Home-made low-cost dosemeter for photon dose measurements in radiobiological experiments and for education in the field of radiation sciences.

Reliable dosimetry systems are crucial for radiobiological experiments either to quantify the biological consequences of ionizing radiation or to reproduce results by other laboratories. Also, they are essential for didactic purposes in the field of radiation research. Professional dosemeters are expensive and difficult to use in exposure facilities with closed exposure chambers.

Blockade of surface-bound TGF-β on regulatory T cells abrogates suppression of effector T cell function in the tumor microenvironment.

Regulatory T cells (T) suppress antitumor immunity by inhibiting the killing of tumor cells by antigen-specific CD8 T cells. To better understand the mechanisms involved, we used ex vivo three-dimensional collagen-fibrin gel cultures of dissociated B16 melanoma tumors. This system recapitulated the in vivo suppression of antimelanoma immunity, rendering the dissociated tumor cells resistant to killing by cocultured activated, antigen-specific T cells.

A Consensus Definitive Classification of Scavenger Receptors and Their Roles in Health and Disease.

Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a diverse variety of ligands including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature.

Standardizing scavenger receptor nomenclature.

Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a variety of ligands, including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature.

Automated flux chamber for investigating gas flux at water-air interfaces.

Aquatic ecosystems are major sources of greenhouse gases (GHG). Representative measurements of GHG fluxes from aquatic ecosystems to the atmosphere are vital for quantitative understanding of relationships between biogeochemistry and climate. Fluxes occur at high temporal variability at diel or longer scales, which are not captured by traditional short-term deployments (often in the order of 30 min) of floating flux chambers.

How many neutrophils are enough (redux, redux)?

Many chemotherapeutic regimens produce neutropenia, which predisposes to microbial infection. However, not all neutropenic individuals develop infections, so the ability to predict this outcome would be a powerful clinical tool. In this issue of the JCI, Malka et al.

Toward integrative cancer immunotherapy: targeting the tumor microenvironment.

The development of cancer has historically been attributed to genomic alterations of normal host cells. Accordingly, the aim of most traditional cancer therapies has been to destroy the transformed cells themselves. There is now widespread appreciation that the progressive growth and metastatic spread of cancer cells requires the cooperation of normal host cells (endothelial cells, fibroblasts, other mesenchymal cells, and immune cells), both local to, and at sites distant from, the site at which malignant transformation occurs.

Complement component c1q mediates mitochondria-driven oxidative stress in neonatal hypoxic-ischemic brain injury.

Hypoxic-ischemic (HI) brain injury in infants is a leading cause of lifelong disability. We report a novel pathway mediating oxidative brain injury after hypoxia-ischemia in which C1q plays a central role. Neonatal mice incapable of classical or terminal complement activation because of C1q or C6 deficiency or pharmacologically inhibited assembly of membrane attack complex were subjected to hypoxia-ischemia.

CD8+ T cell concentration determines their efficiency in killing cognate antigen-expressing syngeneic mammalian cells in vitro and in mouse tissues.

We describe a quantitative model for assessing the cytolytic activity of antigen-specific CD8+ T cells in vitro and in vivo in which the concentration of antigen-specific CD8+ T cells determines the efficiency with which these cells kill cognate antigen-expressing melanoma cells in packed cell pellets, in three-dimensional collagen-fibrin gels in vitro, and in established melanomas in vivo. In combination with a clonogenic assay for melanoma cells, collagen-fibrin gels are 4,500-5,500-fold more sensitive than the packed cell pellet-type assays generally used to measure CD8+ T cell cytolytic activity. An equation previously used to describe neutrophil bactericidal activity in vitro and in vivo also describes antigen-specific CD8+ T cell-mediated cytolysis of cognate antigen-expressing melanoma cells in collagen-fibrin gels in vitro and in transplanted tumors in vivo.

Teachers' participation in research programs improves their students' achievement in science.

Research experience programs engage teachers in the hands-on practice of science. Program advocates assert that program participation enhances teachers' skills in communicating science to students. We measured the impact of New York City public high-school science teachers' participation in Columbia University's Summer Research Program on their students' academic performance in science.

Gemfibrozil inhibits Legionella pneumophila and Mycobacterium tuberculosis enoyl coenzyme A reductases and blocks intracellular growth of these bacteria in macrophages.

We report here that gemfibrozil (GFZ) inhibits axenic and intracellular growth of Legionella pneumophila and of 27 strains of wild-type and multidrug-resistant Mycobacterium tuberculosis in bacteriological medium and in human and mouse macrophages, respectively. At a concentration of 0.4 mM, GFZ completely inhibited L.

