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Background Neuroendocrine tumors of the minor papilla are very rare, and only 20 cases have been reported in the literature. Neuroendocrine carcinoma of the minor papilla with pancreas divisum has not been reported previously, making this the first reported case. Neuroendocrine tumors of the minor papilla have been reported in association with pancreas divisum in about 50% of cases reported in the literature. We herein present our case of neuroendocrine carcinoma of the minor papilla with pancreas divisum in a 75-year-old male with a systematic literature review of the previous 20 reports of neuroendocrine tumors of the minor papilla. Case presentation A 75-year-old Asian man was referred to our hospital for evaluation of dilation of the main pancreatic duct noted on abdominal ultrasonography. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography showed a dilated dorsal pancreatic duct, which was not connected to the ventral pancreatic duct; however, it opened to the minor papilla, indicating pancreas divisum. The common bile duct had no communication with the pancreatic main duct and opened to the ampulla of Vater. A contrast-enhanced computed tomography scan showed a 12-mm hypervascular mass near the ampulla of Vater. Endoscopic ultrasonography showed a defined hypoechoic mass in the minor papilla with no invasion. The biopsies performed at the previous hospital found adenocarcinoma. The patient underwent a subtotal stomach-preserving pancreaticoduodenectomy. The pathological diagnosis was neuroendocrine carcinoma. At the 15-year follow-up visit, the patient was doing well with no evidence of tumor recurrence. Conclusion In our case, because the tumor was discovered during a medical check-up relatively early in the course of disease, the patient was doing well at the 15-year follow-up visit, with no evidence of tumor recurrence. Diagnosing a tumor of the minor papilla is very difficult because of the relatively small size and submucosal location. Carcinoids and endocrine cell micronests in the minor papilla occur more frequently than generally thought. It is very important to include neuroendocrine tumors of the minor papilla in the differential diagnosis of patients with recurrent pancreatitis or pancreatitis of unknown cause, especially for patients with pancreas divisum.

Background The treatment of chronic pancreatitis requires a surgical approach in patients who are refractory to medical therapy. During surgical treatment, ductal decompression is required, but a pancreatectomy is necessary for some patients, such as those with severe stenosis of the pancreatic duct. Indeed, suboptimal procedures lead to recurrent pancreatitis. We used a laparoscopic hybrid approach for patients with severe stenosis of the pancreatic duct. In this report, we present the feasibility and outcomes of our approach. Methods We selected a laparoscopic approach for the distal pancreatectomy, which is relatively safe and the effect of reducing the length of the wound is substantial. We selected an open approach for the Frey procedure because complete ductal compression has a high risk for injury to the vessels posterior to the pancreas. We recorded the operative outcomes, postoperative complications, and recurrence of pancreatitis. Results We performed the laparoscopic hybrid approach on 3patients between January and December 2018. There were no major intraoperative complications (Clavien-Dindo classification IIIa or more) and the postoperative course was uneventful in all patients. There were no recurrences of pancreatitis and no postoperative pain in all patients in > 2 years of follow-up. Conclusion Our hybrid method with a focus on complete ductal compression with safety and minimal invasiveness might be the optimal approach for the surgical treatment of chronic pancreatitis that requires a pancreatectomy with the Frey procedure.

Background An epithelial cyst in an intrapancreatic accessory spleen (ECIPAS) is rare. We report a case of ECIPAS that was treated with robot-assisted distal pancreatectomy with splenectomy. Case presentation The case was a 59-year-old woman who was referred to our hospital after a pancreatic tail tumor was found on computed tomography prior to surgery for small bowel obstruction at another hospital. A cystic lesion in the pancreatic tail was discovered and evaluated by magnetic resonance imaging and endoscopic ultrasonography. Based on clinical and radiological features, mucinous cystic neoplasm was included in the differential diagnosis. The patient underwent robot-assisted distal pancreatectomy with splenectomy. The postoperative course was uneventful. Pathological evaluation revealed a 20-mm ECIPAS in the pancreatic tail. Conclusions If a pancreatic tail tumor is present, ECIPAS should be included in the differential diagnosis. However, preoperative diagnosis is difficult, and a definitive diagnosis is often not obtained until after surgery. Surgery should be minimally invasive. Laparoscopic distal pancreatectomy has become a standard surgical procedure because it is minimally invasive. Robot-assisted surgery is not only minimally invasive, but also advantageous, because it has a stereoscopic magnifying effect and allows the forceps to move smoothly. Robot-assisted distal pancreatectomy may be a good option, when performing surgery for a pancreatic tail tumor.

Background The CXCL12-CXCR4 signaling axis in malignant tumor biology has increased in importance, and these peptides are implicated in tumor growth, invasion and metastasis. The aim of our study was to examine the important role of the axis in pancreatic cancer (PaCa) cells’ relationship with stromal cells in gemcitabine-resistant (GEM-R) tumors and to confirm the effectiveness of CXCR4 antagonists for the treatment of GEM-R PaCa cells. Methods We established two GEM-R PaCa cell lines using MIA PaCa-2 and AsPC-1 cells. The expression of CXCR4 mRNA in PaCa cells and the expression of CXCL12 mRNA in fibroblasts were examined by reverse transcription polymerase chain reaction (RT-PCR). The expression of CXCR4 protein in PaCa cells was examined by immunosorbent assay (ELISA) and immunocytochemistry. Using Matrigel invasion assays and animal studies, we then examined the effects of two CXCR4 antagonists, AMD11070 and KRH3955, on the invasiveness and tumorigenicity of GEM-R PaCa cells stimulated by CXCL12. Results We found that the expression of CXCR4 in GEM-R PaCa cells was significantly enhanced by GEM but not in normal GEM-sensitive (GEM-S) PaCa cells. In RT-PCR and ELISA assays, the production and secretion of CXCL12 from fibroblasts was significantly enhanced by co-culturing with GEM-R PaCa cells treated with GEM. In Matrigel invasion assays, the invasiveness of GEM-R PaCa cells treated with GEM was significantly activated by fibroblast-derived CXCL12 and was significantly inhibited by CXCR4 antagonists, AMD11070 and KRH3955. In vivo, the tumorigenicity of GEM-R PaCa cells was activated by GEM, and it was significantly inhibited by the addition with CXCR4 antagonists. Conclusions Our findings demonstrate that the CXCL12-CXCR4 signaling axis plays an important role in PaCa cells’ resistance to GEM. CXCR4 expression was significantly enhanced by the exposure to GEM in GEM-R PaCa cells but not in GEM-S PaCa cells. Furthermore, CXCR4 antagonists can inhibit the growth and invasion of GEM-R PaCa cells. These agents may be useful as second-line chemotherapy for GEM-R PaCa in the future. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2340-z) contains supplementary material, which is available to authorized users.

