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PubMed1998

Interaction of human tissue plasminogen activator (t-PA) with pregnancy zone protein: a comparative study with t-PA-alpha2-macroglobulin interaction.

Human pregnancy zone protein (PZP) is a major pregnancy-associated plasma protein strongly related to alpha2-macroglobulin (alpha2-M). Interactions of tissue plasminogen activator (t-PA) with PZP and alpha2-M were both investigated in vitro and the complexes were analyzed by polyacrylamide gel electrophoresis (PAGE). The results demonstrated that PZP-t-PA complex formation was evident within 1 h of incubation, whereas alpha2-M-t-PA complexes were formed after 18 h. Conclusions were supported by the following evidence: (i) PZP and alpha2-M complexes revealed changes of the mobility rate in non-denaturing PAGE, similar to those observed with alpha-Ms-chymotrypsin; (ii) both PZP and alpha2-M formed complexes of molecular size >360 kDa by SDS-PAGE, in accordance with the covalent binding of t-PA, which was previously reported for other proteinases; and (iii) PZP underwent a specific cleavage of the bait region with appearence of fragments of 85-90 kDa as judged by reducing SDS-PAGE. In contrast, the proteolytic attack on alpha2-M was found to occur more slowly, requiring several hours of incubation with t-PA for generation of an appreciable amount of fragments of 85-90 kDa. The appearance of free SH-groups of alpha-Ms was further investigated by titration with 5, 5'-dithiobis(2-nitrobenzoic acid). The maximal level of SH-groups raised was 3.9 mol/mol of PZP and 3.5 mol/mol of alpha2-M, indicating approximately one SH-group for each 180-kDa subunit. Finally, t-PA activity in PZP-t-PA complex was evaluated by measuring the hydrolysis of the chromogenic substrate Flavigen t-PA. Our results revealed that prolongation of the incubation period of this complex increased t-PA-mediated hydrolysis of Flavigen t-PA until a plateau was reached, approximately between 60 and 120 min. The present study suggests that PZP, by binding to t-PA, may contribute to the control of the activity of proteinases derived from fibrinolytic systems.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Medical Communication Behavior System. An interactional analysis system for medical interactions.

The study assessed the psychometric properties of the Medical Communication Behavior System. This observation system records time spent by the physicians and patients on specific behaviors in the categories of informational, relational, and negative situation behaviors by using hand-held electronic devices. The study included observations of 101 genetic counseling sessions and also assessed the outcome measures of patient knowledge and satisfaction. In addition, 41 of the sessions were rated using the Roter Interactional Analysis System, and 20 additional control subjects completed the post-counseling information without being observed to examine the effects of recording the session. Results showed good interobserver reliability, and evidence of concurrent, construct, and predictive validity. No differences were found between the observed and unobserved groups of any of the outcome measures.

Behavior↗
PubMed1995

Altered vitamin D metabolism and receptor interaction with the target genes in renal failure: calcitriol receptor interaction with its target gene in renal failure.

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with the vitamin D response elements of the target genes. Although decreased VDR concentration in renal failure could diminish the biological action of calcitriol, recent study indicates that uremic toxins could modify the VDR DNA-binding domain and inhibit the binding of the VDR to the vitamin D response elements. The latter reaction could also account for end-organ resistance in renal failure. The inhibitory action of uremic toxins has been tested in vivo by a method using gene transcription. It was demonstrated that uremic ultrafiltrate blocks calcitriol-induced chloramphenical acetyltransferase reporter constructs containing a synthetic vitamin D response element in JEG-3 cells. Taken together, the findings indicate that uremia could underlie the calcitriol resistance in renal failure. The modification of the VDR may involve Schiff base formation between lysine residues of the VDR DNA-binding domain and reactive aldehydes accumulated in uremia. This suggestion is on the basis of the finding that the VDR and other steroid receptors form Schiff bases with pyridoxal 5'-phosphate and weaken the binding of these receptors to the DNA cellulose.

