Geographical analysis of seroprevalence of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis, in clinics and dog shelters in different Mexican states

This study aimed to determine the seroprevalence and geographical distribution of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis in dogs in Mexico, including owned dogs from veterinary clinics with regular medical care and shelter dogs. The Mexican territory was divided into eight geographical regions; 22 out of 32 states were included; 110 veterinary clinics and 53 dog shelters participated. SNAP® 4Dx Plus® (IDEXX® Laboratories) was used to detect antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis antigens. A total of 3522 apparently healthy dogs were tested, 1648 from clinics and 1874 from shelters. The highest seroprevalence of infection/exposure was found for Ehrlichia spp. (30.9%), followed by Anaplasma spp. (14.6%), D. immitis (5.3%) and B. burgdorferi (0.1%). Significantly more positive dogs were older than 3 years. Regarding differences between facility types, there were only differences for D. immitis which was more prevalent in clinics than in shelters (OR ​= ​1.97; 95% CI: 1.45-2.69; P ​< ​0.0001). Co-infections were detected in 38.4% of the positive samples. Dogs from Mexican states located on the Atlantic and the Pacific coast were significantly more at risk for Ehrlichia spp. and Anaplasma spp. infections than dogs from interior states. Dogs in Atlantic coastal states were more at risk for Dirofilaria immitis infection.

Cell-based artificial APC resistant to lentiviral transduction for efficient generation of CAR-T cells from various cell sources

Background

Adoptive cell therapy with chimeric antigen receptor T cells (CAR-T) has become a standard treatment for patients with certain aggressive B cell malignancies and holds promise to improve the care of patients suffering from numerous other cancers in the future. However, the high manufacturing cost of CAR-T cell therapies poses a major barrier to their broader clinical application. Among the key cost drivers of CAR-T production are single-use reagents for T cell activation and clinical-grade viral vector. The presence of variable amounts of contaminating monocytes in the starting material poses an additional challenge to CAR-T manufacturing, since they can impede T cell stimulation and transduction, resulting in manufacturing failure.

Methods

We created K562-based artificial antigen-presenting cells (aAPC) with genetically encoded T cell stimulation and costimulation that represent an inexhaustible source for T cell activation. We additionally disrupted endogenous expression of the low-density lipoprotein receptor (LDLR) on these aAPC (aAPC-ΔLDLR) using CRISPR-Cas9 gene editing nucleases to prevent inadvertent lentiviral transduction and avoid the sink effect on viral vector during transduction. Using various T cell sources, we produced CD19-directed CAR-T cells via aAPC-ΔLDLR-based activation and tested their in vitro and in vivo antitumor potency against B cell malignancies.

Results

We found that lack of LDLR expression on our aAPC-ΔLDLR conferred resistance to lentiviral transduction during CAR-T production. Using aAPC-ΔLDLR, we achieved efficient expansion of CAR-T cells even from unpurified starting material like peripheral blood mononuclear cells or unmanipulated leukapheresis product, containing substantial proportions of monocytes. CD19-directed CAR-T cells that we produced via aAPC-ΔLDLR-based expansion demonstrated potent antitumor responses in preclinical models of acute lymphoblastic leukemia and B-cell lymphoma.

Conclusions

Our aAPC-ΔLDLR represent an attractive approach for manufacturing of lentivirally transduced T cells that may be simpler and more cost efficient than currently available methods.

Effect of deuterium irradiation on graphite boronized in the NSTX-U tokamak

Boronization has been used in the National Spherical Torus-Upgrade (NSTX-U) as first wall conditioning technique. The technique decreased the oxygen impurities in the plasma and the O% on the Plasma Facing Components (PFC) as measured with an in-vacuo probe. Samples were extracted from tiles removed from the tokamak for post-mortem and controlled studies. Ex-vessel low energy and fluence D₂⁺ and Ar⁺ irradiations were characterized in-situ to elucidate surface evolution of a cored graphite sample with an intrinsic concentration of boron from a tokamak environment. In addition, quadrupole mass spectrometer measurements of emitted D-containing species during irradiation, indicate potential retention of D by the boronized graphite interface and correlated back to the surface chemistry evolution. Classical Molecular Dynamics (CMD) simulations were used to investigate the chemistry of the B-C-O-D system. The results suggest that boron coatings retain oxygen by forming oxidized boron states in the presence of deuterium plasmas and corroborate empirical findings. A four times increase in the O% of the boron coatings was observed following in-situ deuterium exposures, in contrast with a reduction of equal magnitude observed after Ar irradiations. These results illustrate the complex chemistry driven by energetic ions at the edge of tokamaks plasmas on the PFCs.

