Complement activation products in tears of dry eye and meibomian gland dysfunction

Sixty-seven patients (38 woman; median age, 69 years) were enrolled to assess complement activation products (CAPs) in tear fluid with/without dry eye (DE) and with/without meibomian gland dysfunction (MGD). Patients were divided into four groups based on the presence/absence of DE and MGD: group DM had both DE and MGD, group DN had DE without MGD, group NM had MGD without DE, and group NN had neither DE nor MGD. The levels of C3a and C5a in the collected tears were analyzed using a cytometric bead array. The C3a concentrations in the DM, DN, NM, and NN groups were 2326 pg/ml, 1411 pg/ml, 1821 pg/ml, and 978 pg/ml, respectively. The C5a concentrations in the DM, DN, NM, and NN groups were 24.7 pg/ml, 15.3 pg/ml, 24.1 pg/ml, and 12.9 pg/ml, respectively. The concentrations of C3a and C5a in the DM and NM groups were significantly higher than in the NN group (P < 0.05 for both comparisons). The CAPs in the tear fluid in MGD and DE increased. Local dysregulation of the innate immune system can be associated with the development of MGD and DE in elderly patients.

Tear fluid and complement activation products in tears after ocular surgery

PURPOSE

Due to technological advancements, surgical invasiveness has been reduced. However, cataract surgery has been implicated in causing postoperative inflammation, including dry eye syndrome. The innate immune system may be involved in postoperative inflammation, and complement activation could potentially play a crucial role in defense against pathogens, homeostasis, and wound healing. To investigate changes in the tear film complement activation products (CAPs) and ocular surface after vitrectomy combined with cataract surgery.

METHODS

Forty-three patients (23 women; median age, 69 years) were enrolled in this prospective study and underwent phacoemulsification and vitrectomy. We measured Schirmer's test (ST) and CAPs in the tears at baseline (the day before surgery), 4 days and 1 month after the surgery. Tears were collected in microtubes. The CAPs in the tear fluid were analyzed by cytometric bead array.

RESULTS

The median ST (8.5 mm) at baseline increased to 16 mm at 4 days ( P < 0.001) and 10 mm at 1 month (P = 0.44). The C3a levels (1202 pg/ml) at baseline increased to 2753 pg/ml at 4 days (P < 0.001), and 1763 pg/ml at 1 month (P = 0.049). The C4a levels (476 pg/ml) at baseline increased to 880 pg/ml at 4 days (P < 0.001), and 657 pg/ml at 1 month (P = 0.013). The C5a levels (22.6 pg/ml) at baseline increased to 470.9 pg/ml at 4 days (P < 0.001), and 38.3 pg/ml at 1 month (P = 0.0048). The surgical eyes were divided into the short ST group (≦ 10 mm, n = 22) and long ST group (> 10 mm, n = 21) based on the preoperative ST values. At 1 month postoperatively, the C3a levels were 2194 pg/ml in the preoperative short ST group and 1391 pg/ml in the long ST group, with significantly higher C3a concentrations in the short ST group (P < 0.001).

CONCLUSIONS

The CAPs levels in tears increased after vitrectomy combined with cataract surgery. A preoperative deficit in tear secretion might induce prolonged complement activation and delayed recovery of ocular surface parameters postoperatively.

Reconstruction of the elbow using pedicle joint freezing after wide excision for soft tissue sarcoma: A case report

A 35-year-old man presented with a four-year history of a growing mass on the anterior aspect of his left elbow. Magnetic resonance imaging revealed a soft tissue tumor in the brachialis muscle extending to the cubital fossa. Following an open biopsy, the tumor was diagnosed as a monophasic fibrous synovial sarcoma. After neoadjuvant chemotherapy, the patient underwent wide excision and reconstruction of the elbow joint with a pedicle frozen autograft. At the final follow-up four years after surgery, the elbow range of motion was 0-120˚. Although there were signs of osteoarthritis, there was no narrowing of the joint -, and the patient experienced only mild pain. To the best of our knowledge, the present case report is the first to describe wide tumor excision and reconstruction using a pedicle frozen autograft of the elbow. This method should be considered after excision of malignant bone and soft tissue tumors, especially in non-weight-bearing joints. Further cases have to be evaluated to understand the complications and long-term prognosis of this procedure.

Impact of tear metrics on the reliability of perimetry in patients with dry eye

Background

The application of artificial tears before performing perimetry can improve the reliability and results of perimetry in patients with glaucoma and dry eye (DE). However, the effects of ocular surface and tear film conditions on perimetry measurements and reliability have not been fully characterized.

Methods

This prospective, cross-sectional, multicenter study investigated tear metrics in perimetry and assessed the relationships that existed among ocular surface condition, tear condition, and perimetry reliability. Forty-three eyes (43 patients) with DE disease according to the 2016 Japanese diagnostic criteria of DE and 43 eyes (43 subjects) of age- and visual field mean deviation-matched normal control subjects were studied. Perimetry was performed using the Humphrey Field Analyzer (30–2 SITA-Standard). Schirmer’s test, strip meniscometry value, blink rate, tear film break-up time (TFBUT), fluorescein staining of ocular surface, and Dry Eye-related Quality of Life Score (DEQS) were measured. Blink rate was re-measured during perimetry. TFBUT and fluorescein staining were re-evaluated after perimetry. Perimetry reliability was evaluated with fixation loss, false-positive, and false-negative rates.

Results

Blink rate during perimetry was significantly lower for both patients with DE and normal controls (both P<0.001). TFBUT after perimetry was significantly higher than before perimetry in patients with DE (P<0.001). Fluorescein staining of ocular surface was significantly increased in patients with DE and normal control subjects (P = 0.002 and P<0.001, respectively). Spearman correlation analysis revealed that blink rate during perimetry was negatively correlated with fixation-loss rate (r = -0.393, P = 0.009) in patients with DE.

Conclusions

Performing perimetry was associated with a significant change in tear condition and ocular surface condition in both patients with DE and normal control subjects. The changes in tear condition and ocular surface condition may impact the reliability of perimetry in patients with DE.

