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Dielectrophoretic/gravitational field-flow fractionation (DEP/G-FFF) was used to separate cultured human breast cancer MDA-435 cells from normal blood cells mixed together in a sucrose/dextrose medium. An array of microfabricated, interdigitated electrodes of 50 [[micro]meter] widths and spacings, and lining the bottom surface of a thin chamber (0.42 mm H x 25 mm W x 300 mm L), was used to generate DEP forces that levitated the cells. A 10-[[micro]liter] cell mixture sample containing [approximately]50 000 cells was introduced into the chamber, and cancerous and normal blood cells were levitated to different heights according to the balance of DEP and gravitational forces. The cells at different heights were transported at different velocities under the influence of a parabolic flow profile that was established in the chamber and were thereby separated. Separation performance depended on the frequency and voltage of the applied DEP field and the fluid-flow rate. It took as little as 5 min to achieve cell separation. An analysis of the DEP/G-FFF results revealed that the separation exploited the difference in dielectric and density properties between cell populations. The DEP/G-FFF technique is potentially applicable to many biological and biomedical problems, especially those related to microfluidic systems.

The tadpole larvae of the ascidian Halocynthia roretzi have trunk lateral cells (TLCs) in their trunk. TLCs give rise to adult blood cells after metamorphosis. TLCs are exclusively derived from the A7.6 cell pair of 64-cell embryos. When prospective TLC blastomeres were isolated from embryos before the 16-cell stage, they failed to express TLC-specific antigen, a molecular indication of differentiation of TLCs. Isolates after the 32-cell stage, however, autonomously expressed the antigen. Results of experiments involving coisolation and recombination of blastomeres at the 16-cell stage showed that the inductive influence emanating from cells of animal hemisphere (presumptive epidermis blastomeres) is required for TLC formation. The inductive interaction takes place at the 16-cell stage, two cell cycles before the developmental fate becomes exclusively restricted to TLC formation. The inducing activity is distributed widely in animal hemisphere. By contrast, only presumptive TLC blastomeres have competence to be induced to form TLCs.

Two different signals of swelling activate potassium chloride cotransport in sheep red blood cells. The first is macromolecular crowding, a chemical signal of which the sensor is kinase. The other signal is mechanical and not mimicked by urea. This signal activates the cell transport. This experiment shows that volume-sensitive ion transporters responsive to chemical and mechanical signals arise from swelling.

Measurement of extracellular viability and intracellular viability of opaque and translucent colonial Vibrio vulnificus associated with phagocytic oyster hemocytes reveals that the levels of phagocytosis and bactericidal degradation of the opaque isolates are lower than those of the translucent morphotype. Encapsulation plays a role in the resistance to hemocytes-induced ingestion and degradation. V. cholerae and E. coli exhibit higher rates of intracellular death compared to the opaque V. vulnificus isolate. V. vulnificus-inoculated hemocyte monolayers exhibit similar levels of lysozyme activity and acid phosphatase activity.

Culturing of pharyngeal explants of Styela clava, a tunicate, reveals the characteristics of hemopoiesis in marine animals. The study reveals that during culturing, sparse, residential hemocytes are produced in the pharyngeal explants. Hemocytes are produced by the entry of several free cells into the culturing medium. The cells that are coming out of the haemolyph medium are not hemocytes. Study of the movement of these cells will enable the investigation of immune defense response in fish species such as tunicates.

Spectrofluorimetry using fluorescent dye Fluo3 and confocal microscopy are used in the study of the mussel, Mytilus edulis, to determine the cytosolic Ca2+ level's dependence on the effect of Hg2+ and Cu2+. The ionic Hg and Cu produce a concentration and time-dependent enhancement in the cytosolic Ca2+ level in the blood of marine molluscs. The influence of ionic Hg and Cu is reduced when there is a low calcium containing medium and cells are pretreated with channel blockers such as Verapmil. This indicates that ionic Hg and Ca increases the influx of extracellular Ca2+ by activation of Ca2+ channels which are voltage dependent.

Histamine receptor proteins from Triton X-100 solubilized peripheral human blood mononuclear cells which consist of monocytes and lymphocytes are purified. The histamine is released from basophils and mast cells. The release is performed by nonimmunological or immunological processes. Many biological processes are exhibited by histamines released from short acting mediators.

Scid/scid mince and normal mice were studied to detrermine the colonization of murine fetal thymus lobes by donor cells from human umbilical cord blood or human bone marrow. The cells were cultured to yield double positive CD8+ CD8+ cells. CD8+ or CD4+ single-positive T cells undergo accumulation. The existence of CD7+ progenitor T cells determined colonization, and the development of the progenitor T cells is enhanced by thymic organ culture.

The effects of overexpressing cyclin D2 and D3 in a murine interleukin 3 (IL-3) dependent cell line are explored. Cell viability, rate of cell proliferation and dependence on IL-3 for growth are unaffected by constitutive overexpression of D2 or D3. D2 and D3 influence the regulation of the passage of hematopoietic cells through the G1 phase of the cell cycle in the presence of growth factors and the G1 arrest in the absence of growth factors.

The measurement of the turnover of naturally occurring stable isotopes such as carbon-13 in the blood of birds may be a used as a sampling method in avian dietary research. Blood plasma and cell fractions may both be used for such purposes. The technique is ideal when non-destructive diet sampling is desired. Other tissues may be sampled if short-term and long-term dietary information is needed. The use of stable-isotope determinations in the blood of crows to obtain information on the crows' diet is described.

