[Propose for the Benchmark Dose (BD) for the Optimization of Protection in Medical Exposure in General Radiography].

The goal of this research was to create the most appropriate index dose for the optimization of protection in medical exposure in general radiography in Kanagawa prefecture. We distributed questionnaires to 272 medical institutions in Kanagawa prefecture. The investigation period was from October 2015 to February 2016. Entrance surface dose (ESD) was used as the index dose. Investigated regions in general radiography were the adult chest, adult abdomen, and infant chest (anterior-posterior projections for all regions). The effective response rate was 35%. ESD was significantly lower with a flat panel detector (FPD) than with computed radiography (CR) in all regions (adult chest and abdomen: p<0.001; infant chest: p<0.05) [e.g., mean (±standard deviation) ESD in the adult chest was 0.16±0.06 mGy with FPD and 0.24±0.10 mGy with CR]. In the infant chest with CR, ESD was significantly higher using a grid (0.15±0.07 mGy) compared to not using a grid (0.10±0.05 mGy; p<0.05). Based on these results, we propose the benchmark dose of each medical equipment, such as adult chest: FPD, 0.2 mGy; CR, 0.3 mGy.

[A Well-differentiated Mediastinal Liposarcoma that Expanded into the Right Thoracic Cavity with Dedifferentiation].

A 77-year-old man was referred to our hospital because of massive opacification of the right hemithorax on chest radiography. Chest computed tomography (CT) revealed a 25×18-cm heterogeneous tumor in the right hemi-thorax. Chest CT scan obtained 6 years before the referral showed an 8×2-cm homogeneous lipomatous mass in the anterior mediastinum suggesting a well-differentiated liposarcoma. The follow-up chest CT scan obtained 12 months before the referral showed a 4×2-cm heterogeneous solid component within the lipomatous mass of the mediastinum suggesting the development of a dedifferentiated liposarcoma. The tumor was completely resected through a median sternotomy and anterior right thoracotomy. The pathological diagnosis was dedifferentiated liposarcoma originating from a well-differentiated liposarcoma of the anterior mediastinum.

[A Case of Delayed Vascular Injury as a Complication Related to Implanted Central Venous Port Catheter].

A 74-year-old woman with advanced gastric cancer was admitted to our hospital. A central venous (CV) port catheter was implanted into the right subclavian vein for preoperative chemotherapy and parenteral nutritional management. On the 35th day after implantation, she complained of diarrhea, fever and dyspnea. The chest radiograph showed a right-sided massive pleural effusion. As the patient progressively fell into severe respiratory distress, endotracheal intubation was performed for management of respiration by mechanical ventilation. Initially, given the patient's symptoms, she was diagnosed with septic shock. Therefore, after placement of a CV catheter through the right femoral vein, in consideration of the possibility of a port infection, she was treated with thoracentesis and infusion of antibiotics. The patient gradually recovered, and again received parenteral nutrition through the CV port catheter. After the infusion was administered, she complained of dyspnea. A CT scan of the chest revealed a right pleural effusion and displacement of the tip of the CV port catheter out of the wall of the superior vena cava. We diagnosed delayed vascular injury (DVI), and the CV port catheter was removed. She soon recovered with conservative treatment. We speculated that the initial respiratory symptoms such as the pleural effusion were caused by DVI. DVI should therefore be recognized as a complication related to implanted CV port catheters.

[A case of stomal variceal hemorrhage successfully treated using sclerotherapy].

A 72-year-old man underwent transverse colostomy for sigmoid colon cancer with multiple liver metastases. Subsequent chemotherapy effectively reduced liver metastases, and sigmoidectomy was performed. However, the liver metastases recurred and the patient developed stomal varices due to portal hypertension. To control the resulting massive variceal bleeding, we performed percutaneous sclerotherapy through a varicose vein, which was puncutured directly under ultrasound (US) guidance. Although the patient recovered from variceal bleeding, he eventually died due to the primary cancer.