Radiation-induced sarcoma in a 10-year survivor with stage IV EGFR-mutated lung adenocarcinoma

A 70-year-old Japanese man with stage IV EGFR-mutated lung adenocarcinoma complained of right mild back pain. The patient had been heavily treated with several cytotoxic or molecular targeted agents for 10 years and received a palliative radiation therapy of 2^nd sacral vertebra 5 years ago. Computed tomography showed the abnormal lesion in right iliopsoas muscle. A pathological examination confirmed undifferentiated pleomorphic sarcoma, consistent with the diagnosis of radiation-induced sarcoma (RIS). Since RIS is a rare late-onset complication of radiation therapy, to our knowledge, this is the first report of RIS that was associated with advanced lung cancer and detected after palliative radiation therapy. The careful long-term follow-up is thus necessary even after palliative radiation therapy and we have to be aware of the existence of RIS.

Distal locking screw length for volar locking plate fixation of distal radius fractures: Postoperative stability of full-length unicortical versus shorter screws

We compared post-operative distal radius fracture (DRF) displacement after volar locking plate fixation using full-length unicortical and shorter-length distal locking screws. In this non-inferiority, retrospective cohort study, DRFs treated with volar locking plate fixation were evaluated on X-rays. In the full-length group, volar locking plate fixation was performed with full-length unicortical distal locking screws. In the shorter-length group, the distal locking screws were planned pre-operatively to be approximately 75% of the distal radius depth based on the lunate depth, and the same depth was drilled. Three radiographic parameters - ulnar variance, volar tilt, and radial inclination - were measured intra-operatively and at the final follow-up. The displacements were compared between the two groups. Each group contained 34 fractures. The mean ulnar variance between the two periods increased 1.1 mm in the full-length group and 1.3 mm in the shorter group (mean difference, 0.2 mm; 90% confidence interval, -0.3 to 0.6). The shorter group was not significantly inferior to the full-length one. Volar tilt increased 0.6° in the full-length group and -0.1° in the shorter group, while the radial inclination increased 0.1° in the full-length group and 0.2° in the shorter one. The differences in the increases were not significant. The post-operative DRF stability of 75%-length distal locking screws was not inferior to that of full-length unicortical screws. To prevent extensor pollicis longus tendon rupture, shorter distal locking screws and the same drilling depth may be preferable for volar locking plate fixation.

Morphometrical evaluation of the choriocapillaris imaged by swept-source optical coherence tomography angiography

Purpose

To assess the reproducibility of quantitative morphometrical evaluation of the choriocapillaris imaged with swept-source optical coherence tomography angiography (SS-OCTA).

Subjects and methods

This observational, cross-sectional case series included 35 eyes of healthy individuals and 32 eyes of 32 patients. Two images of the fovea were taken using SS-OCTA with 3×3 mm squares. Images of the choriocapillaris within 800×800 pixel squares centered at the fovea were analyzed morphometrically using open-source software "AngioTool" that applies a Gaussian recursive filter and multiscale Hessian enhancement. This program's vessel thickness and intensity parameters can be changed to aid vessel detection. We measured the pairs of images per eye with different parameter sets and calculated the intraclass correlation (ICC) for the morphometrical results. After determining the parameters that produced high reproducibility, we evaluated regional variations in 800×800 pixel mm squares within the fovea.

Results

The ICCs for vessel area, total vessel length, vessel diameter index, and mean lacunarity were over 0.9 using the parameters of "vessel thickness" 3-4 and intensity 15 in the group including all subjects. When measurements were performed using these same parameter values, the vessel density and mean vessel diameter index were 60.5% and 19.1±0.389, respectively. Vessel density, vessel length, vessel diameter index, and mean lacunarity did not change significantly within an 800×800 pixel square centered at the fovea except for the 200×200 pixel square at the foveal center.

Conclusion

SS-OCTA images of the choriocapillaris can be measured with high reproducibility by morphometrical evaluation using open-source software with multiscale Hessian enhancement. Such automated morphometric analysis can provide an objective evaluation of the choriocapillaris.

MRI findings and demographics of elastofibroma dorsi: assessment of diffusion-weighted imaging and contrast enhancement patterns

Background Elastofibroma dorsi is a rare pseudotumoral lesion. Thus, there is no report of magnetic resonance imaging (MRI) findings that investigates multiple patients particularly with respect to diffusion-weighted imaging (DWI) findings and contrast enhancement patterns. Purpose To describe the imaging findings of elastofibroma on MRI, particularly DWI findings and contrast enhancement patterns, and to further investigate patient demographics. Material and Methods Forty-four patients with elastofibroma that underwent MRI were enrolled in this retrospective study. All images were evaluated by two radiologists to visually assess the signal intensity for each sequence. Enhanced elastofibromas were classified into four categories to assess the enhancement pattern. Differences in gender and laterality were also assessed statistically. Results An equal number of men and women were included (n = 22 each). There was no significant difference in laterality ( P = 0.783). All lesions (73 lesions) had low signal intensity on both T1-weighted (T1W) and T2-weighted (T2W) images: heterogeneous in 56, homogeneous in 17. None of the 41 lesions with DWI had true abnormal diffusion restriction. The average ADC value was 1.36 × 10^-3 ± 0.29 mm²/s. All 31 lesions that had contrast-enhanced MRI were classified according to enhancement pattern: homogeneous (three lesions, 9.7%); heterogeneous (15 lesions, 48.4%); streak-like (three lesions, 9.7%); and rim-like (ten lesions, 32.2%). Conclusion There were no statistically significant differences in gender or laterality. Elastofibroma showed homogeneous to heterogeneous low signal intensity on T1W and T2W images. No lesion showed abnormal diffusion restriction, and all lesions demonstrated enhancement on MRI.