Animals↗
PubMed2007

Interaction between allelic variation in IL12B and CCR5 affects the development of AIDS: IL12B/CCR5 interaction and HIV/AIDS.

OBJECTIVE: IL-12 is involved in immune surveillance and response that links the innate and adaptive arms of the immune system. Among its many effects, IL-12 increases the cell surface expression of the CCR5 co-receptor for R5 strains of HIV-1, which are predominantly involved in HIV-1 transmission and spread. In the present study we investigated the effect of epistasis between allelic variants of CCR5 and IL12B on the susceptibility to HIV-1 infection and HIV-1 disease progression. METHODS: HIV-1-positive patients were genotyped for IL12Bpro from two groups of HIV-1 seroincident patients from Western Australia (n = 101 and 200), longitudinal clinical data were available for one of the Western Australian cohorts for a period of over 12 years and a group of seroprevalent individuals from Sydney (n = 112). A group of ethnically matched healthy volunteers (n = 200) was also genotyped as controls. Comparison of allele frequencies between HIV-1 patients and controls was performed to determine the influence on susceptibility to HIV-1 infection, and regression analysis was used to determine the influence on disease progression. RESULTS: Individuals positive for CCR5Delta32 and who carry the IL12Bpro1.1 genotype were underrepresented across all three independent HIV-1-positive cohorts [odds ratio 0.5; 95% confidence interval (CI) 0.28-0.97; P = 0.038]. CCR5wt/wt and IL12Bpro2.2 individuals progressed to AIDS at a significantly faster rate than other CCR5 and IL12Bpro groups (hazards ratio 3.24; 95% CI 1.9-15.1; P = 0.002). CONCLUSION: Epistatic interaction between allelic variants of CCR5 and IL12Bpro exert a significant influence on the clinical outcome of HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Dilute Fermi gas in quasi-one-dimensional traps: from weakly interacting fermions via hard core bosons to a weakly interacting Bose gas.

We study equilibrium properties of a cold two-component Fermi gas confined in a quasi-one-dimensional trap of the transverse size l(perpendicular). In the dilute limit (nl(perpendicular)<<1, where n is the 1D density) the problem is exactly solvable for an arbitrary 3D fermionic scattering length aF. When l(perpendicular)/aF goes from -infinity to +infinity, the system successively passes three regimes: weakly interacting Fermi gas, hard core Bose gas, and weakly coupled Bose gas. The regimes are separated by two crossovers at aF approximately +/-nl2(perpendicular). In conclusion, we discuss experimental implications of these results.

Journal Article↗
PubMed2006

Limits on spin-independent interactions of weakly interacting massive particles with nucleons from the two-tower run of the cryogenic dark matter search.

We report new results from the Cryogenic Dark Matter Search (CDMS II) at the Soudan Underground Laboratory. Two towers, each consisting of six detectors, were operated for 74.5 live days, giving spectrum-weighted exposures of 34 (12) kg d for the Ge (Si) targets after cuts, averaged over recoil energies 10-100 keV for a weakly interacting massive particle (WIMP) mass of 60 GeV/c2. A blind analysis was conducted, incorporating improved techniques for rejecting surface events. No WIMP signal exceeding expected backgrounds was observed. When combined with our previous results from Soudan, the 90% C.L. upper limit on the spin-independent WIMP-nucleon cross section is 1.6 x 10(-43) cm2 from Ge and 3 x 10(-42) cm2 from Si, for a WIMP mass of 60 GeV/c2. The combined limit from Ge (Si) is a factor of 2.5 (10) lower than our previous results and constrains predictions of supersymmetric models.

Journal Article↗
PubMed2000

The geometry of metal-ligand interactions relevant to proteins. II. Angles at the metal atom, additional weak metal-donor interactions.

