Upregulation of expression of the chemokine receptor CCR5 by hydrogen peroxide in human monocytes.

The objective of this study was to test the hypothesis that an oxidative stress can serve as a signal to regulate the expression of CCR5. When human monocytes were exposed to graded concentration of hydrogen peroxide (H(2)O(2)), CCR5 mRNA levels increased maximally at 4 h of exposure to 200 microM of H(2)O(2) and decreased by 24 h of treatment. Pretreatment of monocytes with the NF-kappaB inhibitor BAY 11-8072 blocked the H(2)O(2)-induced augmentation of CCR5 mRNA expression, suggesting a role for this transcription factor in the regulation of CCR5 expression. CCR5 protein expression on the plasma membrane was also increased by treatment with H(2)O(2,) as assessed by flow cytometry. This was accompanied by enhanced responsiveness of H(2)O(2)-pretreated monocytes to the CCR5 ligand MIP-1beta in terms of chemotaxis and c-fos gene activation. Our results suggest that oxidative stress may indeed modulate the expression of chemokine receptors and thus contribute to regulation of the inflammatory process

The Application of Nanodiamond in Biotechnology and Tissue Engineering

Diamond in the allotrope form consists of carbon atoms arranged in a cubic crystal structure covalently bonded in sp3 hybridization. Diamond has emerged as a very promising material for various biomedical applications due to its excellent mechanical properties (hardness, low friction coefficient, good adhesiveness to the underlying substrate, good interlayer cohesion), optical properties (the ability to emit intrinsic luminescence), electrical properties (good insulator in the pristine state and semiconductor after doping), chemical resistance (low chemical reactivity and resistance to wet etching) and biocompatibility (little if any toxicity and immunogenicity). For advanced biomedical applications, diamond is promising particularly in its nanostructured forms, namely nanoparticles, nanostructured diamond films and composite scaffolds in which diamond nanoparticles are dispersed in a matrix (mainly nanodiamond-loaded nanofibrous scaffolds). This chapter summarizes both our long-term experience and that of other research groups in studies focusing on the interaction of cells (particularly bone-derived cells) with nanodiamonds as nanoparticles, thin films and composites with synthetic polymers. Their potential applications in bioimaging, biosensing, drug delivery, biomaterial coating and tissue engineering are also reviewed

Nanofibrous Scaffolds as Promising Cell Carriers for Tissue Engineering

Nanofibers are promising cell carriers for tissue engineering of a variety of tissues and organs in the human organism. They have been experimentally used for reconstruction of tissues of cardiovascular, respiratory, digestive, urinary, nervous and musculoskeletal systems. Nanofibers are also promising for drug and gene delivery, construction of biosensors and biostimulators, and wound dressings. Nanofibers can be created from a wide range of natural polymers or synthetic biostable and biodegradable polymers. For hard tissue engineering, polymeric nanofibers can be reinforced with various ceramic, metal-based or carbon-based nanoparticles, or created directly from hard materials. The nanofibrous scaffolds can be loaded with various bioactive molecules, such as growth, differentiation and angiogenic factors, or funcionalized with ligands for the cell adhesion receptors. This review also includes our experience in skin tissue engineering using nanofibers fabricated from polycaprolactone and its copolymer with polylactide, cellulose acetate, and particularly from polylactide nanofibers modified by plasma activation and fibrin coating. In addition, we studied the interaction of human bone-derived cells with nanofibrous scaffolds loaded with hydroxyapatite or diamond nanoparticles. We also created novel nanofibers based on diamond deposition on a SiO2 template, and tested their effects on the adhesion, viability and growth of human vascular endothelial cells

