P12.15.B Astrocyte immunometabolic regulation of the glioblastoma microenvironment drives tumor pathogenicity

Background

Malignant brain tumors are the cause of a disproportionate level of morbidity and mortality among cancer patients, an unfortunate statistic that has remained constant for decades. Despite considerable advances in the molecular characterization of these tumors, targeting the cancer cells has yet to produce significant advances in treatment. An alternative strategy is to target cells in the glioblastoma microenvironment, such as tumor associated astrocytes. Astrocytes control multiple processes in health and disease, ranging from maintaining the brain's metabolic homeostasis, to modulating neuroinflammation. However, their role in glioblastoma pathogenicity is not well understood.

Material and Methods

Immunocompetent mice were implanted with murine glioma cell lines and the role of astrocyte in the tumor pathogenicity was analyzed, and further investigated using in-vitro co-cultures.

Results

Here we report that depletion of reactive astrocytes regresses glioblastoma and prolongs mouse survival. Analysis of the tumor-associated astrocyte translatome, revealed that astrocytes initiate transcriptional programs that shape the immune and metabolic compartments in the glioma microenvironment. Specifically, their expression of CCL2 and CSF1 governs the recruitment of tumor-associated macrophages and promotes a pro-tumorigenic macrophage phenotype. Concomitantly, we demonstrate that astrocyte-derived cholesterol is key to glioma cell survival, and that targeting astrocytic cholesterol efflux, via ABCA1, halts tumor progression. In summary, astrocytes control glioblastoma pathogenicity by reprogramming the immunological properties of the tumor microenvironment and supporting the non-oncogenic metabolic dependency of glioblastoma on cholesterol.

Conclusion

These findings suggest that targeting astrocyte immunometabolic signaling may help treat this uniformly lethal brain tumor.

Ultrafast Enhancement of Ferromagnetic Spin Exchange Induced by Ligand-to-Metal Charge Transfer

We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground state. We demonstrate this effect in the layered ferromagnetic insulator CrSiTe_{3} by exciting Te-to-Cr charge-transfer transitions using ultrashort laser pulses and detecting coherent phonon oscillations that are impulsively generated by superexchange enhancement via magneto-elastic coupling. This mechanism kicks in below the temperature scale where short-range in-plane spin correlations begin to develop and disappears when the excitation energy is tuned away from the charge-transfer resonance, consistent with our predictions.

Cell shape regulates subcellular organelle location to control early Ca2+ signal dynamics in vascular smooth muscle cells

The shape of the cell is connected to its function; however, we do not fully understand underlying mechanisms by which global shape regulates a cell's functional capabilities. Using theory, experiments and simulation, we investigated how physiologically relevant cell shape changes affect subcellular organization, and consequently intracellular signaling, to control information flow needed for phenotypic function. Vascular smooth muscle cells going from a proliferative and motile circular shape to a contractile fusiform shape show changes in the location of the sarcoplasmic reticulum, inter-organelle distances, and differential distribution of receptors in the plasma membrane. These factors together lead to the modulation of signals transduced by the M3 muscarinic receptor/Gq/PLCβ pathway at the plasma membrane, amplifying Ca2+ dynamics in the cytoplasm, and the nucleus resulting in phenotypic changes, as determined by increased activity of myosin light chain kinase in the cytoplasm and enhanced nuclear localization of the transcription factor NFAT. Taken together, our observations show a systems level phenomenon whereby global cell shape affects subcellular organization to modulate signaling that enables phenotypic changes.

[Postmortem imaging of the lung in cases of COVID-19 deaths]

CLINICAL/METHODOLOGICAL ISSUE

COVID-19 is a new viral disease that is associated with inflammatory pulmonary changes which can be detected in computed tomography (CT). So far postmortem CT (PMCT) has not been used as a screening instrument for the evaluation of deaths with and without autopsy. In this respect, its validity has to be proved in comparison to clinical-radiological experiences.

STANDARD RADIOLOGICAL METHODS

Postmortem CT METHODICAL INNOVATIONS: So far, PMCT can be regarded as a methodological innovation that has not yet been sufficiently evaluated for pneumonia.

PERFORMANCE

CT in clinical routine has a high sensitivity for pneumonia. However, to what extent postmortem artifacts are relevant to PMCT still has to be determined.

ACHIEVEMENTS

There is still no standard procedure for the postmortem radiological diagnosis of COVID-19 disease. Despite postmortem artifacts, PMCT can provide valuable information about the presence of pneumonia with interstitial character, especially without autopsy.

