Effects of TCDD on Ah receptor, ARNT, EGF, and TGF-alpha expression in embryonic mouse urinary tract

Lipoprotein(a) [Lp(a)] biogenesis was examined in primary cultures of hepatocytes isolated from mice transgenic for both human apolipoprotein(a) [apo(a)] and human apoB. Steady-state and pulse-chase labeling experiments demonstrated that newly synthesized human apo(a) had a prolonged residence time (approximately 60 min) in the endoplasmic reticulum (ER) before maturation and secretion. Apo(a) was inefficiently secreted by the hepatocytes and a large portion of the protein was retained and degraded intracellularly. Apo(a) exhibited a prolonged and complex folding pathway in the ER, which included incorporation of apo(a) into high molecular weight, disulfide-linked aggregates. These folding characteristics could account for long ER residence time and inefficient secretion of apo(a). Mature apo(a) bound via its kringle domains to the hepatocyte cell surface before appearing in the culture medium. Apo(a) could be released from the cell surface by apoB-containing lipoproteins. These studies are consistent with a model in which the efficiency of post-translational processing of apo(a) strongly influences human plasma Lp(a) levels, and suggest that cell surface assembly may be one pathway of human Lp(a) production in vivo. Transgenic mouse hepatocytes thus provide a valuable model system with which to study factors regulating human Lp(a) biogenesis.     

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.     

Majority and minority influence: Source-position imbalance as a determinant of message scrutiny.

Two experiments addressed the issue of whether endorsement of a position by a numerical majority or a minority leads to greater scrutiny of the information presented in a persuasive message. In Exp 1, a counterattitudinal position was endorsed by a majority or a minority and was supported by strong or weak arguments. Argument quality had a larger impact on attitudes with majority than with minority endorsement. In Exp 2, a proattitudinal or a counterattitudinal message was endorsed by a majority or a minority and was supported by strong or weak arguments. When the source and message position were unexpected (i.e., majority-counter and minority-pro messages), argument quality had a larger impact on attitudes than when the source and message position were expected (i.e., majority-pro and minority-counter messages). Thus, either majority or minority endorsement can enhance message scrutiny if the source-position pairing is surprising. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

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)     

Interactions between the structural domains of the RNA replication proteins of plant-infecting RNA viruses

Brome mosaic virus (BMV), a positive-strand RNA virus, encodes two replication proteins: the 2a protein, which contains polymerase-like sequences, and the 1a protein, with N-terminal putative capping and C-terminal helicase-like sequences. These two proteins are part of a multisubunit complex which is necessary for viral RNA replication. We have previously shown that the yeast two-hybrid assay consistently duplicated results obtained from in vivo RNA replication assays and biochemical assays of protein-protein interaction, thus permitting the identification of additional interacting domains. We now map an interaction found to take place between two 1a proteins. Using previously characterized 1a mutants, a perfect correlation was found between the in vivo phenotypes of these mutants and their abilities to interact with wild-type 1a (wt1a) and each other. Western blot analysis revealed that the stabilities of many of the noninteracting mutant proteins were similar to that of wt1a. Deletion analysis of 1a revealed that the N-terminal 515 residues of the 1a protein are required and sufficient for 1a-1a interaction. This intermolecular interaction between the putative capping domain and itself was detected in another tripartite RNA virus, cucumber mosaic virus (CMV), suggesting that the 1a-1a interaction is a feature necessary for the replication of tripartite RNA viruses. The boundaries for various activities are placed in the context of the predicted secondary structures of several 1a-like proteins of members of the alphavirus-like superfamily. Additionally, we found a novel interaction between the putative capping and helicase-like portions of the BMV and CMV 1a proteins. Our cumulative data suggest a working model for the assembly of the BMV RNA replicase.     

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.     

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)     

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.     

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.     

Pseudoexstrophy associated with congenital pouch colon

Pseudoexstrophy or covered exstrophy is a rare exstrophy variant. The authors report a case of covered exstrophy that presented as a newborn with widely separated pubic bones and rectus muscles, a low-set umbilicus, and a subcutaneous bladder. The anal opening was absent, and there was a complex malformation of the external genitalia consisting of a small, laterally displaced penis and a right-sided ectopic hemiscrotum. Micturition and urinary continence were normal. The child also had a high anorectal malformation with a coexistent type IV congenital pouch colon (CPC) malformation. Both kidneys were normal. Preliminary surgery consisted of a divided sigmoid colostomy proximal to the colonic pouch. The literature is reviewed and the embryogenesis of pseudoexstrophy and its associated malformations are discussed.     