3-dimensional tissue is formed from cancer cells in vitro on Gelfoam®, but not on Matrigel™

Cell and tissue culture can be performed on different substrates such as on plastic, in Matrigel™, and on Gelfoam(®), a sponge matrix. Each of these substrates consists of a very different surface, ranging from hard and inflexible, a gel, and a sponge-matrix, respectively. Folkman and Moscona found that cell shape was tightly coupled to DNA synthesis and cell growth. Therefore, the flexibility of a substrate is important for cells to maintain their optimal shape. Human osteosarcoma cells, stably expressing a fusion protein of α(v) integrin and green fluorescent protein (GFP), grew as a simple monolayer without any structure formation on the surface of a plastic dish. When the osteosarcoma cells were cultured within Matrigel™, the cancer cells formed colonies but no other structures. When the cancer cells were seeded on Gelfoam(®), the cells formed three-dimensional tissue-like structures. The behavior of 143B osteosarcoma cells on Gelfoam(®) in culture is remarkably different from those of these cells in monolayer culture or in Matrigel™. Tissue-like structures were observed only in Gelfoam(®) culture. The data in this report suggest a flexible structural substrate such as Gelfoam(®) provides a more in vivo-like culture condition than monolayer culture or Matrigel(TM) and that Matrigel(TM) does not result in actual three-dimensional culture.

Abstract 5: Real-time in vivo imaging of osteosarcoma angiogenesis

We report here real-time color-coded imaging of osteosarcoma-induced angiogenesis in vivo. Gelfoam® (5×5 mm) treated with β fibroblast growth factor (bFGF) was initially transplanted subcutaneously in the flank of transgenic nestin-driven green fluorescent protein (ND-GFP) nude mice (n=12). In ND-GFP mice, nascent blood vessels are labeled with GFP, including those growing in Gelfoam®. Seven days after transplantation of Gelfoam®, skin flaps were made and human 143B osteosarcoma cells expressing GFP in the nucleus and red fluorescent protein (RFP) in the cytoplasm were injected into the transplanted Gelfoam®. The control group had only Gelfoam® transplanted without subsequent cancer-cell inoculation. Skin flaps were made at days 14, 21, 28 after transplantation of the Gelfoam® to allow observation of vascularization of the Gelfoam® using fluorescence imaging after both with and without cell inoculation. ND-GFP expressing nascent blood vessels penetrated and spread into the Gelfoam® in both the non-cellular control and after cancer-cell inoculation. The mean length of ND-GFP expressing blood vessels of mice with osteosarcoma cells seeded on the Gelfoam® increased compared to the Gelfoam®-only control at days 14, 21, 28 after transplantation of the Gelfoam® (at day 14, 21 ; p&lt;0.05, at day 28 ; p&lt;0.01). The results demonstrate that the osteosarcoma cells stimulated angiogenesis within the Gelfoam®. This model enables facile imaging of cancer-cell-induced angiogenesis and the study of its mechanism and inhibition.

Citation Format: Fuminari Uehara, Yasunori Tome, Hiroki Maehara, Fuminori Kanaya, Shinji Miwa, Yukihiko Hiroshima, Shuya Yano, Mako Yamamoto, Yasunori Matsumoto, Robert M. Hoffman. Real-time in vivo imaging of osteosarcoma angiogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5. doi:10.1158/1538-7445.AM2014-5

Abstract 13: Color-coded imaging of vessel anastomosis in vivo using RFP and CFP transgenic mice

We previously report the development of a color-coded imaging model that can visualize the anastomosis between blood vessels of red fluorescent protein (RFP)-expressing vessels in Gelfoam® previously vascularized in RFP transgenic mice and blood vessels of nestin-driven green fluorescent protein (ND-GFP) mice that express GFP in nascent vessels (Anticancer Res. 33: 3041-3046, 2013). In the present study, fourteen days after transplantation into RFP transgenic nude mice, the Gelfoam® was removed and re-transplanted into the subcutis on the flank of cyan fluorescent protein (CFP) transgenic mice. Skin flaps were made and anastomosis between the CFP-expressing vessels and RFP blood vessels in the Gelfoam® was imaged 14 and 21 days after re-transplantation. The results presented in this and our previous report suggest a new paradigm of visualizing blood vessel anastomosis and its implications for tumor angiogenesis.

Citation Format: Fuminari Uehara, Yasunori Tome, Hiroki Maehara, Kazuhiro Tanaka, Fuminori Kanaya, Shinji Miwa, Yukihiko Hiroshima, Shuya Yano, Mako Yamamoto, Yasunori Matsumoto, Robert M. Hoffman. Color-coded imaging of vessel anastomosis in vivo using RFP and CFP transgenic mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 13. doi:10.1158/1538-7445.AM2014-13

Abstract 2403: Imaging of UVB and UVC-induced DNA damage repair in cancer cells in Gelfoam histoculture and minimal cancer in mice

We compared the DNA damage repair response of cancer cells after UVB or UVC irradiation. The DNA-damage repair response to UV irradiation was imaged in tumors growing in 3D Gelfoam® histoculture and in superficial tumors grown in mice. UV-induced DNA damage repair was imaged with GFP fused to the DNA damage response (DDR)-related chromatin-binding protein 53BP1 in MiaPaCa-2 human pancreatic cancer cells. 53BP1 forms foci during DNA damage repair. A clonogenic assay initially showed that UVC and UVB inhibited MiaPaCa-2 cell proliferation in a dose-dependent manner, with UVC having more efficacy. Gelfoam® histocultures and confocal imaging enabled 53BP1-GFP nuclear foci to be observed within 1 h after UV irradiation, indicating the onset of DNA damage repair response. Induction of UVB-induced 53BP1-GFP focus formation was observed up to a depth of 120 µm in MiaPaCa-2 cells on Gelfoam®, while UVC induced foci only to a depth of 40 µm. The MiaPaCa-2 cells irradiated by both UVB and UVC light in a skin-flap mouse model had a significant decrease in tumor growth compared to untreated controls. Moreover, UVB-treatment had greater inhibition of tumor growth compared to UVC. Our results demonstrate that both UVB and UVC are useful tools for the treatment of residual cancer, and UVB was more effective than UVC in vivo, possibly due to greater tissue penetration of UVB because of its longer wavelength.