PRACTICAL RECOMMENDATIONS

PMCT is particularly useful in the assessment of suspected cases of COVID-19 pneumonia for morphological assessment in the context of monitoring deaths in the current pandemic situation.

Evidence for systematic autopsies in COVID-19 positive deceased: Case report of the first German investigated COVID-19 death

Forensic medicine and pathology involve specific health risks, whereby health workers are dealing with microorganisms, cells or parasites, which are referred to as biological agents. Biological agents are divided into four categories according to § 3 of the Biological Agents Ordinance. The newly identified coronavirus, severe acute respiratory syndrome, coronavirus 2 (SARS-CoV-2) that has spread rapidly around the world is placed into category 3 of the Biological Agents Ordinance, meaning pathogens that can cause serious illnesses in humans and may pose a risk to workers. The Robert Koch Institute, the German government’s central scientific institution in the field of biomedicine issued the announcement, that aerosol-producing measures (including autopsies) of SARS-CoV‑2 infected bodies should be avoided, despite the fact that autopsies are an important source of understanding the pathomorphological course of new diseases. The first German case of death due to a proven SARS-CoV‑2 infection is presented with global multifocal reticular consolidation in the post-mortem computed tomography (CT) scan, a macroscopic and microscopic viral pneumonia and viral RNA of SARS-CoV‑2 in pharyngeal mucosa and lung tissue.

Floquet Engineering in Quantum Chains

We consider a one-dimensional interacting spinless fermion model, which displays the well-known Luttinger liquid (LL) to charge density wave (CDW) transition as a function of the ratio between the strength of the interaction U and the hopping J. We subject this system to a spatially uniform drive which is ramped up over a finite time interval and becomes time periodic in the long-time limit. We show that by using a density matrix renormalization group approach formulated for infinite system sizes, we can access the large-time limit even when the drive induces finite heating. When both the initial and long-time states are in the gapless (LL) phase, the final state has power-law correlations for all ramp speeds. However, when the initial and final state are gapped (CDW phase), we find a pseudothermal state with an effective temperature that depends on the ramp rate, both for the Magnus regime in which the drive frequency is very large compared to other scales in the system and in the opposite limit where the drive frequency is less than the gap. Remarkably, quantum defects (instantons) appear when the drive tunes the system through the quantum critical point, in a realization of the Kibble-Zurek mechanism.

Infrared photoconductivity and photovoltaic response from nanoscale domains of PbS alloyed with thorium and oxygen

Thin films of lead sulfide alloyed with thorium and oxygen were deposited on GaAs substrates and processed to produce a photo-diode structure. Structural, optical and electrical characterizations indicate the presence of small nanoscale domains (NDs) that are characterized by dense packaging, high quality interfaces and a blue-shift of the energy bandgap toward the short wavelength infrared range of the spectrum. Photocurrent spectroscopy revealed a considerable photoconductivity that is correlated with excitation of carriers in the NDs of lead sulfide alloyed with thorium and oxygen. Furthermore, the appearance of a photovoltaic effect under near infrared illumination indicates a quasi-type II band alignment at the interface of the GaAs and the film of NDs.

Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al

The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ∼2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ω(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.

Anomalous magnetic ground state in an LaAlO3/SrTiO3 interface probed by transport through nanowires

Resistance as a function of temperature down to 20 mK and magnetic fields up to 18 T for various carrier concentrations is measured for nanowires made from the SrTiO3/LaAlO3 interface using a hard mask shadow deposition technique. The narrow width of the wires (of the order of 50 nm) allows us to separate out the magnetic effects from the dominant superconducting ones at low magnetic fields. At this regime hysteresis loops are observed along with the superconducting transition. From our data analysis, we find that the magnetic order probed by the giant magnetoresistance effect vanishes at TCurie=954±20  mK. This order is not a simple ferromagnetic state but consists of domains with opposite magnetization having a preferred in-plane orientation.

On-chip detection of cellular activity

The use of on-chip cellular activity monitoring for biological/chemical sensing is promising for environmental, medical and pharmaceutical applications. The miniaturization revolution in microelectronics is harnessed to provide on-chip detection of cellular activity, opening new horizons for miniature, fast, low cost and portable screening and monitoring devices. In this chapter we survey different on-chip cellular activity detection technologies based on electrochemical, bio-impedance and optical detection. Both prokaryotic and eukaryotic cell-on-chip technologies are mentioned and reviewed.