Heterogeneity of tumor endothelial cells: comparison between tumor endothelial cells isolated from high- and low-metastatic tumors.

An important concept in tumor angiogenesis is that tumor endothelial cells (TECs) are genetically normal and homogeneous. However, we previously reported that TECs differ from normal ECs. Whether the characteristics of TECs derived from different tumors differ remains unknown. To elucidate this, in this study, we isolated two types of TECs from high-metastatic (HM) and low-metastatic (LM) tumors and compared their characteristics. HM tumor-derived TECs (HM-TECs) showed higher proliferative activity and invasive activity than LM tumor-derived TECs (LM-TECs). Moreover, the mRNA expression levels of pro-angiogenic genes, such as vascular endothelial growth factor (VEGF) receptors 1 and 2, VEGF, and hypoxia-inducible factor-1α, were higher in HM-TECs than in LM-TECs. The tumor blood vessels themselves and the surrounding area in HM tumors were exposed to hypoxia. Furthermore, HM-TECs showed higher mRNA expression levels of the stemness-related gene stem cell antigen and the mesenchymal marker CD90 compared with LM-TECs. HM-TECs were spheroid, with a smoother surface and higher circularity in the stem cell spheroid assay. HM-TECs differentiated into osteogenic cells, expressing activated alkaline phosphatase in an osteogenic medium at a higher rate than either LM-TECs or normal ECs. Furthermore, HM-TECs contained more aneuploid cells than LM-TECs. These results indicate that TECs from HM tumors have a more pro-angiogenic phenotype than those from LM tumors.

Methylxanthines inhibit late-onset circulatory collapse in preterm infants.

BACKGROUND: Several drugs, when used chronically in very preterm infants, are considered to be associated with the development of late-onset circulatory collapse (LCC), which can lead to neurodevelopmental impairment. Despite its clinical importance, conclusive risk factors for LCC have yet to be identified. The aim of the present study was to investigate the relationship between LCC and diuretics, methylxanthines, levothyroxine, and sodium chloride. METHODS: Infants born at <28 weeks gestational age were enrolled and divided into two groups: the LCC group and the non-LCC group. Use of diuretics, methylxanthines, or levothyroxine, and the sodium intake in each infant were recorded. We then determined if these represented primary risk factors associated with the development of LCC, using multivariate analysis to exclude confounding factors. RESULTS: Thirty-seven preterm infants were eligible for this study. LCC developed in 10 infants; 27 infants did not develop the disease. Only methylxanthine was significantly associated with a decrease in the incidence of LCC (odds ratio, 0.04; P < 0.05). We also observed a significant positive correlation between sodium intake and the period from diuretic treatment to LCC onset. CONCLUSIONS: Methylxanthine use was significantly associated with LCC onset. Diuretics may have the ability to provoke LCC through sodium wasting, resulting in a negative balance of the electrolyte. The incidence of LCC could be lowered by paying particular attention to infants' sodium balance, and by aggressive methylxanthine treatment.

Evaluation of motion artifacts reduction software that compensate for respiratory movements in the craniocaudal direction during abdominal cone-beam computed tomography.

We acquired cone-beam computed tomography (CBCT) images of a locally made contrast-enhanced hepatic artery phantom under various conditions, both with the phantom still, and while moving it from the cranial to the caudal position. All the motion CBCT images were processed with and without motion artifacts reduction software (MARS). We calculated some quantitative similarity indexes between the still CBCT images (no-motion) and the motion CBCT images both processed with MARS (MARS ON) and without MARS (MARS OFF). In addition, the vessel signal values under the same movement conditions of the MARS ON/OFF and no-motion were evaluated. All quantitative similarity indexes between MARS ON and no-motion were significantly higher than between MARS OFF and no-motion in all movement conditions (p < 0.01). The vessel signal values were higher in MARS ON than in MARS OFF (p < 0.01) and closer to no-motion in all movement conditions.

