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PubMed2004

Phosphaadamantanes as ligands for palladium catalyzed cross-coupling chemistry: library synthesis, characterization, and screening in the Suzuki coupling of alkyl halides and tosylates containing beta-hydrogens with boronic acids and alkylboranes.

A 15-member library of phosphaadamantane ligands has been prepared via P-arylation of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane. Screening of this tertiary phosphine collection has allowed for the rapid determination of the most suitable ligand, specifically 1,3,5,7-tetramethyl-6-(2,4-dimethoxyphenyl)-2,4,8-trioxa-6-phosphaadamantane, for facilitating Suzuki-type couplings of alkyl halides or tosylates containing beta-hydrogens with either boronic acids or alkylboranes.

Journal Article↗

PubMed2003

Tetraorganoindates as nucleophilic coupling partners in Pd-catalyzed cross-coupling reactions.

In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1 degree- and 2 degree-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency. [reaction: see text]

Journal Article↗

PubMed2004

Use of InCl(3) as a cocatalyst and a Cl(2)Pd(DPEphos)-P(2-furyl)(3) catalyst system for one-pot hydrometalation-cross-coupling and carbometalation-cross-coupling tandem processes.

One-pot conversion of alkynes to regio- and stereodefined alkenylmetals containing Al and Zr via hydrometalation or carbometalation followed by their Pd-catalyzed cross-coupling with (E)-ICH=CHBr or (E)-ICH=CHCl proceeds cleanly and selectively to give the corresponding 1-halo-1,3-dienes in excellent yields using a catalyst system consisting of Cl(2)Pd(DPEphos), DIBAL-H, and TFP (catalyst A) with InCl(3) as a cocatalyst.

Alkynes↗

PubMed1979

Specialized transducing phage lambda carrying the genes for coupling factor of oxidative phosphorylation of Escherichia coli: increased synthesis of coupling factor on induction of prophage lambda asn.

Studies were made of the synthesis of the coupling factor complex (F1--F0) of oxidative phosphorylation after prophage induction of a set of Escherichia coli strains lysogenic for defective transducing phage lambda asn, lambda uncA, or lambda bglC. The transducing phages had been isolated from a strain of E. coli carrying prophage lambda cI857 S7 within the bglB gene located near the unc gene cluster [Miki, T., Hiraga, S., Nagata, T. & Yura, T. (1978) Proc. Natl. Acad. Sci. USA 75, 5099--5103]. When lysogenic cells carrying lambda asn and lambda cI857 S7 were induced at high temperature, synthesis of the F1-ATPase portion of the complex increased to severalfold that of the noninduced cells. In contrast, no increase was observed upon thermoinduction of cells carrying lambda uncA or lambda bglC. The number of membrane sites that could bind purified F1-ATPase also increased significantly upon induction by lambda asn but not by lambda uncA or lambda bglC. In addition, F1-depleted membranes prepared from lambda asn-induced bacteria required more dicyclohexylcarbodiimide to seal the proton pathway than did those from noninduced bacteria. These results strongly suggest that lambda asn carries a set of bacterial genes coding for all the F1 polypeptides (the alpha, beta, gamma, delta, and probably the epsilon subunits) and at least some of the genes involved in formation of F0 polypeptides. Although lambda uncA carries the structural gene (uncA) for the alpha subunit of F1-ATPase, it apparently does not carry the whole set of F1--F0 genes.

Adenosine Triphosphatases↗

PubMed1998

Coexpression of ligand-gated P2X and G protein-coupled P2Y receptors in smooth muscle. Preferential activation of P2Y receptors coupled to phospholipase C (PLC)-beta1 via Galphaq/11 and to PLC-beta3 via Gbetagammai3.