One-dimensional quantum wire formed at the boundary between two insulating LaAlO3/SrTiO3 interfaces

We grow a tiled structure of insulating two-dimensional LaAlO3/SrTiO3 interfaces composed of alternating one and three LaAlO3 unit cells. The boundary between two tiles is conducting. At low temperatures this conductance exhibits quantized steps as a function of gate voltage indicative of a one-dimensional channel. The step size of half the quantum of conductance is evidence for the absence of spin degeneracy.

Observation of magnetically induced transparency in a classical magnetized plasma

We report the first demonstration of magnetically induced transmission in an opaque magnetized plasma. Magnetically induced transmission in a plasma is a classical analog to the electromagnetically induced transparency in atomic systems. The transmission of radiation through an axially magnetized plasma is obtained by applying an additional one dimensional transverse spatial periodic magnetic field. The transverse-periodic magnetic field uncouples the right-hand electromagnetic wave from interacting with plasma electrons, rendering the plasma band-stop transparent. This provides means to control the extent of absorption of electromagnetic radiation in magnetized plasma.

Shubnikov-de Haas oscillations in SrTiO3/LaAlO3 interface

Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ρ(xy) is nonlinear at low magnetic fields. ρ(xy) is fitted assuming multiple carrier contributions. We infer the density of the mobile charge carriers from the oscillations frequency and from Hall measurements. The comparison between these densities suggests multiple valley and spin degeneracy. The small amplitude of the oscillation is discussed in the framework of the multiple band scenario.

Elimination of the diffraction of arbitrary images imprinted on slow light

We present a scheme for eliminating the optical diffraction of slow light in a thermal atomic medium of electromagnetically induced transparency. Nondiffraction is achieved for an arbitrary paraxial image by manipulating the susceptibility in momentum space, in contrast to the common approach, which employs guidance of specific modes by manipulating the susceptibility in real space. For negative two-photon detuning, the moving atoms drag the transverse momentum components unequally, resulting in a Doppler trapping of light by atoms in two dimensions.

Feasibility of a nitrogen-recombination soft-x-ray laser using capillary discharge Z pinch

Capillary discharge Z pinches have been shown to be efficient drivers for x-ray lasers (XRLs). In this work we examine the possibility of realizing a H_{alpha} nitrogen recombination laser ( 3-->2 transition) at lambda=13.4nm , using a capillary discharge Z pinch. A pulsed power generator with 60kA peak current and 70ns quarter period have been used to generate Z -pinch plasma in a 90-mm -long and 5-mm -diameter capillary. The plasma conditions were evaluated experimentally, using a filtered x-ray diode detector and time-integrated spectroscopy. The conditions required for the XRL were analytically estimated based on simple steady-state rate equations and then compared to experimental results. We demonstrated above 10% N7+ abundance at pinch time, while at least 50% is required. Then, in the expansion phase, the plasma is cooled in a time less than 5ns to temperatures below 60eV , as needed for the recombination laser. These results suggest that the required conditions for nitrogen-recombination lasing could be achieved in a capillary discharge Z pinch, but a higher-power driver might be needed.

Storing images in warm atomic vapor

Reversible and coherent storage of light in an atomic medium is a promising method with possible applications in many fields. In this work, arbitrary two-dimensional images are slowed and stored in warm atomic vapor for up to 30 micros, utilizing electromagnetically induced transparency. Both the intensity and the phase patterns of the optical field are maintained. The main limitation on the storage resolution and duration is found to be the diffusion of atoms. A technique analogous to phase-shift lithography is employed to diminish the effect of diffusion on the visibility of the reconstructed image.

Topological stability of stored optical vortices

We report an experiment in which an optical vortex is stored in a vapor of Rb atoms. Because of its 2pi phase twist, this mode, also known as the Laguerre-Gauss mode, is topologically stable and cannot unwind even under conditions of strong diffusion. For comparison, we stored a Gaussian beam with a dark center and a uniform phase. Contrary to the optical vortex, which stays stable for over 100 micros, the dark center in the retrieved flat-phased image was filled with light after a storage time as short as 10 micros. The experiment proves that higher electromagnetic modes can be converted into atomic coherences and that modes with phase singularities are robust to decoherence effects such as diffusion. This opens the possibility to more elaborate schemes for classical and quantum information storage in atomic vapors.

