C3a is a chemotaxin for human eosinophils but not for neutrophils. I. C3a stimulation of neutrophils is secondary to eosinophil activation

Inflammatory action of the potent chemotaxin C5a has been well characterized on a variety of human cell types, including neutrophils, monocytes, basophils, and eosinophils. The cellular effects of C3a are less well defined. Contradictory reports have been published for C3a activation of neutrophils. Recent reports that C3a activates both basophils and eosinophils prompted us to reinvestigate the effects of C3a stimulation on eosinophils. We hypothesized that C3a activation of eosinophils, cells that are present in most neutrophil preparations, might lead to neutrophil activation. Using neutrophils of 98% purity, we observed no evidence of cellular activation after stimulation with either C3a, recombinant human C3a (rhC3a), or the synthetic C3a analogue C3a 57-77, Y57. Eosinophils purified to > 98% purity displayed concentration-dependent polarization, chemotaxis, and enzyme release by stimulation with C3a, rhC3a, and the synthetic C3a analogue. An inactive form of C3a, C3adesArg, failed to stimulate either eosinophils or neutrophils. Using neutrophil preparations containing 5-9% eosinophils, up to 20% of neutrophils became polarized after exposure to C3a. Likewise, we demonstrated that supernatant from C3a-stimulated eosinophils promotes neutrophil chemotaxis. Eosinophil polarization experiments were repeated in the presence of antibody to the C5a receptor (C5aR) to show that C3a and C5a interact with different receptors. C3a activates eosinophils in the presence of anti-C5aR antibody at concentrations that fully block C5a activation. We conclude that eosinophils are directly activated by either C3a or C5a, whereas C3a failed to activate neutrophils. C3a acts on eosinophils via a receptor that is distinct from C5aR. Since neutrophils are indirectly stimulated by C3a, eosinophils contaminating neutrophil preparations may explain earlier reports that C3a activates human neutrophils.     

The complete practitioner: Still a work in progress.

When one is reflecting on a career as a practitioner, a number of important influences, themes, and elements that contribute to being a successful practitioner are evident. The achievement of this success is not a solitary activity. Many role models and mentors serve as important influences and guides for developing as a professional over the course of one’s career. Ultimately, the goal is to aspire to become a complete practitioner. This includes being a passionate professional, clinically competent, a psychotherapist and clinician, an active consumer of research findings, ethical, a role model, a mentor, psychologically healthy, an advocate, a leader, a volunteer, an educator, a scholar, a colleague, a business person and entrepreneur, and an innovator and visionary; focusing on diversity and multicultural competence; and having a comprehensive vision of health. Because the goal of being a complete practitioner is aspirational, one never fully masters each of these roles and attributes but remains a work in progress. Yet, the process of endeavoring to become a complete practitioner is rewarding, gratifying, and meaningful. It is a journey well worth taking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variation in lipoprotein(a) concentrations among individuals with the same apolipoprotein (a) isoform is determined by the rate of lipoprotein(a) production

Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein which is similar in structure to, but metabolically distinct from, LDL. Factors regulating plasma concentrations of Lp(a) are poorly understood. Apo(a), the protein that distinguishes Lp(a) from LDL, is highly polymorphic, and apo(a) size is inversely correlated with plasma Lp(a) level. Even within the same apo(a) isoform class, however, plasma Lp(a) concentrations vary widely. A series of in vivo kinetic studies were performed using purified radiolabeled Lp(a) in individuals with the same apo(a) isoform but different Lp(a) levels. In a group of seven subjects with a single S4-apo(a) isoform and Lp(a) levels ranging from 1 to 13.2 mg/dl, the fractional catabolic rate (FCR) of 131I-labeled S2-Lp(a) (mean 0.328 day-1) was not correlated with the plasma Lp(a) level (r = -0.346, P = 0.45). In two S4-apo(a) subjects with a 10-fold difference in Lp(a) level, the FCR's of 125I-labeled S4-Lp(a) were very similar in both subjects and not substantially different from the FCRs of 131I-S2-Lp(a) in the same subjects. In four subjects with a single S2-apo(a) isoform and Lp(a) levels ranging from 9.4 to 91 mg/dl, Lp(a) concentration was highly correlated with Lp(a) production rate (r = 0.993, P = 0.007), but poorly correlated with Lp(a) FCR (mean 0.304 day-1). Analysis of Lp(a) kinetic parameters in all 11 subjects revealed no significant correlation of Lp(a) level with Lp(a) FCR (r = -0.53, P = 0.09) and a strong correlation with Lp(a) production rate (r = 0.99, P < 0.0001). We conclude that the substantial variation in Lp(a) levels among individuals with the same apo(a) phenotype is caused primarily by differences in Lp(a) production rate.     

