Complex Ib Research Articles

Paradigms in Qualitative IB Research: Trends, Analysis and Recommendations

This paper examines trends, challenges and opportunities in terms of research methodologies in qualitative IB research. In particular, it examines trends for the dominant (positivism/(post)positivism) paradigm versus alternative paradigms (i.e., social constructivism, critical realism and interpretivism) and provides a comparative analysis of data collection and methods. Using mixed methods to collect and analyze data on qualitative articles published in International Business Review, Journal of International Business Studies, Journal of World Business, and Management International Review, we examine trends and differences between the dominant and alternative paradigms and use qualitative content analysis to investigate how alternative paradigm papers are conceptualized and presented. Moreover, we interview authors of non-positivist papers to gain in-depth understanding of the findings. We reveal differences across the paradigms and provide evidence of paradigmatic fit between methods and data collection techniques for the dominant paradigm, but more variation for alternative paradigms. Lastly, we provide prescriptions for IB scholars in terms of methodology diversity and how complex IB phenomena can be pursued vis-a-vis alternative paradigms.

Towards Clinical Translation of CD8+ Regulatory T Cells Restricted by Non-Classical Major Histocompatibility Complex Ib Molecules.

In central lymphoid tissues, mature lymphocytes are generated and pathogenic autoreactive lymphocytes are deleted. However, it is currently known that a significant number of potentially pathogenic autoreactive lymphocytes escape the deletion and populate peripheral lymphoid tissues. Therefore, peripheral mechanisms are present to prevent these potentially pathogenic autoreactive lymphocytes from harming one’s own tissues. One such mechanism is dictated by regulatory T (Treg) cells. So far, the most extensively studied Treg cells are CD4+Foxp3+ Treg cells. However, recent clinical trials for the treatment of immune-mediated diseases using CD4+ Foxp3+ Treg cells met with limited success. Accordingly, it is necessary to explore the potential importance of other Treg cells such as CD8+ Treg cells. In this regard, one extensively studied CD8+ Treg cell subset is Qa-1(HLA-E in human)-restricted CD8+ Treg cells, in which Qa-1(HLA-E) molecules belong to a group of non-classical major histocompatibility complex Ib molecules. This review will first summarize the evidence for the presence of Qa-1-restricted CD8+ Treg cells and their regulatory mechanisms. Major discussions will then focus on the potential clinical translation of Qa-1-restricted CD8+ Treg cells. At the end, we will briefly discuss the current status of human studies on HLA-E-restricted CD8+ Treg cells as well as potential future directions.

Host Expression of the CD8 Treg/NK Cell Restriction Element Qa-1 is Dispensable for Transplant Tolerance

Disruption of the non-classical Major Histocompatibility Complex (MHC) Ib molecule Qa-1 impairs CD8 Treg and natural killer (NK) cell function and promotes a lupus-like autoimmune disease. This immune perturbation would be expected to enhance anti-transplant responses and impair tolerance induction, but the effect of Qa-1 deficiency on the transplant response has not been previously reported. Qa-1 deficiency enhanced CD4 TFH and germinal center (GC) B cell numbers in naïve mice and hastened islet allograft rejection. Despite enhanced immunity in B6.Qa-1−/− mice, these mice did not generate an excessive primary CD4 TFH cell response nor an enhanced alloantibody reaction. Both CD8 Tregs and NK cells, which often regulate other cells through host Qa-1 expression, were targets of anti-CD45RB therapy that had not been previously recognized. However, B6.Qa-1−/− mice remained susceptible to anti-CD45RB mediated suppression of the alloantibody response and transplant tolerance induction to mismatched islet allografts. Overall, despite enhanced immunity as demonstrated by augmented CD4 TFH/GC B cell numbers and hastened islet allograft rejection in naïve 12-week old Qa-1 deficient mice, the CD8 Treg/NK cell restriction element Qa-1 does not regulate the primary cellular or humoral alloresponse and is not required for long-term transplant tolerance.

Targeting Non-classical Myelin Epitopes to Treat Experimental Autoimmune Encephalomyelitis.