Geometrical data which could be of relevance in the structure determination, structure refinement, assessment or understanding of metalloproteins have been extracted from the Cambridge Structural Database (CSD). The CSD contains crystallographic data from 'small-molecule' structures determined by X-ray or neutron diffraction to an accuracy and precision much better than that of most current protein structure determinations. Structures of Mg, Mn, Fe, Cu and Zn complexes with ligands whose donor atoms may be only N, O, S or Cl have been selected and analysed in terms of the geometry of the metal coordination group - octahedral, tetrahedral, tetragonal pyramidal etc. The r.m.s. deviation of all the interbond angles around the metal atom provides a measure, delta, of the deviation from ideal geometry. Average values of delta are tabulated for the different metals in each type of complex. For simple non-chelated complexes of Mn, Fe and Zn, distortions of up to 5 degrees in octahedral complexes and 10 degrees in tetrahedral complexes are found to be normal and seem likely to be a consequence of packing effects, ligand bulk or intramolecular effects. Substantially larger distortions are found for some other metals and geometries and are common for chelated complexes. Brief comments on six-, seven- and eight-coordinate Ca complexes are included. Tables are also presented showing that for four- and five-coordinate complexes of Zn and Cu it is quite common to find additional weakly coordinated ligands, usually with N or O donor atoms and with M.N,O distances longer than a normal bond length but shorter than a van der Waals contact, e.g. in the range 2.4-3.0 A for Zn and 2.6-3.0 A for Cu. Although the contributions to bond valency or bonding energy of such interactions may not be great, their effect on geometry can be considerable; they can, for example, cause much larger distortions of tetrahedral Zn complexes than indicated above.

Chelating Agents↗
PubMed1990

Horizontal Interactions in Cat Striate Cortex: III. Ectopic Receptive Fields and Transient Exuberance of Tangential Interactions.

In this study the developmental changes of intracortical connectivity are related to changes of cortical receptor fields (RFs). The RFs of striate cortex neurons of 4- to 8.5-week-old kittens, reared under normal conditions (NR) or in a selective visual environment (SE), were analysed quantitatively and compared with adult cats. To unmask weak inputs from outside the conventional RF (CRF), cell excitability was raised by iontophoretic application of glutamate (GLU) and/or bicuculline methiodide (BIC) or by light stimulation of the CRF. Both the dominant discharge region (DDR) and the total RF (TRF) area were significantly larger in NR and SE kittens than in adult cats. Moreover, in kittens 18% of the cells had additional ectopic fields that were excitatory, had similar orientation preferences as the CRF, and ranged 4 degrees to 23 degrees from the centre of the CRF. In 74% of the cases the ectopic fields were direction-selective and 70% of them preferred stimuli moving toward the CRF. Ectopic fields occurred mainly in supragranular cells, were similarly frequent in simple and complex cells and slightly more frequent in SE (20.7%) than in NR (13.3%) kittens. In adult cats only one of 83 cells tested had an ectopic field. It is concluded that the age-dependent decrease in the RF size, the laminar distribution of cells having an ectopic RF, and the numerical reduction of these cells with age correlate well with the organization and postnatal pruning of tangential projections, suggesting that these contribute to the elaboration of specific response properties. Moreover, the authors infer from the early presence and from the selectivity of ectopic fields that the system of horizontal intrinsic connections mediates far-reaching, excitatory interactions between cortical neurons with similar functional properties and serves as a substrate for the processing of global aspects of visual patterns.

Journal Article↗
PubMed1972

Interaction in the cerebral metabolism of the biogenic amines. Effect of phenelzine on this interaction.

1. Chronic administration of phenelzine to dogs caused the concentrations of homovanillic acid (HVA) in c.s.f. from both the lateral ventricle and cisterna magna to fall to new low levels at which they were maintained.2. After 10-12 days treatment with phenelzine the caudate nucleus had elevated concentrations of dopamine and 3-methoxytyramine and lowered concentrations of 3,4-dihydroxyphenylacetic acid and HVA.3. Intravenous administration of tryptophan to dogs pretreated with phenelzine caused in c.s.f. an increase in the concentrations of HVA and in the caudate nucleus a decrease in dopamine concentration and an increase in the concentrations of its metabolites, 3-methoxytyramine, 3,4-dihydroxyphenylacetic acid and HVA.4. A model is proposed for the cerebral metabolism of dopamine and some of the points at which tryptophan and its metabolites may interact with dopamine metabolism are discussed.

