Ultrashort spin-orbit torque generated by femtosecond laser pulses

To realize the very objective of spintronics, namely the development of ultra-high frequency and energy-efficient electronic devices, an ultrafast and scalable approach to switch magnetic bits is required. Magnetization switching with spin currents generated by the spin-orbit interaction at ferromagnetic/non-magnetic interfaces is one of such scalable approaches, where the ultimate switching speed is limited by the Larmor precession frequency. Understanding the magnetization precession dynamics induced by spin-orbit torques (SOTs) is therefore of great importance. Here we demonstrate generation of ultrashort SOT pulses that excite Larmor precession at an epitaxial Fe/GaAs interface by converting femtosecond laser pulses into high-amplitude current pulses in an electrically biased p-i-n photodiode. We control the polarity, amplitude, and duration of the current pulses and, most importantly, also their propagation direction with respect to the crystal orientation. The SOT origin of the excited Larmor precession was revealed by a detailed analysis of the precession phase and amplitude at different experimental conditions.

Abstract 1509: A signature for tumor neoantigen-reactive T-cells in fresh human lung cancers allows rapid cloning of their receptors

The correlations between tumor mutational load and higher response rates to immune-checkpoint inhibitor (ICI) therapies revealed the importance of targeting tumor neoantigens in cancer immunotherapy. Although ICI therapy has been revolutionary, many patients still do not respond to these treatments. One reason for this may be the absence of an adequate anti-tumor T-cell repertoire. A potential solution is the adoptive transfer of T-cells targeting neoantigens. Despite having some common shared neoantigens such as KRAS and p53, the majority of patients have highly individualized neoantigens and personalized T-cell responses. One method for identifying neoantigen-reactive T-cells from a patient's tumor-infiltrating lymphocytes (TIL) involves: (1) identifying non-synonymous mutations via whole-exome sequencing (WES), (2) using autologous dendritic cells (DC) to display these mutations in the form of electroporated minigenes (as RNA) or pulsed synthetic peptides (to create a tumor cell surrogate) and (3) co-culturing the TIL with these DCs to detect neoantigen-reactive T-cells through the upregulation of T-cell activation markers (e.g., 4-1BB). Each of these steps is labor-intensive, costly, and time-consuming. To address this, we sought to identify neoantigen-reactive TCRs directly from fresh tumors by developing a signature based on the cell surface protein and transcriptomic phenotype of cells proven to be mutation reactive. Knowing the V(D)J sequences for T-cells known to be neoantigen reactive (by the above screening), we performed 10x Genomics single cell RNA-Seq with CITE-Seq analysis on TIL isolated from frozen samples of those fresh tumors. Using the known CDR3 sequences, we compared neoantigen-reactive T-cells (six CD8 reactivities and two CD4 reactivities) versus other T-cells. This analysis led to identifying a set of cell surface proteins and genes that are specifically over- or under-expressed (including but not limited to CD62L-, CD45RA-, IL7Rlow, CD39+, CD27+, CD74+, TIGIT+, CXCL13+, LAYN+, HMOX1+, BATF+) on neoantigen-reactive T-cells. We tested whether CD39+ and CXCL13+ signature in combination with the TCR clonotype frequency could prospectively identify other neoantigen-reactive TCRs. This proved to be the case and applied not only to CD8 TIL but strongly to CD4 reactivities. In all cases, we could identify neoantigen-reactive TCRs, and in one case, 8 out of 10 candidate receptors identified by phenotype signature proved to be neoantigen-reactive. Not only were they neoantigen specific, but new, previously unidentified neoantigens were found when their specificities were analyzed. This method can open the path to treating patients with custom-made TCRs in a timely manner and expand the repertoire of tumor-specific neoantigens and the diversity of the T-cell response discoverable in human tumors.

Citation Format: Kenichi Hanada, Chihao Zhao, Raul Gil-Hoyos, Jared Gartner, Christopher Chow-Parmer, Frank Lowery, Sri Krishna, Samuel Chatmon, Prickett D. Todd, Scott Kivitz, Maria Parkhurst, Michelle Langhan, Thomas Shelton, Zulmarie Franco, Robert Somerville, John Wunderlich, David Danforth, Zachary Rae, Kelly Michael, Nathan Wong, Paul Robbins, Steven Rosenberg, James Yang. A signature for tumor neoantigen-reactive T-cells in fresh human lung cancers allows rapid cloning of their receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1509.

Electrically induced and detected Néel vector reversal in a collinear antiferromagnet

Antiferromagnets are enriching spintronics research by many favorable properties that include insensitivity to magnetic fields, neuromorphic memory characteristics, and ultra-fast spin dynamics. Designing memory devices with electrical writing and reading is one of the central topics of antiferromagnetic spintronics. So far, such a combined functionality has been demonstrated via 90° reorientations of the Néel vector generated by the current-induced spin orbit torque and sensed by the linear-response anisotropic magnetoresistance. Here we show that in the same antiferromagnetic CuMnAs films as used in these earlier experiments we can also control 180° Néel vector reversals by switching the polarity of the writing current. Moreover, the two stable states with opposite Néel vector orientations in this collinear antiferromagnet can be electrically distinguished by measuring a second-order magnetoresistance effect. We discuss the general magnetic point group symmetries allowing for this electrical readout effect and its specific microscopic origin in CuMnAs.

ATP-synthesis capacity of pulsed light-exposed bacteria

The ability of four different bacteria to synthesize new ATP upon exposure to different doses of pulsed-light (PL) irradiation was investigated. The bacterial cells were PL treated on a gel surface, resuspended in phosphate buffered saline (PBS) and subsequently incubated in Tryptic Soy Broth (TSB) at 37°C. Cellular ATP levels were monitored during a 2h incubation period and compared to the respective colony count data. Although PL affected ATP production in a dose dependent manner, the results showed that bacteria, which had rendered unculturable after PL exposure, are still capable of generating significant quantities of ATP. Escherichia coli and Listeria innocua proved to be more resistant to PL than Salmonella enterica and Staphylococcus aureus, which was supported by the colony count data and the ATP synthesis capacity. These findings underline that bacteria undetectable by culture-based methods may still show cellular activity and synthesize new ATP.

