21 research outputs found
Circular polarization reversal of half-vortex cores in polariton condensates
Vortices are topological objects carrying quantized orbital angular momentum
and have been widely studied in many physical systems for their applicability
in information storage and processing. In systems with spin degree of freedom
the elementary excitations are so called half-vortices, carrying a quantum
rotation only in one of the two spin components. We study the spontaneous
formation and stability of localized such half-vortices in semiconductor
microcavity polariton condensates, non-resonantly excited by a linearly
polarized ring-shaped pump. The TE-TM splitting of optical modes in the
microcavity system leads to an effective spin-orbit coupling, resulting in
solutions with discrete rotational symmetry. The cross-interaction between
different spin components provides an efficient method to realize all-optical
half-vortex core switching inverting its circular polarization state. This
switching can be directly measured in the polarization resolved intensity in
the vortex core region and it can also be applied to higher order half-vortex
states.Comment: 8 pages, 8 figure
Externally Controlled Lotka-Volterra Dynamics in a Linearly Polarized Polariton Fluid
Spontaneous formation of transverse patterns is ubiquitous in nonlinear
dynamical systems of all kinds. An aspect of particular interest is the active
control of such patterns. In nonlinear optical systems this can be used for
all-optical switching with transistor-like performance, for example realized
with polaritons in a planar quantum-well semiconductor microcavity. Here we
focus on a specific configuration which takes advantage of the intricate
polarization dependencies in the interacting optically driven polariton system.
Besides detailed numerical simulations of the coupled light-field exciton
dynamics, in the present paper we focus on the derivation of a simplified
population competition model giving detailed insight into the underlying
mechanisms from a nonlinear dynamical systems perspective. We show that such a
model takes the form of a generalized Lotka-Volterra system for two competing
populations explicitly including a source term that enables external control.
We present a comprehensive analysis both of the existence and stability of
stationary states in the parameter space spanned by spatial anisotropy and
external control strength. We also construct phase boundaries in non-trivial
regions and characterize emerging bifurcations. The population competition
model reproduces all key features of the switching observed in full numerical
simulations of the rather complex semiconductor system and at the same time is
simple enough for a fully analytical understanding of the system dynamics.Comment: 11 pages, 8 figure
Structuring co- and counter-flowing currents of polariton condensates in concentric ring-shaped potentials
We investigate the current flow of microcavity polariton condensates loaded
into concentric ring-shaped potentials. The tunneling of the condensates
between different potential rings results in different phase-locked states,
depending on the separation of the potential rings. As a consequence, the
condensate currents in different rings can flow either in the same or opposite
direction depending on the specific configuration of the ring-shaped
potentials. In two concentric standard ring-shaped potentials, the condensates
always circulate in the same direction (co-flowing current) and the vortices
formed in the two rings share the same topological charge because of the
azimuthally uniform distribution of their phase difference. In this case,
increasing the number of the potential rings enables the excitation of
Bessel-like solutions. If the two ring-shaped potentials are engineered into an
eye shape with the inner ring being standard ring-shaped and the outer ring
being elliptically ring-shaped, the phase differences of the condensates in the
two rings along the major and minor axes of the ellipse can be opposite, which
gives rise to a counter-flowing condensate currents
Gemcitabine Maintenance Therapy in Patients With Metastasized Soft Tissue Sarcomas
Background:
Metastasized soft-tissue sarcomas still pose a significant therapeutic challenge given the limited efficacy of currently available multimodal treatment strategies. Recent progress in molecular characterization of sarcoma subtypes has enabled successful personalized therapy approaches in a minority of selected patients with targetable mutations. However, in the majority of patients with refractory soft tissue sarcomas, long-term survival remains poor.
Methods:
We report on three adult patients with various soft tissue sarcomas subjected to Gemcitabine maintenance therapy. Tumor entities included leiomyosarcoma of the pancreas (patient 1), undifferentiated pleomorphic sarcoma of the right femur (patient 2), and peri-aortic leiomyosarcoma (patient 3). Metastatic sites encompassed liver, lung, and bones. All patients received Gemcitabine maintenance therapy until disease progression following prior salvage chemotherapy with Docetaxel and Gemcitabine. Patients were treated outside of clinical trials. Response assessment was based on radiological imaging.
Results:
In response to salvage chemotherapy with Docetaxel and Gemcitabine, one patient exhibited a partial remission, and two patients showed stable disease. Patient 1 exhibited stable disease for 6 months during Gemcitabine maintenance therapy before suffering rapid progression of hepatic metastases. Patient 2 underwent 21 months of Gemcitabine maintenance therapy, which was discontinued after progressive pulmonary metastases were detected. Patient 3 is still being treated with Gemcitabine maintenance therapy. Remarkably, owing to significant chemotherapy-associated hematotoxicity, the dose of Gemcitabine dose was reduced by two-thirds. Nevertheless, stable disease with constant pulmonary metastases has been maintained in this patient for 14 months.
