Concurrent targeting of GSK3 and MEK as a therapeutic strategy to treat pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies worldwide. However, drug discovery for PDAC treatment has proven complicated, leading to stagnant therapeutic outcomes. Here, we identify Glycogen synthase kinase 3 (GSK3) as a therapeutic target through a whole-body genetic screening utilizing a '4-hit' Drosophila model mimicking the PDAC genotype. Reducing the gene dosage of GSK3 in a whole-body manner or knocking down GSK3 specifically in transformed cells suppressed 4-hit fly lethality, similar to Mitogen-activated protein kinase kinase (MEK), the therapeutic target in PDAC we have recently reported. Consistently, a combination of the GSK3 inhibitor CHIR99021 and the MEK inhibitor trametinib suppressed the phosphorylation of Polo-like kinase 1 (PLK1) as well as the growth of orthotopic human PDAC xenografts in mice. Additionally, reducing PLK1 genetically in 4-hit flies rescued their lethality. Our results reveal a therapeutic vulnerability in PDAC that offers a treatment opportunity for patients by inhibiting multiple targets.

Drosophila Screening Identifies Dual Inhibition of MEK and AURKB as an Effective Therapy for Pancreatic Ductal Adenocarcinoma

Significant progress has been made in understanding the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) by generating and using murine models. To accelerate drug discovery by identifying novel therapeutic targets on a systemic level, here we generated a Drosophila model mimicking the genetic signature in PDAC (KRAS, TP53, CDKN2A, and SMAD4 alterations), which is associated with the worst prognosis in patients. The '4-hit' flies displayed epithelial transformation and decreased survival. Comprehensive genetic screening of their entire kinome revealed kinases including MEK and AURKB as therapeutic targets. Consistently, a combination of the MEK inhibitor trametinib and the AURKB inhibitor BI-831266 suppressed the growth of human PDAC xenografts in mice. In patients with PDAC, the activity of AURKB was associated with poor prognosis. This fly-based platform provides an efficient whole-body approach that complements current methods for identifying therapeutic targets in PDAC.

SIGNIFICANCE

Development of a Drosophila model mimicking genetic alterations in human pancreatic ductal adenocarcinoma provides a tool for genetic screening that identifies MEK and AURKB inhibition as a potential treatment strategy.

O-272 Letrozole-induced endometrial preparation improved pregnancy outcomes after frozen blastocyst transfer compared to the natural cycle

Study question

Does letrozole-induced endometrial preparation affect pregnancy outcomes, perinatal outcomes, and congenital anomalies after single vitrified-warmed blastocyst transfers (SVBTs) when compared with the natural cycle?

Summary answer

Letrozole-induced endometrial preparation improved live birth rate without any adverse effects on perinatal outcomes and congenital anomalies after SVBTs.

What is known already

Letrozole treatment is considered an effective option in endometrial preparation for frozen embryo transfers in patients with ovulation disorders or irregular menstruation; however, the effectiveness of letrozole-induced endometrial preparation is still unclear in ovulatory patients. Furthermore, there is no comparative study reporting on pregnancy complications and congenital anomalies after frozen embryo transfers comparing natural and letrozole-assisted cycles.

Study design, size, duration

This retrospective study, at a major academic fertility centre, analysed a total of 14,611 clinical records of women who underwent SVBTs comprising both natural and letrozole-assisted cycles between July 2015 and June 2020. The cycle characteristics, pregnancy outcomes (clinical pregnancy, ongoing pregnancy, and live birth), and the incidence of pregnancy complications and congenital anomalies were statistically compared between the natural and letrozole groups.

Participants/materials, setting, methods

The study reviewed ovulatory patients who underwent their first SVBT during the study period. Some patients took letrozole during the early proliferative phase to promote follicular development and maturation (letrozole group). Ovulation was triggered by GnRH agonist and SVBTs were performed on day five after ovulation. Propensity score matching was performed to reduce any bias from patient characteristics. Multivariate logistic analysis was performed to evaluate the effects of letrozole administration on pregnancy and perinatal outcomes.