Qa-1 epitopes, the peptides that bind to non-classical major histocompatibility complex Ib Qa-1 molecules and are recognized by Qa-1-restricted CD8+ regulatory T (Treg) cells, have been identified in pathogenic autoimmune cells that attack myelin sheath in experimental autoimmune encephalomyelitis (EAE, an animal model for multiple sclerosis [MS]). Additionally, immunization with such epitopes ameliorates the EAE. However, identification of such epitopes requires knowledge of the pathogenic autoimmune cells which are largely unknown in MS patients. Hence, we asked whether the CD8+ Treg cells could directly target the myelin sheath to ameliorate EAE. To address this question, we analyzed Qa-1 epitopes in myelin oligodendrocyte glycoprotein (MOG that is a protein in myelin sheath). Here, we report identification of a MOG-specific Qa-1 epitope. Immunization with this epitope suppressed ongoing EAE, which was abrogated by CD8+ T cell depletion. Additionally, the epitope immunization activated the epitope-specific CD8+ T cells which specifically accumulated in the CNS-draining cervical lymph nodes. Finally, CD8+ T cells primed by the epitope immunization transferred EAE suppression. Hence, this study reveals a novel regulatory mechanism mediated by the CD8+ Treg cells. We propose that immunization with myelin-specific HLA-E epitopes (human homologues of Qa-1 epitopes) is a promising therapy for MS.

Isomers of the acetic acid-water complex trapped in an argon matrix.

The complexes of acetic acid (AcOH) with water have been studied using FTIR matrix isolation spectroscopy and DFT/B3LYP, DFT/B3LYP-D, and MP2 calculations with the aug-cc-pVTZ basis set. The AcOH/H2O/Ar matrices were prepared in two different ways. In one set of experiments, the vapor above a solid AcOH sample, cooled to 203 K, was diluted with H2O/Ar mixture in the vacuum chamber of the cryostat, and the mixture was solidified on the target. In the second set of experiments, the matrix was prepared by simultaneous deposition of AcOH/Ar and H2O/Ar mixtures at room temperature. The first method of matrix preparation strongly favors the formation of the "acyclic" higher energy AcOH-H2O complex I(B) compared to the second one. Warming of matrices containing the higher energy complex, I(B), from 11 to 39 K, results in the decrease of I(B) concentration and formation of the lowest energy cyclic complex I(A). The calculations indicate that I(B) is formed by an O-H···O hydrogen bond between the carbonyl oxygen and a water O-H group and, additionally, by a weak interaction between one of the methyl group hydrogen atoms and the water oxygen atom. The cyclic complex I(A) has a six-membered ring involving two O-H···O bonds. An activation energy of 0.94, 1.71, and 1.38 kcal mol(-1) was calculated for the I(B) → I(A) rearrangement at the B3LYP, B3LYP-D, and MP2 levels of theory, respectively. Van't Hoff plots for the association of H2O and AcOH leading to formation of the complexes I(A) and I(B) are presented and discussed. Evidence is also given for the formation of the AcOH-(H2O)2 and (AcOH)2-H2O complexes in the matrices. A potential atmospheric impact of the enhanced formation of the higher energy I(B) complex at low temperatures is discussed.

Induction of anti-viral genes during acute infection with Viral hemorrhagic septicemia virus (VHSV) genogroup IVa in Pacific herring ( Clupea pallasii)