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.     

Environment-dependent tight-binding potential model

The yellow-pigmented bacterium isolated from a ditch was a gram negative rod with a G+C content of 63 mol%, and was classified in the genus Sphingomonas. Electron microscopy revealed that the bacterial cell surface was covered with many large plaits. When grown in a medium containing a polysaccharide as an essential nutrient, a pit of 0.02-0.1 micrometers in diameter was formed on the cell surface, and a thin section showed the rearrangement of the plaits and the presence of a region where the cell membrane sinks into the cytosol. The dependence of the pit formation on the presence of macromolecule may predict the existence of a direct uptake mechanism for macromolecules through a mouth-like pit, possibly in endocytosis fashion. The confirmation of the pit structure is the first such finding in the history of microbiology and may provide a new insight into the cell morphology and biochemistry of macromolecule transport in microbial cell system.     

Citalopram in premenstrual dysphoria: is intermittent treatment during luteal phases more effective than continuous medication throughout the menstrual cycle?

This article describes a barrier-free burn center that is accessible to persons with disabilities and that complies with Title III of the Americans with Disabilities Act. The burn center has 3 separate components: patient rooms, patient support facilities, and staff support facilities. Thirteen rooms are used to care for 16 patients. Two of the 13 rooms are accessible to people with disabilities. These 2 rooms have wide doors that permit a wheelchair to pass through, and they have enough clear floor space for a wheelchair to make a 180 degrees turn. The rooms have a sink that is accessible from a wheelchair. The bathrooms have large, clear floor spaces that allow for the turning of a wheelchair, elevated toilets, grab bars, and showers that permit wheelchair access. Special wheelchairs that provide easier shower and commode access are available. The patient support services feature a large hydrotherapy room that contains a table-shower system that allows a person in a wheelchair to gain access to both sides of the shower table. A tub room has been constructed to provide compact patient bathing and hydromassage, and it is also accessible to people in wheelchairs. The staff support services include a locker room that has a shower accessible to people with disabilities so that staff members with mobility disorders can work in the burn center. Grade II braille writing marks all of the signs that designate the permanent rooms and spacing in the burn center and in the contiguous common use areas. The common use area has a restroom accessible to people with disabilities and a waiting room with a telephone communications system for people with mobility disorders or mobility impairment.     

Apolipoprotein(a) binds via its C-terminal domain to the protein core of the proteoglycan decorin. Implications for the retention of lipoprotein(a) in atherosclerotic lesions

Although it is known that lipoprotein(a) (Lp(a)) binds to proteoglycans, the mechanism for this binding has not been fully elucidated. In order to shed light on this subject, we examined the interactions of decorin, a proteoglycan with a well defined protein core and a single glycosaminoglycan (GAG) chain, with Lp(a) and derivatives, namely Lp(a) deprived of apo(a), or Lp(a-), free apo(a), and the two main proteolytic fragments, F1 and F2. By circular dichroism criteria, the decorin preparations used had the same secondary structure as that previously reported for native decorin. Authentic low density lipoprotein from the same human donor was used as a control. In a solid phase system, Lp(a-)and low density lipoprotein bound to decorin in a comparable manner. This binding required Ca2+/Mg2+ ions, was lysine-mediated, and was markedly decreased in the presence of GAG-depleted decorin, suggesting the ionic nature of the interaction likely involving apoB100 and the GAG component of decorin. Free apo(a) also bound to decorin; however, the binding was neither cation-dependent nor lysine-mediated, unaffected by sialic acid depletion of apo(a), and markedly decreased when either reduced and alkylated apo(a) or reduced and alkylated decorin was used in the assay. Of note, the binding of apo(a) was unaffected when it was incubated with a spectrally native decorin that had been renatured from either 4 M guanidine hydrochloride by extensive dialysis or cooled from 65 to 25 degrees C. On the other hand, the binding significantly increased when decorin was depleted of GAGs, which by themselves had no affinity for apo(a). The binding of apo(a) to the decorin protein core was also elicited by the C-terminal domain of apo(a), and it was favored by high NaCl concentrations, 1 to 2 M. No binding was exhibited by the N-terminal domain accounting for the lack of effect of apo(a) size polymorphism on the binding. In the case of whole Lp(a), the binding to immobilized decorin was mostly GAG-dependent and ionic in nature. A minor contribution by apo(a) was detected when GAG-depleted decorin was used in the assay. Our results indicate that the binding of Lp(a) to decorin involves interactions both electrostatic (apoB100-GAG) and hydrophobic (apo(a)-decorin protein core), and that the binding of apo(a) requires decorin protein core to be in its native state.     