Main results and the role of chance

After propensity score matching, the characteristics of patients and transferred blastocysts were comparable between groups. The serum progesterone level was also significantly increased in the letrozole group (P < 0.0001). Although no difference was observed regarding implantation rate between groups, the rates of clinical pregnancy, ongoing pregnancy, and delivery in the letrozole group were all significantly higher than that in the natural group (P = 0.0273, P = 0.0162, P = 0.0479, respectively). The incidence of early pregnancy loss, miscarriage, and stillbirth were comparable between groups. Multivariate logistic regression analysis also demonstrated that the administration of letrozole during an SVBT cycle significantly improved the live birth rate (AOR, 1.160; P = 0.0355). The incidence of pregnancy complications was comparable between groups. The caesarean section rate was significantly lower in the letrozole group than that in the natural group (P = 0.0464). Gestational age, birth length, birth weight, and infant sex, as well as the incidence of pregnancy complications and birth defects, were statistically comparable between groups. Furthermore, multivariate logistic regression analysis showed that perinatal outcomes were not affected by letrozole-induced endometrial preparation, although the incidence of caesarean section was decreased in the letrozole group (AOR, 0.788; P = 0.0355).

Limitations, reasons for caution

Our findings are not compared with reported incidences of pregnancy complications and congenital anomalies in natural pregnancy. Furthermore, the study was retrospective in nature, and further multicentre studies are required to ascertain the generalisability of these findings for other clinics with different protocols and/or patient demographics.

Wider implications of the findings

Letrozole administration both extended the proliferative phase and increased luteal function, resulting in an improvement of live birth rates without any adverse effects. Therefore, letrozole-induced endometrial preparation might be a safe and more effective strategy for patients with shortened proliferative phase or insufficient luteal function.

Trial registration number

not applicable

Bacteremia after hepatectomy and biliary reconstruction for biliary cancer: the characteristics of bacteremia according to occurrence time and associated complications

PURPOSE

Bacteremia occurring after extensive hepatic resection and biliary reconstruction (Hx + Bx) for biliary cancer is a critical infectious complication. This study evaluated postoperative bacteremia and examined the potential usefulness of surveillance cultures.

METHODS

We retrospectively reviewed 179 patients who underwent Hx + Bx for biliary cancer from January 2008 to December 2018 in our department.

RESULTS

Bacteremia occurred in 41 (23.0%) patients. Patients with bacteremia had a longer operation time and more frequent intraoperative transfusion and more frequently developed organ/space surgical site infection (SSI) than those without bacteremia. The most frequently isolated bacterial species from blood cultures were Enterococcus faecium (29.3%), Enterobacter cloacae (24.4%), and Enterococcus faecalis (22.0%). The SIRS duration of bacteremia associated with organ/space SSI was significantly longer than that of other infectious complications (median 96 h vs. 48 h; p = 0.043). Bacteremia associated with organ/space SSI occurred most often by postoperative day (POD) 30. The concordance rate of bacterial species between blood and surveillance cultures within POD 30 was 67-82%.

CONCLUSIONS

Bacteremia associated with organ/space SSI required treatment for a long time and typically occurred by POD 30. Postoperative surveillance cultures obtained during this period may be useful for selecting initial antibiotic therapy because of their high concordance rate with blood cultures.

Comparison of pregnancy outcomes following fresh and electively frozen single blastocyst transfer in natural cycle and clomiphene-stimulated IVF cycles

STUDY QUESTION

Are there any differences in live birth rates (LBR) following fresh blastocyst transfer in natural or clomiphene-stimulated cycles, or after elective blastocyst freezing in clomiphene-stimulated cycles followed by thawing and transfer at different time-points?

SUMMARY ANSWER

Clomiphene citrate (CC) administration adversely affected the LBR after single fresh blastocyst transfer (SBT) in CC cycles compared with that in natural cycles, while this adverse effect of CC is not present when a single vitrified-warmed blastocyst transfer (SVBT) is performed in subsequent natural ovulatory cycles, regardless of the duration between CC administration and the day of SVBT.