Inertial displacement of a domain wall excited by ultra-short circularly polarized laser pulses

Domain wall motion driven by ultra-short laser pulses is a pre-requisite for envisaged low-power spintronics combining storage of information in magnetoelectronic devices with high speed and long distance transmission of information encoded in circularly polarized light. Here we demonstrate the conversion of the circular polarization of incident femtosecond laser pulses into inertial displacement of a domain wall in a ferromagnetic semiconductor. In our study, we combine electrical measurements and magneto-optical imaging of the domain wall displacement with micromagnetic simulations. The optical spin-transfer torque acts over a picosecond recombination time of the spin-polarized photo-carriers that only leads to a deformation of the initial domain wall structure. We show that subsequent depinning and micrometre-distance displacement without an applied magnetic field or any other external stimuli can only occur due to the inertia of the domain wall.

Domain wall motion driven by ultra-short laser pulses has potential for storage of information in magnetoelectronic devices. Here the authors demonstrate the conversion of a circularly polarized femtosecond laser light into inertial displacement of a domain wall in a ferromagnetic semiconductor.

Recent findings in pulsed light disinfection

Nonthermal disinfection technologies are gaining increasing interest in the field of minimally processed food in order to improve the microbial safety or to extend the shelf life. Especially fresh-cut produce or meat and fish products are vulnerable to microbial spoilage, but, due to their sensitivity, they require gentle preservation measures. The application of intense light pulses of a broad spectral range comprising ultraviolet, visible and near infrared irradiation is currently investigated as a potentially suitable technology to reduce microbial loads on different food surfaces or in beverages. Considerable research has been performed within the last two decades, in which the impact of various process parameters or microbial responses as well as the suitability of pulsed light (PL) for food applications has been examined. This review summarizes the outcome of the latest studies dealing with the treatment of various foods including the impact of PL on food properties as well as recent findings about the microbicidal action and relevant process parameters.

Abstract P2-04-02: Recognition of autologous neoantigens by tumor infiltrating lymphocytes derived from breast cancer metastases

Background & Translational Relevance: Adoptive transfer of tumor infiltrating lymphocytes (TIL) can effect long-term durable regression in patients with metastatic melanoma but has not been widely tested in common epithelial cancers. When examining the TIL of successfully treated patients with melanoma, a heterogeneous T cell population can be identified with reactivity against melanoma differentiation antigens, cancer germline antigens, and personalized non-synonymous somatic mutations. Common epithelial cancers, including breast cancer, express far fewer somatic mutations than melanoma, however, a patient with metastatic cholangiocarcinoma was treated with autologous CD4+ TIL enriched for neoantigen specificity and has experienced an ongoing partial response (>2 years). It is known that the presence of TIL on pathologic examination of triple-negative breast cancers is a positive prognostic marker for disease-free survival and overall survival. The identification of enriched populations of neoantigen-specific TIL could form the basis for personalized cell therapy for patients with metastatic breast cancer. This pilot study investigates the ability to grow TIL from breast cancer metastases, to identify personalized non-synonymous somatic mutations and potential neoantigens, and to adoptively transfer TIL into patients with breast cancer.

Methods: Eligible patients were evaluated and treated under IRB-approved protocols for tissue procurement, genomic testing, and adoptive cell transfer. Portions of resected tumors were placed in culture under standard TIL conditions. DNA was extracted from tumor and matched normal peripheral blood samples for whole exome sequencing (WES). Non-synonymous somatic mutations were identified and tested for potential immunogenicity.

Results: Nine patients have undergone surgical resection in this ongoing pilot study, and TIL was successfully grown from the tumors of all patients. All were primarily CD3+ (median 79%) with a small population of natural killer cells. Of the CD3+ cells, 7 of 9 patients had a predominantly CD4+ population (median CD4:CD8 ratio 2.2, range 0.4-5.8). With the exception of a single patient with inflammatory breast cancer, tumor purity allowed for WES of the tumors of eight patients, and non-synonymous somatic mutations were identified as potential neoantigens (median 96.5, range 71-148). Autologous T cell reactivity has been identified against tumor-specific mutations in 4 of 6 patients studied. The TIL of one patient demonstrated in vitro reactivity to a mutated form of RBPJ, a DNA-binding protein involved in Notch1 signaling. In addition, specimens obtained from this patient at autopsy contained the specific RBPJ mutation (RBPJ c.A611T) in every sampled tumor (n=16). Other patient-specific neoantigens identified by autologous reactivity include SLC3A2, KIAA0368, and a mutated TCRBV domain.

Conclusions: Tumor-infiltrating lymphocytes derived from metastatic breast cancer can react to tumor-specific non-synonymous somatic mutations in vitro. TIL grown from breast cancers are predominantly CD4+ and can form the basis of an adoptive cell transfer experimental approach to patients with metastatic breast cancer.

Citation Format: Goff SL, Zacharakis N, Assadipour Y, Prickett T, Gartner J, Somerville R, Black MA, Xu H, Chinnasamy H, Kriley I, Lu L, Statler M, Wunderlich J, Robbins PF, Rosenberg SA, Feldman SA. Recognition of autologous neoantigens by tumor infiltrating lymphocytes derived from breast cancer metastases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-02.

Impact of pulsed light on cellular activity of Salmonella enterica

AIMS

The objective of this study was a comprehensive characterization of physiological changes of Salmonella enterica induced by intense broad spectrum pulsed light (PL). After exposing the bacteria to this nonthermal decontamination technology on a gel surface, multiple viability parameters beyond culturability were assessed.