Study of the properties of thin Li films and their relationship with He plasmas using ion beam analysis in the DIONISOS experiment

Plasma facing component (PFC) conditioning dramatically affects plasma performance in magnetic confinement fusion experiments. Lithium (Li) has been used in several machines to condition PFC with subsequent improvements to plasma performance. Multiple studies have investigated the interactions of Li with deuterium (D) and oxygen (O) in order to ascertain the mechanisms behind the enhanced plasma performance. Ion Beam Analysis (IBA) is a useful tool to interrogate PFC surfaces as they interact with plasmas. Dynamics of ion implantation and sputtering of surfaces (DIONISOS) is a linear plasma device, capable of generating discharges with fluxes ∼10²¹ m^-2 s^-1 and Te ∼6 eV, coupled to an ion accelerator. DIONISOS is capable of analyzing samples using Elastic Recoil Detection (ERD) and Rutherford Backscattering Spectroscopy (RBS) during plasma exposures. The facility has been equipped with a Li deposition system for evaporation of thin coatings on different substrates. The evaporator enables real time ERD and RBS measurements of deposition and erosion of Li coatings on different substrates and the interaction of the Li with the vacuum and plasma. Considerations for ERD, e.g., ion species, energy, and data acquisition frequency, are presented. This work is the basis for further investigation of He, H, and D retention in solid and liquid Li.

Reducing Ex Vivo Culture Improves the Antileukemic Activity of Chimeric Antigen Receptor (CAR) T Cells

The success of chimeric antigen receptor (CAR)-mediated immunotherapy in acute lymphoblastic leukemia (ALL) highlights the potential of T-cell therapies with directed cytotoxicity against specific tumor antigens. The efficacy of CAR T-cell therapy depends on the engraftment and persistence of T cells following adoptive transfer. Most protocols for T-cell engineering routinely expand T cells ex vivo for 9 to 14 days. Because the potential for engraftment and persistence is related to the state of T-cell differentiation, we hypothesized that reducing the duration of ex vivo culture would limit differentiation and enhance the efficacy of CAR T-cell therapy. We demonstrated that T cells with a CAR-targeting CD19 (CART19) exhibited less differentiation and enhanced effector function in vitro when harvested from cultures at earlier (day 3 or 5) compared with later (day 9) timepoints. We then compared the therapeutic potential of early versus late harvested CART19 in a murine xenograft model of ALL and showed that the antileukemic activity inversely correlated with ex vivo culture time: day 3 harvested cells showed robust tumor control despite using a 6-fold lower dose of CART19, whereas day 9 cells failed to control leukemia at limited cell doses. We also demonstrated the feasibility of an abbreviated culture in a large-scale current good manufacturing practice-compliant process. Limiting the interval between T-cell isolation and CAR treatment is critical for patients with rapidly progressing disease. Generating CAR T cells in less time also improves potency, which is central to the effectiveness of these therapies. Cancer Immunol Res; 6(9); 1100-9. ©2018 AACR.

Determinants of response and resistance to CD19 chimeric antigen receptor (CAR) T cell therapy of chronic lymphocytic leukemia