WHAT IS KNOWN ALREADY

CC affects uterine receptivity associated with a thinning of the uterine endometrium through an antioestrogenic effect. However, the duration that this adverse effect of CC on uterine endometrium persists after initial use is still unknown.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 157 natural cycle IVFs followed by SBT and 1496 minimal ovarian stimulation with CC IVF cycles followed by SBT (n = 24) or SVBT (n = 1472) from January 2010 to December 2014 was conducted. SVBT cycles were classified into two groups according to the period between the last day of CC administration and the day of SVBT (A: ≤60 d and B: ≥61 d). All groups were then compared based on pregnancy outcomes (natural-SBT group: n = 157, CC-SBT group: n = 24, SVBT-A: n = 1143, SVBT-B: n = 329).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women were aged 30–39 years at oocyte retrieval. In SVBT cycles, blastocysts were vitrified and warmed using a Cryotop safety kit. SVBT was performed in subsequent natural ovulatory cycles. The main outcomes were LBR and neonatal outcome, and both were compared among the groups.

MAIN RESULTS AND THE ROLE OF CHANCE

The LBR in the CC-SBT group (29.2%, 7/24) was significantly lower compared with the natural-SBT (56.1%, 88/157) (P = 0.01) and SVBT-A (50.0%, 572/1143) (P = 0.04), but not SVBT-B (47.4%, 156/329), groups. Furthermore, multivariate logistic regression analysis revealed that the LBR was comparable among the natural-SBT and SVBT groups, but was significantly lower in the CC-SBT group (adjusted odds ratio: 0.324, 95% CI: 0.119–0.800, P = 0.01). No significant differences among all groups were observed for gestational age (P = 0.19), birthweight (P = 0.41) and incidence of malformation (P = 0.53).

LIMITATIONS, REASONS FOR CAUTION

In this study we analysed a biased sample, based on clinical judgement regarding endometrial thickness, and the study was limited by its retrospective nature. The low statistical power caused by the group size disparity was also a limitation, especially in the CC-SBT group. Although the outcome showing inferiority of CC-SBT compared to natural-SBT is consistent with general findings in the literature, further large-scale clinical studies, ideally RCTs, are necessary to validate our results and clarify the prolonged effect of CC in SVBT cycles on pregnancy and neonatal outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Our observation suggests that CC administered in minimal ovarian stimulation cycles affects adversely the pregnancy outcomes when SBT is performed. Therefore, for a CC-based minimal stimulation IVF cycle, we suggest that frozen embryo transfer should be performed in a subsequent natural ovulatory cycle to avoid the possibility of implantation failure associated with CC administration.

STUDY FUNDING/COMPETING INTERESTS

The authors have no conflicts of interest to declare. No external funding was either sought or obtained.

Mass Preparation of Primary Porcine Hepatocytes and the Design of a Hybrid Artificial Liver Module using Spheroid Culture for a Clinical Trial

To isolate a large number of porcine hepatocytes, we originally developed a mass preparation method that combined the usual collagenase perfusion method of a whole liver with a collagenase redigestion method of tissue fragments after liver perfusion. Using a pig of 10kg, collagenase perfusion only resulted in a yield of 63 ± 78 x 108 total cells with a viability of 69.2 ± 25.3 %, but our combined method had a yield of 167 ± 31 x 108 total cells with a viability of 87.9 ± 4.4 % (mean ± SD). Also, the combined method was applied to two pigs of 10kg body weight at the same time, and isolated 387 ± 89 x 108 hepatocytes with a viability of 87.1 ± 6.9 % and a purity of 93.6 ± 2.8 % in 11 experiments.