METHODS AND RESULTS

By applying flow cytometry, a luciferin-luciferase bioluminescence assay and a microplate assay to measure the current redox activity, the impact of pulsed light on the membrane potential, membrane integrity, esterase activity, efflux pump activity, expression of the green fluorescent protein (GFP), respiration activity and ATP-content of Salm. enterica ATCC BAA-1045 was determined. These culture-independent methods for assessing the bacterial activity were compared to the ability to grow on tryptic soy agar. It is shown that this strain is rather sensitive to PL considering colony count reductions, while on the other hand unculturable bacteria still exhibit significant cellular energetic functions. However, this residual activity after PL exposure significantly decreases during sample storage in buffer for 24 h. This study also shows that the GFP expression of PL-treated cells which have rendered unculturable is severely reduced.

CONCLUSIONS

This study reveals that although not all cellular functions of Salm. enterica are immediately shut down after PL exposure, the synthesis of new GFP is strongly reduced and affected to a similar extent as the culturability.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is shown for the first time, that even there is significant bacterial activity measurable after PL exposure, it is likely that nongrowing pathogenic bacteria like Salm. enterica are unable to express proteins, which is of great importance regarding their pathogenicity.

Long-range and high-speed electronic spin-transport at a GaAs/AlGaAs semiconductor interface

Spin-valves or spin-transistors in magnetic memories and logic elements are examples of structures whose functionality depends crucially on the length and time-scales at which spin-information is transferred through the device. In our work we employ spatially resolved optical pump-and-probe technique to investigate these fundamental spin-transport parameters in a model semiconductor system. We demonstrate that in an undoped GaAs/AlGaAs layer, spins are detected at distances reaching more than ten microns at times as short as nanoseconds. We have achieved this unprecedented combination of long-range and high-speed electronic spin-transport by simultaneously suppressing mechanisms that limit the spin life-time and the mobility of carriers. By exploring a series of structures we demonstrate that the GaAs/AlGaAs interface can provide superior spin-transport characteristics whether deposited directly on the substrate or embedded in complex semiconductor heterostructures. We confirm our conclusions by complementing the optical experiments with dc and terahertz photo-conductivity measurements.

Antiferromagnetic spintronics

Antiferromagnetic materials are internally magnetic, but the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets externally invisible. This implies that information stored in antiferromagnetic moments would be invisible to common magnetic probes, insensitive to disturbing magnetic fields, and the antiferromagnetic element would not magnetically affect its neighbours, regardless of how densely the elements are arranged in the device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. Among the outstanding questions is how to manipulate and detect the magnetic state of an antiferromagnet efficiently. In this Review we focus on recent works that have addressed this question. The field of antiferromagnetic spintronics can also be viewed from the general perspectives of spin transport, magnetic textures and dynamics, and materials research. We briefly mention this broader context, together with an outlook of future research and applications of antiferromagnetic spintronics.

Electrical switching of an antiferromagnet

Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 10(6) ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics.

Adoptive transfer of autologous tumor-infiltrating lymphocytes in metastatic human papilloma virus-induced carcinoma (VAC7P.1040)

Given the constitutive tumor-specific expression of high risk human papilloma virus (HPV) E6 and E7 oncoproteins in HPV+ carcinomas, we evaluated whether adoptive transfer of autologous tumor-infiltrating lymphocytes (TIL) selected for HPV E6/E7 reactivity could mediate regression of metastatic HPV+ carcinomas. TIL were selected preferentially for HPV E6/E7 peptide pool reactivity, when possible. Patients received a single TIL infusion and interleukin-2 to tolerance after non-myeloablative chemotherapy. The treatment regimen led to objective clinical responses in 6/23 patients, including 4/15 cervical cancer, 1/5 anal cancer and 1/3 head and neck cancer patients. Two complete responses occured in cervical carcinoma that are ongoing 20 and 26 months after treatment. The other four responses were partial, three lasted from 3 to 5 months, and one is ongoing at 3 months. The frequency of HPV reactive T cells in the TIL infusion of 17 patients analyzed thus far (including five with a clinical response), as measured by IFNg ELISPOT and CD137 upregulation, correlated with clinical response (P=0.0238 and P=0.0485). In addition, the magnitude of HPV reactivity as measured by IFNg production correlated with clinical response (P=0.0003). Regression of metastatic HPV+ carcinomas can occur after TIL therapy in some patients. Exploratory studies suggest a correlation between HPV reactivity of the infusion product and clinical response.

PD-1 expression on peripheral blood lymphocytes enables direct enrichment of mutation-specific lymphocytes (VAC12P.1117)

Identification and isolation of mutation-specific T-cells is a major obstacle to the development of effective cancer immunotherapies. The tumor is a natural sink for neo-antigen specific cells, but these are far less frequent in peripheral blood, a more accessible and abundant source of T cells. Previous studies have revealed that PD-1 expression in the tumor microenvironment can identify the patient-specific repertoire of tumor and mutation-specific cells infiltrating human tumors. Here, we evaluated the potential utility of PD-1 expression on circulating lymphocytes to identify and enrich for mutation-specific cells. Selection of CD8+PD-1+ lymphocytes circulating in peripheral blood, but not the bulk or CD8+PD-1- cells, led to the direct enrichment of mutation-specific cells in three melanoma samples tested, with at least 1, 3 and 5 unique patient-specific neo-antigens recognized, respectively. The PD-1+ derived cells also displayed autologous tumor recognition. Furthermore, CD8+PD-1+ and PD-1hi cells isolated and expanded from the blood from a patient with colorectal cancer led to the identification of mutation-specific cells targeting two tumor neo-antigens. These findings provide a novel strategy to harness naturally-occuring mutation-specific T cells present in peripheral blood for the development of personalized T -cell based therapies to treat cancer.

Optical spin-transfer-torque-driven domain-wall motion in a ferromagnetic semiconductor

We demonstrate optical manipulation of the position of a domain wall in a dilute magnetic semiconductor, GaMnAsP. Two main contributions are identified. First, photocarrier spin exerts a spin-transfer torque on the magnetization via the exchange interaction. The direction of the domain-wall motion can be controlled using the helicity of the laser. Second, the domain wall is attracted to the hot spot generated by the focused laser. Unlike magnetic-field-driven domain-wall depinning, these mechanisms directly drive domain-wall motion, providing an optical tweezerlike ability to position and locally probe domain walls.