Tolerance to self-antigens prevents the elimination of cancer by the immune system^1,2. We used synthetic chimeric antigen receptors (CARs) to overcome immunological tolerance and mediate tumor rejection in patients with chronic lymphocytic leukemia (CLL). Remission was induced in a subset of subjects, but most did not respond. Comprehensive assessment of patient-derived CAR T cells to identify mechanisms of therapeutic success and failure has not been explored. We performed genomic, phenotypic and functional evaluations to identify determinants of response. Transcriptomic profiling revealed that CAR T cells from complete-responding patients with CLL were enriched in memory-related genes, including IL-6/STAT3 signatures, whereas T cells from nonresponders upregulated programs involved in effector differentiation, glycolysis, exhaustion and apoptosis. Sustained remission was associated with an elevated frequency of CD27⁺CD45RO^-CD8⁺ T cells before CAR T cell generation, and these lymphocytes possessed memory-like characteristics. Highly functional CAR T cells from patients produced STAT3-related cytokines, and serum IL-6 correlated with CAR T cell expansion. IL-6/STAT3 blockade diminished CAR T cell proliferation. Furthermore, a mechanistically relevant population of CD27⁺PD-1^-CD8⁺ CAR T cells expressing high levels of the IL-6 receptor predicts therapeutic response and is responsible for tumor control. These findings uncover new features of CAR T cell biology and underscore the potential of using pretreatment biomarkers of response to advance immunotherapies.

CARs in the Lead Against Multiple Myeloma

The recent clinical success of CD19-directed chimeric antigen receptor (CAR) T cell therapy in chronic and acute leukemia has led to increased interest in broadening this technology to other hematological malignancies and solid tumors. Now, advances are being made using CAR T cell technology to target myeloma antigens such as B cell maturation antigen (BCMA), CD138, and kappa-light chain as well as CD19 on putative myeloma stem cells. To date, only a limited number of multiple myeloma patients have received CAR T cell therapy but preliminary results have been encouraging. In this review, we summarize the recently reported results of clinical trials conducted utilizing CAR T cell therapy in multiple myeloma (MM).

The Flipside of the Power of Engineered T Cells: Observed and Potential Toxicities of Genetically Modified T Cells as Therapy

Autologous T cells modified to recognize novel antigen targets are a novel form of therapy for cancer. We review the various potential forms of observed and hypothetical toxicities associated with genetically modified T cells. Despite the focus on toxicities in this review, re-directed T cells represent a powerful and highly effective form of anti-cancer therapy; we remain optimistic that the common toxicities will become routinely manageable and that some theoretical toxicity will be exceedingly rare, if ever observed.

Gene expression signatures of response to anti-CD19 chimeric antigen receptor (CAR) T-cell therapy in patients with CLL and ALL

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Background: The adoptive transfer of autologous T cells genetically modified to express a CD19-specific, 4-1BB/CD3ζ-signaling CAR (CTL019) has shown remarkable activity and induces long-term remissions in a subset of patients with relapsed/refractory chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL). In ALL, CTL019 induces a complete response (CR) in over 90% of patients while in CLL 25% of patients obtain a CR. It is not fully understood why only certain patients respond to therapy. Methods: We employed next generation sequencing of RNA (RNAseq) to identify predictive indicators of response to CTL019. We performed RNAseq on leukapheresis and manufactured product T cells prior to re-infusion from 35 CLL and 7 pediatric ALL patients with heavily pre-treated and high-risk disease. To characterize potency, we performed RNAseq on the infusion product after stimulation with the CAR. Results: We find that durable remission in CLL is associated with gene expression signatures of early memory and T-effector cells, while T cells from non-responding patients are enriched in signatures of T-regulatory cells, terminal differentiation, and exhaustion. In following the results from CLL, we find that pediatric ALL manufactured T cells are significantly enriched for an early memory, naïve T cell state and all achieved a CR. In parallel in vitro experiments, stimulation of the infusion product further demonstrated that CTL019 cells from CRs have an increased capacity for activation upon stimulation. We tested if we could extend these observations to identify a phenotype of T cells that is predictive of response prior to CTL019 manufacturing and find that the signatures predictive of response at the pre-infusion stage are also observed at the earlier leukapheresis time point. Conclusions: These findings suggest that intrinsic T cell fitness dictates response to CAR T cells. These gene expression signatures, along with additional immunological biomarkers, may be used to identify which patients are most likely to respond to adoptive transfer strategies and suggest manufacturing modifications that might potentiate the generation of maximally efficacious infusion products. Clinical trial information: NCT01029366, NCT01747486, NCT01626495.