P2 receptor subtypes and their signaling mechanisms were characterized in dispersed smooth muscle cells. UTP and ATP stimulated inositol 1,4,5-triphosphate formation, Ca2+ release, and contraction that were abolished by U-73122 and guanosine 5'-O-(3-thio)diphosphate, and partly inhibited (50-60%) by pertussis toxin (PTX). ATP analogs (adenosine 5'-(alpha, beta-methylene)triphosphate, adenosine 5'-(beta, gamma-methylene)triphosphate, and 2-methylthio-ATP) stimulated Ca2+ influx and contraction that were abolished by nifedipine and in Ca2+-free medium. Micromolar concentrations of ATP stimulated both Ca2+ influx and Ca2+ release. ATP and UTP activated Gq/11 and Gi3 in gastric and aortic smooth muscle and heart membranes, Gq/11 and Gi1 and/or Gi2 in liver membranes, and Go and Gi1-3 in brain membranes. Phosphoinositide hydrolysis stimulated by ATP and UTP was mediated concurrently by Galphaq/11-dependent activation of phospholipase (PL) C-beta1 and Gbetagammai3-dependent activation of PLC-beta3. Phosphoinositide hydrolysis was partially inhibited by PTX or by antibodies to Galphaq/11, Gbeta, PLC-beta1, or PLC-beta3, and completely inhibited by the following combinations (PLC-beta1 and PLC-beta3 antibodies; Galphaq/11 and Gbeta antibodies; PLC-beta1 and Gbeta antibodies; PTX with either PLC-beta1 or Galphaq/11 antibody). The pattern of responses implied that P2Y2 receptors in visceral, and probably vascular, smooth muscle are coupled to PLC-beta1 via Galphaq/11 and to PLC-beta3 via Gbetagammai3. These receptors co-exist with ligand-gated P2X1 receptors activated by ATP analogs and high levels of ATP.

Adenosine Monophosphate↗

PubMed1999

Pleiotropic coupling of G protein-coupled receptors to the mitogen-activated protein kinase cascade. Role of focal adhesions and receptor tyrosine kinases.

G protein-coupled receptors (GPCRs) initiate Ras-dependent activation of the Erk 1/2 mitogen-activated protein kinase cascade by stimulating recruitment of Ras guanine nucleotide exchange factors to the plasma membrane. Both integrin-based focal adhesion complexes and receptor tyrosine kinases have been proposed as scaffolds upon which the GPCR-induced Ras activation complex may assemble. Using specific inhibitors of focal adhesion complex assembly and receptor tyrosine kinase activation, we have determined the relative contribution of each to activation of the Erk 1/2 cascade following stimulation of endogenous GPCRs in three different cell types. The tetrapeptide RGDS, which inhibits integrin dimerization, and cytochalasin D, which depolymerizes the actin cytoskeleton, disrupt the assembly of focal adhesions. In PC12 rat pheochromocytoma cells, both agents block lysophosphatidic acid (LPA)- and bradykinin-stimulated Erk 1/2 phosphorylation, suggesting that intact focal adhesion complexes are required for GPCR-induced mitogen-activated protein kinase activation in these cells. In Rat 1 fibroblasts, Erk 1/2 activation via LPA and thrombin receptors is completely insensitive to both agents. Conversely, the epidermal growth factor receptor-specific tyrphostin AG1478 inhibits GPCR-mediated Erk 1/2 activation in Rat 1 cells but has no effect in PC12 cells. In HEK-293 human embryonic kidney cells, LPA and thrombin receptor-mediated Erk 1/2 activation is partially sensitive to both the RGDS peptide and tyrphostin AG1478, suggesting that both focal adhesion and receptor tyrosine kinase scaffolds are employed in these cells. The dependence of GPCR-mediated Erk 1/2 activation on intact focal adhesions correlates with expression of the calcium-regulated focal adhesion kinase, Pyk2. In all three cell types, GPCR-stimulated Erk 1/2 activation is significantly inhibited by the Src kinase inhibitors, herbimycin A and 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo-D-3,4-pyrimidine (PP1), suggesting that Src family nonreceptor tyrosine kinases represent a point of convergence for signals originating from either scaffold.