Pulsed light decontamination of endive salad and mung bean sprouts and impact on color and respiration activity

The objective of this study was the determination of the efficiency of pulsed light (PL) treatments for the decontamination of endive salad and mung bean sprouts, as well as the assessment of quality changes in relation to discoloration and alteration of respiration activity. Produce samples were artificially inoculated with two bacterial test strains Escherichia coli (DSM 498) and Listeria innocua (DSM 20649) and exposed to PL at different energy doses. The inactivation efficiency with regard to the naturally occurring microbiota was also investigated. Besides microbiological investigations, color changes were determined as well as the produce respiration during chilled storage. The results indicated that inactivation of more than 2 log was possible with one flash in the case of fresh-cut salad, while the reduction on mung bean sprouts was limited to approximately 1.6 log with one flash, irrespective if the natural flora or inoculated E. coli or L. innocua were considered. The UV part of the PL proved to be exclusively responsible for the inactivation of microorganisms. Significant lower levels of microbial counts of treated compared with untreated samples were maintained for up to 6 days. In the case of endive salad, a dose-dependent progressive discoloration and increase in respiration was diminished by applying optical bandpass filters, which only slightly affected the inactivation efficiency. In contrast, PL treatments showed a positive effect on color and general appearance of mung bean sprouts, while the respiration was almost unaffected. However, care must be taken with regard to efficiency-limiting matrix effects and impact on food quality. These aspects have to be assessed for each treated product. The integration of PL in industrial food processing plants could be an alternative way to improve the microbial quality of fresh produce, and therefore have a positive impact on public health by reducing the risk of contaminations with pathogenic bacteria.

Antimicrobial activity of hop extracts against foodborne pathogens for meat applications

AIMS

The objective of this study was the fundamental investigation of the antimicrobial efficiency of various hop extracts against selected foodborne pathogens in vitro, as well as their activity against Listeria monocytogenes in a model meat marinade and on marinated pork tenderloins.

METHODS AND RESULTS

In a first step, the minimum inhibitory concentrations (MIC) of three hop extracts containing either α- or β-acids or xanthohumol were determined against test bacteria including L. monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli by a colorimetric method based on the measurement of bacterial metabolic activity. Moreover, the influence of either lactic or citric acid on the antimicrobial activity of the hop extracts was evaluated. The efficiency of hop extracts as a natural food preservative was then tested in a model meat marinade at 2 and 8°C, respectively, and finally on marinated pork. The experiments showed that Gram-positive bacteria were strongly inhibited by hop extracts containing β-acids and xanthohumol (MIC values of 6.3 and 12.5 ppm, respectively), whereas the antimicrobial activity of the investigated α-acid extract was significantly lower (MIC values of 200 ppm). Gram-negative bacteria were highly resistant against all tested hop extracts. Acidification of the test media led to a decrease of the MIC values. The inhibitory activity of the hop extracts against L. monocytogenes was strongly reduced in a fat-containing model meat marinade, but the efficiency of β-acids in this matrix could be increased by lowering pH and storage temperatures. By applying 0.5 % β-acids at pH = 5 in a model marinade, the total aerobic count of pork tenderloins was reduced up to 0.9 log10 compared with marinated pork without hop extract after 2 weeks of storage at 5°C.

CONCLUSIONS

β-acid containing hop extracts have proven to possess a high antimicrobial activity against Gram-positive bacteria in vitro and in a practice-related application for food preservation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Antimicrobial hop extracts could be used as natural preservatives in food applications to extend the shelf life and to increase the safety of fresh products.

Relativistic Néel-order fields induced by electrical current in antiferromagnets

We predict that a lateral electrical current in antiferromagnets can induce nonequilibrium Néel-order fields, i.e., fields whose sign alternates between the spin sublattices, which can trigger ultrafast spin-axis reorientation. Based on microscopic transport theory calculations we identify staggered current-induced fields analogous to the intraband and to the intrinsic interband spin-orbit fields previously reported in ferromagnets with a broken inversion-symmetry crystal. To illustrate their rich physics and utility, we consider bulk Mn(2)Au with the two spin sublattices forming inversion partners, and a 2D square-lattice antiferromagnet with broken structural inversion symmetry modeled by a Rashba spin-orbit coupling. We propose an antiferromagnetic memory device with electrical writing and reading.

HPV-targeted tumor-infiltrating lymphocytes for cervical cancer

LBA3008

Background: Adoptive T-cell therapy (ACT) is a promising cancer treatment modality with potentially broad application. It is not known if ACT can mediate regression of carcinomas, the most common solid tumors in humans. We studied carcinoma of the uterine cervix, a virally induced malignancy that constitutively expresses the HPV E6 and E7 oncoproteins, as a model cancer to test if ACT can mediate regression of an epithelial malignancy. Methods: We initiated a clinical trial to treat metastatic HPV+ cancers with tumor-infiltrating lymphocytes (TIL) selected for HPV E6- and E7-reactivity (HPV-TIL). Patients from the cervical cancer cohort are reported here. HPV-TIL infusion was preceded b y non-myeloablative conditioning and followed by high-dose bolus aldesleukin. HPV-reactivity was assessed by ELISPOT, IFN-gamma production, and CD137 expression assays. Results: Nine patients were treated on the study. They received a median of 81 x 109 T cells (range 33 to 159 x 109) as a single infusion. The infused cells possessed reactivity against high-risk HPV E6 and/or E7 in 6/8 patients. The two patients with no HPV reactivity did not respond to treatment. 3/6 patients with HPV reactivity demonstrated objective tumor responses by RECIST (1 PR and 2 CR). One patient had a 39% best response. Two patients with widespread metastases had complete tumor responses that are ongoing 18 and 11 months after treatment. One patient with a complete response had a chemotherapy-refractory HPV-16+ squamous cell carcinoma and the other a chemoradiation-refractory HPV-18+ adenocarcinoma. Both patients demonstrated prolonged repopulation with HPV-reactive T cells following treatment. Increased frequencies of HPV-specific T cells were detectable after 13 months in one patient and 6 months in the other. Two patients with HPV-reactive TIL that did not respond to treatment did not display repopulation with HPV-reactive T cells. Conclusions: HPV-TIL can mediate durable, complete regression of metastatic cervical cancer. Continued investigation of HPV-TIL for cervical cancer, and possibly other HPV+ malignancies, is warranted. Cellular therapy can mediate complete regression of an epithelial malignancy. Clinical trial information: NCT01585428.