Unraveling wall conditioning effects on plasma facing components in NSTX-U with the Materials Analysis Particle Probe (MAPP)

A novel Plasma Facing Components (PFCs) diagnostic, the Materials Analysis Particle Probe (MAPP), has been recently commissioned in the National Spherical Torus Experiment Upgrade (NSTX-U). MAPP is currently monitoring the chemical evolution of the PFCs in the NSTX-U lower divertor at 107 cm from the tokamak axis on a day-to-day basis. In this work, we summarize the methodology that was adopted to obtain qualitative and quantitative descriptions of the samples chemistry. Using this methodology, we were able to describe all the features in all our spectra to within a standard deviation of ±0.22 eV in position and ±248 s^-1 eV in area. Additionally, we provide an example of this methodology with data of boronized ATJ graphite exposed to NSTX-U plasmas.

Shortened T cell culture with IL-7 and IL-15 provides the most potent chimeric antigen receptor (CAR)-modified T cells for adoptive immunotherapy

Adoptive T cell immunotherapy involves the isolation, ex vivo expansion and reinfusion of T cells, and is dependent on T cell engraftment and persistence for efficacy. IL-2 is the most commonly used cytokine for ex vivo T cell culture; however, there is renewed interest in IL-7 and IL-15 due to their ability to enhance the survival and proliferation of stem cell memory (Tscm) T cells. Peripheral blood (PB) contains substantial numbers of Tscm, central memory (Tcm) and effector subsets. During ex vivo culture, PB T cells differentiate into cells with a predominantly CD45RO+, CD27−, CCR7− effector phenotype. Exogenous IL-7/15 delays this transition in phenotype and preserves a greater proportion of Tscm and Tcm cells. We hypothesize that limited ex vivo T cell culture in the presence of IL-7/15 rather than IL-2 will enhance engraftment and persistence of T cells in vivo. We show that T cells can be harvested from ex vivo cultures as early as day 3 (d3) following activation. T cells expressing a chimeric antigen receptor targeting CD19 (CART-19) show potent yet specific cytotoxicity in vitro. We investigated the therapeutic potential of cells harvested at d3 versus later time points using a Nalm-6 leukemic cell xenograft mouse model. We demonstrate that d3 CART-19 cells show potent anti-leukemic activity compared to day 5 or day 9 cells. Comparing CART19 cells cultured in IL-2 or IL-7/15 for 3 or 9 days, we show that mice treated with d3 cells cultured in IL-7/15 exhibit the greatest anti-leukemic efficacy at a 10-fold lower dose compared with day 9 cells. In summary, we show that limiting T cell culture ex vivo to the minimum required for lentiviral transduction, in the presence of IL-7/15, provides the most efficacious T cells for adoptive immunotherapy.

Chimeric Antigen Receptor T Cells: Self-Replicating Drugs for Cancer

The chimeric antigen receptor (CAR) technology started out as a tool to understand lymphocyte biology but rapidly developed into a T cell therapeutic agent for the treatment of cancers. Here, we describe the technological advances in the field of CARs and highlight critical components of its success. Additionally, we describe how various laboratories have worked toward developing new, safer, and more potent CARs for cancer.

Distinct modes of antigen presentation promote the formation, differentiation, and activity of foxp3+ regulatory T cells in vivo

How the formation and activity of CD4(+)Foxp3(+) regulatory T cells (Tregs) are shaped by TCR recognition of the diverse array of peptide:MHC complexes that can be generated from self-antigens and/or foreign Ags in vivo remains poorly understood. We show that a self-peptide with low (but not high) stimulatory potency promotes thymic Treg formation and can induce conventional CD4(+) T cells in the periphery to become Tregs that express different levels of the transcription factor Helios according to anatomical location. When Tregs generated in response to this self-peptide subsequently encountered the same peptide derived instead from influenza virus in the lung-draining lymph nodes of infected mice, they proliferated, acquired a T-bet(+)CXCR3(+) phenotype, and suppressed the antiviral effector T cell response in the lungs. However, these self-antigen-selected Tregs were unable to suppress the antiviral immune response based on recognition of the peptide as a self-antigen rather than a viral Ag. Notably, when expressed in a more immunostimulatory form, the self-peptide inhibited the formation of T-bet(+)CXCR3(+) Tregs in response to viral Ag, and Ag-expressing B cells from these mice induced Treg division without upregulation of CXCR3. These studies show that a weakly immunostimulatory self-peptide can induce thymic and peripheral Foxp3(+) Treg formation but is unable to activate self-antigen-selected Tregs to modulate an antiviral immune response. Moreover, a strongly immunostimulatory self-peptide expressed by B cells induced Tregs to proliferate without acquiring an effector phenotype that allows trafficking from the draining lymph node to the lungs and, thereby, prevented the Tregs from suppressing the antiviral immune response.

