4D In-Situ Microscopy of Aerosol Filtration in a Wall Flow Filter

The transient nature of the internal pore structure of particulate wall flow filters, caused by the continuous deposition of particulate matter, makes studying their flow and filtration characteristics challenging. In this article we present a new methodology and first experimental demonstration of time resolved in-situ synchrotron micro X-ray computed tomography (micro-CT) to study aerosol filtration. We directly imaged in 4D (3D plus time) pore scale deposits of TiO2 nanoparticles (nominal mean primary diameter of 25 nm) with a pixel resolution of 1.6 μm. We obtained 3D tomograms at a rate of ∼1 per minute. The combined spatial and temporal resolution allows us to observe pore blocking and filling phenomena as they occur in the filter’s pore space. We quantified the reduction in filter porosity over time, from an initial porosity of 0.60 to a final porosity of 0.56 after 20 min. Furthermore, the penetration depth of particulate deposits and filtration rate was quantified. This novel image-based method offers valuable and statistically relevant insights into how the pore structure and function evolves during particulate filtration. Our data set will allow validation of simulations of automotive wall flow filters. Evolutions of this experimental design have potential for the study of a wide range of dry aerosol filters and could be directly applied to catalysed automotive wall flow filters.     

Abnormal function of the bone marrow microenvironment in chronic myelogenous leukemia: role of malignant stromal macrophages

The bone marrow microenvironment supports and regulates the proliferation and differentiation of hematopoietic cells. Dysregulated hematopoiesis in chronic myelogenous leukemia (CML) is caused, at least in part, by abnormalities in CML hematopoietic progenitors leading to altered interactions with the marrow microenvironment. The role of the microenvironment itself in CML has not been well characterized. We examined the capacity of CML stroma to support the growth of long-term culture-initiating cells (LTC-IC) obtained from normal and CML marrow. The growth of normal LTC-IC on CML stroma was significantly reduced compared with normal stroma. This did not appear to be related to abnormal production of soluble factors by CML stroma because normal LTC- IC grew equally well in Transwells above CML stroma as in Transwells above normal stroma. In addition, CML and normal stromal supernatants contained similar quantities of both growth-stimulatory (granulocyte colony-stimulating factor (CSF), interleukin-6, stem cell factor, granulocyte-macrophage CSF, and interleukin-1 beta) and growth- inhibitory cytokines (transforming growth factor-beta, macrophage inflammatory protein-1 alpha, and tumor necrosis factor-alpha). The relative proportion of different cell types in CML and normal stroma was similar. However, polymerase chain reaction and fluorescence in situ hybridization studies showed the presence of bcr-abl-positivo cells in CML stroma, which were CD14+ stromal macrophages. To assess the effect of these malignant macrophages on stromal function, CML and normal stromal cells were separated by fluorescence-activated cell sorting into stromal mesenchymal cell (CD14-) and macrophage (CD14+) populations. CML and normal CD14- cells supported the growth of normal LTC-IC equally well. However, the addition of CML macrophages to normal or CML CD14- mesenchymal cells resulted in impaired progenitor support. This finding indicates that the abnormal function of CML bone marrow stroma is related to the presence of malignant macrophages. In contrast to normal LTC-IC, the growth of CML LTC-IC on allogeneic CML stromal layers was not impaired and was significantly better than that of normal LTC-IC cocultured with the same CML stromal layers. These studies demonstrate that, in addition to abnormalities in CML progenitors themselves, abnormalities in the CML marrow microenvironment related to the presence of malignant stromal macrophages may contribute to the selective expansion of leukemic progenitors and suppression of normal hematopoiesis in CML.     

The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors

CD47, a "don't eat me" signal for phagocytic cells, is expressed on the surface of all human solid tumor cells. Analysis of patient tumor and matched adjacent normal (nontumor) tissue revealed that CD47 is overexpressed on cancer cells. CD47 mRNA expression levels correlated with a decreased probability of survival for multiple types of cancer. CD47 is a ligand for SIRPα, a protein expressed on macrophages and dendritic cells. In vitro, blockade of CD47 signaling using targeted monoclonal antibodies enabled macrophage phagocytosis of tumor cells that were otherwise protected. Administration of anti-CD47 antibodies inhibited tumor growth in orthotopic immunodeficient mouse xenotransplantation models established with patient tumor cells and increased the survival of the mice over time. Anti-CD47 antibody therapy initiated on larger tumors inhibited tumor growth and prevented or treated metastasis, but initiation of the therapy on smaller tumors was potentially curative. The safety and efficacy of targeting CD47 was further tested and validated in immune competent hosts using an orthotopic mouse breast cancer model. These results suggest all human solid tumor cells require CD47 expression to suppress phagocytic innate immune surveillance and elimination. These data, taken together with similar findings with other human neoplasms, show that CD47 is a commonly expressed molecule on all cancers, its function to block phagocytosis is known, and blockade of its function leads to tumor cell phagocytosis and elimination. CD47 is therefore a validated target for cancer therapies.     