Dual-color fluorescence cross-correlation spectroscopy (FCCS) is a promising technique for quantifying protein-protein interactions1,2,3,4,5. In this technique, two different fluorescent labels are excited and detected simultaneously within a common measurement volume. Difficulties in aligning two laser lines and emission crossover between the two fluorophores, however, make this technique complex. To overcome these limitations, we developed a fluorescent protein with a large Stokes shift. This protein, named Keima, absorbs and emits light maximally at 440 nm and 620 nm, respectively. Combining a monomeric version of Keima with cyan fluorescent protein allowed dual-color FCCS with a single 458-nm laser line and complete separation of the fluorescent protein emissions. This FCCS approach enabled sensitive detection of proteolysis by caspase-3 and the association of calmodulin with calmodulin-dependent enzymes. In addition, Keima and a spectral variant that emits maximally at 570 nm might facilitate simultaneous multicolor imaging with single-wavelength excitation.

Background: A methylene tetrahydrofolate reductase (MTHFR) deficiency at site C677T renders the enzyme thermolabile and consequently represents a risk factor for vascular disease, neural tube defects, preeclampsia, and thrombosis. Highly specific identification techniques for genotyping are mandatory to give guidance for the diagnosis and monitoring of this deficiency. Methods: A new approach for performing genotyping has been introduced with the identification of single nucleotide polymorphisms of the human MTHFR. It is based on PCR followed by two-color cross-correlation fluorescence spectroscopy (FCS). Experiments were carried out with green- and red-tagged allele-specific primers, which were fully compatible with the two-color fluorescence cross-correlation setup at 488nm and 633nm excitation wavelengths. Results: The measured data of the amplification mixes (tubes) were normalized as the maximum correlation amplitude of each tube. Correlated and uncorrelated data were optically separated in the amplification mixes by their characteristic correlation times, which significantly differed from each other. The correlated data were generated in the presence of the proper mutated genotype template, whereas uncorrelated data were due to the absence of the proper genotype template. Furthermore, the specific association of the two-color fluorescence correlated signals with the target DNA was experimentally proven. Using this novel two-color cross-correlation approach, the MTHFR genotypes, which were determined in 21 clinical samples, showed concordance with methods involving a PCR-based assay with hexachloro-6-carboxy-fluorescein (HEX)- and 6-carboxy-fluorescein (FAM)-tagged allele-specific primers and a subsequent separation step with capillary electrophoresis, yet are simpler to perform. There was no evidence of a central trend of false-positive or false-negative results. We demonstrated how the novel, ultrasensitive typing system could be applied to studies where researchers are trying to perfect their assays and are often working with the unknown, or application to problematic assays in a clinical environment for those involved in molecular diagnosis. Conclusions: We present an alternative method to those commonly used in genotyping. Two-color cross-correlation FCS allows the detection of the fluorescence signals specifically associated with the heterozygous mutated, the homozygous mutated, and normal individuals, as exemplified in this study. The presence of nonspecific amplification products, which interfere with subsequent DNA analysis, could therefore highlight the need for two-color cross-correlation FCS as a means of discriminating between specific association of the fluorescence signals with the target DNA and DNA not related to the target.

We report a pH-insensitive and photostable ultramarine fluorescent protein, Sirius, with an emission peak at 424 nm, the shortest emission wavelength among fluorescent proteins reported to date. The pH-insensitivity of Sirius allowed prolonged visualization of biological events in an acidic environment. Furthermore, two FRET (fluorescence resonance energy transfer) pairs, Sirius-mseCFP and Sapphire-DsRed, allow dual-FRET imaging with single wavelength excitation, enabling detection of Ca^[2+] concentration and caspase-3 activation in the same apoptotic cells.

Genetically encoded fluorescent indicators for bioimaging are powerful tools for visualizing biological phenomena in specified cell types or cellular compartments. However, available gene promoters or localization sequences are not applicable for visualizing all expression events. Furthermore, a visualization technique focusing on single cells or cellular compartments is required for characterizing specific cellular properties including individuality of cells in the cell population. To address these limitations, we developed a genetically encoded caged Ca2+ indicator for which expression timing and location could be controlled. This indicator, PA-TNXL, comprises a Ca2+-binding protein and troponin between a photoactivatable FRET donor (PA-GFP) and a FRET quencher (dim variant of YFP). Ultraviolet irradiation activates the FRET Ca2+ indicator. Using this indicator, we successfully imaged Ca2+ dynamics in a given set of HeLa cells and cultured hippocampal neurons. This technology can be applied for developing other photoactivatable indicators, thereby opening a new area of biological research.