Conclusions:
Gemcitabine maintenance therapy following prior Docetaxel and Gemcitabine chemotherapy is manageable and reveals potential benefits for patients with aggressive metastasized soft tissue sarcomas. Prospective trials evaluating Gemcitabine maintenance therapy are encouraged
Coronavirus disease 2019 induces multiâlineage, morphologic changes in peripheral blood cells
The clinical course of coronavirus disease 2019 (COVIDâ19) varies from mild symptoms to acute respiratory distress syndrome, hyperinflammation, and coagulation disorder. The hematopoietic system plays a critical role in the observed hyperinflammation, particularly in severely ill patients. We conducted a prospective diagnostic study performing a blood differential analyzing morphologic changes in peripheral blood of COVIDâ19 patients. COVIDâ19 associated morphologic changes were defined in a training cohort and subsequently validated in a second cohort (n = 45). Morphologic aberrations were further analyzed by electron microscopy (EM) and flow cytometry of lymphocytes was performed. We included 45 COVIDâ19 patients in our study (median age 58 years; 82% on intensive care unit). The blood differential showed a specific pattern of pronounced multiâlineage aberrations in lymphocytes (80%) and monocytes (91%) of patients. Overall, 84%, 98%, and 98% exhibited aberrations in granulopoiesis, erythropoiesis, and thrombopoiesis, respectively. Electron microscopy revealed the ultrastructural equivalents of the observed changes and confirmed the multiâlineage aberrations already seen by light microscopy. The morphologic pattern caused by COVIDâ19 is characteristic and underlines the serious perturbation of the hematopoietic system. We defined a hematologic COVIDâ19 pattern to facilitate further independent diagnostic analysis and to investigate the impact on the hematologic system during the clinical course of COVIDâ19 patients
Carcinoma cells misuse the host tissue damage response to invade the brain
The metastatic colonization of the brain by carcinoma cells is still barely understood, in particular when considering interactions with the host tissue. The colonization comes with a substantial destruction of the surrounding host tissue. This leads to activation of damage responses by resident innate immune cells to protect, repair, and organize the wound healing, but may distract from tumoricidal actions. We recently demonstrated that microglia, innate immune cells of the CNS, assist carcinoma cell invasion. Here we report that this is a fatal side effect of a physiological damage response of the brain tissue. In a brain slice coculture model, contact with both benign and malignant epithelial cells induced a response by microglia and astrocytes comparable to that seen at the interface of human cerebral metastases. While the glial damage response intended to protect the brain from intrusion of benign epithelial cells by inducing apoptosis, it proved ineffective against various malignant cell types. They did not undergo apoptosis and actually exploited the local tissue reaction to invade instead. Gene expression and functional analyses revealed that the C-X-C chemokine receptor type 4 (CXCR4) and WNT signaling were involved in this process. Furthermore, CXCR4-regulated microglia were recruited to sites of brain injury in a zebrafish model and CXCR4 was expressed in human stroke patients, suggesting a conserved role in damage responses to various types of brain injuries. Together, our findings point to a detrimental misuse of the glial damage response program by carcinoma cells resistant to glia-induced apoptosis
Relaxins enhance growth of spontaneous murine breast cancers as well as metastatic colonization of the brain
Critical evaluation of molecular tumour board outcomes following 2 years of clinical practice in a Comprehensive Cancer Centre
Recently, molecular tumour boards (MTBs) have been integrated into the clinical routine. Since their benefit remains debated, we assessed MTB outcomes in the Comprehensive Cancer Center Ostbayern (CCCO) from 2019 to 2021.
Methods and results
In total, 251 patients were included. Targeted sequencing was performed with PCR MSI-evaluation and immunohistochemistry for PD-L1, Her2, and mismatch repair enzymes. 125 treatment recommendations were given (49.8%). High-recommendation rates were achieved for intrahepatic cholangiocarcinoma (20/30, 66.7%) and gastric adenocarcinoma (10/16, 62.5%) as opposed to colorectal cancer (9/36, 25.0%) and pancreatic cancer (3/18, 16.7%). MTB therapies were administered in 47 (18.7%) patients, while 53 (21.1%) received alternative treatment regimens. Thus 37.6% of recommended MTB therapies were implemented (47/125 recommendations). The clinical benefit rate (completeâ+âpartialâ+âmixed responseâ+âstable disease) was 50.0% for MTB and 63.8% for alternative treatments. PFS2/1 ratios were 34.6% and 16.1%, respectively. Significantly improved PFS could be achieved for m1A-tier-evidence-based MTB therapies (median 6.30 months) compared to alternative treatments (median 2.83 months; Pâ=â0.0278).
Conclusion
The CCCO MTB yielded a considerable recommendation rate, particularly in cholangiocarcinoma patients. The discrepancy between the low-recommendation rates in colorectal and pancreatic cancer suggests the necessity of a weighted prioritisation of entities. High-tier recommendations should be implemented predominantly
Identification of Disparities in Personalized Cancer CareâA Joint Approach of the German WERA Consortium
(1) Background:
molecular tumor boards (MTBs) are crucial instruments for discussing and allocating targeted therapies to suitable cancer patients based on genetic findings. Currently, limited evidence is available regarding the regional impact and the outreach component of MTBs;
(2) Methods:
we analyzed MTB patient data from four neighboring Bavarian tertiary care oncology centers in WĂŒrzburg, Erlangen, Regensburg, and Augsburg, together constituting the WERA Alliance. Absolute patient numbers and regional distribution across the WERA-wide catchment area were weighted with local population densities;
(3) Results:
the highest MTB patient numbers were found close to the four cancer centers. However, peaks in absolute patient numbers were also detected in more distant and rural areas. Moreover, weighting absolute numbers with local population density allowed for identifying so-called white spotsâregions within our catchment that were relatively underrepresented in WERA MTBs;
(4) Conclusions:
investigating patient data from four neighboring cancer centers, we comprehensively assessed the regional impact of our MTBs. The results confirmed the success of existing collaborative structures with our regional partners. Additionally, our results help identifying potential white spots in providing precision oncology and help establishing a joint WERA-wide outreach strategy