We designed a large multi-capillary polyurethane foam (MC-PUF) packed-bed module containing 1 x 1010 porcine hepatocytes on a clinical trial scale. The porcine hepatocytes in the module formed spherical multicellular aggregates (spheroids) of 200 – 500 μm diameter. Most hepatocytes forming spheroids were viable judged by fluorescein diacetate and ethidium bromide staining. The activities of ammonia removal, albumin secretion and oxygen consumption of the large MC-PUF module were the same as for a small MC-PUF module containing 2 x 108 porcine hepatocytes, and were maintained for at least 9 days of culture. These results show that a large MC-PUF module is successfully scaled up 50 times.

In conclusion, we succeeded in developing a mass preparation method of porcine hepatocytes and a large hybrid artificial liver module on a clinical trial scale.

The Efficacy of Nafamostat Mesilate on the Performance of a Hybrid-artificial Liver using a Polyurethane foam/porcine Hepatocyte Spheroid Culture System in Human Plasma

Nafamostat mesilate (FUT) is a protease inhibitor of complement activation. The present study investigates whether FUT protects porcine hepatocytes from being injured by human plasma in a multi-capillary polyurethane foam packed-bed culture system (MC-PUF) such as the hybrid-artificial liver (PUF-HAL). Human plasmas with 1 mM of added ammonia were perfused using a small-scale PUF-HAL with porcine hepatocytes. FUT was continuously infused (10 μ g/ml, 50 μ g/ml,). The ammonia detoxification was maintained in human plasma for 24 hours and for 48 hours with FUT which suppressed the rapid increase of asparaginic acid aminotransferase (AST) and alanine aminotransferase (ALT). After 60 hours of perfusion, hepatocyte spheroids completely collapsed in the human plasma, but a small amount of hepatocyte spheroid was maintained by FUT. The effect of FUT was slightly greater at 50 μ g/ml than at 10 μ g/ml. Our results suggest that FUT has protective effects against porcine hepatocytes in human plasma, and our PUF-HAL using porcine hepatocytes can function in human plasma for about 48 hours with FUT.

Electrochemical microdevices for rapid and on-site determination of the minimum inhibitory concentration of antibiotics

A tool for rapid selection of appropriate antibiotics may be useful to maximize the benefits of their effectiveness against severe infectious diseases.

Differentiation Effects by the Combination of Spheroid Formation and Sodium Butyrate Treatment in Human Hepatoblastoma Cell Line (Hep G2): A Possible Cell Source for Hybrid Artificial Liver

The aim of this study was to investigate the feasibility of human hepatoblastoma cell line (Hep G2), which differentiates by spheroid formation, and treatment with sodium butyrate (SB) as a cell source for hybrid artificial liver (HAL). Hep G2 spontaneously formed spheroids in polyurethane foam (PUF) within 3 days of culture and restored weak ammonia removal activity. Treatment with SB, which is a histone deacetylase inhibitor, further increased the ammonia removal activity of Hep G2 spheroids in a concentration-dependent manner. The activation of ornithine transcarbamylase—a urea cycle enzyme—was significantly related to the upregulation of ammonia removal by spheroid formation, but scarcely contributed to the further upregulation following SB treatment. In contrast with ammonia removal, treatment with SB reduced the albumin secretion of Hep G2 spheroids in a concentration-dependent manner. In the PUF-HAL module in a circulation culture, the ammonia removal rate and albumin secretion rate (per unit volume of the module) of Hep G2 spheroids treated with 5 mM SB were almost the same as those of primary porcine hepatocyte spheroids. These results suggest that simultaneous use of spheroid formation and SB treatment in Hep G2 is beneficial in enhancing the functions of human hepatocytes with potential applications in regenerative medicine and drug screening.

Glycolipid-based nanostructures with thermal-phase transition behavior functioning as solubilizers and refolding accelerators for protein aggregates

The self-assembly of synthetic glycolipids produced nanostructures such as vesicles and nanotubes consisting of bilayer membranes, which underwent a gel-to-liquid crystalline thermal phase transition. Vesicles formed at temperatures above the thermal phase transition temperatures (T_g-l) could solubilize aggregates of denatured proteins by trapping them in the fluid bilayer membranes. Cooling to temperatures below T_g-l caused a morphological transformation into nanotubes that accompanied the thermal phase transition from the fluid to the solid state. This phenomenon allowed the trapped proteins to be quickly released into the bulk solution and simultaneously facilitated the refolding of the proteins. The refolding efficiency strongly depended on the electrostatic attraction between the bilayer membranes of the nanostructures and the proteins. Because of the long shape (>400 nm) of the nanotubes, simple membrane filtration through a pore size of 200 nm led to complete separation and recovery of the refolded proteins (3-9 nm sizes).