Drug exposure and the acquisition and retention of a conditioned taste aversion

Two experiments examined the effects of preexposure and postexposure to a drug on the acquisition and retention of a conditioned taste aversion induced by that drug. Experiment 1 demonstrated that although drug preexposure attenuated a subsequent conditioned aversion, repeated taste-drug pairings reversed the initial attenuation effect and resulted in nearly complete avoidance of consumption. Experiment 2, however, demonstrated that drug postexposure did not alter a previously established conditioned aversion, although the postexposure experiences were effective in attenuating a conditioned aversion to a second novel solution. It was suggested that conditioned aversions are mediated by ACTH and that preexposure to a drug results in tolerance to that drug, yielding a smaller ACTH response and thereby a weaker aversion.     

Urinary excretion of apo(a) fragments in NIDDM patients

Lp(a), one of the most atherogenic lipoproteins, is believed to contribute significantly to vascular diseases in non-insulin-dependent diabetic (NIDDM) patients. Contradictive data have been published on these patients concerning plasma concentrations of Lp(a) and their relation to renal function. Since apo(a) fragments appear in urine, we measured urinary apo(a) in 134 NIDDM patients and 100 matched controls and related urinary apo(a) concentrations to plasma Lp(a) levels and kidney function. Plasma Lp(a) values were found to be significantly higher in NIDDM patients. NIDDM patients also secreted significantly more apo(a) into their urine as compared to control subjects. There was no correlation between creatinine clearance or albumin excretion and urinary apo(a) concentrations. Patients with macroalbuminuria exhibited a twofold higher apparent fractional excretion of apo(a) in comparison to patients with normal renal function. Urinary apo(a) values in both patients and control subjects were highly correlated to plasma Lp(a), yet no correlation was found with HbA1c or serum lipoproteins. It is concluded that urinary apo(a) excretion is correlated to plasma Lp(a) levels but not to creatinine clearance in patients suffering from NIDDM.     

Kringle 2 mediates high affinity binding of plasminogen to an internal sequence in streptococcal surface protein PAM

Many cells express receptors for plasminogen (Pg), although the responsible molecules in most cases are poorly defined. In contrast, the group A streptococcal surface protein PAM contains a domain with two 13-amino acid residue long repeated sequences (a1 and a2) responsible for Pg binding. Here we identify the region in Pg that interacts with PAM. A radiolabeled proteolytic plasminogen fragment containing the first three kringles (K1-K3) interacted with streptococci expressing PAM or a chimeric surface protein harboring the a1a2 sequence. In contrast, plasminogen fragments containing kringle 4 or kringle 5 and the activable serine proteinase domain failed to bind to PAM-expressing group A streptococci. A synthetic and a recombinant polypeptide containing the a1a2 sequence both bound to immobilized recombinant K2 (rK2) but not to rK1 or rK3. The interaction between the a repeat region and rK2 was reversible, and rK2 completely blocked the binding of Pg to the a1a2 region. The binding of the a repeat containing polypeptide to K2 occurred with an equilibrium association constant of 4.5 x 10(7) M-1, as determined by surface plasmon resonance, a value close to that (1.6 x 10(7) M-1) calculated for the a1a2-Pg interaction. Inhibition experiments suggested involvement of the lysine-binding site of K2 in the interaction. These data demonstrate that K2 contains the major Pg-binding site for PAM, providing the first well defined example of an interaction between an internal Pg-binding region in a protein and a single kringle domain.