Animals↗

PubMed2001

Src and Pyk2 mediate G-protein-coupled receptor activation of epidermal growth factor receptor (EGFR) but are not required for coupling to the mitogen-activated protein (MAP) kinase signaling cascade.

The epidermal growth factor receptor (EGFR) and the non-receptor protein tyrosine kinases Src and Pyk2 have been implicated in linking a variety of G-protein-coupled receptors (GPCR) to the mitogen-activated protein (MAP) kinase signaling cascade. In this report we apply a genetic strategy using cells isolated from Src-, Pyk2-, or EGFR-deficient mice to explore the roles played by these protein tyrosine kinases in GPCR-induced activation of EGFR, Pyk2, and MAP kinase. We show that Src kinases are critical for activation of Pyk2 in response to GPCR-stimulation and that Pyk2 and Src are essential for GPCR-induced tyrosine phosphorylation of EGFR. By contrast, Pyk2, Src, and EGFR are dispensable for GPCR-induced activation of MAP kinase. Moreover, GPCR-induced MAP kinase activation is normal in fibroblasts deficient in both Src and Pyk2 (Src-/-Pyk2-/- cells) as well as in fibroblasts deficient in all three Src kinases expressed in these cells (Src-/-Yes-/-Fyn-/- cells). Finally, experiments are presented demonstrating that, upon stimulation of GPCR, activated Pyk2 forms a complex with Src, which in turn phosphorylates EGFR directly. These experiments reveal a role for Src kinases in Pyk2 activation and a role for Pyk2 and Src in tyrosine phosphorylation of EGFR following GPCR stimulation. In addition, EGFR, Src family kinases, and Pyk2 are not required for linking GPCRs with the MAP kinase signaling cascade.

Animals↗

PubMed2000

Investigation of the infertile couple: investigation of the infertile couple in the era of assisted reproductive technology: a time for reappraisal.

At present, several of the elements in widespread use in basic infertility testing are in dispute, marked variability exists in the work-up among specialists, and practice patterns are influenced both by modern assisted reproductive technologies (ART) and the increasing age of couples seeking help for infertility. This article is intended to stimulate the debate on a possible (lack of) usefulness of conventional methods of infertility evaluation in relation to both the modern techniques of assisted reproduction and the woman's age.

Coitus↗

PubMed2004

Chromosomal abnormalities in couples undergoing intracytoplasmic sperm injection. A study of 370 couples and review of the literature.

Intracytoplasmic sperm injection (ICSI) is now widely acknowledged as the most effective therapeutic approach to severe male infertility or unsuccessful in vitro fertilization. Cytogenetic investigations were performed in 370 females and 335 males prior to ICSI between January 1997 and April 2003. Nine men (2.7%) and 48 women (13%) had an abnormal karyotype, 44 females having some degree of numerical sex chromosome mosaicism. A review of the literature showed the prevalence of all types of chromosomal abnormalities to be much higher among male and female partners of couples examined prior to ICSI than among newborns. As most ICSIs are performed with ejaculated spermatozoa from oligospermic men, the distribution and the prevalence of the several types of chromosomal abnormalities are closer to those of oligospermic rather than azoospermic males. Our results combined with those of the literature stress the importance of karyotyping both male and female partners before ICSI is started. Adequate genetic counselling, possibly followed by prenatal diagnosis, should be offered if a chromosomal anomaly is detected.

Chromosome Aberrations↗

PubMed1990

Reconstitution of photophosphorylation in EDTA-treated thylakoids by added chloroplast coupling factor 1 (ATPase) and chloroplast coupling factor 1 lacking the delta subunit. Structural or functional?