Infection with the aquatic rhabdovirus Viral hemorrhagic septicemia virus (VHSV) genogroup IVa results in high mortality in Pacific herring ( Clupea pallasii) and is hypothesized to be a potential limiting factor for herring recovery. To investigate anti-viral immunity in the Pacific herring, four immune response genes were identified: the myxovirus resistance ( Clpa-Mx), a major histocompatibility complex IB (named Clpa-UAA.001), the inducible immunoproteosome subunit 9 ( Clpa-PSMB9) and the neutrophil chemotactic factor ( Clpa-LECT2). Reverse transcriptase quantitative PCR (RT-qPCR) assays were developed based on these gene sequences to investigate the host immune response to acute VHSV infection following both injection and immersion challenge. Virus levels were measured by both plaque assay and RT-qPCR and peaked at day 6 during the 10-day exposure period for both groups of fish. The interferon stimulated genes ( Clpa-Mx, −UAA.001, and −PSMB9) were significantly up-regulated in response to VHSV infection at both 6 and 10 days post-infection in both spleen and fin. Results from this study indicate that Pacific herring mount a robust, early antiviral response in both fin and spleen tissues. The immunological tools developed in this study will be useful for future studies to investigate antiviral immunity in Pacific herring.

Synthesis, structure, and 13C and 31P CP/MAS NMR of crystalline modifications of the polynuclear thallium(I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}] n

Two crystalline modifications (Ia and Ib) of the polynuclear thallium (I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}]n have been synthesized and characterized by CP/MAS NMR (13C, 31P). From full 31P CP/MAS NMR spectra, the χ2 plots were constructed to calculate the 31P chemical shift anisotropy 31P − δaniso = (δzz − δiso) and asymmetry parameters η = (δyy − δxx)/(δzz − δiso). The data obtained for the O,O′-dicyclohexyl phosphorodithioate (Dtph) groups (in both modifications) are evidence that the 31P chemical shift tensors are intermediate between rhombic and axially symmetric. However, whereas the rhombic component dominates for Ia, the tensor for Ib is close to axially symmetric (for δzz < δyy ≈ δxx). The same pattern of the MAS spectra corresponding to negative δaniso (δzz < δyy < δxx) points to a bridging or terminal/bridging coordination mode of the Dtph groups. X-ray crystallography shows that complex Ib has a polynuclear structure (of the chain polymer type). The chains are composed of alternating structurally nonequivalent noncentrosymmetric binuclear molecules [Tl2{S2P(O-cyclo-C6H11)2}2]. All Dtph ligands have the terminal/μ3-bridging coordination mode.

The physicochemical properties of cis-trans isomers of substituted epoxycyclohexanes and their molecular complexes with maleic anhydride

AM1, IR, and NMR studies of 1-methoxycarbonyl- and 1-acryloyloxymethyl-3,4-epoxycyclohexanes showed that the ratios between their trans and cis isomers were of 0.60: 0.40 and 0.45: 0.55, respectively. The equatorial forms were most favorable energetically (0.86 and 0.67 mole fractions). The trans-e and cis-e H-complexes of the epoxycyclohexanes with maleic anhydride were obtained; their heats of formation ranged from 0.8 to 3.3 kcal/mol according to AM1 calculations. The participation of the epoxide, carbonyl, and methyl or vinyl group in complex formation gave structures I, III, IIa or IIb, and IV with C-H⋯O (I–III) and C-H⋯π (IV) interactions. The vinyl group was a proton donor in complex II and a proton acceptor in complex IV. The presence of H-bonds in the structures caused the polarization of C=C bonds in 1-acryloyloxymethyl-3,4-epoxycyclohexane and maleic anhydride, which increased their reactivities. Structures IIIb and IV should exhibit the highest reactivity in copolymerization, and complex Ib should exhibit that in oxirane ring opening.

Effect of Xiaoyu Zhixue Tablet (消瘀止血片) on the expression of platelet membrane glycoprotein I b/IX/V complex in patients with chronic renal failure