Abstract 1429: Contribution of membrane-bound carboxypeptidase M to tumor growth and metastasis by regulating epithelial mesenchymal transition in esophageal squamous carcinoma

Carboxypeptidase M (CPM) is a membrane-bound exopeptidase that recognizes the arginine (Arg) and lysine (Lys) residues in a C-terminal of polypeptide chain or protein. The cleavage of some soluble factors such as SDF-1 and EGF by CPM leads to the alteration of binding affinity to their receptors. In this study, we examined the properties of CPM for tumor growth and metastasis in human esophageal carcinoma cells. In order to investigate the expression of CPM on human tumor cells, we established the monoclonal antibody specific for human CPM and found the constitutive expression of CPM on various human carcinomas by flow cytometry and confocal laser microscopy. Treatment of cancer cells with EMT-mediated cytokines, including TGF-beta, IL-6 and OSM, increased CPM expression on their cell surface followed by enhancement of cell migration and change of cell shapes from epithelial to mesenchymal type. Silencing CPM expression by small interfering RNA (siRNA) specific for CPM in esophageal and breast carcinoma cells were confirmed by flow cytometry. We found that CPM-silenced carcinoma exhibited reduced cell proliferation not only in 2D culture flask but also in 3D spheroid culture plate. Importantly, the treatment of siRNA for CPM inhibited the expression of EMT-related genes such as snail and slug which are important for cancer motility. Consistently, we found that CPM-silenced carcinoma exhibited reduced motility of cell in wound healing assay. Taken together, these data indicate that CPM contributes to cell growth and EMT and might be a therapeutic target in esophageal carcinoma.

Citation Format: Yuji Kudo, Junki Fukuda, Ritsuko Harigai, Kazunori Kato. Contribution of membrane-bound carboxypeptidase M to tumor growth and metastasis by regulating epithelial mesenchymal transition in esophageal squamous carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1429. doi:10.1158/1538-7445.AM2015-1429

Three-dimensional positioning and control of colloidal objects utilizing engineered liquid crystalline defect networks

Topological defects in liquid crystals not only affect the optical and rheological properties of the host, but can also act as scaffolds in which to trap nano or micro-sized colloidal objects. The creation of complex defect shapes, however, often involves confining the liquid crystals in curved geometries or adds complex-shaped colloidal objects, which are unsuitable for device applications. Using topologically patterned substrates, here we demonstrate the controlled generation of three-dimensional defect lines with non-trivial shapes and even chirality, in a flat slab of nematic liquid crystal. By using the defect lines as templates and the electric response of the liquid crystals, colloidal superstructures are constructed, which can be reversibly reconfigured at a voltage as low as 1.3 V. Three-dimensional engineering of the defect shapes in liquid crystals is potentially useful in the fabrication of self-healing composites and in stabilizing artificial frustrated phases.

Topological defects can be used not only to modify the properties of liquid crystals but also as scaffolds to build new structures by trapping particles. Here, Yoshida et al. construct three-dimensional colloidal superstructures in a nematic host, which are reconfigurable in an electric field.