Upon EDTA treatment thylakoids lose the chloroplast coupling factor 1 (CF1) part of their ATP synthase, CF0CF1, this exposes the proton channel, CF0. The previously established ability of the CF1 subunit delta to block the proton leak through CF0 prompted us to study (a) the ability of complete CF1 and, for comparison, CF1 lacking the delta subunit to block proton leakage and thereby to reconstitute structurally some photophosphorylation activity of the remaining CF0CF1 molecules and (b) their ability to form functional enzymes (functional reconstitution). In order to discriminate between activities caused by added CF1 or CF1(-delta) and remaining CF0CF1, the former were inhibited by chemical modification of subunit beta by N,N'-dicyclohexyl carbodiimide (DCCD) and the latter by tentoxin. We found that added CF1 acted both structurally and functionally while added DCCD-treated CF1 (DCCD-CF1) acted only structurally. In contrast to previous observations, CF1(-delta) and DCCD-CF1(-delta) also acted structurally although the reduction of proton leakage was smaller than with DCCD-CF1. Hence there was no functional reconstitution without subunit delta present. Previous studies indicated that only a small fraction of exposed CF0 is highly conducting and that this small fraction is distinguished by its high affinity for added CF1. The results of this study point rather to a wider distribution of CF0 conductance states and binding affinities.

Cell-Free System↗

PubMed1981

Dye coupling and possible electrotonic coupling in the guinea pig neocortical slice.

Iontophoretic injection of the fluorescent dye Lucifer Yellow CH into single neurons of guinea pig neocortical slices resulted in the staining of more than one cell. Dye-coupled neuronal aggregates were found only in the superficial cortical layers and were often organized in vertical columns. Antidromic stimuli evoked all-or-none, subthreshold depolarizations in some superficial cells. These potentials were not eliminated by manganese and did not collide with spikes originating in the soma, suggesting that they arose from electrotonic interaction between superficial cortical neurons.

Action Potentials↗

PubMed2000

Overexpression of G protein-coupled receptor kinase-2 in smooth muscle cells attenuates mitogenic signaling via G protein-coupled and platelet-derived growth factor receptors.

BACKGROUND: Neointimal hyperplasia involves activation of smooth muscle cells (SMCs) by several G protein-coupled receptor (GPCR) agonists, including endothelin-1, angiotensin II, thrombin, and thromboxane A(2). Signaling of many GPCRs is diminished by GPCR kinase-2 (GRK2). We therefore tested whether overexpression of GRK2 in SMCs could diminish mitogenic signaling elicited by agonists implicated in the pathogenesis of neointimal hyperplasia. METHODS AND RESULTS: Overexpression of GRK2 was achieved in primary rabbit aortic SMCs with a recombinant adenovirus. Control SMCs were infected with an empty vector adenovirus. Inositol phosphate responses to endothelin-1, angiotensin II, thrombin agonist peptide, and platelet-derived growth factor (PDGF) were attenuated by 37% to 72% in GRK2-overexpressing cells (P<0.01), but the response to the thromboxane A(2) analogue U46619 was unaffected. GRK2 also inhibited SMC [(3)H]thymidine incorporation stimulated not only by these agonists (by 30% to 60%, P<0.01) but also by 10% FBS (by 35%, P<0. 05). However, GRK2 overexpression had no effect on epidermal growth factor-induced [(3)H]thymidine incorporation. Agonist-induced tyrosine phosphorylation of the PDGF-beta receptor, but not the epidermal growth factor receptor, was reduced in GRK2-overexpressing SMCs. GRK2 overexpression also reduced SMC proliferation in response to endothelin-1, PDGF, and 10% FBS by 62%, 51%, and 29%, respectively (P<0.01), without any effect on SMC apoptosis. CONCLUSIONS: GRK2 overexpression diminishes SMC mitogenic signaling and proliferation stimulated by PDGF or agonists for several GPCRs. Gene transfer of GRK2 may therefore be therapeutically useful for neointimal hyperplasia.