PAF-receptor antagonists, lovastatin, and the PTK inhibitor genistein inhibit H2O2 secretion by macrophages cultured on oxidized-LDL matrices.

Adhesion of mononuclear phagocytes (Macs) to extracellular matrices containing oxidized low-density lipoproteins (oxLDL) stimulates these cells to secrete reactive oxygen species (e.g., O2-, H2O2) that are believed to promote atherogenesis.

Determination of the critical concentration of neutrophils required to block bacterial growth in tissues.

We showed previously that the competition between bacterial killing by neutrophils and bacterial growth in stirred serum-containing suspensions could be modeled as the competition between a first-order reaction (bacterial growth) and a second-order reaction (bacterial killing by neutrophils). The model provided a useful parameter, the critical neutrophil concentration (CNC), below which bacterial concentration increased and above which it decreased, independent of the initial bacterial concentration. We report here that this model applies to neutrophil killing of bacteria in three-dimensional fibrin matrices and in rabbit dermis.

Adult mouse astrocytes degrade amyloid-beta in vitro and in situ.

Alzheimer disease (AD) is a progressive neurodegenerative disorder characterized by excessive deposition of amyloid-beta (Abeta) peptides in the brain. One of the earliest neuropathological changes in AD is the accumulation of astrocytes at sites of Abeta deposition, but the cause or significance of this cellular response is unclear. Here we show that cultured adult mouse astrocytes migrate in response to monocyte chemoattractant protein-1 (MCP-1), a chemokine present in AD lesions, and cease migration upon interaction with immobilized Abeta(1-42).

Scavenger receptors in neurobiology and neuropathology: their role on microglia and other cells of the nervous system.

Scavenger receptor class A (SR-A, CD204), scavenger receptor-BI (SR-BI), and CD36 are cell surface proteins that mediate cell adhesion to, and endocytosis of, various native and pathologically modified substances, and participate in intracellular signaling, lipid metabolism, and host defense against bacterial pathogens. Microglia, Mato cells, astrocytes, cerebral microvascular endothelial cells, cerebral arterial smooth muscle cells, and retinal pigment epithelial cells express one or more of these SR. Expression of SR-A and SR-BI by microglia is developmentally regulated.

A critical concentration of neutrophils is required for effective bacterial killing in suspension.

We have examined the effect of neutrophil concentration on killing of a clinical isolate of Staphylococcus epidermidis. Human neutrophils at concentrations varying from 10(5) to 10(7) per ml were mixed in suspension with S. epidermidis at concentrations varying from 10(3) to 10(8) colony-forming units/ml, and the concentration of viable bacteria was assayed after various times at 37 degrees C.

Different G(i)-coupled chemoattractant receptors signal qualitatively different functions in human neutrophils.

fMLP- or TNF-alpha-stimulated neutrophils produced H(2)O(2) when they adhered to fibrinogen-coated surfaces but not when they adhered to collagen I-, collagen IV-, or Matrigel-coated surfaces. In contrast, LTB4- or IL-8-stimulated neutrophils did not produce H(2)O(2) when they adhered to any of these surfaces. fMLP and TNF-alpha were much more potent than LTB4 and IL-8 in stimulating neutrophils to up-regulate and to activate their alpha(M)beta(2) integrins, as measured by the binding of specific monoclonal antibodies.

CD36, a class B scavenger receptor, is expressed on microglia in Alzheimer's disease brains and can mediate production of reactive oxygen species in response to beta-amyloid fibrils.

A pathological hallmark of Alzheimer's disease is the senile plaque, composed of beta-amyloid fibrils, microglia, astrocytes, and dystrophic neurites. We reported previously that class A scavenger receptors mediate adhesion of microglia and macrophages to beta-amyloid fibrils and oxidized low-density lipoprotein (oxLDL)-coated surfaces. We also showed that CD36, a class B scavenger receptor and an oxLDL receptor, promotes H(2)O(2) secretion by macrophages adherent to oxLDL-coated surfaces.

The bacterial peptide N-formyl-Met-Leu-Phe inhibits killing of Staphylococcus epidermidis by human neutrophils in fibrin gels.

To study human neutrophil (polymorphonuclear leukocyte (PMN)) migration and killing of bacteria in an environment similar to that found in inflamed tissues in vivo, we have used fibrin gels. Fibrin gels (1500 microm thick) containing Staphylococcus epidermidis were formed in Boyden-type chemotaxis chambers. PMN migrated < 300 microm into these gels in 6 h and did not kill S.