Citation Format: Fuminari Uehara, Shinji Miwa, Yasunori Tome, Hiroki Maehara, Fuminori Kanaya, Yukihiko Hiroshima, Shuya Yano, Mako Yamamoto, Yasunori Matsumoto, Elena V. Efimova, Robert M. Hoffman. Imaging of UVB and UVC-induced DNA damage repair in cancer cells in Gelfoam histoculture and minimal cancer in mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2403. doi:10.1158/1538-7445.AM2014-2403

Osteosarcoma cells enhance angiogenesis visualized by color-coded imaging in the in vivo Gelfoam® assay

We previously described a color-coded imaging model that can quantify the length of nascent blood vessels using Gelfoam® implanted in nestin-driven green fluorescent protein (ND-GFP) nude mice. In ND-GFP mice, nascent blood vessels are labeled with GFP. We report here that osteosarcoma cells promote angiogenesis in the Gelfoam® angiogenesis assay in ND-GFP mice. Gelfoam® was initially transplanted subcutaneously in the flank of transgenic ND-GFP nude mice. Seven days after transplantation of Gelfoam®, skin flaps were made and human 143B osteosarcoma cells expressing green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in cytoplasm were injected into the transplanted Gelfoam®. The control-group mice had only implanted Gelfoam®. Skin flaps were made at days 14, 21, and 28 after transplantation of the Gelfoam® to allow imaging of vascularization in the Gelfoam® using a variable-magnification small animal imaging system and confocal fluorescence microscopy. ND-GFP expressing nascent blood vessels penetrated and spread into the Gelfoam® in a time-dependent manner in both control and osteosarcoma-implanted mice. ND-GFP expressing blood vessels in the Gelfoam® of the osteosarcoma-implanted mice were associated with the cancer cells and larger and longer than in the Gelfoam®-only implanted mice (P < 0.01). The results presented in this report demonstrate strong angiogenesis induction by osteosarcoma cells and suggest this process is a potential therapeutic target for this disease.

High lung-metastatic variant of human osteosarcoma cells, selected by passage of lung metastasis in nude mice, is associated with increased expression of α(v)β(3) integrin

Altered expression of αvβ3 integrin is associated with tumor progression and metastasis in several types of cancer, including metastatic osteosarcoma. In this study, we demonstrate that in vivo passaging of lung metastasis in nude mice can generate an aggressive variant of human osteosarcoma cells. Experimental metastases were established by injecting 143B human osteosarcoma cells, expressing green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in the cytoplasm, in the tail vein of nude mice. Lung metastases were harvested under fluorescence microscopy from nude mice to establish cell lines which were then injected via the tail vein of additional nude mice. This procedure was repeated for four passages in order to isolate highly metastatic variant sublines. When the parental and metastatic variants were transplanted orthotopically into the tibia of nude mice, the 143B-LM4 variant had the highest metastatic rate, approximately 18-fold higher than the parent (p<0.01). αvβ3 integrin expression was increased approximately 5.6-fold in 143B-LM4 compared to parental cells (p<0.05). Thus, serial passage of lung metastases created a highly metastatic variant of human osteosarcoma cells which had increased expression of αvβ3 integrin, suggesting that αvβ3 integrin plays an essential role in osteosarcoma metastasis. With this highly metastatic variant overexpressing αvβ3 integrin, it will now be possible to further investigate the mechanism by which αvβ3 integrin facilitates metastasis.

Real-time imaging of αv integrin molecular dynamics in osteosarcoma cells in vitro and in vivo

αv Integrin is involved in various steps of cancer metastasis. In this report, we describe real-time imaging of αv integrin molecular dynamics in human 143B osteosarcoma cells in vitro and in vivo. We first generated osteosarcoma cells expressing αv integrin green fluorescent protein (GFP) by transfection of an αv integrin GFP fusion vector (pCMV6-AC-ITGAV-GFP) into 143B cells. Confocal laser-scanning microscopy demonstrated that αv integrin immunofluorescence staining co-localized with αv integrin-GFP fluorescence in 143B cells. When αv integrin-GFP-expressing 143B osteosarcoma cells were seeded on a dish coated with fibronectin, which is bound by αv integrin, punctate αv integrin-GFP was observed by confocal laser-scanning microscopy. When the 143B αv integrin-GFP cells were seeded onto uncoated plastic, αv integrin-GFP was diffuse within the cells. When αv integrin-GFP 143B osteosarcoma cells (1×10(6)) were orthotopically transplanted into the tibia of nude mice, the cells aligned along the collagen fibers within the tumor and had punctuate expression of αv integrin-GFP. In the orthotopic model, the invading osteosarcoma cells had punctate αv integrin-GFP in the muscle tissue at the primary tumor margin. These results show that αv integrin-GFP enables the imaging of the molecular dynamics of αv integrin in osteosarcoma cells in vitro and in vivo.

Color-coded imaging of spontaneous vessel anastomosis in vivo

Vessel anastomosis is important in tumor angiogenesis as well as for vascularization therapy for ischemia and other diseases. We report here the development of a color-coded imaging model that can visualize the anastomosis between blood vessels of red fluorescent protein (RFP)-expressing vessels in vascularized Gelfoam® previously transplanted into RFP transgenic mice and then re-transplanted into nestin-driven green fluorescent protein (ND-GFP) mice where nascent blood vessels express GFP. Gelfoam® was initially transplanted subcutaneously in the flank of transgenic RFP nude mice. Skin flaps were made at 14 days after transplantation of Gelfoam® to allow observation of vascularization of the Gelfoam® using confocal fluorescence imaging. The implanted Gelfoam® became highly vascularized with RFP vessels. Fourteen days after transplantation into RFP transgenic nude mice, the Gelfoam® was removed and re-transplanted into the subcutis on the flank of ND-GFP transgenic nude mice in which nascent blood vessels express GFP. Skin flaps were made and anastomosis between the GFP-expressing nascent blood vessels of ND-GFP transgenic nude mice and RFP blood vessels in the Gelfoam® was imaged 14 and 21 days after re-transplantation. The results presented in this report indicate a possible mechanism for tumor angiogenesis and suggest a new paradigm of therapeutic revascularization of ischemic organs requiring new blood vessels and in other diseases.