Animals↗
PubMed1980

The interaction of human haemoglobin with allosteric effectors as a model for drug-receptor interactions.

1 The release of bound oxygen from oxyhaemoglobin by allosteric effectors is considered as a model for those drug-receptor interactions where the primary response to agonist binding is the release of a second messenger species. 2 A theory of haemoglobin oxygenation, based on the two-state model of Monod, Wyman & Changeux (1965) is used to predict the relationship between 'pharmacological' response and dose of agonist. This relationship is the same as that derived from classical pharmacological occupancy theory. 3 The potency of an agonist is a weighted average of its affinities for the two conformational states of the receptor. 4 The efficacy of an agonist depends not only upon its binding to one of the two conformational states, but also on its ability to alter the functional properties of that state by lowering the affinity of the state for the second messenger. 5 2,3-Diphosphoglycerate and adenosine triphosphate are approximately equipotent and of similar efficacy, but inositol hexaphosphate is about 500 times more potent and has a higher efficacy.

Adenosine Triphosphate↗
PubMed1978

Specificity of salivary-bacterial interactions: role of terminal sialic acid residues in the interaction of salivary glycoproteins with Streptococcus sanguis and Streptococcus mutans.

Four highly purified salivary glycoproteins were used to study salivary-bacterial interactions. One pair of glycoproteins was mucin-like in composition, whereas the second pair was not. By an agglutination assay, it was found that only the mucin-glycoproteins agglutinated Streptococcus sanguis and S. mutans. Removal of sialic acid from these molecules resulted in a loss of agglutination of S. sanguis but not of S. mutans. The agglutination phenomenon was shown to require a salivary macromolecule of at least 150,000 daltons.

Agglutination↗
PubMed1994

Bacterium-host cell interactions at the cellular level: fluorescent labeling of bacteria and analysis of short-term bacterium-phagocyte interaction by flow cytometry.

Flow cytometry is a potentially powerful tool for analyzing the interactions of facultative intracellular bacteria and macrophages on a cellular level, particularly when fluorochromes are used to label the bacteria. We labeled Listeria monocytogenes and Salmonella typhimurium with a lipophilic dye, PKH-2, and used flow cytometry to investigate phagocytosis by J774A.1 cells and short-term bacterial survival. Labeled and unlabeled bacteria were identical in terms of viability, growth kinetics, and survival within macrophages, although recovery per macrophage was much greater for L. monocytogenes than for S. typhimurium. Using L. monocytogenes as a prototypical facultative intracellular bacterium, we estimated bacterial survival during phagocytosis on the basis of linear fluorescence measurements of infected J774A.1 cells and recovery of L. monocytogenes from sorted cells. The lower percentage of surviving L. monocytogenes in macrophages containing higher bacterial loads indicated the accumulation of nonviable bacteria within phagocytes. Removal of the external source of viable bacteria by washes and gentamicin treatment reduced the percentage of surviving intracellular L. monocytogenes to a baseline level, and all baseline levels were similar, regardless of bacterial load. Listeria enrichment recoveries, derived from individually sorted J774A.1 cells, demonstrated the heterogeneity of macrophages in intracellular bacterial survival, especially within heavily infected cells. These results indicated that survival of L. monocytogenes was dependent on the adaptations of a small fraction of bacteria within a population of macrophages which permit intracellular growth.

Adaptation, Physiological↗
PubMed2004

Global nature of dynamic protein-chromatin interactions in vivo: three-dimensional genome scanning and dynamic interaction networks of chromatin proteins.