Development progress of the Materials Analysis and Particle Probe

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques.

Viral antigen induces differentiation of Foxp3+ natural regulatory T cells in influenza virus-infected mice

We examined the formation, participation, and functional specialization of virus-reactive Foxp3(+) regulatory T cells (Tregs) in a mouse model of influenza virus infection. "Natural" Tregs generated intrathymically, based on interactions with a self-peptide, proliferated in response to a homologous viral Ag in the lungs and, to a lesser extent, in the lung-draining mediastinal lymph nodes (medLNs) of virus-infected mice. In contrast, conventional CD4(+) T cells with identical TCR specificity underwent little or no conversion to become "adaptive" Tregs. The virus-reactive Tregs in the medLNs and the lungs of infected mice upregulated a variety of molecules associated with Treg activation, as well as acquired expression of molecules (T-bet, Blimp-1, and IL-10) that confer functional specialization to Tregs. Notably, however, the phenotypes of the T-bet(+) Tregs obtained from these sites were distinct, because Tregs isolated from the lungs expressed significantly higher levels of T-bet, Blimp-1, and IL-10 than did Tregs from the medLNs. Adoptive transfer of Ag-reactive Tregs led to decreased proliferation of antiviral CD4(+) and CD8(+) effector T cells in the lungs of infected hosts, whereas depletion of Tregs had a reciprocal effect. These studies demonstrate that thymically generated Tregs can become activated by a pathogen-derived peptide and acquire discrete T-bet(+) Treg phenotypes while participating in and modulating an antiviral immune response.

Viral antigen induces differentiation of Foxp3+ natural regulatory T cells in influenza virus-infected mice (P1043)

We have examined the formation, participation and functional specialization of virus-reactive Foxp3+ regulatory T cells (Tregs) in a mouse model of influenza virus infection. “Natural” Tregs generated intra-thymically based on interactions with a self-peptide proliferated in response to a homologous viral antigen in the lungs, and to a lesser extent in the lung-draining mediastinal LN (medLN), of virus-infected mice. By contrast, conventional CD4+ T cells with identical TCR specificity underwent little or no conversion to become “adaptive” Tregs. The virus-reactive Tregs in the medLN and the lungs of infected mice upregulated a variety of molecules associated with Treg activation, and also acquired expression of molecules (T-bet, Blimp-1 and IL-10) that confer functional specialization to Tregs. Notably, however, the phenotypes of the T-bet+ Tregs obtained from these sites were distinct, since Tregs isolated from the lungs expressed significantly higher levels of T-bet, Blimp-1 and IL-10 than did Tregs from the medLN. Adoptive transfer of antigen-reactive Tregs led to decreased proliferation of anti-viral CD4+ and CD8+ effector T cells in the lungs of infected hosts, while depletion of Tregs had a reciprocal effect. These studies demonstrate that thymically-generated Tregs can become activated by a pathogen-derived peptide and acquire discrete T-bet+ Treg phenotypes while participating in and modulating an antiviral immune response.

