects of increases in the number of firms. We show that increasing not only the ...number of
inefficient firms but also that of
efficient firms reduces welfare, which sharply contrasts to a static outcome. It is discussed that the closed-loop property of feedback strategies plays a decisive role in this finding.
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