To investigate the effect of Xiaoyu Zhixue Tablet (XYZXT) on the expression of platelet membrane glycoprotein (GP) Ib/IX/V complex and GP I b alpha in patients with chronic renal failure (CRF) in early metaphase. Fifty-one patients with CRF in early metaphase (treated group) were treated with XYZXT, 3 months as the course of treatment for 2 courses. The previous therapies remained unchanged. Flow cytometry was used to assess the expression of platelet GP Ib/IX/V complex and GP Ib alpha in patients with CRF, and turbidity method was used to determine the platelet maximum aggregation rate (MAR), meanwhile the renal function was measured. The final data were compared with those before the treatment, and with those in the normal control group (31 healthy subjects). Compared with the normal control group, expressions of GP I b/IX/V complex and GP I b alpha, and platelet MAR in CRF patients were significantly lower (P=0.007, P=0.001, P=0.009) before the treatment; after the treatment with XYZXT, the above indexes in CRF patients were remarkably increased (P=0.033, P=0.026, P=0.045), but still lower than those in the normal control group, however, it was not statistically significant. (1) The expression of GP I b/IX/V complex in CRF patients of early metaphase was decreased, which lead to platelet aggregation dysfunction. This might be one of the reasons for the hemorrhagic trend in CRF. (2) XYZXT was able to upgrade expressions of GP I b/IX/V complex and GP I b alpha in CRF patients, improve platelet function and down-regulate platelet activation in patients with CRF.

The nose knows who's who: chemosensory individuality and mate recognition in mice

Individual recognition is an important component of behaviors, such as mate choice and maternal bonding that are vital for reproductive success. This article highlights recent developments in our understanding of the chemosensory cues and the neural pathways involved in individuality discrimination in rodents. There appear to be several types of chemosensory signal of individuality that are influenced by the highly polymorphic families of major histocompatibility complex (MHC) proteins or major urinary proteins (MUPs). Both have the capability of binding small molecules and may influence the individual profile of these chemosignals in biological fluids such as urine, skin secretions, or saliva. Moreover, these proteins, or peptides associated with them, can be taken up into the vomeronasal organ (VNO) where they can potentially interact directly with the vomeronasal receptors. This is particularly interesting given the expression of major histocompatibility complex Ib proteins by the V2R class of vomeronasal receptor and the highly selective responses of accessory olfactory bulb (AOB) mitral cells to strain identity. These findings are consistent with the role of the vomeronasal system in mediating individual discrimination that allows mate recognition in the context of the pregnancy block effect. This is hypothesized to involve a selective increase in the inhibitory control of mitral cells in the accessory olfactory bulb at the first level of processing of the vomeronasal stimulus.

Functionalization of η1,η2-Bridging Cyaphide (C⋮P)-Ligands: Trinuclear η1,η1,η2-Bridging Cyaphide and Dinuclear Bridging Isocyaphide (C⋮PR) Complexes of Platinum

The oxidative addition reaction of Pt(PEt3)4 with Cl2CPN(SiMe3)2 at low temperature (−50 °C) forms the η1-phosphavinyl complex cis-Cl(Et3P)2Pt[C(Cl)PN(SiMe3)2] (Ia), which isomerizes to the trans-isomer (Ib) upon warming to 0 °C; the structure of Ib was determined by X-ray diffraction studies. Complex Ib reacts with Pt(PEt3)2Cl2 in the presence of 3 equiv of sodium benzophenone to generate the bridging, dinuclear η1,η2-cyaphide complex Cl(Et3P)2Pt(μ-η1,η2-C⋮P)Pt(PEt3)2 (II) in good yield, providing a much simpler and higher yield preparation of II, which was synthesized and characterized previously by a more circuitous route. Compound II reacts with 0.5 equiv of [Cl2Pt(PEt3)]2 or with 1 equiv of W(CO)5(THF) to generate the trinuclear metal−cyaphide complexes Cl(Et3P)2Pt[μ-η1,η1,η2-C⋮P{Pt(PEt3)(Cl)2}]Pt(PEt3)2 (III) and Cl(Et3P)2Pt[μ-η1,η1,η2-C⋮P{W(CO)5}]Pt(PEt3)2 (IV), respectively, in which the lone pair of electrons on the C⋮P phosphorus atom is coordinated to a Pt(PEt3)(Cl)2 fragment in the former and to a W(CO)5 fragment in the latter; the structure of IV was determined by X-ray diffraction studies. Compound II also reacts with MeI to form the methyl isocyaphide complex (Cl)(Et3P)Pt(μ-CPMe)Pt(PEt3)2(I) (Vc), in which the cyaphide (C⋮P-) ligand is converted to a methyl isocyaphide (C⋮PMe) ligand in a semibridging coordination mode. When compound II is reacted with MeOTf, the product is the cationic isocyaphide complex [(Cl)(Et3P)2Pt(μ-η1,η2-C⋮PMe)Pt(PEt3)2](OTf) (Va), which is likely coordinated in an η1,η2-bridging mode. Compound Va reacts with NaI to form Vc, which suggests that Va forms as an intermediate before Vc in the reaction of II with MeI.