Assessment of Plasmodium falciparum PfMDR1 transport rates using Fluo-4

Mutations in the multidrug resistance transporter of Plasmodium falciparum PfMDR1 have been implicated to play a significant role in the emergence of worldwide drug resistance, yet the molecular and biochemical mechanisms of this transporter are not well understood. Although it is generally accepted that drug resistance in P. falciparum is partly associated with PfMDR1 transport activity situated in the membrane of the digestive vacuole, direct estimates of the pump rate of this transport process in the natural environment of the intact host–parasite system have never been analysed. The fluorochrome Fluo-4 is a well-documented surrogate substrate of PfMDR1 and has been found to accumulate by actively being transported into the digestive vacuole of several parasitic strains. In the present study, we designed an approach to use Fluo-4 fluorescence uptake as a measure of compartmental Fluo-4 concentration accumulation in the different compartments of the host–parasite system. We performed a ‘reverse Fluo-4 imaging' approach to relate fluorescence intensity to changes in dye concentration rather than Ca²⁺ fluctuations and were able to calculate the overall rate of transport for PfMDR1 in Dd2 parasites. With this assay, we provide a powerful method to selectively measure the effect of PfMDR1 mutations on substrate transport kinetics. This will be of high significance for future compound screening to test for new drugs in resistant P. falciparum strains.

An antidamping spin-orbit torque originating from the Berry curvature

Magnetization switching at the interface between ferromagnetic and paramagnetic metals, controlled by current-induced torques, could be exploited in magnetic memory technologies. Compelling questions arise regarding the role played in the switching by the spin Hall effect in the paramagnet and by the spin-orbit torque originating from the broken inversion symmetry at the interface. Of particular importance are the antidamping components of these current-induced torques acting against the equilibrium-restoring Gilbert damping of the magnetization dynamics. Here, we report the observation of an antidamping spin-orbit torque that stems from the Berry curvature, in analogy to the origin of the intrinsic spin Hall effect. We chose the ferromagnetic semiconductor (Ga,Mn)As as a material system because its crystal inversion asymmetry allows us to measure bare ferromagnetic films, rather than ferromagnetic-paramagnetic heterostructures, eliminating by design any spin Hall effect contribution. We provide an intuitive picture of the Berry curvature origin of this antidamping spin-orbit torque as well as its microscopic modelling. We expect the Berry curvature spin-orbit torque to be of comparable strength to the spin-Hall-effect-driven antidamping torque in ferromagnets interfaced with paramagnets with strong intrinsic spin Hall effect.

Piezoelectric control of the mobility of a domain wall driven by adiabatic and non-adiabatic torques

The rich internal degrees of freedom of magnetic domain walls make them an attractive complement to electron charge for exploring new concepts of storage, transport and processing of information. Here we use the tunable internal structure of a domain wall in a perpendicularly magnetized GaMnAsP/GaAs ferromagnetic semiconductor and demonstrate devices in which piezoelectrically controlled magnetic anisotropy yields up to 500% mobility variations for an electrical-current-driven domain wall. We observe current-induced domain wall motion over a wide range of current-pulse amplitudes and report a direct observation and the piezoelectric control of the Walker breakdown separating two regimes with different mobilities. Our work demonstrates that in spin-orbit-coupled ferromagnets with weak extrinsic domain wall pinning, the piezoelectric control allows one to experimentally assess the upper and lower boundaries of the characteristic ratio of adiabatic and non-adiabatic spin-transfer torques in the current-driven domain wall motion.

Abstract LB-48: Somatic mutation of the NMDAR subunit GRIN2A in malignant melanoma results in loss of tumor suppressor activity

Glutamate receptors regulate many different cellular processes such as; homeostasis, growth, neurotransmission, proliferation, survival and cell death. These receptors are composed of two different major types; the ionotropic and the metabotropic family. The ionotropic glutamate receptors are composed of large complexes of multi-protein subunits creating ion channels in the cell plasma membranes that allow for influx or efflux of mono- or divalent cations (e.g., Ca2+)1. Upon binding of glutamate, these ligand gated-ion channels change their conformation giving rise to ion permeability and oscillations that in many neuronal cells (cerebellar granule cells, neurons, astrocytes, and glial cells) are important for synaptic transmissions, cellular migration and survival. We recently discovered the high prevalence of somatic mutations within one of the ionotropic glutamate receptors, GRIN2A, in malignant melanoma (1). Whole-exome sequencing of 14 tumor and matched normal samples from treatment naïve melanoma patients revealed that GRIN2A harbored 34 somatic mutations across 125 melanoma samples (25.2%). The mutations were distributed throughout the gene, with clustering of mutations within important functional domains. We also observed three recurrent alterations (S278F, E371K, and E1175K) as well as 5 nonsense mutations. Recently, additional groups have since observed high mutation frequencies of GRIN2A within separate melanoma cohorts, suggesting that genetic alteration of this gene is important (2-3). Functional characterization of a subset of GRIN2A mutants demonstrated loss of complex formation between GRIN1 and GRIN2A, decreased cell death, increased anchorage-independent growth in soft agar, increased migration and decreased Ca2+-channel influx promoting cell survival whilst expression of GRIN1:GRIN2A wild-type complexes resulted in decreased cell proliferation via Ca2+ -mediated programmed cell death. Depletion of endogenous GRIN2A in melanoma cells expressing wild-type GRIN2A resulted in increased proliferation compared to control. In contrast, shRNA depletion of GRIN2A in mutant cell lines had little to no effect. Our data shows that somatic mutation of GRIN2A results in decreased Ca2+-mediated apoptosis in melanoma cells causing increased survival and is the first to demonstrate the functional implications of GRIN2A mutations in melanoma. Importantly, our whole-exome study was the first to demonstrate that the glutamate signaling pathway is significantly altered in melanoma.