Dedifferentiated liposarcoma primary to the chest wall with spontaneous shrinking: report of a case.

An 80-year-old man presented to our emergency department complaining of a mass on the right side of his chest and pain in the right flank of his back. A chest computed tomography (CT) scan showed a relatively heterogenous oval-shaped tumor measuring 7.5 × 6.0 cm eroded to the 8th rib, with slightly dense fluid accumulation inside and calcification of the tumor wall. A 1-month follow-up CT scan showed spontaneous shrinkage of the tumor. The tumor was completely excised from the thoracic wall and the wall was reconstructed with a polytetrafluoroethylene mesh. Pathological examination showed coagulation necrosis in the chest wall tumor, but immunohistochemical staining revealed murine double minute 2- and Cyclin-dependent kinase 4-positive cells with irregular nuclear size and bizarre morphology. Therefore, dedifferentiated liposarcoma (DDLPS) was the final pathological diagnosis. Remarkable infiltration of CD8+ lymphocytes into the tumor was observed, along with a 90% positive ratio for programmed cell death-ligand 1. The patient has been followed-up for 1 year without any recurrence, despite not receiving any additional treatment. Liposarcoma is one of the most common types of soft tissue sarcomas; however, spontaneous regression of primary DDLPS arising from the chest wall is extremely rare. Herein, we report a case of DDLPS primary to the chest wall with spontaneous regression, probably due to a spontaneously induced T cell response.

Laparoscopic cholecystectomy after transcatheter arterial embolisation for haemobilia due to a pseudoaneurysm in the gallbladder: A case report.

Pseudoaneurysms of the cystic artery are a rare but significant complication of acute cholecystitis. Laparoscopic cholecystectomy may be a safe alternative to open cholecystectomy in such cases. We report the case of a female patient in her seventies, who presented with anaemia, jaundice, and hepatic dysfunction during hospitalisation for right knee pyogenic arthritis. The patient had no pain in the right upper quadrant. Her serum haemoglobin level was 6.5 g/dL, and upper gastrointestinal endoscopy revealed no abnormalities. Six days later, jaundice worsened, and endoscopic retrograde cholangiopancreatography revealed bloody bile. An endoscopic biliary drainage tube was inserted at the discretion of the gastroenterology department. Contrast-enhanced computed tomography revealed a haematoma in the gallbladder and a pseudoaneurysm in the lateral wall of the gallbladder. On the same day, the endoscopic biliary drainage tube was replaced with an endoscopic nasobiliary drainage tube, which indicated the degree of haemorrhage and enabled lavage of the lumen in cases of obstruction. The next day, angiography revealed a pseudoaneurysm of the deep branch of the cystic artery and coil embolisation was performed at the periphery of the cystic artery. Uninterrupted laparoscopic cholecystectomy was performed. Although laparoscopic cholecystectomy is difficult when bleeding is uncontrolled, it was safely performed following haemostasis using transcatheter arterial embolisation. Laparoscopic cholecystectomy is feasible in haemodynamically stable patients with cystic artery pseudoaneurysms after transcatheter arterial embolisation.

Low Radiation Protocol for Intraoperative Robotic C-Arm Can Enhance Adolescent Idiopathic Scoliosis Deformity Correction Accuracy and Safety.