Transcriptional Analysis of the EhPgp5 Promoter of Entamoeba histolytica Multidrug-resistant Mutant

We report here the cloning and transcriptional characterization of the EhPgp5 multidrug resistance gene promoter isolated from the drug-resistant clone C2 of Entamoeba histolytica. The EhPgp5 promoter has the TATA-like motif at -31 base pairs; transcription initiates three nucleotides upstream from the ATG in trophozoites grown in 225 microM emetine (clone C2(225)), whereas in those grown without the drug (clone C2) a product with no open reading frame was detected. The promoter was active in transfected clone C2 trophozoites, its activity increased when trophozoites were cultured in 40 microM emetine, while it was turned off in the drug-sensitive clone A. The first -235 base pair kept full promoter activity, suggesting that it has important drug responsive elements. Gel shift assays detected the complex Ib in clone C2, which was augmented in clone C2(225). Competition experiments suggested that complex Ib may be constituted by HOX and AP-1 like factors in clone C2, whereas in clone C2(225), complex Ib was only competed by the HOX sequence. Complexes Ie, detected in clones A and C2 but not in C2(225), and Ia, present in all clones, were competed by the TATA box oligonucleotide. Our results suggest that proteins forming complexes Ib and Ie may be participating in the regulation of the EhPgp5 gene expression.

Reactions of PhCOPdX(PPh 3) 2 (X  I, Cl) with alkylmetals under carbon monoxide; formation of α-diketones and α-hydroxyketones under stoichiometric and catalytic conditions

The reactions of PhCOPdX(PPh 3) 2 (Ia: X  I; Ib: X  Cl) with alkylmetals under carbon monoxide have been investigated. The reactivity of ethylmetals toward Ia was found to decrease in the order: Et 2M (M  Zn, Cd, Hg) ∼ etZnCl ∼ EtCu > EtMgBr ∼ EtMnI ∼ Et 3Al > Et 2AlCl > Et 3B ∼ Et 4Sn (no reaction). In these reactions, the simple coupling product, PhCOEt (II) and/or the carbonylative coupling products IIIa–IIIc (IIIa: PhCOCOEt; IIIb: PhCEt(OH)COEt; IIIc: PhCOCEt 2 (OH)) were formed depending on the nature of the ethylmetal. Et 2Hg and Et 3Al gave exclusively II. EtMgBr, EtCu, and EtZnCl gave both of II and III. EtMnI and Et 2M (M  Zn, Cd) selectively gave III. The use of Ar 2Zn(Ar  Ph, p-Tol) in place of Et 2Zn gave decreased yields of the carbonylative coupling products. The palladium complex Ib showed almost the same reactivity toward Et 2Zn as Ia. Further to this palladium-catalyzed carbonylation reactions of PhCOCl with alkylmetals were examined. The reaction with Et 2Zn catalyzed by PdCl 2(PR 3) 2 (R  Ph, pFC 6H 4) afforded III (mainly IIIb and IIIc, about 200%/Pd). The combination of Pd(PPh 3) 4 and Et 3Al more effectively afforded III (mainly acyloin-type reduced products, about 900%/Pd).

Enzymatic and structural modifications of mitochondrial NADH-ubiquinone reductase with autolysis as experimental model.