Fabrication of patterned cell co-cultures on albumin-based substrate: applications for microfluidic devices

A surface coated with cross-linked albumin film resists the adhesion of cells, and subsequent exposure to UV irradiation or electrostatic adsorption of a cationic polymer switches the surface from non-adherent to adherent. Taking advantage of this unique property of cross-linked albumin, the authors fabricated patterned cell co-cultures with desired patterns and cell types. In this scheme, the cell-adherent region was initially created in the cell-non-adhesive albumin substrate, on which a first cell type was attached. Subsequently, the remaining region was also changed to adherent for the attachment of secondary cells in the same manner, thereby allowing distinctly localized co-cultures. As a proof of concept demonstration of the feasibility of this approach, a patterned co-culture of Neuro-2a cells with L929 cells was successfully prepared on the substrate. Furthermore, combining this technique with a microfluidic technique, a micropatterned co-culture of PA6 cells with 3T3 fibroblasts was created inside microfluidic devices. This approach could potentially be a useful tool for fundamental investigations of cell-cell interactions and for tissue engineering applications.

Intraoperative surgical clearance confirmation of tongue carcinomas using ultrasound

OBJECTIVES

The existence of tumour cells on the surgical margin can be shown in frozen sections. However, there has been no method to obtain information about surgical clearance intraoperatively. We propose a simple method to confirm the surgical clearance of tongue carcinomas during surgery.

METHODS

Just after the resection of a tumour in a conventional manner, the resected fresh specimen was immersed in a gelatine solution, maintaining its original shape and orientation, and refrigerated for solidification of the gelatine. Then ultrasound observation of the gelatine-embedded specimen was performed from the surface of the gelatine.

RESULTS

Very fine images could be obtained easily and without any specialist skills.

CONCLUSIONS

With this method, the operator can easily obtain information about surgical clearance during the operation.

Changes in temporomandibular disc position during growth in young Japanese

PURPOSE

To detect the initial changes in temporomandibular disc position during growth with MRI examination in a prospective longitudinal study of a young Japanese population.

METHODS

Forty-four temporomandibular joints in 22 healthy asymptomatic volunteers, mean age 11.8 years, age range 9-16 years, were examined by MRI. They were re-examined 2-3 years later. The mean age and age range at the second examination were 14.5 years and 12-19 years, respectively. The discs were assessed at three different locations by oblique sagittal planes at the lateral, central and medial parts, and the displacement was evaluated as a partial anterior or total anterior position.

RESULTS

Six joints already had a partial anterior position of the disc at the initial examination and no developmental change in disc position was observed during the examination period. Nine joints developed partial disc displacement during the examination period. Every partial displacement was observed at the lateral part of the disc. One joint developed a total anterior position from the lateral to the medial images.

CONCLUSIONS

Initial changes in the disc position are likely to start from the lateral part of the joint in the early teenage years and are often asymptomatic.

Configuration of a chiral smectic-C film with a circular inclusion

It was shown experimentally (P.V. Dolganov et al., Europhys. Lett. 76, 250 (2006)) and by numerical calculations (C. Bohley, R. Stannarius, Eur. Phys. J. E 23, 25 (2007)) that the c -director profile of a two-dimensional chiral smectic-C (SmC) film around a circular inclusion adopts dipolar rather than quadrupolar configuration observed in achiral SmC films. We give an analytical argument on how spontaneous bend inherent in chiral SmC liquid crystals influences the configuration of a SmC liquid crystal film around a circular inclusion imposing tangential anchoring. We find how the angle alpha between two surface defects seen from the center of the inclusion depends on the radius of the inclusion R and the strength of the spontaneous bend q . We show, however, that the contribution of the spontaneous bend to the free energy suffers from mathematical ambiguity; it depends on the mathematical treatment of the outer boundary even when it is at infinity. This might indicate that the shape as well as the treatment of the outer boundary of the film can significantly influence the equilibrium configuration of the c -director and the position of the surface defects.

Functional evaluations of the parotid and submandibular glands using dynamic magnetic resonance sialography

PURPOSE

To evaluate the functional differences between the parotid and submandibular glands using dynamic MR sialography.

METHODS

In 30 volunteers, the time-dependent changes (dynamic changes) in the maximum area of the detectable parotid and submandibular gland ducts on dynamic MR sialographic images were analysed.