Hydrodynamic flow of ions and atoms in partially ionized plasmas

We have derived the hydrodynamic equations of motion for a partially ionized plasma, when the ionized component and the neutral components have different flow velocities and kinetic temperatures. Starting from the kinetic equations for a gas of ions and a gas of atoms we have considered various processes of encounters between the two species: self-collisions, interspecies collisions, ionization, recombination, and charge exchange. Our results were obtained by developing a general approach for the hydrodynamics of a gas in a binary mixture, in particular when the components drift with respect to each other. This was applied to a partially ionized plasma, when the neutral-species gas and the charged-species gas have separate velocities. We have further suggested a generalized version of the relaxation time approximation and obtained the contributions of the interspecies encounters to the transport equations.

Plasma dynamics in capillary discharge soft x-ray lasers

The dynamics and stability of collapsing gas columns, generated by a fast capillary discharge setup, are studied for obtaining soft x-ray amplification in highly ionized ions. Electron temperature and density measurements at the peak of the compression stage are used for tuning the discharge parameters. Once the needed conditions were achieved, strong amplification of the 3s-3p transition in Ne-like Ar ions at 469 A is observed. A gain coefficient of >0.75 cm(-1) and a beam divergence of <5 mrad are measured along plasma columns of <150 microm diameter and up to 165 mm length.

Cell pairing and methylation in Tetrahymena thermophila are altered by exogenous homocysteine

Homocysteine is causally associated with birth defects such as spina bifida, and with premature vascular disease. We have investigated the effects of homocysteine on a cell-cell interaction in a fundamental eukaryotic system, the free-living ciliate Tetrahymena. Exogenously added homocysteine inhibits cell pairing in a dose-dependent manner. These effects are exacerbated by adenosine, which by itself has little demonstrable influence on pairing. S-adenosylhomocysteine (SAH) is a product of the reaction between adenosine and homocysteine, and is an inhibitor of methyl transferases. We therefore predicted that protein methylation would be significantly inhibited by homocysteine. A direct test of that hypothesis involved a demonstration that incorporation of an isotopically labeled methyl group from methionine into proteins was significantly reduced by homocysteine. The undermethylated proteins are of low molecular weight, and might correspond to known methylatable signaling proteins. We show that vanadate, an inhibitor of protein phosphatase, also inhibits cell pairing, and that the effects of vanadate and homocysteine are additive. This is the first demonstration that methylation and possibly phosphorylation play a regulatory role in cell-cell interactions in ciliates.

[Cortical blindness following coronary angiography]

Cortical blindness has been occasionally reported as a complication after cerebral angiography, but is rare after coronary angiography. The contrast agent is believed to be responsible for the sudden development of blindness. Although the exact mechanism is unknown, it appears that the contrast agent disrupts the blood brain barrier, mostly in the occipital areas. We report a 77-year-old man who suddenly developed transient, bilateral cortical blindness 4 hours after coronary angiography. Using contrast enhancement, the CT scan showed typical, symmetrical involvement of both occipital lobes. There were no other neurological deficits. Vision and CT findings returned to normal within 48 hours.

Negatively charged quantum well polaritons in a GaAs/AlAs microcavity: An analog of atoms in a cavity

The negatively charged exciton (X-) is observed to strongly couple with the microcavity- (MC-)confined photons in a GaAs quantum well containing a two-dimensional electron gas with 0<n(e)</=3x10(10) cm(-2). This strong coupling results in a formation of charged polaritons. The coupling strength is found to depend on sqrt[n(e)], in analogy to two-level atoms in a cavity. The analysis of the reflection and photoluminescence spectra shows that X- is strongly admixed with the neutral exciton via their coupling with the MC photons. The linewidth dependence on n(e) indicates that electron-polariton scattering is effective.

The reform of the rural cooperative medical system in the People's Republic of China: interim experience in 14 pilot counties

During the 1960's and 1970's the Chinese government encouraged the 'rural cooperative medical systems' (RCMS), in order to ensure access to basic health care among the rural population. There was a break in the development of the RCMS in the early 1980's, as a consequence of market economic reforms. These reforms involved a shift from a communal to a household production system. As a result the collective way of financing rural health care was more or less abandoned. However, the government of the People's Republic of China was aware of the need to provide social protection against health care expenses. In March 1994 the government initiated a project to reestablish the RCMS. This project was implemented on a pilot basis in 14 counties of seven provinces. The reestablishment of the RCMS would be guided by the basic principles of health insurance. In October 1995, a first mid-term evaluation of the RCMS Project was held. One of the major research questions concerned the extent to which the RCMS had reduced the risk of paying health care bills that would otherwise be a burden on families. This article addresses this question and assesses the results obtained after two years of RCMS experimental work. A general finding is that the population structure by occupation and income varies, and that the RCMS has adapted itself to this variety. It is also confirmed that the burden of health care costs on families was reduced, more so in some counties than in others, but this reduction has been modest. The research results indicate that there is ample room for improvement. The outlook is hopeful, however. At the national level, there is now systematic thinking about RCMS. The current RCMS work is also having a considerable influence on other counties that are keen to reestablish the RCMS.