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

The modulation of immune function by a-L-fucose

Carbohydrate moieties serve as important antigenic and receptor sites for many lymphocyte activities. The addition of exogeneous monosaccharides and their effects on various leukocyte fonctions has provided useful probes for the study of cell-cell interaction. In this report we studied the potential role of a-L-fucose in the cellular interactions involved in mitogen-, antigen- and alloantigen-induced proliferation and the activation of nonspecific cytolytic cells. Different monosaccharides were tested for their activity when added to uni- and bidirectional mixed lymphocyte reaction [MLC] as well as to mitogen [ConA. PHA, PWM]-stimulated cultures. Only a-L-fucose blocked the MLC reaction in a dose-dependent fashion while having no effect on mitogen stimulation although antigen-specific stimulation was also blocked by fucose. Similarly a-L-fucose specifically inhibited the MLC-induced generation of suppressor cells. The generation and the effector phase of ConA-induced suppressor cells was net affected by fucose, indicating that different receptors are involved than in the generation of antigen- specific suppression. Pretreatment of the MLC responder cells with fucose deshydrogenase abolished the MLC reaction while stimulator cell pretreatment had no effect, suggesting that the recognition site of the responders contained a-L-fucose. In addition, a-fucose, significantly enhanced the cytolytic capacity of MLC-induced or preincubated effector cells. The increase in activity was seen against cytotoxic T lymphocyte [CTL] targets [:relevant PHA blasts], natural killer [NK] cell targets [:K5B2] and natural cytotoxic cell [NC] targets [:MA-160]. In addition, traditionally NK-insensitive targets [Raji cells. irrelevant and autologous PHA blasts] were lysed after preincubation of effector cells is with fucose, although ADCC activity did not increase. NK or CTL activity was not significantly changed by the addition of fucose directly to assay cultures. The proportion of target-binding cells was not affected but the percentage of lytic conjugates was doubled when effector cells were preincubated with fucose. Significant augmentation of NK activity could be observed within 24 hours of incubation with a-L-fucose. Conversely, when fucose was added more than 24 hours after initiation of the culture, the increase in cytolytic activity was not seen. Parallel to the increase in cytolytic activity, following preincubation with a-L-fucose, an increase in the expression of a newly defined human NC cell marker, HNC-1A3 was observed. The populations expressing antigens defined by the antibodies OKT8, Leu7, Leu11 and CKM1 showed no quantitative change. The treatment of cells with OKM1 and complement [C], before culture, ellminated fucose-enhanced killing, whereas simliar treatment with OKT8 or OKT3 and C’ had no significant effect. Enriched OKM1+ cells were capable of responding to fucose. The effector cells of fucose-activated killing were not mainly HNC-1A3+ cells in spite of their significant increase after fucose induction, but the activity was partially sensitive to depletion by OKM1, Leu11, OKT8 antibodies plus C' and only very slightly to OKT3 antibody plus C’. The production of interferon or interleukin 1 was not augmented in fucose-induced cultures whereas there was a slight increase in interleukin 2 production. Fucose activation was not inhibited by the presence of anti IL-2 antibodies or cyclosporin A which suggests that IL-2 does not play a major role in fucose-induction of killing. These results provide evidence that a-L-fucose is capable of augmentingnon-specific cytotoxic activity by an IL-2 independant mechanism. In addition, apparent competitive inhibition by exogenous fucose of cell-cell interaction required for the MLC reaction suggests that this monosaccharide is an essential constituent of allogeneic recognition sites

Study of the immune maternal and fetal relationship in humans

We approached the problem of the survival of the fetal semi-allograft in the maternal environment by studying in vitro reactivity of the respective leukocyte populations. Mixed lymphocyte culture (MLC) reactions between parental, related newborn, unrelated newborn, and control cells were performed. The bidirectional MLC revealed weak responses between maternal and related newborn lymphocytes when compared to all other MLC combinations. Similarly, this weak maternal/newborn reaction could be seen in the unidirectional mixed lymphocyte reaction. This hyporeactivity was not due to impaired responses of either the maternal or newborn populations, as they showed normal reactivity with all other populations tested. The removal of TG lymphocytes from the responding (maternal or newborn) population resulted in an increase of reactivity of this population. The magnitude of this increase was specific for the stimulating population in the maternal/newborn cultures. The presence of specific suppressor cells was also confirmed by the irradiation of the stimulating population: The responding population showed an increased reactivity towards the irradiated stimulators when compared to a stimulating population treated with mitomycin C. Maternal and cord plasma both significantly suppressed bi- and unidirectional MLC, without having specific suppressive factors for any of the populations used. The action of the plasmas may be useful in vivo for the diminution of immune processes at the placental level, and may be additive to the more- specific suppressor cell activities described above. Cord lymphocyte competency was evaluated through mitogen blastogenesis, the presence of short-lived suppressor cells, the inducibility of Con A-activated suppressor cells, and the production of, and response to, lymphokines. Cord cells respond adequately, although the specific response is lower than that of adult cells, to all mitogens used: Concanavalin A (Con A), Phytohemagglutinin (PHA), Pokeweed Mitogen (PWM), and Staphage Lysate (SL). Similarly, their capacity for suppression is comparable to, or even better than adults, as evaluated through the presence of short-lived suppressor cells in the cord cell population, and the possibility of induction of Con A-activated suppressor cells in this same population. The production of the lymphokine Blastogenic Factor (BF) was slightly impaired, when compared to adult production, and although adult lymphocytes were capable of responding to neonatal BF, newborn cells were not. Neonatal Lymphocyte Derived Cheraotactic Factor (LDCF) production equaled that of adult cells and neonatal polymorphonuclear leukocytes (PMN) responded to both the adult- and neonatal-derived (LCDF) equally. The results suggest that the cord lymphocyte is essentially immunocompetent, but there may be a delay in maturation of some lymphocyte subpopulations. We suggest that, as both maternal and neonatal lymphocyte populations are immunocompetent, the observed hyporeactivity of maternal/newborn mixed lymphocyte cultures is due to the modulation of the reaction by specific suppressor cells present in both populations