STUDY DESIGN: Retrospective case-series study. OBJECTIVES: To assess (1) low cone beam CT (CBCT) mediated intraoperative navigation to limit radiation exposure without compromising surgical accuracy, and (2) the potential of intraoperative C-arm CBCT navigation to augment pedicle screw (PS) placement accuracy in AIS surgery compared to pre-surgery CT-based planning. METHODS: The first part involved a prospective phantom study, comparing radiation doses for conventional CT, and standard (6sDCT) and a low dose (5sDCT) Artis Zeego®-imaging. Next, 5sDCT- and 6sDCT-navigation were compared on PS accuracy and radiation exposure during AIS correction. The final part compared surgical AIS deformity correction through intraoperative 5sDCT navigation to a matched cohort treated using conventional pre-surgery CT-scans for navigation. Outcome parameters included operation time, skin dose (SD), dose area product (DAP), intraoperative blood loss, postoperative complications, and PS deviation rates. RESULTS: The phantom study demonstrated a reduction in radiation for the 5sDCT protocol. Moreover, 5sDCT-imaged patients (n = 15) showed a significantly lower SD (-27.41%) and DAP (-30.92%), without compromising PS accuracy compared with 6sDCT-settings (n = 15). Finally, AIS correction through intraoperative CBCT C-arm navigation (n = 27) significantly reduced screw deviation rates (6.83% versus 10.75%, P = .016) without increasing operation times, compared with conventional CT (n = 37). CONCLUSIONS: Intraoperative navigation using a CBCT C-arm system improved the accuracy of PS insertion and reduced surgery time. Moreover, it reduced radiation exposure compared with conventional CT, which was further curtailed by adapting the low-dose 5sDCT protocol. In short, our study highlights the benefits of intraoperative CBCT navigation for PS placement in AIS surgery.

[Measurement as a Personal Dose Equivalent of X-ray Room Scattered Dose in ERCP Inspection].

PURPOSE: In the revised Regulation on Prevention of Ionizing Radiation Hazards (April 2020), the equivalent dose limit for the lens of the eye was lowered to "100 mSv in 5 years and 50 mSv in 1 year." It is necessary to reduce occupational exposure in the healthcare sector. The purpose of this study was to facilitate comparison with the equivalent dose limit in an endoscopic retrograde cholangiopancreatography (ERCP) examination by measuring the scattered dose in an X-ray room as an individual dose equivalent. METHODS: The scattered dose was measured by dosimeters positioned in a grid pattern in the X-ray room. The dose rate was measured with and without the use of a protective cloth (0.25 mm Pb equivalent) suspended around the X-ray tube extending to the patient. The dose reduction rate of the material was evaluated during the simulated ERCP. RESULTS: The maximum dose rate at the position of the surgeon performing an ERCP inspection in the standing position was 2.9 mSv/h (3 mm dose equivalent rate) at 150 cm from the ground. The number of ERCP examinations to comply with the equivalent dose limit of the equivalent dose of the lens of the eye without the protective cloth was 28 per year. CONCLUSION: The results of this study suggest that individual dose equivalent measurements in the X-ray clinic may facilitate comparison with the equivalent dose limit.

Successful therapeutic strategy for a patient with obese end-stage kidney disease by simultaneous laparoscopic sleeve gastrectomy and implantation of a buried peritoneal dialysis catheter: A case report.

For morbidly obese patients with end-stage kidney disease (ESKD), there are often difficulties in accessing, implementing, and maintaining kidney replacement therapy (KRT). Although recent weight-loss surgery has the potential to solve these problems, its therapeutic strategy and appropriate perioperative management for morbidly obese patients with ESKD have not been established. Here, we describe the case history of a 47-year-old man diagnosed with ESKD due to obesity-related glomerulopathy with an uncorrected estimated glomerular filtration rate (eGFR) of 16.1 ml/min. He hoped for kidney transplantation but was not eligible due to his high body mass index (BMI) (36.9 kg/m2). Therefore, a combination strategy for both attaining weight loss and preparing for KRT was needed. We performed modified laparoscopic sleeve gastrectomy (LSG) combined with a buried catheter for peritoneal dialysis (PD), which resulted in reduction of multiple surgical invasions while simultaneously preparing for PD. After these operations, his body mass dropped to below 30.0 kg/m2, making him a candidate for kidney transplantation, while maintaining PD. Finally, he was able to have kidney transplantation with success. Collectively, in this case, our novel therapeutic approach was able to avoid multiple surgeries, to assist catheter insertion by laparoscopy, and to provide optimal KRT for an obese patient with ESKD. Simultaneous LSG and implantation of a buried PD catheter may be a promising strategy for morbidly obese patients with ESKD.

