Glutamate hyperexcitability and seizure-like activity throughout the brain and spinal cord upon relief from chronic glutamate receptor blockade in culture

Cortical structures such as the hippocampus and cerebral cortex are considered to be particularly susceptible to seizure and epileptiform electrical activity and, as such, are the focus of intense investigation relative to hyperexcitability. To determine whether parallel glutamate-mediated hyperexcitability and seizure-like activity in the rat can be generated by neurons irrespective of their origin within the CNS, we maintained cells from the spinal cord,hippocampus, olfactory bulb, striatum, hypothalamus, and cortex in the long-term presence of glutamate receptor antagonists 2-amino-5-phosphonovalerate and 6-cyano-7-nitroquinoxaline-2-3-dione. After removal of chronic (three to 11 weeks) glutamate receptor block, whole-cell patch-clamp recordings from current-clamped neurons (n = 94) revealed an immediate increase in large excitatory postsynaptic potentials and a depolarization of 20-35 mV that was often sustained for recording periods lasting 5 min (54% of 66 neurons from all six areas). The intense activity was not seen in age-matched control neurons not subjected to chronic glutamate receptor block. Selective blockade of ionotropic glutamate receptors showed that the hyperexcitability was due to an enhanced response through both AMPA/kainate and N-methyl-D-aspartate receptors. Relief from chronic glutamate receptor block also increased inhibitory activity, as revealed by an increase in inhibitory postsynaptic currents while neurons were voltage-clamped at -25 mV. These inhibitory postsynaptic currents could be blocked with bicuculline, indicating that they were mediated by an enhanced GABA release. This enhanced GABA activity reduced, but did not eliminate, the glutamate-mediated hyperactivity, shown by an increase in both intracellular Ca2+ and excitatory electrical activity when bicuculline was added. When the glutamate receptor block was removed, cells (n > 1000) from all six regions showed exaggerated Ca2+ activity, characterized by abnormally high increases in intracellular Ca2+, rising from basal levels of 50-100 nM up to 150-1600 nM. Cd2+ eliminated the hyperexcitability by blocking Ca2+ channels, and reducing excitatory transmitter release and response. Fura-2 digital imaging revealed Ca2+ oscillations with periods ranging from 4 to 60 s. Ca2+ peaks in oscillations in oscillations were synchronized among most neurons recorded simultaneously. That synchronization was dependent on a mechanism involving voltage-dependent Na+ channels was demonstrated with experiments with tetrodotoxin that blocked Ca2+ rises and synchronous cellular behavior. Removal of the glutamate receptor antagonists resulted in the glutamate-mediated death of 44% of the cells after 23 days of chronic block and 82% cell death after 40 days of chronic block. Nimodipine substantially reduced cell death, indicating that one mechanism responsible for the enhanced cell death after relief from chronic glutamate receptor block was increased intracellular Ca2+ entry through L-type voltage-gated calcium channels. These data indicate that glutamate is released by neurons from all areas studied, including the spinal cord. Sufficient amounts of glutamate can be released from axon terminals from all areas to cause cell hippocampal and cortical neurons, but also by neurons from any of the brain regions tested after chronic deprivation of glutamate receptor stimulation during development. This hyperexcitability is mediated by glutamatergic mechanisms independent of the specific excitatory connections existing in vivo. The epileptiform activity of neurons from one region is indistinguishable from that of another in culture, underlining the importance of synaptic connections in vivo that define the responses characteristic of neurons from different brain regions.

Glyco-engineered anti-EGFR mAb elicits ADCC by NK cells from colorectal cancer patients irrespective of chemotherapy

Background:

The epidermal growth factor receptor (EGFR) is overexpressed in colorectal cancer (CRC), and is correlated with poor prognosis, making it an attractive target for monoclonal antibody (mAb) therapy. A component of the therapeutic efficacy of IgG1 mAbs is their stimulation of antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells bearing the CD16 receptor. As NK cells are functionally impaired in cancer patients and may be further compromised upon chemotherapy, it is crucial to assess whether immunotherapeutic strategies aimed at further enhancing ADCC are viable.