Abstract 1638: Imaging the interaction of αv integrin-GFP in osteosarcoma cells with RFP-expressing host stromal cells and tumor scaffold collagen in nude mice

Human 143B osteosarcoma cells were stably transfected with an αv integrin-GFP vector. Confocal microscopy demonstrated that αv integrin immunofluorescence staining co-localized with αv integrin-GFP fluorescence. The αv integrin-GFP expressing tumors were established in transgenic nude mice ubiquitously expressing red fluorescent protein (RFP). The primary tumors acquired RFP-expressing stroma and were passaged orthotopically in the tibia in non-colored nude mice, which maintained the RFP stroma. The interaction of αv integrin-GFP expression in 143B cells with RFP-expressing host stromal cells was observed by confocal microscopy using the Olympus FV1000. Collagen fibers were imaged simultaneously in reflectance mode. The RFP-expressing stroma included cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) in the tumors which persisted even 3 weeks after passage. CAFs expressing RFP were aligned between collagen fibers and cancer cells expressing αv integrin-GFP. Six weeks after transplantation, pulmonary metastases expressing αv integrin-GFP could be identified. TAMs expressing RFP accompanied osteosarcoma cells expressing αv integrin-GFP in the lung. The present study demonstrates the importance of αv integrin interaction with stromal elements.

Citation Format: Yasunori Tome, Fuminori Uehara, Hiroki Maehara, Shinji Miwa, Hiroyuki Tsuchiya, Katsuro Tomita, Fuminori Kanaya, Michael Bouvet, Robert M. Hoffman. Imaging the interaction of αv integrin-GFP in osteosarcoma cells with RFP-expressing host stromal cells and tumor scaffold collagen in nude mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1638. doi:10.1158/1538-7445.AM2013-1638

Abstract 1641: Color-coded imaging of interaction between RFP-expressing blood vessels and αv integrin-GFP expressing osteosarcoma cells

We report here imaging the interaction between αv integrin tagged to GFP in human osteosarcoma cells and blood vessels growing on Gelfoam@ implanted subcutaneously in mice. 143B osteosarcoma cells expressing αv integrin-GFP were generated by transfection of an αv integrin-GFP vector. Gelfoam@ (5×5 mm) was treated with basic fibroblast growth factor (bFGF) and transplanted subcutaneously in RFP transgenic nude mice. Skin-flap imaging windows were made at days 7, 14, 21, 28 after transplantation of Gelfoam@. Angiogenesis was observed in the Gelfoam@ using fluorescence imaging via the skin flap windows. Frozen sections were made at day 28 after Gelfoam@ transplantation. RFP-expressing blood vessels were imaged growing into the Gelfoam@. Immunohistochemical (IHC) staining showed that CD31 and RFP fluorescence co-localized in the newly formed RFP-expressing blood vessels in the Gelfoam@. To observe the interaction of tumor cells and RFP blood vessels, 143B cells (5×105),expressing αv integrin-GFP, were injected into the Gelfoam@ 7 days after transplantation. Seven days after cancer-cell injection, the cancer cells were observed in the Gelfoam@ by confocal microscopy via skin-flap windows. 143B cells expressing αv integrin-GFP proliferated into the Gelfoam@ as observed by skin-flap-window imaging. Strong expression of αv integrin-GFP cells was observed near RFP vessels in the Gelfoam@ in the RFP mice 28 days after cancer cell injection. The results show that Gelfoam@ is a useful tool to observe angiogensis in vivo and the interactions of αv integrin-GFP with blood vessels which will allow further understanding of its role in angiogenesis and tumor progression.

Citation Format: Fuminori Uehara, Yasunori Tome, Hiroki Maehara, Fuminori Kanaya, Robert M. Hoffman. Color-coded imaging of interaction between RFP-expressing blood vessels and αv integrin-GFP expressing osteosarcoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1641. doi:10.1158/1538-7445.AM2013-1641

A color-coded imaging model of the interaction of αv integrin-GFP expressed in osteosarcoma cells and RFP expressing blood vessels in Gelfoam® vascularized in vivo

The integrin family of proteins has been shown to be involved in the malignant behavior of cells. We report here development of a color-coded imaging model that can visualize the interaction between αv integrin linked to green fluorescent protein (GFP) in osteosarcoma cells and blood vessels in Gelfoam® vascularized after implantation in red fluorescent protein (RFP) transgenic nude mice. Human 143B osteosarcoma cells expressing αv integrin-GFP were generated by transfection with an αv integrin-GFP vector. Gelfoam® (5×5 mm) was transplanted subcutaneously in transgenic RFP nude mice. The implanted Gelfoam® became highly vascularized with RFP vessels within 14 days. Skin flaps were made at days 7, 14, 21, 28 after transplantation of Gelfoam® for observing vascularization of the Gelfoam® using fluorescence imaging. Gelfoam® is a useful tool to observe angiogenesis in vivo. 143B cells (5 × 10(5)) expressing αv integrin-GFP were injected into the Gelfoam® seven days after transplantation of Gelfoam®. Seven days after cancer-cell injection, cancer cells and blood vessels were observed in the Gelfoam® by color-coded confocal microscopy via the skin flap. The 143B cells expressing αv integrin-GFP proliferated into the Gelfoam®, which contained RFP-expressing blood vessels. Strong expression of αv integrin-GFP in 143B cells was observed near RFP vessels in the Gelfoam®. The observation of the behavior of αv integrin-GFP and blood vessels will allow further understanding of the role of αv integrin in cancer cells.