Effect of number of medications and use of potentially inappropriate medications on frailty among early-stage older outpatients.

BACKGROUND: Frailty is an urgent concern among an aging population worldwide. However, the relationship between frailty and number and types of medications has not been studied in detail among early-stage older patients, and it is unclear what prescriptions may have a role in preventing frailty. This study aimed to clarify the effects of number of medications and use of potentially inappropriate medications (PIMs) on frailty among early-stage older outpatients in Japan. METHODS: A cross-sectional study was undertaken. Frailty scores and medications of outpatients aged 65-74 years who regularly visited community pharmacies were investigated. Frailty scores were classified as 0 (non-frailty), 1-2 (pre-frailty), and ≥ 3 (frailty). The association between frailty and number of medications was analyzed by age and compared between PIM use and non-use groups. The proportion of patients who used PIMs was also analyzed by frailty score. RESULTS: Of 923 older outpatients, 49 (5.3%) and 318 (34.5%) patients had frailty and pre-frailty scores, respectively. The numbers of medications among patients with pre-frailty and frailty were significantly higher than among those with non-frailty (p <  0.001 for both). A similar increase was shown for PIM use groups aged 69-71 and 72-74 years, but not for the PIM use group aged 65-68 years and all groups without PIM use. An increasing linear trend was observed for the relationship between the proportion of patients who used any PIM, as well as some subcategories of PIMs (such as NSAIDs, benzodiazepines, loop diuretics and antithrombotic drugs) and frailty score. CONCLUSIONS: Unnecessary medication use among early-stage older outpatients, especially patients aged ≥69 years who use PIMs and many medications, seems to be associated with frailty, but further research is needed to confirm these findings.

Respiratory changes in the length of the vena cava: implications for optimal positioning of inferior vena cava filter.

BACKGROUND: A transjugular temporary inferior vena cava (IVC) filter may change position with respiration, leading to serious complications such as filter migration to the right atrium (RA) or renal veins. We therefore evaluated respiratory changes in the length and diameter of the vena cava using MRI. METHODS: In 20 volunteers, the length and diameter of the vascular segments from the right brachiocephalic vein (BCV) to infrarenal IVC were measured with MRI. RESULTS: The mean lengths in mm of the BCV, superior vena cava (SVC), RA, suprarenal IVC, and infrarenal IVC during expiration vs. inspiration were 32.7±7.3 vs. 43.0±8.0, 44.6±9.6 vs. 58.5±12.7, 77.8±12.4 vs. 98.9±10.0, 104.6±19.1 vs. 85.0±14.9, and 49.0±8.7 vs. 33.8±9.7, respectively (all P<0.01). The distances in mm from the BCV to RA, upper confluence of the renal vein, and lower confluence of the renal vein during expiration vs. inspiration were 155.2±18.5 vs. 200.4±20.1, 259.7±28.5 vs. 285.4±23.5, and 308.7±31.6 vs. 319.1±24.9, respectively (all P<0.01). The diameter of the SVC decreased with inspiration, while that of the infrarenal IVC increased. The diameter of the suprarenal IVC did not change significantly with respiration. CONCLUSIONS: The distances from the BCV to RA, upper, and lower confluences of the renal vein were 4.5, 2.6, and 1.0 cm longer on average at inspiration than at expiration, respectively. These respiratory-associated changes of the vena cava length should be taken into account when deploying an IVC filter to prevent its migration.

Conversion therapy for pancreatic cancer with peritoneal metastases using intravenous and intraperitoneal paclitaxel with S-1.