Citation Format: Todd D. Prickett, Victoria Hill, Jared Gartner, Brad Zerlanko, Jiji Jiang, May Samaan, John Wunderlich, Silvio Gutkind, Steven A. Rosenberg, Yardena Samuels. Somatic mutation of the NMDAR subunit GRIN2A in malignant melanoma results in loss of tumor suppressor activity. [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 LB-48. doi:10.1158/1538-7445.AM2013-LB-48

Detection of electrically modulated inverse spin hall effect in an Fe/GaAs microdevice

We report the detection of the inverse spin Hall effect (ISHE) in n-gallium arsenide (n-GaAs) combined with electrical injection and modulation of the spin current. We use epitaxial ultrathin-Fe/GaAs injection contacts with strong in-plane magnetic anisotropy. This allows us to simultaneously perform Hanle spin-precession measurements on an Fe detection electrode and ISHE measurements in an applied in-plane hard-axis magnetic field. In this geometry, we can experimentally separate the ordinary from the spin-Hall signals. Electrical spin injection and detection are combined in our microdevice with an applied electrical drift current to modulate the spin distribution and spin current in the channel. The magnitudes and external field dependencies of the signals are quantitatively modeled by solving drift-diffusion and Hall-cross response equations.

Electrical measurement of antiferromagnetic moments in exchange-coupled IrMn/NiFe stacks

We employ antiferromagnetic tunneling anisotropic magnetoresistance to study the behavior of antiferromagnetically ordered moments in IrMn exchange coupled to NiFe. Experiments performed by common laboratory tools for magnetization and electrical transport measurements allow us to directly link the broadening of the NiFe hysteresis loop and its shift (exchange bias) to the rotation and pinning of antiferromagnetic moments in IrMn. At higher temperatures, the broadened loops show zero shift, which correlates with the observation of fully rotating antiferromagnetic moments inside the IrMn film. The onset of exchange bias at lower temperatures is linked to a partial rotation between distinct metastable states and pinning of the IrMn antiferromagnetic moments in these states. The observation complements common pictures of exchange bias and reveals an electrically measurable memory effect in an antiferromagnet.

Spin-orbit-driven ferromagnetic resonance

Ferromagnetic resonance is the most widely used technique for characterizing ferromagnetic materials. However, its use is generally restricted to wafer-scale samples or specific micro-magnetic devices, such as spin valves, which have a spatially varying magnetization profile and where ferromagnetic resonance can be induced by an alternating current owing to angular momentum transfer. Here we introduce a form of ferromagnetic resonance in which an electric current oscillating at microwave frequencies is used to create an effective magnetic field in the magnetic material being probed, which makes it possible to characterize individual nanoscale samples with uniform magnetization profiles. The technique takes advantage of the microscopic non-collinearity of individual electron spins arising from spin-orbit coupling and bulk or structural inversion asymmetry in the band structure of the sample. We characterize lithographically patterned (Ga,Mn)As and (Ga,Mn)(As,P) nanoscale bars, including broadband measurements of resonant damping as a function of frequency, and measurements of anisotropy as a function of bar width and strain. In addition, vector magnetometry on the driving fields reveals contributions with the symmetry of both the Dresselhaus and Rashba spin-orbit interactions.

A spin-valve-like magnetoresistance of an antiferromagnet-based tunnel junction

A spin valve is a microelectronic device in which high- and low-resistance states are realized by using both the charge and spin of carriers. Spin-valve structures used in modern hard-drive read heads and magnetic random access memoriescomprise two ferromagnetic electrodes whose relative magnetization orientations can be switched between parallel and antiparallel configurations, yielding the desired giant or tunnelling magnetoresistance effect. Here we demonstrate more than 100% spin-valve-like signal in a NiFe/IrMn/MgO/Pt stack with an antiferromagnet on one side and a non-magnetic metal on the other side of the tunnel barrier. Ferromagneticmoments in NiFe are reversed by external fields of approximately 50  mT or less, and the exchange-spring effect of NiFe on IrMn induces rotation of antiferromagnetic moments in IrMn, which is detected by the measured tunnelling anisotropic magnetoresistance. Our work demonstrates a spintronic element whose transport characteristics are governed by an antiferromagnet. It demonstrates that sensitivity to low magnetic fields can be combined with large, spin-orbit-coupling-induced magnetotransport anisotropy using a single magnetic electrode. The antiferromagnetic tunnelling anisotropic magnetoresistance provides a means to study magnetic characteristics of antiferromagnetic films by an electronic-transport measurement.

Modification of bacterial structures by a low-temperature gas plasma and influence on packaging material

AIMS

To investigate the effect of a cascaded dielectric barrier discharge (CDBD) treatment on the biological structure of a selected bacterium and on the properties of different polymer films.

METHODS AND RESULTS

Inactivation kinetics were measured using air as the process gas and using Bacillus atrophaeus spores and vegetative cells, which had been homogeneously distributed on a surface. The changes to the outer coats and the DNA of the endospores and cells after plasma treatment were determined using biomolecular and chemical methods. The experiments showed that damage to the DNA molecules and changes in the cell walls can be observed as a consequence of the CDBD treatment. Furthermore, the influence of the plasma treatment on the properties of various polymer films was investigated using a variety of test methods. Except the sealing strength where a slight decrease was observed (max. 20%), no negative changes of the material properties have occurred.