Complex I (nicotinamide adenine dinucleotide-ubiquinone reductase) is a complex enzyme system located in the inner mitochondrial membrane. It has the ability to catalyze several different enzymatic reactions in electron transport, and is known to be one of the respiratory chain components most sensitive to ischaemia. Mitochondria and two complexes I (complex IA and complex IB) were isolated from normal and ischaemic myocardial tissue. Enzymatic activities, polypeptide composition, as well as other components such as non-haem iron, acid-labile sulphur and ubiquinone, were determined. The results indicated that complex IB reflected the enzymatic changes in the mitochondria during myocardial ischaemia, but complex IA did not. The lesion that resulted from ischaemia was localised as altered enzymatic activities due to a different polypeptide composition, as well as loss of ubiquinone and non-haem iron from complex IB.

Synthesis, spectroscopic studies (Mössbauer and infrared), and the crystal and molecular structure of the organotin(IV)-pyrazine adducts [Sn(CH 3) 2Cl 2] 2pyz and [Sn(CH 3) 2Br 2pyz

Two adducts [Sn(CH 3) 2Cl 2] 2pyz ( Ia) and Sn- (CH 3) 2Br 2pyz] ( Ib) (pyz = pyrazine) have been synthesized and characterized in the solid state. Infrared and Mössbauer spectroscopies suggest a five- coordinated species for the Ia complex with an angular CSnC bond and a six-coordinated compound with a linear CSnC bond for the Ib complex. X-ray diffraction studies confirm a distorted trigonal bipyramidal geometry with N, Cl axial atoms and Cl and methyls in the equatorial plane for Ia where the Cl axSnN bond angle is the lowest one reported to date and the Cl eqSn bond distance the longest one with regard to similar complexes. This molecule has a short contact of 3.47 Å between the tin and the axial chlorine atoms. The molecular structure of complex Ib points out all equivalent bonds in the trans position arising from a polymeric chain with bridged pyrazine ligand. The complex Ib is centro- symmetric at the tin atom.

Isolation of a physiologically active and a physiologically inactive mitochondrial NADH-ubiquinone reductase (complex I) from donkey hearts

The method described for the isolation of mitochondrial complex I (NADH-ubiquinone reductase) from bovine hearts could not be applied to donkey hearts as unacceptably large losses in enzyme activity occurred. This method was modified for the isolation of complex I using donkey hearts and two complexes were obtained: complex IA which was physiologically inactive and complex IB which was physiologically active as it catalyzed the reaction from NADH to ubiquinone. Both complexes had relatively low enzyme activity with artificial electron acceptors, except with potassium ferricyanide, and had more or less the same amount of acid-labile sulfur and nonheme iron although the polypeptide composition differed to a great extent.

Preparation and reactions of palladium(II) complexes with C2-bonded heteroaromatic ligands trans[PdCl(R N)(PPh 3) 2] (R N = 2-pyridyl, 2-pirazyl, 2-pyrimidyl group). A new reaction pathway in the insertion of isocyanides into the Pdc bond of trans-[PdXR(L) 2] compounds

The complexes trans-[PdCl(R N)(PPh 3) 2] (I) [R N = 2-pyridyl (2-Py), 2-pyrazyl (2-pyz), 2-pyrimidyl (2-pym) group] have been prepared in high yield by deprotonation with NEt 3 of the corresponding cationic compounds trans[PdCl(R NH) (PPh 3) 2] + (R NH = N-protonated C 2-heteroaromatic ligand) in the presence of an excess of PPh 3. In chlorinated solvents, complexes I undergo a slow reversible dimerization into the binuclear derivatives [PdCl(μ-R N)(PPh 3)] 2 (II) (μ-R N = C 2, N 1-bridging ligand). From the 31P NMR spectra in 1,2-dichloroethane the following dissociation constants were obtained: 1.9 mol 1 −1 (R N= 2-py), 5.1 × 10 −2 (2-pym), 6.6 × 10 −3 (2-pyz). The dimerization becomes fast and quantitative if the PPh 3, involved in the equilibrium is removed by oxidation or by reaction with [PdCl(η 3-2-MeC 3H 4)] 2. Only the 2-pyridyl complex Ia reacts (slowly) with CO yielding the migratory insertion product trans-[PdCl{C(2-py)O}(PPh 3) 2], together with the dimer IIa. All the complexes I undergo migratory insertion of t-butylisocyanide with formation of trans-[PdCl{C(R N) = NCMe 3}(PPh 3) 2]] at rates which depend on the heterocyclic group (R N = 2-py > 2-pyz ⪢ 2-pym). The reaction of the 2-pyrazyl complex Ib with CNCMe 3 has been studied in detail by conductivity measurements and by IR and 31P NMR spectroscopy. The data suggest a complex mechanism in which insertion occurs through rearrangement of a four-coordinate intermediate [PdCl(2-pyz)(CNCMe 3)(PPh 3)], and through interaction of a cationic intermediate trans-[Pd(2-pyz)(CNCMe 3)(PPh 3) 2] + (Vb) with Cl − and with the free isocyanide of the initial equilibria. The occurrence of the latter reactions is confirmed by independent experiments in which the cationic complex Vb (isolated as perchlorate salt) is treated with an equimolar amount of [AsPh 4]Cl or CNCMe 3. The isocyanide-promoted insertion step represents a new mechanistic pathway for isocyanide insertion into the PdC bond of trans-[PdXR(L) 2] complexes.

