Search for η^{'} Bound Nuclei in the ^{12}C(γ,p) Reaction with Simultaneous Detection of Decay Products

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}<-0.9 was obtained to be 2.2  nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}N→ηN process and/or a shallow η^{'}-nucleus potential.

Abstract P4-06-23: Feasibility of sygeneic mice models of breast cancer for research of immune checkpoint blockades

Background: With the increasing success of immune checkpoint blockades for cancer treatment, we increasingly need well-characterized preclinical models. Syngeneic mice models (with a fully competent immune system) have advantages that they are easily established and cost less, though they do not reflect genetic complexity of human tumors. We evaluated feasibility of syngeneic mice models of breast cancer by analyzing efficacy of immune checkpoint blockade and dynamic change of tumor immune microenvironment.

Methods: We used syngeneic mice model of JC, 4T1, and EMT6 cells, which are all murine triple negative breast cancer in BALB/c mice. At the time when subcutaneous tumors reach at 50˜100mm^3, each mice models were divided into 2 groups for treatment versus no-treatment control. In the treatment group, mice version of anti-PD-1 antibody was intraperitoneally injected (q 3 days, x 6). Anti-tumor efficacy was monitored by measuring tumor volume. 'Tumor response' was defined as a case with tumor volume less than that of control group by a standard error at a determined time point. Immune microenvironment was evaluated by measuring serum cytokines (IL-2, IL-6, IL-10, IFNγ, and TNFα) with legendplex and immune cells (CD3, CD4, CD8, CD56, and FOXP3) of peripheral blood with FACS before injection of PD-1 blockade, after 1st injection, and when euthanized. Tumor-infiltrating immune cells were evaluated with FACS, when euthanized.

Results: The tumor response rate to PD-1 blockade was highest in the 4T1 model (54.5%, 6/11) compared to JC model (40%, 4/10) or EMT6 model (36.4%, 4/11). Bleeding 3 times and tumor obtainment when euthanized in each mouse were feasible for profiling of cytokines and immune cells. Although before treatment with PD-1 blockade, CD3+T cells in peripheral blood were slightly lower in 4T1 model (18.3±8.1%) than JC model (24.6±4.7%) or EMT6 model (27.9±6.3%), after injection of one dose of PD-1 blockade, CD3+T cells increased 1.5 times in 4T1 model (18.3% to 27.3%), whereas those CD3+T cells decreased slightly in JC model and EMT6 model. Dynamic changes were not observed in other subsets of peripheral immune cells in all 3 models. Serum TNFα (with statistical significance) and IFNγ (with borderline significance) were higher in responders than in non-responders or no-treatment control.

Conclusions: Syngeneic mice models of breast cancer were feasible to investigate immune checkpoint blockades and monitor dynamic change of immune microenvironment. In this regard, such models may be used to evaluate immune checkpoint blockade-based combination therapy as well.

Citation Format: Moon YW, Park N, Hur J, Pandey K, Cho YB, Kim SK, Lee SA, Son GW, Jo JM, An H-J. Feasibility of sygeneic mice models of breast cancer for research of immune checkpoint blockades [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-23.

Corneal hydration affects ablation during laser in situ keratomileusis surgery

BACKGROUND

Studies in animal eyes indicate that the level of corneal hydration affects the ablation rate of laser surgery; the greater the hydration is, the less the ablation for a given laser pulse. Our study is an assessment in human eyes comparing the effects on ablation by blotting the corneal stromal surface under a corneal flap created for laser in situ keratomileusis (LASIK) procedures between sets of excimer laser pulses, with ablation depth in eyes not blotted between sets of laser pulses.

METHODS

We modified the surgical technique for LASIK procedures to assess the effects of the level of hydration on excimer laser ablation depth per pulse. In group 1, 40 eyes underwent LASIK surgery without any modification. Group 2 was composed of 36 eyes having LASIK procedures, but the corneal surfaces were kept relatively dry by blotting of the stromal surface between sets of laser pulses.

RESULTS

Six months after surgery, the mean spherical equivalent refractive change was from -8.38 diopters (D) to -1.44 D in group 1 and from -7.93 D to -0.09 D in group 2. For predictability, the deviation from the target refraction after surgery was assessed. Thirty-three percent (13 of 40) in group 1 and 25% (9 of 36) in group 2 were within +/-0.5 D. Forty-eight percent (19 of 40) in group 1 and 50% (18 of 36) in group 2 were within +/-1 D. Six months after surgery, 80% or more in both groups were within +/-2 D. There was myopic regression in all patients. Three months after surgery, regression averaged -0.71 D in group 1 and -1.15 D in group 2.

CONCLUSIONS

Corneal hydration levels affect the efficiency of laser ablation in LASIK procedures. With less hydrated corneas, ablation effects were greater than for corneas not blotted during the procedure, but these patients appear to undergo greater myopic regression.

Localized in vivo high-resolution NMR imaging using gradient subencoding technique

A new spatial localization technique for in vivo high-resolution imaging is presented here. In contrast to other localization techniques that use a series of rf pulses to define a volume of interest, only one rf pulse is utilized in the proposed method for selection of a region to be imaged. Instead of rf pulses for region selection, subencoding gradient pulses are used for the localization together with a convolution process on each phase-encoding gradient by a set of additional gradients (e.g., y direction). Then the 2-D localization is completed by restricting the bandwidth in the readout direction (e.g., x direction). The latter is simply achieved by using a low-pass filter in the receiver system. By applying this technique on a human body, localized in vivo high-resolution images are obtained for the knee with much improved resolution. 100 x 100 microns in-plane (x,y plane) resolution images obtained from the human knee demonstrate that localized in vivo high-resolution imaging for both human and animals is possible with an in-plane resolution of below 100 microns.

Nuclear magnetic resonance microscopy with 4-microns resolution: theoretical study and experimental results

Nuclear magnetic resonance (NMR) microscopy with 4-microns resolution, a step closer to the 1-micron resolution with which in vivo cellular imaging would be possible is described. An analysis of the ultimate resolution and voxel size dependent signal-to-noise ratio (SNR) in NMR microscopy is presented and experimentally verified. For microscopic scale objects (less than 1-mm diameter), the SNR based on the geometrical scale factor(s) is found to be proportional to sn where n less than 2, rather than n = 3 as previously supposed. This comes about because of a drastic reduction in sample noise coupled with a significant sensitivity gain realized in small diameter radiofrequency coils. A new pulse sequence which reduces both diffusion dependent resolution degradation and signal attenuation is presented. The selection of optimal bandwidth and acquisition time for maximal SNR is discussed. Experimental results obtained on both a 2.0-T whole-body system and a 7.0-T small bore system adapted for microscopy indicate the potentials of 4-microns resolution microscopy with the existing magnets.