Methods:

CRC patients before, during and after chemotherapy were immunophenotyped by flow cytometry for major white blood cell populations. ADCC-independent NK cell functionality was assessed in cytotoxicity assays against K562 cells. ADCC-dependent killing of EGFR⁺ A431 cancer cells by NK cells was measured with a degranulation assay where ADCC was induced by GA201, an anti-EGFR mAb glyco-engineered to enhance ADCC.

Results:

Here, we confirm the observation that NK cells in cancer patients are dysfunctional. However, GA201 was able to induce robust NK cell-dependent cytotoxicity in CRC patient NK cells, effectively overcoming their impairment.

Conclusions:

These findings support the evaluation of the therapeutic potential of GA201 in combination with chemotherapy in CRC patients.

Propagation style controls lava-snow interactions

Understanding interactions between volcanic eruptions and the cryosphere (a.k.a. glaciovolcanism) is important for climate reconstructions as well as for hazard mitigation at ice-clad volcanoes. Here we present unique field observations of interactions between snowpack and advancing basaltic lava flows during the 2012-13 eruption at Tolbachik volcano, Kamchatka, Russia. Our observations show that lava-snow heat transfer is slow, and that styles of lava propagation control snowpack responses. 'A'a and sheet lava flows advance in a rolling caterpillar-track motion on top of the rigid, snowpack substrate with minor lava-snow interaction. In contrast, pahoehoe lava propagates by inflation of lobes beneath/inside the snowpack, producing rigorous lava-snow interaction via meltwater percolation down into the incandescent lava causing production of voluminous steam, rapid surface cooling and thermal shock fragmentation. The textures produced by pahoehoe-snowpack interactions are distinctive and, where observed at other sites, can be used to infer syn-eruption seasonality and climatic conditions.

Measurement of Lepton-Jet Correlation in Deep-Inelastic Scattering with the H1 Detector Using Machine Learning for Unfolding

The first measurement of lepton-jet momentum imbalance and azimuthal correlation in lepton-proton scattering at high momentum transfer is presented. These data, taken with the H1 detector at HERA, are corrected for detector effects using an unbinned machine learning algorithm (multifold), which considers eight observables simultaneously in this first application. The unfolded cross sections are compared with calculations performed within the context of collinear or transverse-momentum-dependent factorization in quantum chromodynamics as well as Monte Carlo event generators.

Determination of the strong coupling constant α s ( m Z ) in next-to-next-to-leading order QCD using H1 jet cross section measurements: H1 Collaboration

The strong coupling constant α s is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value ofα s ( m Z ) at the Z-boson mass m Z are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to beα s ( m Z ) = 0.1157 ( 20 ) exp ( 29 ) th . Complementary,α s ( m Z ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The valueα s ( m Z ) = 0.1142 ( 28 ) tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

Estimation of the X-rays RBE Uncerainty Related to Determination of Absorbed Dose in Radiobiological Experiments