CONCLUSIONS

CDBD treatment can affect the DNA of spores and cells, depending on the treatment time. At the same time, practically relevant inactivation rates on packaging materials were observed, without any significant changes to the material properties.

SIGNIFICANCE AND IMPACT OF THE STUDY

Knowledge about CDBD mechanisms was acquired from a biological point of view, and the suitability of the method for treating polymer films was demonstrated.

Activation of the phosphoinositide-3-kinase and mammalian target of rapamycin signaling pathways are associated with shortened survival in patients with malignant peritoneal mesothelioma

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is a rare malignancy of the serosal membranes of the abdominal cavity. This cancer is ultimately fatal in almost all afflicted individuals; however, there is marked variability in its clinical behavior: Some patients die rapidly, and others survive for many years. In the current study, the authors investigated the molecular nature of MPM to obtain insights into the heterogeneity of its clinical behavior and to identify new therapeutic targets for intervention.

METHODS

Fresh pretreatment tumor samples were collected from 41 patients with MPM who underwent surgical cytoreduction and received regional intraoperative chemotherapy perfusion. From those samples, gene expression analyses were performed. The major cellular pathways that were identified in this cancer were inhibited using a pathway-specific inhibitor.

RESULTS

Unsupervised clustering of genes identified 2 distinct groups of patients with significantly different survivals (Group A: median survival, 24 months; Group B: median survival, 69.5 months; P = .035). Phosphoinositide-3-kinase (PI3K) and the closely interacting mammalian target of rapamycin (mTOR) signaling pathways were overexpressed predominantly in the poor survival group; and the genes of these pathways, phosphoinositide-3-kinase, catalytic, α polypeptide (PIK3CA) and rapamycin-insensitive companion of mammalian target of rapamycin (RICTOR), were highly significantly predictive of shortened patient survival in Group A. The role of these pathways in MPM tumor progression was also investigated by treating 2 MPM cell lines with BEZ235, a dual-class PI3K and mTOR inhibitor, and the authors observed significant inhibition of downstream cell signaling and cell proliferation.

CONCLUSIONS

Taken together, the results from this study revealed that, based on gene expression profiles, there were 2 distinct patient groups with significantly different survival and that targeting the PI3K and mTOR signaling pathways may have significant therapeutic value in patients with MPM.

Abstract 2221: Analysis of the protein tryosine kinome in melanoma revealed recurrent mutations in ERBB4

One of the most important features of cellular signaling involves the addition (or removal) of phosphate groups. Protein phosphorylation is coordinately regulated by protein kinases and phosphatases. Protein kinases are the largest superfamily of conserved genes in the genome, and represent the largest family of genes implicated in human cancer. Protein tyrosine kinases (PTKs) are frequently mutated in cancer and since they are amenable to pharmacologic inhibition, further analysis of the PTK gene family may identify new therapeutic strategies.

In the current study we focused on mutational analysis of the PTK gene family in cutaneous metastatic melanoma, identifying 30 somatic mutations in the kinase domain of 19 PTKs. The entire coding region of these 19 PTKs was further evaluated for somatic mutations in 79 melanoma cell lines derived from different patients. Our analysis revealed novel somatic mutations in ERBB4 in 19% of melanoma cell lines. Seven missense mutations in ERBB4 were examined and found to increase intrinsic kinase activity as evidenced by their ability to transform NIH 3T3 cells as well the human melanoma cell line SK-Mel-2. Melanoma cells expressing mutant ERBB4 exhibited reduced cellular proliferation after shRNA-mediated knockdown of ERBB4 or treatment with the pan-ERBB inhibitor lapatinib (GW2016). Furthermore, we found that cells expressing mutant ERBB4 had increased Akt phosphorylation compared to wild-type ERBB4 cells and that treatment with lapatinib (pan-ERBB inhibitor) specifically inhibited Akt phosphorylation and increased apoptosis in cells expressing mutant ERBB4 compared to cells expressing WT ERBB4. Collectively, our results suggest that melanoma cells harboring mutant ERBB4 are “oncogenically addicted” and that mutational activation of ERBB4 may be essential for tumorigenesis. To further elucidate the biological role of ERBB4, we plan on generating isogenic cell lines through homologous recombination to knock-out either wild-type or mutant alleles of ERBB4 or create isogenic cell lines expressing endogenously epitope-tagged (EET) wild-type ERBB4 or mutant ERBB4. Both of these approaches should provide clues to the function ERBB4 plays in tumorigenesis and may identify additional therapeutic targets applicable to the clinic. Furthermore, our characterization of ERBB4 mutations offers promise for clinical investigation using small molecule inhibitors such as lapatinib forming the basis for a clinical protocol for melanoma patients. Based on these results, a clinical trial using lapatinib in patients with metastatic melanoma harboring ERBB4 mutations is being planned at the Surgery Branch/ NCI under the leadership of Dr. Steven Rosenberg.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2221.

Antimicrobial efficiency of titanium dioxide-coated surfaces

AIMS

Development and evaluation of an antimicrobially active titanium dioxide coating.

METHODS AND RESULTS

For this purpose, titanium dioxide coatings were applied to glass slides by using a sol-gel method and then exposed to a light source. The antimicrobial efficiency was determined by a count reduction test for selected test strains (Aspergillus niger, Bacillus atrophaeus, Kocuria rhizophila), which were homogenously sprayed onto surface. The bacterial count of K. rhizophila was reduced by up to 3.3 log(10) on titanium dioxide samples within 4 h of UV-A light exposure. Experiments with spore formers did not lead to any significant log reduction. A further aspect of this work was to evaluate the effect of selected parameters (relative humidity, inoculation density, radiation intensity) on the antimicrobial efficiency to gain knowledge for further optimization procedures. At a high relative humidity (85% r.h.), increased inactivation was observed for K. rhizophila (up to 5.2 log(10)). Furthermore, a dependency of the antimicrobial effect on the radiation intensity and the inoculation density was identified.