A Psi of relief.

The American Psychological Association (APA) introduced a new logo symbol for the association in 1991. The symbol attempted to modernize the representation of the organization, melding the clinical and experimental arms of the discipline through the use of organic arms attached to a central unifying pole. To determine what this symbol represented to a naive audience, the authors undertook a questionnaire-based investigation with a total of 176 undergraduates. The most common images evoked were a sunrise, a disguised version of the AT&T logo, a window, an organizational logo (not APA), a plant, a human face, a bird, or a tool or implement. The authors discuss these interpretations as symbols for the future goals of APA. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concept-Based Method for Extracting Valid Subsets from an EXPRESS Schema

An EXPRESS schema is a data schema defined in EXPRESS, an international standard language for defining product data schemas. This technical paper proposes and formally defines a set of conditions for generating a minimum valid subset of an EXPRESS schema corresponding to a concept, where a concept is a general idea and a subset is a partial model of a data schema. We introduce a notion of “minimal set” to define the relationships between a subset and other subsets, and also between a subset and concepts. A minimal set is the smallest complete subset of a schema that corresponds to a concept. Using IFC, an international standard data model for the architecture, engineering, and construction industry, the proposed conditions have been implemented in a software application developed for extracting subsets from the IFC schema matching the concepts. A number of examples are demonstrated.     

Transition to Self-Similarity of Diffusion of Tracer in Turbulent Patch

A mixing of a passive tracer inside a turbulent patch generated by a localized short-time perturbation is studied numerically and analytically. Two kinds of an initial distribution of a tracer are considered: two-layer and continuous with constant gradient. For the turbulent patch shaped as a layer, it is shown that, regardless of details of initial distributions of a turbulent energy and dissipation, a tracer concentration evolves to self-similar regimes as time elapses. Analytical self-similar solutions to turbulent diffusion equations are found for three symmetric shapes of a turbulent patch: layer, cylinder, and sphere. Distributions of the concentration inside a patch are found to be substantially nonuniform, with a typical ratio of a concentration gradient in the middle of a patch to its initial value of about 0.5.     

Dynamic interaction between a coherent precipitate and an edge dislocation

Dynamic interaction between a coherent precipitate and an edge dislocation is analyzed by means of a discrete atom method, which is based on classical statistical mechanics and linear elasticity. Precipitates having a dilatational misfit strain and elastic constants different from those of the matrix phase are treated in anisotropic elastic systems under a plane strain condition. A coherent interface transforms into a semicoherent one by nucleating dipolar dislocations at a stress concentration in a coherent precipitate. One of the dipolar dislocations glides along the precipitate-matrix interface to become a misfit dislocation, and the other slips into the matrix phase to become a lattice dislocation. In accordance with continuum elasticity, a coherent particle with a positive misfit strain migrates to the tension side of an edge dislocation, whereas a particle with a negative misfit diffuses to the region of compression. Morphological change is, however, caused by the dislocation as the particle tries to capitalize on the dislocation stress field, and the particle shape depends on its stiffness and elastic anisotropy. Under an applied shear, a hard coherent particle with a positive misfit strain is sheared along the shear direction, but a soft particle responds in the opposite direction. Elastic interaction between a coherent particle and an edge dislocation can be so strong that the particle-dislocation complex remains coupled even at a high shear strain applied to the system. Some composite applied stresses can cause an edge dislocation to split into two partials. One of the partials, a glissile component, is found to engage actively in the morphological evolution of a particle during a diffusional relaxation. This article is based on a presentation made in the symposium “Kinetically Determined Particle Shapes and the Dynamics of Solid:Solid Interfaces,” presented at the October 1996 Fall meeting of TMS/ASM in Cincinnati, Ohio, under the auspices of the ASM Phase Transformations Committee.     