Peripheral Foxp3+ regulatory T cell development in response to self-peptides (65.2)

It is generally accepted that developing thymocytes can become Foxp3+ regulatory T cells (Tregs) through recognition of self-antigens during thymic selection. Tregs can also develop from conventional CD4+ T cells responding to exogenously administered peptides (including food antigens) in vivo, and via TGF-β signaling during activation in vitro, but the processes by which Treg induction may occur in response to self-peptides in the periphery remain unclear. We are examining this question by transferring conventional CD4+CD25-Foxp3- T cells specific for influenza virus hemagglutinin (HA) into mice that express varying amounts of the HA molecule as a self-antigen (HA Tg mice). We find that conventional CD4+ T cells can convert into Foxp3+ Tregs upon recognition of a self-antigen in the lymph nodes and spleens, and that accumulation of HA-specific Tregs is greater in mice expressing HA at lower levels than it is in mice expressing relatively higher levels of HA. Conversion occurs most efficiently at sites draining mucosal surfaces, in agreement with published studies demonstrating the existence of specialized subsets of dendritic cells at these locations that promote Treg induction. We also find that the extent of Treg induction in response to a self-antigen is essentially unaffected by acute viral infection. These studies are defining parameters that determine the ability of self-peptides to induce the formation of Foxp3+ Tregs in the periphery.

Identification of mitochondrial genome concatemers in AIDS-associated lymphomas and lymphoid cell lines

Since most oncogenic viruses persist as extrachromosomal covalently closed circular DNA (cccDNA) in tumor cells, we developed an assay to visualize and identify cccDNA in primary lymphomas. We identified concatemers of the mitochondrial genome in all samples analyzed, but not in normal lymphocytes. One AIDS-associated lymphoma (EL) was further studied in detail as its mitochondrial genome consisted of tandem head-to-tail duplications. Insertion of C-residues was noted near the origin of replication of EL mtDNA. EL cells responded weakly to Fas-apoptotic stimulus, displayed reduced mitochondrial activity and mass, and produced higher levels of reactive oxygen intermediates. Screening of several AIDS-associated lymphomas and established lymphoid cell lines also revealed the presence of mitochondrial genome concatemers consisting of interlinked monomer molecules. Taken together, our results suggest that formation of mtDNA concatemers is associated with oncogenic transformation in lymphoid cells.

Pyrin-only protein 2 modulates NF-kappaB and disrupts ASC:CLR interactions

NF-kappaB is pivotal for transactivation of cell-cycle regulatory, cytokine, and adhesion molecule genes and is dysregulated in many cancers, neurodegenerative disorders, and inflammatory diseases. Proteins with pyrin and/or caspase recruitment domains have roles in apoptosis, innate immunity, and inflammation. Many pyrin domain (PYD) proteins modulate NF-kappaB activity as well as participate in assembling both the perinuclear "apoptotic speck" and the pro-IL1beta/IL-18-converting inflammasome complex. "Pyrin-only" proteins (POP) are attractive as negative regulators of PYD-mediated functions and one such protein, POP1, has been reported. We report the identification and initial characterization of a second POP. POP2 is a 294 nt single exon gene located on human chromosome 3 encoding a 97-aa protein with sequence and predicted structural similarity to other PYDs. Highly similar to PYDs in CATERPILLER (CLR, NLR, NALP) family proteins, POP2 is less like the prototypic pyrin and ASC PYDs. POP2 is expressed principally in peripheral blood leukocytes and displays both cytoplasmic and nuclear expression patterns in transfected cells. TNF-alpha-stimulated and p65 (RelA)-induced NF-kappaB-dependent gene transcription is inhibited by POP2 in vitro by a mechanism involving changes in NF-kappaB nuclear import or distribution. While colocalizing with ASC in perinuclear specks, POP2 also inhibits the formation of specks by the CLR protein CIAS1/NALP3. Together, these observations demonstrate that POP2 is a negative regulator of NF-kappaB activity that may influence the assembly of PYD-dependent complexes.

Respiratory burst is decreased by human hyperlipemic serum in rat peritoneal macrophages

The effect of hyperlipemic human serum on superoxide anion (O2-) production by rat peritoneal macrophages was investigated. Phorbol myristate acetate (PMA)-stimulated O2- production was inhibited when cells were preincubated with hyperlipemic human serum. This inhibition was specifically carried out by a lipid fraction and was dependent on both cholesterol and triglyceride serum levels. This inhibitory effect was not exerted by a direct effect on NADPH-oxidase activity, nor by a putative superoxide dismutase activity present in the serum. With human neutrophils, we observed a decreased mobility of the cytosolic factor p47-phox to the membrane during the activation process, caused by hyperlipemic serum. We did not find any effect of hyperlipemic serum on NO2- production by cultured rat macrophages. These results suggest that a pathological increase of circulating plasma lipids may be associated with an impaired inflamatory capacity of macrophages.