CONCLUSIONS

Antimicrobial surfaces and coatings based on titanium dioxide have the potential to effectively inactivate vegetative micro-organisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

Knowledge about the antimicrobial efficiency of titanium dioxide was gained. This is a prerequisite for industrial applications to improve hygiene, food quality and safety.

Frequent mutations in the MITF pathway in melanoma

Microphthalmia-associated transcription factor (MITF) is involved in melanocyte cell development, pigmentation and neoplasia. To determine whether MITF is somatically mutated in melanoma, we compared the sequence of MITF from primary and metastatic lesions to patient-matched normal DNA. In the 50 metastatic melanoma tumor lines analysed, we discovered four samples that had genomic amplifications of MITF and four that had MITF mutations in the regions encoding the transactivation, DNA binding or basic, helix-loop-helix domains. Sequence analysis for SOX10, a transcription factor, which both acts upstream of MITF and synergizes with MITF, identified an additional three samples with frameshift or nonsense mutations. Microphthalmia-associated transcription factor and SOX10 were found to be mutated in a mutually exclusive fashion, possibly suggesting disruption in a common genetic pathway. Taken together we found that over 20% of the metastatic melanoma cases had alterations in the MITF pathway. We show that the MITF pathway is also altered in primary melanomas: 2/26 demonstrated mutations in MITF and 6/55 demonstrated mutations in SOX10. Our findings suggest that altered MITF function during melanomagenesis can be achieved by MITF amplification, MITF single base substitutions or by mutation of its regulator SOX10.

Adoptive cell therapy for patients with metastatic melanoma: evaluation of intensive myeloablative chemoradiation preparative regimens

PURPOSE

The two approved treatments for patients with metastatic melanoma, interleukin (IL)-2 and dacarbazine, mediate objective response rates of 12% to 15%. We previously reported that adoptive cell therapy (ACT) with autologous antitumor lymphocytes in lymphodepleted hosts mediated objective responses in 51% of 35 patients. Here, we update that study and evaluate the safety and efficacy of two increased-intensity myeloablative lymphodepleting regimens.

PATIENTS AND METHODS

We performed two additional sequential trials of ACT with autologous tumor-infiltrating lymphocytes (TIL) in patients with metastatic melanoma. Increasing intensity of host preparative lymphodepletion consisting of cyclophosphamide and fludarabine with either 2 (25 patients) or 12 Gy (25 patients) of total-body irradiation (TBI) was administered before cell transfer. Objective response rates by Response Evaluation Criteria in Solid Tumors (RECIST) and survival were evaluated. Immunologic correlates of effective treatment were studied.

RESULTS

Although nonmyeloablative chemotherapy alone showed an objective response rate of 49%, when 2 or 12 Gy of TBI was added, the response rates were 52% and 72% respectively. Responses were seen in all visceral sites including brain. There was one treatment-related death in the 93 patients. Host lymphodepletion was associated with increased serum levels of the lymphocyte homeostatic cytokines IL-7 and IL-15. Objective responses were correlated with the telomere length of the transferred cells.

CONCLUSION

Host lymphodepletion followed by autologous TIL transfer and IL-2 results in objective response rates of 50% to 70% in patients with metastatic melanoma refractory to standard therapies.

Curie point singularity in the temperature derivative of resistivity in (Ga,Mn)As

We observe a singularity in the temperature derivative drho/dT of resistivity at the Curie point of high-quality (Ga,Mn)As ferromagnetic semiconductors with Tc's ranging from approximately 80 to 185 K. The character of the anomaly is sharply distinct from the critical contribution to transport in conventional dense-moment magnetic semiconductors and is reminiscent of the drho/dT singularity in transition metal ferromagnets. Within the critical region accessible in our experiments, the temperature dependence on the ferromagnetic side can be explained by dominant scattering from uncorrelated spin fluctuations. The singular behavior of drho/dT on the paramagnetic side points to the important role of short-range correlated spin fluctuations.

Tunneling anisotropic magnetoresistance in multilayer-(Co/Pt)/AlO_(x)/Pt structures

We report observations of tunneling anisotropic magnetoresitance (TAMR) in vertical tunnel devices with a ferromagnetic multilayer-(Co/Pt) electrode and a nonmagnetic Pt counterelectrode separated by an AlOx barrier. In stacks with the ferromagnetic electrode terminated by a Co film the TAMR magnitude saturates at 0.15% beyond which it shows only weak dependence on the magnetic field strength, bias voltage, and temperature. For ferromagnetic electrodes terminated by two monolayers of Pt we observe order(s) of magnitude enhancement of the TAMR and a strong dependence on field, temperature and bias. The discussion of experiments is based on relativistic ab initio calculations of magnetization orientation dependent densities of states of Co and Co/Pt model systems.

Anisotropic magnetoresistance components in (Ga,Mn)As

We explore the basic physical origins of the noncrystalline and crystalline components of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As. The sign of the noncrystalline AMR is found to be determined by the form of spin-orbit coupling in the host band and by the relative strengths of the nonmagnetic and magnetic contributions to the Mn impurity potential. We develop experimental methods yielding directly the noncrystalline and crystalline AMR components which are then analyzed independently. We report the observation of an AMR dominated by a large uniaxial crystalline component and show that AMR can be modified by local strain relaxation. Generic implications of our findings for other dilute moment systems are discussed.

Absence of skew scattering in two-dimensional systems: testing the origins of the anomalous Hall effect

We study the anomalous Hall conductivity in spin-polarized, asymmetrically confined two-dimensional electron and hole systems, taking into account the intrinsic, side-jump, and skew-scattering contributions to the transport. We find that the skew scattering, principally responsible for the extrinsic contribution to the anomalous Hall effect, vanishes for the two-dimensional electron system if both chiral Rashba subbands are partially occupied, and vanishes always for the two-dimensional hole gas studied here, regardless of the band filling. Our prediction can be tested with the proposed coplanar two-dimensional electron-hole gas device and can be used as a benchmark to understand the crossover from the intrinsic to the extrinsic anomalous Hall effect.