Genome structure and gene expression depend on a multitude of chromatin-binding proteins. The binding properties of these proteins to native chromatin in intact cells are largely unknown. Here, we describe an approach based on combined in vivo photobleaching microscopy and kinetic modeling to analyze globally the dynamics of binding of chromatin-associated proteins in living cells. We have quantitatively determined basic biophysical properties, such as off rate constants, residence time, and bound fraction, of a wide range of chromatin proteins of diverse functions in vivo. We demonstrate that most chromatin proteins have a high turnover on chromatin with a residence time on the order of seconds, that the major fraction of each protein is bound to chromatin at steady state, and that transient binding is a common property of chromatin-associated proteins. Our results indicate that chromatin-binding proteins find their binding sites by three-dimensional scanning of the genome space and our data are consistent with a model in which chromatin-associated proteins form dynamic interaction networks in vivo. We suggest that these properties are crucial for generating high plasticity in genome expression.

Animals↗
PubMed2004

Central and peripheral visual interactions in disparity-induced vergence eye movements: I. Spatial interaction.

PURPOSE: To evaluate the interaction between central and peripheral disparities in the initiation of vergence eye movements. METHODS: Eye movements were recorded in eight normal subjects using an infrared limbus tracker. Three-dimensional visual stimuli were back projected onto a tangent screen by using two liquid crystal display (LCD) projectors through crossed polarizers. The central target was a vertical bar, which always jumped from 2 to 1 m. The peripheral target was a random-dot pattern that jumped from 2 to 0.75, 1, or 1.5 m (near planes), 2 m (no change), or 3 m (far plane) simultaneously with the central target jump. Latency, amplitude at 150 ms, and average amplitude over 1 to 2 seconds after vergence onset; peak velocity; and the main-sequence relationship of the initial vergence response were calculated. How far the central target appeared to jump was scored subjectively. RESULTS: In half of the subjects, there was a clear effect of the peripheral disparity on the dynamics of the vergence response to the central disparity. The amplitude of vergence at 150 ms, as an index of open-loop gain, was significantly greater when the peripheral target moved closer, but steady state amplitude (average during 1-2 seconds) did not change, and the vergence latency was significantly greater when the peripheral target jumped away. There was no obvious relationship between the perceived amount of movement of the central target and the parameters of the dynamic properties of the vergence response. CONCLUSIONS: Peripheral disparity can modulate the dynamics of the initial vergence response to a central disparity and is probably independent of the perception of motion in depth.

Adult↗
PubMed2000

Cell-cell interactions in synovitis. Interactions between T lymphocytes and synovial cells.

Mechanisms whereby T lymphocytes contribute to synovial inflammation in rheumatoid arthritis are poorly understood. Here we review data that indicate an important role for cell contact between synovial T cells, adjacent macrophages and fibroblast-like synoviocytes (FLS). Thus, T cells activated by cytokines, endothelial transmigration, extracellular matrix or by auto-antigens can promote cytokine, particularly TNF alpha, metalloproteinase production by macrophages and FLS through cell-membrane interactions, mediated at least through beta-integrins and membrane cytokines. Since soluble factors thus induced may in turn contribute directly to T cell activation, positive feedback loops are likely to be created. These novel pathways represent exciting potential therapeutic targets.

Animals↗
PubMed2005

Transcriptional intermediary factor 1alpha mediates physical interaction and functional synergy between the coactivator-associated arginine methyltransferase 1 and glucocorticoid receptor-interacting protein 1 nuclear receptor coactivators.

In previous studies transcriptional intermediary factor 1alpha (TIF1alpha) was identified as a direct binding partner and potential transcriptional coactivator for nuclear receptors (NRs) but its overexpression inhibited, rather than enhanced, transcriptional activation by NRs. Here we show that TIF1alpha bound to and enhanced the function of the C-terminal activation domain (AD) of coactivator associated arginine methyltransferase 1 (CARM1) and the N-terminal AD of glucocorticoid receptor-interacting protein 1 (GRIP1). Furthermore, although TIF1alpha had little or no NR coactivator activity by itself, it cooperated synergistically with GRIP1 and CARM1 to enhance NR-mediated transcription. Inhibition of endogenous TIF1alpha expression reduced transcriptional activation by the GRIP1 N-terminal domain but not by the CARM1 C-terminal domain, suggesting that TIF1alpha may be more important for mediating the activity of the former than the latter. Reduction of endogenous TIF1alpha levels also compromised the androgen-dependent induction of an endogenous target gene of the androgen receptor. Finally, TIF1alpha formed a ternary complex with the GRIP1 N-terminal and CARM1 C-terminal domains. Thus, we conclude that TIF1alpha cooperates with NR coactivators GRIP1 and CARM1 by forming a stable ternary complex with them and enhancing the AD function of one or both of them.