Animals↗

PubMed1999

Quantification of G-Protein Coupled Receptor Internatilization Using G-Protein Coupled Receptor-Green Fluorescent Protein Conjugates with the ArrayScantrade mark High-Content Screening System.

Many G-protein coupled receptors (GPCRs) undergo ligand-dependent homologous desensitization and internalization. Desensitization, defined as a decrease in the responsiveness to ligand, is accompanied by receptor aggregation on the cell surface and internalization via clathrin-coated pits to an intracellular endosomal compartment. In this study, we have taken advantage of the trafficking properties of GPCRs to develop a useful screening method for the identification of receptor mimetics. A series of studies were undertaken to evaluate the expression, functionality, and ligand-dependent trafficking of GPCR-green fluorescent protein (GFP) fusion conjugates stably transfected into HEK 293 cells. These GPCR-GFP expressing cells were then utilized in the validation of the ArrayScantrade mark (Cellomicstrade mark, Pittsburgh, PA), a microtiter plate imaging system that permits cellular and subcellular quantitation of fluorescence in whole cells. These studies demonstrated our ability to measure the internalization of a parathyroid hormone (PTH) receptor-GFP conjugate after ligand treatment by spatially resolving internalized receptors. Internalization was time- and dose-dependent and appeared to be selective for PTH. Similar results were obtained for a beta(2)-adrenergic receptor (beta(2) AR)-GFP conjugate stably expressed in HEK 293 cells. The internalized GFP-labeled receptors were visualized as numerous punctate ³spots² within the cell interior. An algorithm has been developed that identifies and collects information about these spots, allowing quantification of the internalization process. Variables such as the receptor-GFP expression level, plating density, cell number per field, number of fields scanned per well, spot size, and spot intensity were evaluated during the development of this assay. The method represents a valuable tool to screen for receptor mimetics and antagonists of receptor internalization in whole cells rapidly.

Journal Article↗

PubMed1994

Studies on the preparation of bioactive lignans by oxidative coupling reaction. II. Oxidative coupling reaction of methyl(E)-3-(4,5-dihydroxy-2-methoxyphenyl)propenoate and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reaction of methyl (E)-3-4(4,5-dihydroxy-2-methoxyphenyl)propenoate (10), obtainable from esculetin, has been studied using silver oxide and potassium hexacyanoferrate(III). The products were separated, after acetylation, by silica gel column chromatography. 1-Aryl-1,2-dihydronaphthalene derivative 12 was obtained as a major product, accompanied by the benzo[kl]xanthene derivative 13. In the oxidation with silver oxide, a benzodioxane compound 14a was produced additionally in a minor amount. Thus, the course of the reaction differed notably from those of ferulic or caffeic acid derivatives. The compounds 11, 12, 13 and 14a were tested for their inhibitory effects on lipid peroxidation in rat brain homogenate and rat liver microsomes. They showed activities more effective than that of idebenone in rat brain homogenate, and were found to be more potent than benzofuran lignans 4 and 5, and much more potent than (+/-)-alpha-tocopherol in rat liver microsomes.

Animals↗

PubMed1994

Studies on the preparation of bioactive lignans by oxidative coupling reaction. III. Synthesis of polyphenolic benzofuran and coumestan derivatives by oxidative coupling reaction of methyl (E)-3-(4-hydroxy-2-methoxyphenyl)propenoate and their inhibitory effect on lipid peroxidation.

Three dihydrobenzofuran derivatives 11, 19, 22, a Pummerer's ketone 20 and a dimeric phenylpropanoid 24 were synthesized by oxidative coupling reaction of methyl (E)-3-(4-hydroxy-2-methoxyphenyl)propenoate 10, which was prepared from umbelliferone. The major product 11 was converted into its acetate 21 and schizotenuin D analogs 27, 28, 29. A new coumestan derivative 13 was synthesized from 29. Ten synthetic compounds thus obtained were tested for inhibitory effects on lipid peroxidation in rat brain homogenate.