Imprinting, learning, and memory.

If a visually naive chick is exposed to one of a wide range of conspicuous objects, the chick may learn its characteristics. A series of biochemical studies has implicated a restricted part of the forebrain in this process of imprinting; a specific region (IMHV) has been identified which may be a site of information storage. Changes in the morphology of synapses occur in this region as a consequence of training. The left and right IMHV regions play different roles in the imprinting process. Exposure to a simple artificial object, a rotating red box, has different neural consequences from those associated with exposure to a complex object, a rotating stuffed jungle fowl, which resembles a conspecific. These differences may be related to the differences in complexity of the two training objects. Another possibility is that two neural systems are implicated in imprinting: (a) a system that underlies a predisposition to approach objects resembling conspecifics and (b) a learning system, of which IMHV is a crucial component, that is engaged by particular objects and that in "natural" circumstances also allows the chick to learn the characteristics of its mother. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a blood cardioplegia delivery system for children

We have developed a blood cardioplegia delivery system for children. Essential points of a delivery system in pediatric cardiac surgery are (1) a small amount of priming volume of a delivery system, and (2) slow, steady infusion of a cardioplegic solution. We changed a heat exchanger to a smaller one for reduction of priming volume, and changed a roller pump tube to a smaller one for slow, steady infusion. Thus, priming volume of a delivery system has reduced from 180 to 100 ml, and we can infuse a cardioplegic solution at a steady rate less than 10 ml/min. Our clinical experience with this system suggests that this blood cardioplegia delivery system is useful for pediatric cardiac surgery.     

Obituary: Molly R. Harrower (1906–1999).

Memorializes Molly R. Harrower who is remembered as a gifted clinician and a serious researcher, a fine university teacher and one of the first psychologists in full-time private practice, a Gestalt psychologist and devotee of psychoanalysis, a psychologist and poet. Harrower developed a group Rorschach and used in widely. She published a classic article concerning the psychology of Nazi war criminals as determined by the Rorschach. Harrower developed a scale, based on a set of projective techniques, that effectively predicted which patients would profit from psychoanalytic treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of viscosity on the escape rate from metastability—creep at low temperature

Experiments on the stress relaxation of lead alloys at low temperatures show a bimodal behavior. The first mode is shown experimentally to be related to a viscous process, while the second mode is a thermally activated process. In the case of lead alloys we show, through a variety of measurements, that the second mode can be varied by changing the viscosity a dislocation experiences. These experiments demonstrate that the log of the relaxation rate, R, for the second mode, for superconducting materials, exhibits a minimum and a maximum as a function of the inverse of the temperature, 1/T. We present an analysis which is consistent with all the experimental observations. This analysis shows that, in the case of underdamped oscillators, viscosity can affect a rate process. It also allows us to provide a value for the radiation damping term a moving dislocation is subject to.     

'Doctor, have I got a fracture or a break'?

Many patients apparently believe there is a difference between a fracture and a break. In a survey of 100 patients, 81 thought there was a difference. Of these, 71 thought a fracture was better than a break, and 65 believed that bone was undisplaced in a fracture and displaced in a break. These results suggest that greater care, including visual means, should be used in informing patients of their injuries.     

Impact of apo(a) length polymorphism and the control of plasma Lp(a) concentrations: evidence for a threshold effect

Plasma lipoprotein(a) [Lp(a)] levels are believed to be controlled predominantly by the apolipoprotein(a) [APO(a)] gene, which encodes the apo(a) glycoprotein, a key constituent of the Lp(a) particle. Previously, it has been accepted that the plasma Lp(a) level is inversely proportional to apo(a) length. To examine this relationship in greater detail, 1500 unrelated, homogeneous (sex, race, age, plasma lipids) subjects were studied, from which 769 were identified with a single-expressing APO(a) allele. A bimodal frequency distribution of apo(a) isoforms was observed. As expected, there was a general inverse relationship between apo(a) isoform size and Lp(a) level. However, when groups with equivalent single-expressing apo(a) isoforms were studied, it was clear that although smaller isoforms were associated on average with higher levels, they were also associated with the greatest variability in level. After logarithmic transformation of Lp(a) data, the overall contribution of the apo(a) length polymorphism was calculated to be 38%. However, in subjects with apo(a) isoforms of 20 K-4 repeats, the corresponding contribution is 10%. We conclude that the contribution of the apo(a) isoform size to the control of plasma Lp(a) level is considerably lower than previously calculated, because the variability in plasma Lp(a) concentration is not uniform across the apo(a) size spectrum.     

