Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Induction of carcinoembryonic antigen (cea)‐specific cytotoxic t‐lymphocyte responses In vitro using autologous dendritic cells loaded with cea peptide or cea rna in patients with metastatic malignancies expressing cea

The application of dendritic cells (DC) to the active immunotherapy of cancer currently relies on the generation of potent DC capable of presenting tumor antigens such as carcinoembryonic antigen (CEA). It is unknown whether the T cells of patients with advanced malignancies can be reliably stimulated against tumor antigens by their autologous DC. In this study, starting with the peripheral blood mononuclear cells (PBMC) of patients with metastatic malignancies expressing CEA, autologous DCs were generated in vitro in serum‐free media supplemented with GM‐CSF and IL‐4. The DCs from HLA A2 positive patients were loaded with the CEA peptide CAP‐1 and the DCs from HLA A2 negative patients were depleted of bystander lymphocytes and loaded with mRNA encoding CEA. The DC preparations were tested to determine their phenotype and were used to stimulate autologous PBMC twice, separated by 10–14 days. The stimulated cells were then tested for their ability to lyse CEA‐expressing target cells. We successfully generated an adequate number of DC for a clinical trial from all patients. The harvested DC preparations contained 49% DC and 87% DC if depleted of bystander lymphocytes. Phenotypic analysis showed the typical pattern of CD11c+CD40+CD86+HLA‐DR+ CD80lowCD83lowCD14low. All preparations but one were able to stimulate CEA‐specific cytotoxic T‐lymphocyte (CTL) activity, suggesting that the majority of patients are not anergic to CEA and possess functional DC. The CTL activity was similar for the CEA peptide and CEA RNA‐loaded DC. Int. J. Cancer 82:121–124, 1999. © 1999 Wiley‐Liss, Inc

Optical spike amplitude weighting and neuromimetic rate coding using a joint VCSEL-MRR neuromorphic photonic system

Spiking neurons and neural networks constitute a fundamental building block for brain-inspired computing, which is poised to benefit significantly from photonic hardware implementations. In this work, we experimentally investigate an interconnected optical neuromorphic system based on an ultrafast spiking vertical cavity surface emitting laser (VCSEL) neuron and a silicon photonics (SiPh) integrated micro-ring resonator (MRR). We experimentally demonstrate two different functional arrangements of these devices: first, we show that MRR weight banks can be used in conjunction with the spiking VCSEL-neurons to perform amplitude weighting of sub-ns optical spiking signals. Second, we show that a continuously firing VCSEL-neuron can be directly modulated using a locking signal propagated through a single weighting MRR, and we utilize this functionality to perform optical spike firing rate-coding via thermal tuning of the MRR. Given the significant track record of both integrated weight banks and photonic VCSEL-neurons, we believe these results demonstrate the viability of combining these two classes of devices for use in functional neuromorphic photonic systems

Autologous dendritic cells transfected with prostate-specific antigen RNA stimulate CTL responses against metastatic prostate tumors

Autologous dendritic cells (DCs) transfected with mRNA encoding prostate-specific antigen (PSA) are able to stimulate potent, T cell–mediated antitumor immune responses in vitro. A phase I trial was performed to evaluate this strategy for safety, feasibility, and efficacy to induce T cell responses against the self-protein PSA in patients with metastatic prostate cancer. In 13 study subjects, escalating doses of PSA mRNA–transfected DCs were administered with no evidence of dose-limiting toxicity or adverse effects, including autoimmunity. Induction of PSA-specific T cell responses was consistently detected in all patients, suggesting in vivo bioactivity of the vaccine. Vaccination was further associated with a significant decrease in the log slope PSA in six of seven subjects; three patients that could be analyzed exhibited a transient molecular clearance of circulating tumor cells. The demonstration of vaccine safety, successful in vivo induction of PSA-specific immunity, and impact on surrogate clinical endpoints provides a scientific rationale for further clinical investigation of RNA-transfected DCs in the treatment of human cancer

Ecologismo, ambientalismo e ecologia política: diferentes visões da sustentabilidade e do território Ecologism, environmentalism and political ecology: different views on sustainability and on territory

No quadro da evolução histórica do que se entende por sustentabilidade, e considerando as potenciais implicações desse processo sobre os usos do território, o objetivo do texto é investigar como diferentes perspectivas tratam a temática territorial. Com o apoio de contextualizações, busca-se compreender permanências, mudanças e tendências. A análise acompanha a criação da ecologia como ramo científico, passa pelo surgimento do ambientalismo moderado, e segue até enfoques mais recentes, como o da ecologia política. A primeira parte do texto argumenta que a visão da sustentabilidade começa a ser moldada a partir das idéias da ecologia radical, relacionadas com o protecionismo e com o conservacionismo; ela adquire características mais moderadas quando se apresenta na forma conciliatória do ambientalismo, desdobrando-se na proposta de desenvolvimento sustentável; e acaba por transformar-se em instrumento de crítica social, quando enfocado sob o prisma da ecologia política. A segunda parte do texto argumenta que a ecologia radical, o ambientalismo moderado e a ecologia política encaram a sustentabilidade territorial em sintonia com distintos contextos históricos e ambientais e diferenciadas visões de natureza. Conclui que as propostas variam também em função das escalas geográficas em que atuam e dos interesses envolvidos. Diante da crise ambiental atual, os diferentes enfoques, ao priorizarem dimensões específicas, como o quadro natural, as relações entre ambiente e sociedade e as desigualdades socioambientais, podem oferecer subsídios para a busca de alternativas viáveis.<br>Given the historical evolution of how one understands sustainability and considering their implications on the different uses of territory, this paper explores how these different approaches discuss and deal with the territory. Using the different settings to understand the continuities, changes and tendencies of the process, the text examines the creation of ecology as a science, followed by the emergence of moderate environmentalism, and finally more recent approaches such as political ecology. In the first part, the concept of sustainability is presented as it begins to be shaped by means of ideas of nature protection and conservation, typical of radical ecology; then, it discusses the more moderate version of the concept, when it was expressed in the conciliatory terms of environmentalism and evolves to sustainable development; and finally, the concept is analyzed as it changes into a means of social critique, when seen through the framework of political ecology. The second part the text argues that radical ecology, moderate environmentalism and political ecology face territorial sustainability depending on the various historical and environmental settings and visions of nature. It concludes that different views change depending on the geographical scales in which they engage and on what is at stake in each one of them. Considering the current environmental crisis, these views can present viable alternatives, given that they assign priority to specific aspects such as the natural landscape, nature-society relations and socio-environmental inequalities