Primer dosing of S. typhimurium A1-R potentiates tumor-targeting and efficacy in immunocompetent mice

We developed the tumor-targeting strain Salmonella typhimuium A1-R (A1-R) and have shown it to be active against a number of tumor types in nude mice. However, in immunocompetent mice, dosing of A1-R has to be adjusted to avoid toxicity. In the present study, we developed a strategy to maximize efficacy and minimize toxicity for A1-R tumor-targeting in immunocompetent mice implanted with the Lewis lung carcinoma. A small primer dose of A1-R was first administered (1×10(6) colony forming unit [cfu] i.v.) followed by a high dose (1×10(7) cfu i.v.) four hours later. The primer-dose strategy resulted in smaller tumors and no observable side-effects compared to treatment with high-dose-alone. The serum level of tumor necrosis factor (TNF-α) was elevated in the mice treated with primer dose compared to mice only given the high dose. Tumor vessel destruction was enhanced by primer dosing of A1-R in immuno-competent transgenic mice expressing the nestin-driven green fluorescent protein, which is selectively expressed in nascent blood vessels. The primer-dose may activate TNF-α and other cytokines in the mouse, necessary for invasion of the tumor by the bacteria, as well as enhance tumor vessel destruction, thereby allowing a subsequent therapeutic dose to be effective and safe. The results of the present study suggest effective future clinical strategies of bacterial treatment of cancer.

Abstract 1691: A primer dose followed by low-bolus dose schedule of tumor-targeting of S. typhimurium A1-R is effective for tumor-targeted therapy

The S. typhimurium A1-R mutant, which is auxotrophic for leu-arg, and selected for high antitumor virulence, has been shown to be effective as monotherapy against human prostate, breast, pancreatic, and fibrosarcoma tumors. In the present study, we developed a strategy to maximize efficacy and minimize toxicity for bacterial tumor treatment in immunocompetent mice with subcutaneous Lewis lung carcinoma expressing red fluorescent protein (RFP). A small dose of S. typhimurium A1-R bacteria was first administered to tumor-bearing animals (the primer dose, 1×106 cfu i.v.) as pre-treatment followed by a high dose (1×107 cfu i.v.) 4 hours later. Compared with non-primer-dose bacteria treatment, the primer-dose strategy resulted in smaller tumors and no observable side effects. The serum lever of TNF-α was elevated in the primer-dose arms compared to non-primer dose arms. Vessel destruction by S. typhimurium A1-R was observed in immunocompetent mice expressing nestin-driven green fluorescent protein (ND-GFP), which is selectively expressed in nascent blood vessels. Vessel destruction was enhanced in the primer-dose arms compared to non-primer-dose arms. The primer dose may activate the immune system and induce cytokines in the mouse necessary for invasion of the tumor by the bacteria allowing a relatively small subsequent dose to be effective and safe.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1691. doi:1538-7445.AM2012-1691

Abstract 2684: Imaging lung colony formation by osteosarcoma cells expressing αv integrin-GFP in nude mice

We report here imaging the behavior of αv integrin linked to GFP in osteosarcoma cells which are colonizing the lung of nude mice. 143B osteosarcoma cells expressing αv integrin-GFP were generated by transfection of an αv integrin-GFP vector. Confocal microscopy with the FV1000 (Olympus Corp., Tokyo, Japan) demonstrated that αv integrin immunofluorescence staining colocalized with αv integrin-GFP fluorescence. To generate pulmonary colonies, osteosarcoma cells, stably expressing αv integrin-GFP, were injected intravenously (1×106) via the tail vein of nude mice. Eight weeks after injection, both lungs were harvested and observed by confocal microscopy within 1 hour after harvesting. Scattered-expression of αv integrin-GFP was observed in the pulmonary osteosarcoma colonies. In contrast, osteosarcoma cells strongly expressed αv integrin-GFP when aligned along the edge of colonies and around blood vessels. Expression of αv integrin-GFP can be imaged in lung metastasis which will allow further understanding of its role in this process.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2684. doi:1538-7445.AM2012-2684

Abstract 5547: Oral delivery of tumor-targeting Salmonella typhimurium A1-R is effective therapeutically

The S. typhimurium A1-R mutant, which is auxotrophic for leu-arg to attenuate growth in normal tissue, and selected for high antitumor virulence, has been shown to be effective as monotherapy against human prostate, breast, pancreatic, and fibrosarcoma tumors. In the present study, we first administered A1-R to nude with subcutaneous murine colon cancer Colon-26 which expressed red fluorescent protein (RFP). S. typhimurium A1-R (1×107 cfu) was administered intravenously (i.v.) or intratumorally (i.t.) to the subcutaneous tumor as a positive control. The size of tumor was measured by weekly fluorescence imaging. Both i.v.- and i.t.-treated mice had smaller tumors and survived longer (p&lt;0.05) compared to the control group treated with PBS. When S. typhimurium A1-R was administered orally to nude mice with orthotopically-transplanted Colon-26 RFP, tumor growth was inhibited (p&lt;0.05) and animals survived longer than untreated controls (p&lt;0.05). Furthermore, orally-treated mice had no observable side effects suggesting oral delivery of tumor-targeting S. typhimurium A1-R is a promising route for bacterial therapy of cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5547. doi:1538-7445.AM2012-5547

Abstract 5553: Real-time imaging of αv integrin-GFP expression in osteosarcoma cells trafficking in blood vessels of nude mice

We report here real-time imaging of αv integrin-GFP expression during osteosarcoma cell trafficking in blood vessels in nude mice. 143B osteosarcoma cells were transfected with an αv integrin-GFP vector. Confocal microscopy demonstrated that αv integrin immunofluorescent staining colocalized with αv integrin-GFP. Osteosarcoma 143B cells expressing αv integrin-GFP (1×106) were injected in the epigastric cranialis vein. Subsequently, round osteosarcoma cells diffusely expressing αv integrin-GFP were observed in larger veins. In contrast, punctuated αv integrin-GFP was imaged in stretched cells attached to narrow vessel walls. Osteosarcoma cells, arrested in venous valves, were observed to strongly express αv integrin-GFP. αv integrin-GFP allows the imaging of αv integrin expression during cancer cell trafficking and arrest in blood vessels which will enable the further understanding of its role in this process.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5553. doi:1538-7445.AM2012-5553

Abstract 5177: Molecular targeting of αvβ3 integrin by echistatin inhibits tumor progression and metastasis in osteosarcoma