RESULTS

Dynamic changes in the parotid gland ducts were detectable on MR sialographic images in all volunteers, but images of the submandibular gland ducts were detectable in only 23 volunteers. In addition, the dynamic changes in the submandibular gland ducts in these 23 subjects were less than those seen in the parotid gland ducts. A relationship was found between the changing ratio of parotid (Pearson r=0.448, P=0.013) or submandibular gland ducts (Pearson r=0.418, P=0.047) and the salivary flow rate during the stimulation period.

CONCLUSIONS

Dynamic MR sialography allows evaluation of rest and stimulated functioning and morphological evaluation of the parotid and submandibular glands. This technique appears to have many possible applications in the dental, medical and biological fields.

Morphological features of cartilage observed during mandibular distraction in rabbits

Ossification during distraction osteogenesis can be classified as intramembranous or endochondral. It is not known whether cartilage in the distraction gap is transformed into new bone. The aim of this study was to investigate the morphological features of ossification in the transition of cartilage to bone during mandibular distraction osteogenesis in a rabbit model. A cortical osteotomy was performed and custom-made devices were applied. Immediately after surgery, the devices were lengthened by 0.25 mm every 12h for up 10 days, during which time four rabbits were killed at 0, 5 and 10 days and examined using histological staining and immunohistochemical methods. Apoptotic cells were identified by an in-situ detection assay for nuclear DNA fragmentation using a modified TUNEL procedure, with several sections analyzed using software for histomorphometric analysis. The results showed that the amount of cartilage in the distraction gap was significantly decreased. The cartilage had ossified in two ways, termed endochondral ossification and transchondroid bone formation.

Local delivery system of cytotoxic agents to tumors by focused sonoporation

Recently, ultrasound-targeting microbubble destruction has been employed in molecular gene therapy, and a new potent nonviral gene transfer method known as 'sonoporation' has been developed. We investigated the efficiency of sonoporation toward growth inhibition of human gingival squamous carcinoma cell line, Ca9-22, in vitro and in vivo. The cytotoxicity of bleomycin (BLM) was investigated using flow-cytometric analysis and Hoechst's staining in vitro assay systems. We found that the delivery of BLM by sonoporation induced cytotoxic effect toward Ca9-22 cells in vitro. Our in vivo results showed that tumors nearly disappeared in Ca9-22 cell-implanted nude KSN/slc mice treated with a low dose of BLM followed by sonoporation during the 4-week experimental period. Histological analysis revealed that the cytotoxic effect was mainly apoptosis. We previously reported that the cytolethal distending toxin B (cdtB) from Actinobacillus actinomycetemcomitans, a periodontopathic bacterium, is responsible for cell cycle arrest and apoptosis in vitro. Thus, we used sonoporation to transfect a cdtB-expressing plasmid into Ca9-22 cells and examined cell viability in vitro and in vivo. We found that an administration of cdtB-expressing plasmid followed by sonoporation-induced marked growth inhibition of Ca9-22 cells and apoptotic cells were also observed in vitro and in vivo. These findings suggest that local administration of cytotoxic agents with sonoporation is a useful method for molecular cancer therapy.

Stability of the director profile of a nematic liquid crystal around a spherical particle under an external field

We study numerically the effect of an external magnetic or electric field on the director profiles of a nematic liquid crystal around a spherical particle. We pay particular attention to the stability of a hyperbolic hedgehog defect accompanying the particle, which transforms into a Saturn-ring defect encircling the particle under a sufficiently strong external field. We focus on the particle size dependence of the two important threshold field strengths: the "thermodynamic-transition" field strength H1 at which the hedgehog and the Saturn-ring configurations have the equal free energy, and the critical field strength H2 at which the hedgehog loses its (meta)stability. Our numerical results demonstrate that while H1 is non-monotonically dependent on the particle radius R0, H2 monotonically increases with R0 and the dependence of H2 is weak for large R0. The non-monotonic dependence of H1 on R0 can be explained by comparing the energies of the two configurations and assuming the dependence of those energies on a rescaled field. A crude argument of the energetics of a hyperbolic hedgehog defect under an external field shows that for an asymptotically large R0 the critical field strength is independent of R0, which agrees with our numerical finding.