Combination chemotherapy consisting of systemic and intraperitoneal agents against peritoneal metastases from several types of cancer has shown promising results. We herein report a case in which combination therapy with intravenous and intraperitoneal paclitaxel with S-1 converted an unresectable pancreatic cancer with peritoneal metastases into a resectable one. The patient was a 65-year old woman with recurrent pancreatitis for 5 months. Endoscopic ultrasonography-guided fine-needle aspiration revealed minute epithelial masses composed of cells with irregular nuclei in the pancreatic body. The patient underwent abdominal surgery, but no excision was performed, as two peritoneal metastases in the bursa omentalis were detected. Combination therapy was initiated, consisting of intravenous and intraperitoneal paclitaxel with S-1 as a single-center clinical trial. The regimen consisted with 2-week administration of S-1 (80 mg per day) followed by 1 week of rest, intravenous paclitaxel 50 mg/m2, and intraperitoneal paclitaxel 20 mg/m2 by a peritoneal access device on days 1 and 8. Over the seven cycles of the chemotherapy, the primary lesion did not change in size, and peritoneal lavage cytology remained negative. After confirming the disappearance of the peritoneal lesions by exploratory laparoscopy, the patient underwent distal pancreatectomy combined with resection of the transverse mesocolon and stomach wall. Thus, the 2-way chemotherapy of intravenous and intraperitoneal paclitaxel with S-1 was well-tolerated and was able to convert pancreatic cancer with peritoneal metastases to resectable disease.

Tumour endothelial cells in high metastatic tumours promote metastasis via epigenetic dysregulation of biglycan.

Tumour blood vessels are gateways for distant metastasis. Recent studies have revealed that tumour endothelial cells (TECs) demonstrate distinct phenotypes from their normal counterparts. We have demonstrated that features of TECs are different depending on tumour malignancy, suggesting that TECs communicate with surrounding tumour cells. However, the contribution of TECs to metastasis has not been elucidated. Here, we show that TECs actively promote tumour metastasis through a bidirectional interaction between tumour cells and TECs. Co-implantation of TECs isolated from highly metastatic tumours accelerated lung metastases of low metastatic tumours. Biglycan, a small leucine-rich repeat proteoglycan secreted from TECs, activated tumour cell migration via nuclear factor-κB and extracellular signal-regulated kinase 1/2. Biglycan expression was upregulated by DNA demethylation in TECs. Collectively, our results demonstrate that TECs are altered in their microenvironment and, in turn, instigate tumour cells to metastasize, which is a novel mechanism for tumour metastasis.

A negative regulatory element required for light-dependent pinopsin gene expression.

In vertebrates, a variety of light-stimulated genes are distributed in the retina, the pineal gland, and the suprachiasmatic nucleus, but a cis-element(s) responsible for the light-dependent transcriptional regulation is left unexplored. Focusing on the pinopsin gene, a light-stimulated gene in the chick pineal gland, we performed a transcriptional analysis in the primary culture of the chick pineal cells that were transiently transfected with a luciferase reporter gene fused with various lengths of the 5' upstream region of the pinopsin gene. Light-dependent enhancer activity was detectable in the construct with the upstream region between -1156 and +31. Introduction of mutations within the 18 bp sequence at positions -1103 to -1086 (TGGCACGTGGGGTTCCTC), including a CACGTG E-box sequence, elevated the transcriptional activity in the dark and thereby abrogated the light dependency, suggesting that the 18 bp sequence is essential for a reduction of the transcriptional activity in the dark. In an electrophoretic mobility-shift assay, we identified a pineal nuclear factor(s) capable of binding to the 18 bp element in a sequence-specific manner. When a 49 bp fragment (-1122 to -1074) including the 18 bp sequence was placed upstream of the simian virus 40 promoter, the transcriptional activity was dramatically suppressed regardless of light conditions in the chick pineal cells, and a more pronounced repression was observed in nonpineal/nonphotosensory LMH and NIH 3T3 cells. These results suggest that the 18 bp element in the pinopsin promoter constitutes the binding site of a ubiquitous factor that serves for the transcriptional repression that is required, although not sufficient, for the light-dependent expression of pinopsin gene in the chick pinealocytes.