NGOs in community health insurance schemes: examples from Guatemala and the Philippines

In poor rural communities, access to basic health care is often severely limited by inadequate supply as well as financial barriers to seeking care. National policies may introduce social health insurance, but these are likely to begin with the salaried public and private sector workers while the informal sector population may be the last to be covered. Community initiatives to generate health care financing require a complex development process. This paper covers attempts to develop such schemes in rural populations in Guatemala and the Philippines through non-government organizations and notes the major factors which have contributed to unequal progress in the two schemes. The scheme of the Association por Salud de Barillas (ASSABA) in Guatemala was not sufficiently established as an administrative body at the conceptual stage and there was no clear national policy on health care financing. By the time the necessary action was taken, local conflicts hindered progress. In the Philippines, the ORT Health Plus Scheme (OHPS) was implemented during the period of legislation of a national health insurance act. The appraisal after three years of operation shows that OPHS has made health care affordable and accessible to the target population, composed mainly of low and often unstable income families in rural areas. The major success factors are probably the administrative structure provided by a cooperative and controls in the delivery system and in expenditures, through the salaried primary health care team, referral process and the capitation agreement for hospital-based services. The proliferation of such schemes could benefit from national guidelines, a formal accreditation process and an umbrella organization to provide assistance in design, training and information services, involving government, non-government and academic institutions as an integral part of the development process.

Prediction of successful induction of labor: comparison of transvaginal ultrasonography and the Bishop score

OBJECTIVE

To determine whether transvaginal ultrasonography of the cervix before induction of labor is a better predictor of successful induction than the Bishop score.

STUDY DESIGN

Eighty-six consecutive patients scheduled for induction of labor underwent digital cervical examination followed by transvaginal ultrasonography to measure cervical length and to determine the presence of wedging. Patients were induced with either oxytocin or intracervical prostaglandin E2 gel followed by oxytocin when required. The agent for induction was selected on the basis of the digital examination. The primary outcome criteria were successful induction and the duration of labor.

RESULTS

Successful induction and the duration of labor were significantly associated with the Bishop score and cervical length. Cervical wedging was associated only with successful induction. However, in a logistic regression model that included these parameters as independent variables, only the Bishop score and parity were significantly correlated with successful induction and the duration of labor.

CONCLUSIONS

Transvaginal ultrasonographic evaluation of the cervix before induction of labor does not improve the prediction of cervical inducibility obtained by the Bishop score.

Quality improvement through review of inpatient deaths

Emphasis on hospital mortality as a monitoring tool has raised concerns about the validity of mortality rates as a measure of quality of care. An indepth review of all mortalities at Beth Israel Medical Center was conducted from 1988 through 1993. Clinical issues identified from chart review were referred for departmental physician peer review, and quarterly reports of trends and issues were disseminated to all levels of the institution. Mortality rates declined 21% over the 6 years, from 3.3% to 2.6% of all discharges. Clinical quality issues were identified in less than 3% of all mortalities. The majority of problems were related to delays and appropriateness of treatment (57% of quality issues). The review program identified specific hospital processes for improvement, and, more importantly, created a "watchful concern" about quality-of-care issues throughout the hospital.

Can placental surface area and neonatal weight be predicted from placental surface measurements? Preliminary observations on normal-term pregnancies

OBJECTIVE

To evaluate the relations between chorionic plate measurements and neonatal weight as prerequisites for possible prediction of fetal weight using antenatal placental measurements.

METHODS

We examined freshly delivered placentas. The surface area (chorionic plate) was measured using millimeter paper, and the two longest diameters (at right angles to each other) were determined (L1 and L2). The mean longest diameter [Lm = (L1 + L2)/2] was calculated. The relation of these diameters to neonatal and placental weight was studied.

RESULTS

We examined 57 randomly selected placentas after normal pregnancy and delivery. The three chorionic plate diameters significantly correlated with the surface area and the placental and neonatal weights. The strongest correlation (r = 0.94; p < 10(-6) was found between Lm and placental surface area.

CONCLUSIONS

Our preliminary results suggest that chorionic plate measurements may be suitable to predict placental surface area and neonatal birth weight in normal-term pregnancies. Further studies to verify prospectively these relations at various gestational ages and in cases of abnormal fetal growth are required.