Cyclosporin A inhibits phorbol ester-induced activation of superoxide production in resident mouse peritoneal macrophages

Peritoneal resident macrophages from mice are sensitive to inhibition by cyclosporin A (CsA) of phorbol 12-myristate 13-acetate (PMA)-stimulated oxidative burst. Inhibition was assessed in terms of superoxide anion (O2.-) and H2O2 production. Key findings were as follows. (a) CsA inhibited in a dose-dependent manner the production of O2.- when cells were stimulated with PMA. CsA did not alter the respiratory burst induced by other stimuli (zymosan, concanavalin A and fMet-Leu-Phe). It was verified that CsA itself had no scavenger effect. (b) A concomitant decrease in H2O2 liberation following CsA exposure was found. This inhibition was observed both in the initial rate of synthesis and in the accumulation after 15 min of incubation. (c) NADPH oxidase activity in the crude supernatant was unaffected by the previous incubation of macrophages with CsA. CsA does not inhibit glucose transport measured as 14CO2 production. (d) The production of O2.- was strongly dependent on the glucose concentration. Sodium oleate also stimulated O2.- production in resident macrophages. These data might be correlated with the inhibitory effect of CsA upon other functions of macrophages.

Studies on the mechanism of the antifungal action of benzoate

A method is described for the determination of the pH of intracellular water based on the distribution of [14C]benzoate (0.01 mM) between intra- and extra-cellular water. Benzoate at higher concentrations (2-10mM) enters the yeast cell in the undissociated form, and its neutralization within the cell can cause a shift of the pH of the intracellular water by more than 1 pH unit. Benzoate causes an accumulation of the two hexose monophosphates of yeast glucose fermentation and a decrease in intermediates beyond phosphofructokinase, suggesting inhibition at this stage. Benzoate also causes a concomitant fall in [ATP]. Phosphofructokinase is inhibited to a greater extent than hexokinase at acid pH. There is a relationship between intracellular pH, phosphofructokinase inhibition and CO2 production, suggesting that the antifungal action of benzoate is caused by an accumulation of benzoate at low external pH, which lowers the intracellular pH into the range where phosphofructokinase is sensitive. The subsequent inhibition of glycolysis causes a fall in [ATP] and thus restricts growth.

Restoring effects of refeeding and dibutyril cyclic AMP on the increased glucagon secretion of rat pancreatic islets during starvation

The glucagon release in the presence of glucose and the interaction of dibutyril cyclic AMP was studied in isolated pancreatic islets from fed and 96 h-fasted rats incubated for 30 min. In both states the increase of glucose concentration produced a similar inhibition of glucagon release and stimulation of cyclic AMP content. Higher glucagon secretion and lower cyclic AMP contents were observed in islets from fasted than in those from fed animals at both 2.75 and 16.7 mM glucose. Islets from rats starved for 96 h and refed for 48 h with normal diet or oral 20% glucose showed glucagon release patterns similar to those of controls. Addition of 2 mM dibutyril cyclic AMP to the incubation medium inhibited the fasting-induced increase of glucagon secretion at both glucose levels. These results show an inverse correlation between glucagon secretion and islet cyclic AMP content. However, the sensitivity of the islet to glucose-induced inhibition of glucagon secretion appears to be independent of the islet cyclic AMP levels.

Effect of prolonged fasting upon insulin and glucagon secretion from isolated rat pancreatic islets

To study insulin-glucagon interrelationships in the regulation of pancreatic islet functions, glucose-mediated insulin and glucagon secretion have been studied in isolated pancreatic islets from fed and from 4 and 8-day fasted rats. At low glucose levels (50 mg %) a continuous decrease of insulin and increase of glucagon secretion were observed during prolonged fasting. High glucose concentrations 300 mg %) stimulated insulin and inhibited glucagon secretion until 4 days, but did not cause any effect after 8 days fasting. These results suggest that the secretory mechanisms of the two hormones may have a common basis.