The relation of Vibrio vulnificus to phagocytic oyster hemocytes was investigated. Experiments were conducted with time, temperature, bacterial concentration, hemolymph pretreatment and V. vulnificus translucent and opaque colony morphotypes as its parameters. The utility of these cellular interactions for understanding the retention of this bacterium in oyster tissues and its ecology in estuarine environments were demonstrated.

Bacterial infections are a primary cause of death and illness in the newborn, particularly in premature infants. The high incidence of bacterial infection of the blood in the newborn may be due to the incomplete development of the immune system. The risk of bacterial infection is increased by abnormal function of the polymorphonuclear leukocytes (PMN), a type of white blood cell, and abnormal antibody-mediated immunity (involving immune proteins specifically directed against foreign particles such as bacteria). The highest incidence of bacterial infection of the blood occurs during the first week of life. The incidence decreases during the first month of life, despite the decline in maternal antibodies, limited number of PMNs, and inadequate number of bone marrow cells. Studies suggest that the PMNs of newborns may have decreased chemotaxis (the movement of cells in response to a chemical stimulus); impaired ability to adhere to a surface; and defective chemiluminescence (production of light without heat as a result of chemical reactions, characteristic of certain bacteria and fungi). The age-related changes in PMN chemiluminescence and chemotaxis were assessed during the first month of life in 38 premature infants born at less than 32 weeks gestation. Chemiluminescence and chemotactic motility were examined at 9.8 days of age, and then each week over a 21-day period. The results were compared with the same measurements performed on 14 healthy newborns who were less than 72 hours old, and similar data were obtained from seven normal adults. On day one, PMN chemiluminescence and chemotactic motility were lower in premature infants than in full-term newborns; adults had higher values than either infant group. PMN chemiluminescence and chemotactic motility values increased gradually at days 7, 14, and 21 in the premature infants. Although PMN chemiluminescence was similar for both premature and full-term infants at day 21, the chemotactic motility values remained lower in premature infants than in full-term newborns. The chronologic age had a greater effect on maturation of PMN functions than gestational age. (Consumer Summary produced by Reliance Medical Information, Inc.)

Depending on their size and morphology, anthozoan polyps and colonies may be diffusion-limited in their oxygen consumption, even under well-stirred, air-saturated conditions. This is indicated by an enhancement of oxygen consumption under steady-state hyperoxic conditions that simulate the levels of [O.sub.2] produced photosynthetically by zooxanthellae in the hosts' tissues. Such hyperoxia in the tissues of zooxanthellate species negates the effect of the diffusive boundary layer, and increases the rate of oxygen consumption; thus, in many cases, the rate of respiration measured under normoxia in the dark may not be representative of the rate during the day when the zooxanthellae are photosynthesizing and when the supply of oxygen for respiration is in the tissues themselves, not from the environment. These results have implications in respirometric methodology and in calculating the rate of gross photosynthesis in energetic studies. The activity of cytochrome c oxidase is higher in aposymbiotic than in zooxanthellate specimens of the sea anemone Aiptasia pulchella, and this may indicate a compensation for the relative hypoxia in the tissues of the former, enhancing the delivery of oxygen to the mitochondria from the environment.

Tensile mechanical force was long assumed to increase the detachment rates of biological adhesive bonds (Bell, 1978). However, in the last few years, several receptor-ligand pairs were shown to form 'catch bonds,' whose lifetimes are enhanced by moderate amounts of force. These include the bacterial adhesive protein FimH binding to its ligand mannose (Thomas et al., 2002; Thomas et al., 2006), blood cell adhesion proteins P- and L-selectin binding to sialyl Lewis X ([sLe.sup.X])-containing ligands (Marshall et al., 2003; Evans et al., 2004; Sarangapani et al., 2004), and the myosin-actin motor protein interaction (Guo and Guilford, 2006). The structural mechanism behind this counterintuitive force-enhanced catch bond behavior is of great interest.

Platelet activation is inhibited through hematophagous arthropods that secrete a salivary apyrase by catabolizing ADP released from damaged tissues and blood cells. The human apyrase was redesigned using a comparative structural biology approach so as to enhance its ADPase activity by more than 100-fold.

Hemocytes serve as the main immune system in molluscs. They proliferate within connective tissues and are released into the blood, circulating as spherical cells until activated to adopt a phagocytic function and morphology. In Lymnaea stagnalis, hemocyte activation is correlated with a rapid shift in cytoskeletal organization resulting in directed amoeboid movement. We are examining signal transduction mechanisms relevant to hemocyte activation, starting with the regulation of intracellular calcium. S100 proteins are a family of small calcium-binding modulator proteins with cell-type-specific expression. Previous reports of S-100 immunoreactivity in molluscs limited expression to neural tissues. We now report that a polyclonal antiserum generated against a mammalian S-100 protein recognizes a cytoplasmic molecule within both non-activated and activated Lymnaea hemocytes. In activated hemocytes the immunoreactivity is localized initially to the perinuclear cytoplasm. As the cell begins to spread, however, the immunoreactivity moves outward with roughly the same time course as microtubule polymerization, suggesting a possible role in mediating the cytoskeletal dynamics of molluscan hemocytes.

Blood vessels reach every organ and tissue in the body, indicating that the blood and the integrity of the blood vessels are essential to maintaining the body's health and functioning. [...]