Purpose: Determining the absorbed dose produced by photons, it is often assumed that it is equal to the radiation kerma. This assumption is valid only in the presence of an electronic equilibrium, which in turn is never ensured in practice. It leads to some uncertainty in determining the absorbed dose in the irradiated sample during radiobiological experiments. Therefore, it is necessary to estimate the uncertainty in determining the relative biological effectiveness of X-rays associated with uncertainty in the determination of the absorbed dose. Material and methods: The monochromatic X-ray photon emission is simulated through a standard 25 cm2 plastic flask containing 5 ml of the model culture medium (biological tissue with elemental composition C5H40O18N). The calculation of the absorbed dose in a culture medium is carried out in two ways: 1) the standard method, according to which the ratio of the absorbed dose in the medium and the ionization chamber is equal to the ratio of kerma in the medium and air; 2) determination of the absorbed dose in the medium and in the sensitive volume of the ionization chamber by computer simulation and calculating the ratio of these doses. For each primary photon energies, 108 histories are modeled, which makes it possible to achieve a statistical uncertainty not worse than 0.1 %. The energy step was 1 keV. The spectral distribution of X-ray energy is modeled separately for each set of anode materials, thickness and materials of the primary and secondary filters. The specification of the X-ray beams modeled in this work corresponds to the standards ISO 4037 and IEC 61267. Within the linear-quadratic model, the uncertainty of determining the RBEmax values is directly proportional to the uncertainty in the determination of the dose absorbed by the sample under study. Results: At energy of more than 60 keV, the ratios for water and biological tissue practically do not differ. At lower energies, up to about 20 keV, the ratio of the coefficients of air and water is slightly less than that of air and biological tissue. The maximum difference is ~ 1 % than usual and the equality of absorbed doses in the ionization chamber and sample is justified. At photon energy of 60 keV for the geometry in question, the uncertainty in determining the dose is about 50 %. For non-monochromatic radiation, the magnitude of the uncertainty is determined by the spectral composition of the radiation, since the curves vary greatly in the energy range 10–100 keV. It is shown that, depending on the spectral composition of X-ray radiation, uncertainty in the determination of the absorbed dose can reach 40–60 %. Such large uncertainty is due to the lack of electronic equilibrium in the radiation geometry used in practice. The spread of RBE values determined from the data of radiobiological experiments carried out by different authors can be determined both by differences in the experimental conditions and by uncertainty in the determination of the absorbed dose. Using Fricke dosimeters instead of ionization chambers in the same geometry allows you to reduce the uncertainty approximately 2 times, up to 10–30 %. Conclusion: The computer simulation of radiobiological experiments to determine the relative biological effectiveness of X-ray radiation is performed. The geometry of the experiments corresponds to the conditions for the use of standard bottles placed in the side holders. It is shown that the ratio of absorbed doses and kerma in the layers of biological tissue and air differ among themselves with an uncertainty up to 60 %. Depending on the quality of the beam, the true absorbed dose may differ from the one calculated on the assumption of kerma and dose equivalence by 50 %. Uncertainty in determining the RBE in these experiments is of the same order. The results are presented for X-ray beams with negligible fraction of photons with energies less than 10 keV. For beams of a different quality, the uncertainty in determination can significantly increase. For the correct evaluation of RBE, it is necessary to develop a uniform standard for carrying out radiobiological experiments. This standard should regulate both the geometry of the experiments and the conduct of dosimetric measurements.

Pharmacological composition based on bacteriocinnisin in experiments in vitro and in vivo

Background

Antibiotic resistance is a global health problem related to the transmission of bacteria and genes between humans and animals. The development of new drugs with antimicrobial activity research is an urgent task of modern science.

Aim

The article presents data of in vitro and in vivo experiments on new pharmaceutical composition based on nisin.

Methods

The antimicrobial activity was studied on the mastitis pathogens. To identify microorganisms the Matrix-Assisted Lazer Desorption/Ionization Time-of-Flight (MALDI-TOF) (mass spectrometry) method was performed using. To determine sensitivity, the serial dilution method and the diffusion method were used. On laboratory animals, biochemical, hematological, and histological research methods were used. Female nonlinear white laboratory rats were used, which were divided into one control group and three experimental ones.

Results

"Duration" factor was statistically significant for the following indicators: hemoglobin, hematocrit, leukocytes, lymphocytes, erythrocyte sedimentation rate, and eosinophils. The "Dose" factor did not show significance for any indicator, which means that the effect was similar regardless of the dose chosen. When analyzing the biochemical indicators, significant differences were found in the "Duration" and "Dose" factors, in the direction of a decrease in the indicators of total protein, globulins, urea, and an increase in the concentration of alkaline phosphatase. When conducting histological studies in the first experimental group, it was established that there were no changes in the structural and functional units of the organs. In animals of the second experimental group, the presence of reversible pathological processes of a compensatory nature was noted. More profound changes in the structure of the studied organs were recorded in the third experimental group.

Conclusion

An in vitro study on cell cultures showed that the pharmacological composition has high antimicrobial activity against isolates from the mammary gland secretion of cows with mastitis. An in vivo study on laboratory animals showed that the developed composition belongs to the IV class of substances "low-hazard substances". Histological examination made it possible to select the safest dose of the pharmacological composition of no more than 500 mg/kg.