Animals↗
PubMed2006

Angiotensin II-induced neural differentiation via angiotensin II type 2 (AT2) receptor-MMS2 cascade involving interaction between AT2 receptor-interacting protein and Src homology 2 domain-containing protein-tyrosine phosphatase 1.

Angiotensin II (Ang II) type 2 (AT2) receptors are abundantly expressed not only in the fetal brain where they probably contribute to brain development, but also in pathological conditions to protect the brain against stroke; however, the detailed mechanisms are unclear. Here, we demonstrated that AT2 receptor signaling induced neural differentiation via an increase in MMS2, one of the ubiquitin-conjugating enzyme variants. The AT2 receptor, MMS2, Src homology 2 domain-containing protein-tyrosine phosphatase 1 (SHP-1), and newly cloned AT2 receptor-interacting protein (ATIP) were highly expressed in fetal rat neurons and declined after birth. Ang II induced MMS2 expression in a dose-dependent manner, reaching a peak after 4 h of stimulation, and this effect was enhanced with AT1 receptor blocker, valsartan, but inhibited by AT2 receptor blocker PD123319. Moreover, we observed that an AT2 receptor agonist, CGP42112A, alone enhanced MMS2 expression. Neurons treated with small interfering RNA of MMS2 failed to exhibit neurite outgrowth and synapse formation. Moreover, the increase in AT2 receptor-induced MMS2 mRNA expression was enhanced by overexpression of ATIP but inhibited by small interfering RNA of SHP-1 and overexpression of catalytically dominant-negative SHP-1 or a tyrosine phosphatase inhibitor, sodium orthovanadate. After AT2 receptor stimulation, ATIP and SHP-1 were translocated into the nucleus after formation of their complex. Furthermore, increased MMS2 expression mediates the inhibitor of DNA binding 1 proteolysis and promotes DNA repair. These results provide a new insight into the contribution of AT2 receptor stimulation to neural differentiation via transactivation of MMS2 expression involving the association of ATIP and SHP-1.

Angiotensin II↗
PubMed1988

Tissue interactions and cell differentiation: neurone-sensory cell interaction during otic development.

Statoacoustic ganglion neurones (SAG) are produced by the same group of cells (otic placode) that produce all of the receptor cells that populate the sensory areas of the inner ear. The observation that ingrowth of SAG neurites to presumptive sensory areas of the inner ear preceded cytodifferentiation of those receptor cells suggested a causal relationship. Results from in vivo, in ovo and in vitro studies do not support a causal relationship. These studies support the hypothesis that the programme for labyrinthine sensory cell differentiation is intrinsic and does not require the extrinsic stimulus of neuronal interaction to trigger its expression. In contrast, developing statoacoustic ganglion neurones appear to require a trophic influence that is supplied by either their peripheral or central target tissues for their survival and maturation in vitro. A mechanism for the ingrowth of SAG dendrites to their appropriate target sites within the inner ear proposes that attractant fields produced by areas of differentiating sensory cells act to guide the nerve growth cones of ingrowing SAG neurites to the appropriate tissues. Preliminary results from a heterochronic series of SAG implants to common age otocysts suggest that these SAG neurones are capable of responding to the attractant fields which are produced by presumptive labyrinthine sensory epithelium over an extended period of otic development. Both in ovo and in vitro studies suggest that spatiotemporal patterns of extracellular matrix molecules may be important components of the attractant fields which are produced by the sensory areas of the developing inner ear and may ultimately result in the specificity of their neuronal connections.

Animals↗