Expression of αvβ3 integrin is associated with tumor progression and metastasis in several types of cancer, including metastatic osteosarcoma. We tested echistatin, an antagonist of αvβ3 integrin, as a molecular targeting drug, in an imageable orthotopic mouse model of human metastatic osteosarcoma. αvβ3 integrin expression was measured in a series of human osteosarcoma cell lines (143B parental and LM1-LM4) with increasing metastatic potential, using RT-PCR and immunoprecipitation. The cell lines expressed GFP in the nucleus and RFP in the cytoplasm and therefore could be imaged down to the subcellular level in vitro and in vivo. αvβ3 integrin expression correlated with the metastatic potential of the cells, with the LM4 cells showing the highest expression and highest metastatic capability, 6-fold and 18-fold, respectively, compared to parental 143B cells. In vitro cell proliferation of LM4 was inhibited by echistatin (p&lt;0.01). In vitro migration, invasion, and adhesion of LM4 were also inhibited by echistatin (p&lt;0.01). Tumor-induced angiogenesis by LM4 in the chick CAM model was also inhibited by echistatin (p&lt;0.05). Mice treated with an echistatin-doxorubicin conjugate had significantly smaller primary tumors and longer survival compared to control untreated tumor-bearing mice (p&lt;0.05 and p&lt;0.01, respectively). Treatment with echistatin resulted in decreased experimental pulmonary metastases, imaged at the cellular level, in a nude mouse model compared to the untreated control (p&lt;0.01). The results of this study indicate that αvβ3 integrin plays an essential role in osteosarcoma metastasis and that echistatin has potential to target αvβ3 integrin and inhibit tumor progression and metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5177. doi:1538-7445.AM2012-5177

Abstract 5176: Imaging αv integrin-GFP during tumor blood vessel interaction in the chick CAM

In this study, we describe imaging of αv integrin-GFP in cancer cells interacting with blood vessels. Osteosarcoma cells (143B) (5×106) expressing αv integrin-GFP were injected in the 10-day old chick chorioallontoic membrane (CAM). In vivo imaging with the Olympus OV-100, visualized tumor-induced angiogenesis one week after transplantation. Osteosarcoma cells expressing αv integrin-GFP were aligned along the tumor-induced blood vessels. High resolution ex vivo imaging with the Olympus FV1000 confocal microscope showed narrow capillary vessels surrounded by osteosarcoma cells which strongly expressing αv integrin-GFP compared to those cells far from vessels. This result imply that expressed of osteosarcoma αv integrin is related to the interaction of the osteosarcoma cells and blood vessels. The ability to image αv integrin during interaction of cancer cells and blood vessels will enable the further understanding of its role in this process.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5176. doi:1538-7445.AM2012-5176

Abstract 5182: Real-time molecular imaging of αv-integrin GFP-expression in osteosarcoma cells in vitro and in vivo

We describe here real-time imaging of αv integrin-GFP expression in osteosarcoma cells (143B) in vitro and in vivo. 143B cells were stably transfected with an αv integrin-GFP vector. Confocal microscopy demonstrated that αv integrin immunofluorescent staining colocalized with αv integrin-GFP fluorescence. In vitro, when αv integrin-GFP osteosarcoma cells were seeded on a dish coated with fibronectin, which bonds αv integrin. αv integrin adhesion plaques were observed by confocal microscopy using the Olympus FV1000. When αv integrin-GFP-expressing 143B cells (1×106) were transplanted in the tibia or injected subcutaneously in nude mice, the cells aligned along collagen orthotopic fibers. In the orthotopic model, osteosarcoma cells punctate expression of αv integrin-GFP was imaged in the osteosarcoma cells as they invaded muscular tissue. In the subcutaneous model, osteosarcoma cells, strongly expressing αv integrin-GFP, were observed around the blood vessels in the tumor. These results show that αv integrin-GFP allows the real-time imaging of the role of αv integrin during cancer cell invasion allowing the further understanding of its role in the process.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5182. doi:1538-7445.AM2012-5182

Abstract 4232: GFP imaging of DNA repair after UV irradiation of cancer cells

The ability to image DNA repair in cancer cells after irradiation as well as its inhibition by potential therapeutic agents is important for the further development of radiotherapy of cancer. The relocalization of GFP fused to the chromatin-binding domain of a check-point-adapter protein 53BP1 was imaged after UV irradiation of breast cancer and MiaPaca-2 human pancreatic cancer cells. 53BP1 is a DNA repair protein that is over-expressed when double-stranded breaks occur in DNA. During live-cell imaging, 53BP1-GFP foci formation was observed within 15 minutes after UV irradiation. Most 53BP1 foci resolved by 90 min. To block UV-induced double stranded break (DSB) repair in cancer cells, we targeted poly (ADP-ribose) polymerase (PARP) with ABT-888 (veliparib). PAPR inhibition markedly enhanced UV-irradiation-induced foci persistence, even more than 90 min after UV irradiation, and decreased cell proliferation of breast and pancreatic cancer cells. The results suggest UV-irradiation and PAPR inhibition are a promising therapeutic combination for breast and pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4232. doi:1538-7445.AM2012-4232

Abundance of calpain and aggrecan-cleavage products of calpain in degenerated human intervertebral discs

OBJECTIVE

To assess the expression of calpains and calpain-induced aggrecan fragmentation in early and advanced stages of degeneration of human intervertebral discs (IVDs).

DESIGN

Disc tissue samples of 55 patients (mean age, 51.2 ± 22.3 years) who underwent intervertebral fusion were divided into groups with early and advanced degeneration based on the Thompson magnetic resonance imaging (MRI) scale. In advanced degeneration group, five patients (mean age, 35.5 ± 11.4 years) of lumbar disc herniation (LDH) were included. Protein levels of m- and μ-calpains and their inhibitor calpastatin were assayed, and immunohistochemical techniques were used to localize and quantify the production of the enzymes. To investigate calpain activity, we assayed purified aggrecan fragmentation in disc tissue by Western blotting and immunohistochemistry with VPGVA antibody, which recognizes the m-calpain generated neo-epitope GVA.