Three differentiation states risk-stratify bladder cancer into distinct subtypes

Current clinical judgment in bladder cancer (BC) relies primarily on pathological stage and grade. We investigated whether a molecular classification of tumor cell differentiation, based on a developmental biology approach, can provide additional prognostic information. Exploiting large preexisting gene-expression databases, we developed a biologically supervised computational model to predict markers that correspond with BC differentiation. To provide mechanistic insight, we assessed relative tumorigenicity and differentiation potential via xenotransplantation. We then correlated the prognostic utility of the identified markers to outcomes within gene expression and formalin-fixed paraffin-embedded (FFPE) tissue datasets. Our data indicate that BC can be subclassified into three subtypes, on the basis of their differentiation states: basal, intermediate, and differentiated, where only the most primitive tumor cell subpopulation within each subtype is capable of generating xenograft tumors and recapitulating downstream populations. We found that keratin 14 (KRT14) marks the most primitive differentiation state that precedes KRT5 and KRT20 expression. Furthermore, KRT14 expression is consistently associated with worse prognosis in both univariate and multivariate analyses. We identify here three distinct BC subtypes on the basis of their differentiation states, each harboring a unique tumor-initiating population.     

Therapeutische Hypothermie

Background and objectives

Nowadays mild therapeutic hypothermia (MTH) is the standard of care in treatment of patients after cardiac arrest. Beside the protective effect on neurological recovery, MTH may interfere with metabolic and hemodynamic variables. We therefore investigated fluid balance and lactate/glucose levels during MTH.

Materials and methods

A total of 88 patients treated with MTH were included. Initial values at admission and 24 h thereafter for lactate and glucose were collected. Furthermore, fluid intake, diuresis, and cumulative doses of insulin and vasopressors were recorded. The data were compared to a historical control group consisting of 56 patients treated in the era prior to MTH.

Results

Lactate levels did not differ between the two groups. There was also no difference in the need of insulin. Patients with MTH received significantly more fluids in the first 24 h (4800 vs. 3500 ml/24 h, p?=?0.0001) and required higher doses of norepinephrine (2 vs. 0 mg/24 h, p?=?0.02). Diuresis was not different compared to the control group (2075 vs. 2025 ml, p?=?0.93).

Conclusion

Our data suggest that patients treated with MTH have a pronounced need of fluids and vasopressors. Lactate monitoring may be feasible during MTH.

     

IVIG enters the central nervous system during treatment of experimental autoimmune encephalomyelitis and is localised to inflammatory lesions

Intravenous immunoglobulin (IVIG) treatment reduces the relapse rate in relapsing–remitting multiple sclerosis (MS) and may interfere with MS pathology through its various anti-inflammatory and immunomodulatory properties. It is presently unknown whether IVIG enters the central nervous system (CNS) in sufficient amounts to influence the local immune response within the brain and spinal cord, or if the treatment effects are entirely due to peripheral actions of IVIG. The purpose of the present study was to evaluate if IVIG radiolabeled with ^99mTc enters the CNS during treatment of experimental autoimmune encephalomyelitis (EAE) in the susceptible rat strain Dark Agouti. After in vivo administration of ^99mTc-IVIG we observed significantly increased accumulation in the brain and spinal cord from rats with EAE. Accumulation of ^99mTc-IVIG was not detectable in CNS tissue from control animals. In peripheral tissue samples minor increases in ^99mTc-IVIG organ binding were observed in the liver and kidney during EAE. Localisation of ^99mTc-IVIG in the brain tissue was visualised by autoradiography and revealed significant accumulation of IVIG only in areas also affected by perivascular inflammation and leakage of serum proteins. In conclusion, the results indicate that significant extravasation of IVIG to the CNS only occurs when blood–brain barrier function is compromised during EAE.     

The clinical use of dermatomal somatosensory evoked potentials in lumbosacral spinal stenosis

DSEPs provide clinicians with a safe, noninvasive technique useful in determining which patients with anatomic spinal stenosis have the added component of neurogenic compromise. Based on physiologic principles, level-by-level prolongation of DSEP latencies, reduction of amplitude, asymmetry, or a complete absence of response is associated with dysfunction in that particular afferent neurologic pathway. This dysfunction does not correspond to the exact level of stenosis noted on MRI because the rootlets in the lumbar and sacral regions pass through multiple spinal segments as they course rostrally through the spinal canal. Given that LSSS typically develops over time, the degree of abnormality likely would correspond to the physiologic slowing occurring in the multiple rootlets of the cauda equina. These recordings are not easy to perform and interpret, but when done correctly, they provide the best evidence for the type of neurophysiologic dysfunction in LSSS that responds favorably to surgical decompression. Similarly, DSEPs might provide a means of neurophysiologically monitoring clinically significant findings in a program of conservative management.