Involvement of p27(KIP1) degradation by Skp2 in the regulation of proliferation in response to wounding of corneal epithelium.

PURPOSE: To examine the expression of the p27(KIP1)in the normal and epithelial-scraped cornea and whether degradation of p27(KIP1)by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium. METHODS: C57Bl6, p27(KIP1-/-), Skp2(-/-), and Skp2(-/-)/p27(KIP1-/-) double-knockout mice were examined. Normal and epithelial-scraped corneas were analyzed by immunocytochemistry using anti-p27(KIP1) antibody. Cells in the S phase of DNA synthesis were analyzed by immunocytochemistry using anti-bromodeoxyuridine (BrdU) antibody. RESULTS: The p27(KIP1) was expressed in basal cells of the central and peripheral region of the cornea and limbus. This expression was not detected 24 hours after the epithelial scraping, when there were many cells in the S phase of DNA synthesis in the corneal epithelium. There were no obvious differences in the thickness and anti-BrdU staining in the corneal epithelium of p27(KIP1-/-) mice from that of control animals. Twenty-four hours after epithelial scraping in the Skp2(-/-) mice, the corneal epithelium was thinner than in wild-type mice and had many p27(KIP1)-positive cells and few BrdU-positive cells. In contrast, 24 hours after epithelial scraping in the Skp2(-/-)/p27(KIP1)(-/-) double-knockout mice, the corneal epithelium was as thick as in wild-type mice and had many BrdU-positive cells. CONCLUSIONS: These results suggest that degradation of p27(KIP1) by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium.

Bromotheoynic acid, a brominated acetylenic acid from the marine sponge Theonella swinhoei.

A new brominated C(17) acetylenic acid (1) designated as bromotheoynic acid has been isolated from the marine sponge Theonella swinhoei, collected off the coast of Tanegashima, Kagoshima Prefecture, Japan. The structure was determined on the basis of the analysis of its extensive 2D NMR spectroscopic data as well as HRMS. Bromotheoynic acid (1) inhibited maturation of starfish oocytes and cell division of fertilised starfish eggs. Bromotheoynic acid (1) also inhibited proliferation of human leukaemia U937 and HL60 cells, human lung cancer A549 and H1299 cells, and human embryonic kidney 293 (HEK293) cells.

Application of POLARIC™ fluorophores in an in vivo tumor model.

Fluorescent and luminescent tools are commonly used to study the dynamics of cancer progression and metastases in real-time. Fluorophores have become essential tools to study biological events. However, few can sustain fluorescence long enough during long-term studies. In the present study, we focused on a series of new amphiphilic fluorophores known as POLARIC™, which emit strong fluorescence in lipid bilayers and can be readily modified using the Suzuki-Miyaura cross-coupling reaction. Appropriate chemical modifications of substituent groups can improve target-site specificity, reduce cytotoxicity and prolong emission. Therefore, in contrast to conventional fluorescent probes, these fluorophores show promise for long-term monitoring of biological processes. In the present study, we conducted long-term observations of tumor growth and metastasis using a POLARIC derivative as a novel fluorescent probe. For this purpose, we studied the metastatic melanoma cell line A375-SM, which proliferates at a high rate. We compared the characteristics of the POLARIC probe with the commercially available fluorescent dye PKH26 and fluorescent protein mRFP1. A375-SM cells were labeled with these fluorescent probes and orthotopically implanted into nude mice. The fluorescence emitted by POLARIC was detected more than five weeks after implantation without causing detectable harmful effects on tumor growth. By contrast, fluorescence of cells labeled with PKH26 could not be detected at this same time. Furthermore, POLARIC-, but not PKH26-labeled cells, were also detected in lung metastases. These results indicate that labeling cells with POLARIC fluorophores can significantly extend the time course of in vivo studies on tumor cell growth.