RESULTS

Discs at early stages of degeneration expressed low levels of m- and μ-calpains and calpastatin, and few cells expressed degenerative enzymes. At more advanced stages of degeneration, the expression and number of cells immunopositive for m-calpain, μ-calpain and calpastatin were significantly higher. Further finding showed that anti-GVA-reactive aggrecan fragments were significantly higher in discs at advanced compared with early stages of degeneration. Herniated disc samples showed stronger expression and more cells immunopositive for calpains, calpastatin and GVA in the nucleus pulposus than in the annulus fibrous.

CONCLUSIONS

The expression of calpains, together with m-calpain-induced degradation products of extracellular matrix, was correlated with the degree of disc degeneration in human IVD tissue. These findings suggest that calpains may be involved in IVD degeneration via proteoglycan (PG) cleavage.

Abstract 1686: Effect of echistatin on proliferation, migration, invasion and angiogenesis of integrin αvβ3-expressing human osteosarcoma

Expression of integrin αvβ3 has been shown to be associated with tumor progression and metastasis in several types of cancer. To investigate the specific role of integrin αvβ3 expression in human osteosarcoma, we compared integrin αvβ3 expression in a series of osteosarcoma cell sublines (143B parental and LM1-LM4) with increasing metastatic potential. We quantified integrin αvβ3 expression using RT-PCR and Western-blotting. Integrin αvβ3 expression correlated with the metastatic potential of the cells, with the LM4 cells showing the highest expression and highest metastatic capability. LM4 in vitro cell proliferation decreased after treatment with echistatin, which is an antagonist of integrin αvβ3. In vitro migration and invasion of LM4 were also inhibited by echistatin. Tumor-induced angiogenesis by LM4 in the chick chorioallantoic membrane was also inhibited by echistatin. These data indicated that integrin αvβ3 overexpression may play a role in metastasis and that echistatin has potential as an inhibitor of cancer cell migration and invasion.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1686. doi:10.1158/1538-7445.AM2011-1686

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

Mutations in CD96, a member of the immunoglobulin superfamily, cause a form of the C (Opitz trigonocephaly) syndrome

The C syndrome is characterized by trigonocephaly and associated anomalies, such as unusual facies, psychomotor retardation, redundant skin, joint and limb abnormalities, and visceral anomalies. In an individual with the C syndrome who harbors a balanced chromosomal translocation, t(3;18)(q13.13;q12.1), we discovered that the TACTILE gene for CD96, a member of the immunoglobulin superfamily, was disrupted at the 3q13.3 breakpoint. In mutation analysis of nine karyotypically normal patients given diagnoses of the C or C-like syndrome, we identified a missense mutation (839C-->T, T280M) in exon 6 of the CD96 gene in one patient with the C-like syndrome. The missense mutation was not found among 420 unaffected Japanese individuals. Cells with mutated CD96 protein (T280M) lost adhesion and growth activities in vitro. These findings indicate that CD96 mutations may cause a form of the C syndrome by interfering with cell adhesion and growth.

Midkine as a novel target for antibody therapy in osteosarcoma

Osteosarcoma is a malignant tumor with poor prognosis, and lack of accurate prognostic factors is one of the reasons that make this tumor difficult to cure. The heparin-binding growth factor, midkine is involved in generation and progression of many types of tumors. However, the relationship between midkine and osteosarcoma has been unclear. We show here that midkine is overexpressed in osteosarcoma and the level of midkine expression is correlated with prognosis (P<0.05; log-rank test). Treatment with functional antibodies against midkine suppresses growth of osteosarcoma cell lines, 9N2, 3N1, Saos-2, and NOS-1, to 25-65% of untreated controls. Our results suggest that midkine is useful as a prognostic marker, and is a candidate therapeutic target for osetosarcomas.

Spin-torque diode effect in magnetic tunnel junctions

There is currently much interest in the development of 'spintronic' devices, in which harnessing the spins of electrons (rather than just their charges) is anticipated to provide new functionalities that go beyond those possible with conventional electronic devices. One widely studied example of an effect that has its roots in the electron's spin degree of freedom is the torque exerted by a spin-polarized electric current on the spin moment of a nanometre-scale magnet. This torque causes the magnetic moment to rotate at potentially useful frequencies. Here we report a very different phenomenon that is also based on the interplay between spin dynamics and spin-dependent transport, and which arises from unusual diode behaviour. We show that the application of a small radio-frequency alternating current to a nanometre-scale magnetic tunnel junction can generate a measurable direct-current (d.c.) voltage across the device when the frequency is resonant with the spin oscillations that arise from the spin-torque effect: at resonance (which can be tuned by an external magnetic field), the structure exhibits different resistance states depending on the direction of the current. This behaviour is markedly different from that of a conventional semiconductor diode, and could form the basis of a nanometre-scale radio-frequency detector in telecommunication circuits.

Synergistic inhibition by combination of fluoride and xylitol on glycolysis by mutans streptococci and its biochemical mechanism

The purpose of this study was to evaluate the combined inhibitory effect of fluoride and xylitol on acid production by mutans streptococci, Streptococcus mutans NCTC10449 and Streptococcus sobrinus 6715, from glucose under strictly anaerobic conditions at fixed pH 5.5 and 7.0. The bacteria were grown in a tryptone-yeast extract broth under strictly anaerobic conditions (N2: 80%; H2: 10%; CO2: 10%). Reaction mixtures for acid production from glucose contained bacterial cells with fluoride (0-6.4 mM) and/or xylitol (60 mM). Acidic end products of glucose fermentation and intracellular glycolytic intermediates were assayed. The combination of fluoride and xylitol inhibited acid production more effectively than fluoride or xylitol alone. In the presence of fluoride and xylitol, the proportion of lactic acid in the total amount of acidic end products decreased, while the proportion of formic and acetic acids increased. Analyses of intracellular glycolytic intermediates revealed that xylitol inhibited the upper part of the glycolytic pathway, while fluoride inhibited the lower part. This study indicates that fluoride and xylitol together have synergistic inhibitory effects on the acid production of mutans streptococci and suggests that xylitol has the potential to enhance inhibitory effects of low concentrations of fluoride.