C3a and C5a are chemotaxins for human mast cells and act through distinct receptors via a pertussis toxin-sensitive signal transduction pathway

Mast cells are known to accumulate at sites of inflammation, however, the chemotaxins involved are undefined. Since most natural leukocyte secretagogues also induce cell migration, and since the anaphylatoxins C3a and C5a are mast cell secretagogues, we hypothesized that both C3a and C5a are also mast cell chemotaxins. Here we report that C3a and C5a are, in fact, potent chemotaxins for the human mast cell line HMC-1. The optimal concentrations, half-maximal effective concentrations (a measure of agonist potency) and the efficacy (response at the optimal concentration) compared with medium control were, for C3a: 10 nM, 0.5 nM, and 256%, respectively; for C5a: 1 nM, 10 pM and 145%. Chemotaxis of HMC-1 cells to both C3a and C5a was blocked by pertussis toxin, suggesting that Gi-coupled receptors are involved in signal transduction. C3a and C5a also induced transient pertussis toxin-inhibitable increases in [Ca2+]i (ED50 = 1 nM for both) that could be homologously but not heterologously desensitized, suggesting that the receptors for C3a and C5a are distinct. These results make C3a the most effective mast cell chemotaxin identified to date. The chemotactic potency described here for C3a is also 100- to 1000-fold greater than for all of its previously described cellular actions. Direct chemoattraction of mast cells by C3a and C5a may help explain the rapid accumulation of mast cells at sites of inflammation.     

Presecretory degradation of apolipoprotein [a] is mediated by the proteasome pathway

Plasma levels of atherogenic lipoprotein [a] (Lp[a]) vary over a 1000-fold range and are largely determined by the gene for its unique glycoprotein, apolipoprotein [a] (apo[a]). The apo[a] locus comprises more than 100 alleles, encoding proteins from <300 to >800 kDa. Using primary baboon hepatocyte cultures, we previously demonstrated that differences in the secretion efficiency of apo[a] allelic variants contribute to the variation in plasma Lp[a] levels. In the current study, we investigated the mechanism of apo[a] presecretory degradation. The proteasome inhibitors, acetyl-leucyl-leucyl-norleucinal and lactacystin, prevented apo[a] degradation and increased apo[a] secretion. Transfection with an HA-tagged ubiquitin construct demonstrated the accumulation of ubiquitinated apo[a] in the presence of lactacystin. These results suggest a role for the cytoplasmic proteasome in apo[a] proteolysis. Apo[a] that accumulated intracellularly in the presence of lactacystin remained sensitive to endo-B-N-glucosaminidase H, and apo[a] degradation was reversibly inhibited by brefeldin A, suggesting that transport to a post-endoplasmic reticulum (ER) pre-medial Golgi compartment is required for apo[a] degradation. Newly synthesized apo[a] bound to the ER chaperone calnexin and conditions that enhanced this interaction prevented apo[a] degradation, suggesting that calnexin can protect apo[a] from proteolysis. These studies provide further support for the role of the proteasome in endoplasmic reticulum quality control, and expand this role to one that influences plasma levels of the atherogenic lipoprotein Lp[a].-White, A. L., B. Guerra, J. Wang, and R. E. Lanford. Presecretory degradation of apolipoprotein[a] is mediated by the proteasome pathway.     

Membrane Micro Air Vehicles with Adaptive Aerodynamic Twist: Numerical Modeling

Micro air vehicles are typically characterized by a low aspect ratio wing operating at low Reynolds numbers (104): aerodynamics involve a three-dimensional flow field with numerous regions of separated flow. Furthermore, aerodynamic twist can be built into the wing through the use of a thin membrane skin, to adaptively increase the wing camber. This work formulates a static aeroelastic model of such a wing, by coupling a linear membrane model to a well-validated steady laminar Navier–Stokes solver. The membrane deformation causes a significant pressure redistribution which increases lift and longitudinal static stability, though a drag penalty also develops. The efficiency of a rigid wing increases with Reynolds number, but decreases for a membrane wing, as the deformation generally provides a nonoptimal airfoil shape. Membrane deformation leads to larger separation bubbles, and acts as a barrier to the tip vortex formation. At high angles of attack, the aerodynamic twist causes a direct interaction between the recirculating flow and the tip vortices, indicating potential roll instabilities.     