Mechanism of the historical and the ongoing Vulcanian eruptions of Ebeko volcano, Northern Kuriles

Ebeko is one of the most active volcanoes of the Kurile island arc, producing frequent mild Vulcanian explosions with eruption clouds up to 5 km high. The volcano poses a serious threat to the Severo-Kurilsk town with a population of around 2500 inhabitants, located at a distance of only 7 km on a fan of the volcano's laharic deposits. Here, we report an overview of the activity of the volcano in the 20th-21st centuries and the results of our geological and petrological investigations of the ongoing Vulcanian eruption that started in 2016. We have found that eruptions of Ebeko span a range of mechanisms from purely magmatic to phreatic/hydrothermal. Three of its historical eruptions (the 1934-1935, 1987-1991, and the 2016-ongoing) involved fresh magma, while during the others (1967-1971, 2009-2011) fresh magma was not erupted. Juvenile material of the ongoing eruption represents highly crystalline and highly viscous (more than 10⁸ pa s) low-silica (56-58 wt% SiO₂) andesite. Historical data and our observations of the ongoing eruption allowed us to suggest a functional model of the volcano where Vulcanian explosions are caused by shallow intrusions of small diapir-like batches of strongly crystallized and highly viscous andesitic magma ascending into water-saturated, hydrothermally altered rocks composing the volcano summit. We suggest that the diapir's ascent is governed by their positive buoyancy. Some of the diapirs reach and breach the ground surface producing magmatic eruptions of Ebeko, while the others are stuck at the shallow subsurface level and feed intensive hydrothermal activity as well as phreatic eruptions of the volcano. Positive buoyancy of the diapirs is too weak to allow them to extrude high above the ground surface to form lava domes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00445-020-01426-z.

PD08-10: High Frequency of Triple Negative Mammary Carcinomas in the Dog as Model of Human Breast Cancer

Background Information: Relevant animal models of human breast cancer are currently lacking, especially regarding the triple-negative breast cancer (TNBC) subtype, for which efficient therapies are needed. Recent studies indicate that spontaneous canine mammary carcinomas (CMCs) (which are common in France due to absence of early neutering) resemble human breast cancers, by pathology, tumor genetics, and biological behavior. However, the current molecular classification of human breast cancer has not been evaluated in canine samples yet.

Objective: To establish the prognostic value of the human immunophenotypic classification in dogs To evaluate CMCs as a model of human breast cancer including TNBC.

Methods: 350 CMCs treated by surgery alone were obtained from the Nantes Atlantic College of Veterinary Medicine, Food Science and Engineering (France) from 2005 to 2008. Recorded clinical data included breed, neutering, age at diagnosis, presence of metastases, cause and time to death. Histological records included the subtype of carcinoma, Elston & Ellis grade, presence of emboli and lymph node metastasis. By immunohistochemistry (IHC) using ER, PR, Her2 (Herceptest and Pathway® Her2), CK5/6, EGF-R and KI67, CMCs were classified into the subtypes of human breast cancer according to Nielsen et al. IHC analyses were independently reviewed by four pathologists.

Results: The preliminary data in this abstract are based on 200 cases. The mean age at diagnosis was 10.8±2.1 years. 72,7% of dogs were intact female (27,3% of late neutering). 41% of dogs died due to cancer progression (metastasis rate of 30%). The most common histologic subtype was simple tubulopapillary CMC (53%), then solid CMC (32%). The most common grades were grade II (49%) and III (43%). 53% of the tumours showed lymphatic emboli. 4 immunophenotypes were defined: luminal A (11.9%), luminal B (5.1%), basal-like (59.3%) and non basal-like (23.7%) triple negative CMCs. 8.8% of the CMCs were scored Her2 2+ but none were considered Her2-overexpressing as defined by a 3+ score, despite appropriate staining with the two well established methods. Predictive factors for specific survival were: dog weight (p=0.01), histologic subtype (p=0.001), presence of emboli (p<0.0001) or lymph node metastasis (p=0.02), Ki67 index (p=0.03). Triple-negative carcinomas showed a significantly shorter specific survival (median=224 days) when compared to luminal A CMCs (median=641 days) (MannWhitney, p=0.016).

Conclusion: The molecular classification of human breast cancer identifies 4 subtypes of invasive CMCs with different prognoses. In dogs, a low rate of luminal tumors are observed, and no Her2-overexpressing tumors are found (defined by a score of 3+ by Her2 immunohistochemistry). 83% of CMCs were of the triple-negative subtype, associated with a shorter survival, as reported in human breast cancer. Infiltrative mammary cancer in dogs could be an interesting model for preclinical investigations. Final data based on 350 animals will be presented at the meeting.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD08-10.