Animals↗

PubMed1995

Studies on the preparation of bioactive lignans by oxidative coupling reaction. IV. Oxidative coupling reaction of methyl (E)-3-(3,4-dihydroxy-2-methoxyphenyl)propenoate and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reaction of the hydroxycinnamate 11 derived from daphnetin has been investigated. The reaction with silver oxide afforded, after acetylation, a dihydrobenzofuran derivative 17 and a benzodioxane derivative 16a as major products accompanied with a small amount of a bis(benzylidene)succinate 18 and a dihydronaphthalene 19, while the oxidation with iron(III) chloride gave the dihydronaphthalene derivative 20 corresponding to 19. The reaction with potassium hexacyanoferrate(III) and Na2CO3 produced, after acetylation, 16a and 19 in lower yields. The propensity for product formation in the reaction of 11 is discussed in relation to data for the reactions of hydroxycinnamate derivatives studied so far. The obtained compounds were tested for inhibitory effects on lipid peroxidation in rat brain homogenate and rat liver microsomes. In the rat brain homogenate the five compounds showed inhibitory activity more potent than that of idebenone. Compounds 17 and 20 were then tested in rat liver microsomes, and found to be more potent than schizotenuin A and much more potent than (+/-)-alpha-tocopherol.

Animals↗

PubMed1995

Studies on the preparation of bioactive lignans by oxidative coupling reaction. V. Oxidative coupling reaction of methyl (E)-3-(2-hydroxyphenyl)propenoate derivatives and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reactions of 2-hydroxycinnamates were investigated as a continuation of our previous studies on 4-hydroxy derivatives. The reaction of 2-hydroxycinnamate 1 and 2-hydroxy-4-methoxycinnamate 3 with silver oxide afforded polymerized lignin-like products, while that of 2-hydroxy-bis(methoxymethoxy)cinnamates 5 and 6, after acetylation, gave the enol acetates, 8 and 14, of oxotetrahydrobenzoxanthene derivatives, respectively. These two products were also obtained by the oxidation of 5 and 6 with potassium hexacyanoferrate(III). In the reactions of 5 and 6 with iron(III) chloride, the major products were the partially demethoxymethoxylated compounds 9 and 15, respectively. Thus, the course of the reactions in the oxidation of 2-hydroxycinnamates is quite different from that in the case of 4-hydroxy derivatives. The product 8 and the corresponding oxotetrahydrobenzoxanthene derivative were found to show moderate inhibitory effects upon lipid peroxidation.

Animals↗

PubMed2002

The transition to marriage and changes in alcohol involvement among black couples and white couples.

OBJECTIVE: The purpose of this study was to assess whether the reduction in alcohol involvement typically associated with the transition to marriage differs for blacks, compared with whites. METHOD: Couples (n = 248, white; n = 100, black) in which both partners were entering into their first marriage were assessed at the time of marriage, their first anniversary and their second anniversary. At each wave, husbands and wives were each given an identical questionnaire packet to complete independently at home and a postage-paid envelope for packet return. A broad range of constructs was assessed, including personality characteristics, relationship functioning, drinking behaviors and social network characteristics. Alcohol involvement measures included average daily volume of consumption, frequency of heavy drinking, alcohol-related problems and alcohol dependence. RESULTS: Whites decreased their frequency of heavy drinking and alcohol dependence over the early marital years, whereas blacks remained relatively stable. Alcohol problem trajectories were similar for wives of both races. White men reported a decline in alcohol problems, whereas black men reported an increase in problems over the first 2 years of marriage. Racial differences in the alcohol involvement trajectories could not be attributable to racial differences in family formation or demographic factors. CONCLUSIONS: Findings suggest limited generalizability of previous research, indicating a reduction in alcohol involvement associated with the transition to marriage. Individuals who continue to drink heavily after this transition may be at an especially high risk for the subsequent development of serious alcohol and marital problems.

Adolescent↗