Thrombospondin 2 expression is correlated with inhibition of angiogenesis and metastasis of colon cancer

Apolipoprotein[a] phenotyping is a critically important method to explore the role of kringle-4 repeat number as a modulator of lipoprotein[a]-associated cardiovascular risk. The availability of a kringle-4 number-based reference standard is therefore necessary for a reliable and generally accepted classification of apo[a] phenotypes. We propose here a battery of recombinant apo[a] isoforms that may be used as the reference standard in various gel systems. Five plasmids encoding for r-apo[a] containing a known number (n = 9, 13, 17, 25, 33) of plasminogen-like kringle-4 copies were constructed, and transfected into the human embryonic kidney cell line 293. The electrophoretic mobility of the recombinant apo[a] isoforms expressed by these cells in a hollow-fiber bioreactor was determined after reduction by SDS-gel (agarose, acrylamide or a mixture of both) electrophoresis and immunoblotting using an antibody specific for human apo[a]. The equation of the linear relationship between log r-apo[a] kringle number and relative migration was used to determine the isoform size of apo[a] in normal human plasma. A very good correlation (r = 0.97) was found with the genotype (pulsed-field gel eletrophoresis of kpnI-digested restriction fragments of genomic DNA) and among electrophoretic methods. The proposed recombinant standard offers the possibility to identify apo[a] isoforms within a large range of molecular sizes, 9 to 33 kringle-4 copies, using simple electrophoretic techniques and a nomenclature based on its molecular structure, i.e., the number of kringle-4 repeats.-Anglés-Cano, E., S. Loyau, G. Cardoso-Salda?a, R. Couderc, and P. Gillery. A novel kringle-4 number-based recombinant apo[a] standard for human apo[a] phenotyping.     

Light-induced photoactivation of hypericin affects the energy metabolism of human glioma cells by inhibiting hexokinase bound to mitochondria

Glucose-dependent energy required for glioma metabolism depends on hexokinase, which is mainly bound to mitochondria. A decrease in intracellular pH leads to a release of hexokinase-binding, which in turn decreases glucose phosphorylation, ATP content, and cell proliferation. Thus, intracellular pH might be a target for therapy of gliomas, and a search for agents able to modulate intracellular pH was initiated. Hypericin, a natural photosensitizer, displays numerous biological activities when exposed to light. Its mechanism and site of action at the cellular level remain unclear, but it probably acts by a type II oxygen-dependent photosensitization mechanism producing singlet oxygen. Hypericin is also able to induce a photogenerated intracellular pH drop, which could constitute an alternative mechanism of hypericin action. In human glioma cells treated for 1 h with 2.5 microg/ml hypericin, light exposure induced a fall in intracellular pH. In these conditions, mitochondria-bound hexokinase was inhibited in a light- and dose-dependent manner, associated with a decreased ATP content, a decrease of mitochondrial transmembrane potential, and a depletion of intracellular glutathione. Hexokinase protein was effectively released from mitochondria, as measured by an ELISA using a specific anti-hexokinase antibody. In addition to decreased glutathione, a response to oxidative stress was confirmed by the concomitant increase in mRNA expression of gamma-glutamyl cysteine synthetase, which catalyzes the rate-limiting step in overall glutathione biosynthesis, and is subject to feedback regulation by glutathione. Hypericin also induced a dose- and light-dependent inhibition of [3H]thymidine uptake and induced apoptosis, as demonstrated by annexin V-FITC binding and cell morphology. This study confirmed the mitochondria as a primary target of photodynamic action. The multifaceted action of hypericin involves the alteration of mitochondria-bound hexokinase, initiating a cascade of events that converge to alter the energy metabolism of glioma cells and their survival. In view of the complex mechanism of action of hypericin, further exploration is warranted in a perspective of its clinical application as a potential phototoxic agent in the treatment of glioma tumors.