Porphyrins. 20. Interaction of 2-formyl-5,10,15,20-tetraphenylporphyrin with ch acids

The reactions of 2-formyl-5,10,15-20-tetraphenylporphyrin (Ia) with nitromethane and of its Cu complex (Ib) with nitromethane, malonic acid, and its esters have been investigated. On interacting porphyrins (Ia,b) with nitromethane in AcOH/BuNH2 the 2-(2-nitrovinyl)porphyrins (IIa,b) were formed, in liquid NH3 the nitroalcohols (IIIa,b) were formed, and in DMF/BuNH2 the dinitro derivatives (IVa,b) were formed. The interaction of porphyrin (Ib) with malonic acid and its esters led to the corresponding condensation products in high yield.

Activated and non-activated glucocorticoid-receptor complexes in rat thymus cells: Kinetics of formation and relation to steroid structure

Previously we showed that when glucocorticoids initially enter rat thymus cells incubated at 37°C. non-activated hormone-receptor complexes are formed within 15 s and are then rapidly replaced by activated complexes. Activated and non-activated forms were identified in cytosols from the cells by DEAE-cellulose chromatography, where they are eluted with progressively higher salt concentrations in what are referred to as Peaks I and II. On DNA-cellulose columns dexamethasone-receptor complexes in cytosols that on DEAE-cellulose give mainly Peak II (the non-activated complex, referred to as Complex II) are not bound significantly: they are eluted at the lowest salt concentration along with free steroid, from which they can be separated by binding to hydroxyapatite. This DNA-cellulose peak is referred to as Peak a. Complexes in cytosols that give only Peak I on DEAE, however, on DNA separate into two components. One of these (Complex Ia) is not bound significantly and appears in Peak a. The other (Complex Ib, presumably the true activated complex) appears in a later Peak b. These three complexes have been measured by first adsorbing Ib with DNA-cellulose, then separating Complexes Ia and II. which are not adsorbed on DNA. by means of a DEAE-cellulose column. When [ 3H]-dexamethasone is added to cells at 37°C. II is formed within 15 s and is rapidly replaced by Ib, in agreement with our earlier results. Complex Ia accounts for 15–20% of total complexes at all times, and is also present after 120 min at 0°C. Various steroids have been compared on DNA-cellulose after 30 min at 37°C. when the amount of Complex II is negligible. The ratio of Ib to Ia is highest for dexamethasone and triamcinolone acetonide, intermediate for cortisol and corticosterone and lowest for cortexolone (which seems to form only Ia), roughly in proportion to intrinsic glucocorticoid activity. Complex Ia may thus be a third normal form of extranuclear glucocorticoid-rcceptor complex, but the possibility remains that it is an artifact formed after cells are broken. The relation of Complexes Ia, Ib and II to glucocorticoid activity is discussed.

Linear Oligomerization of olefins via nickel chelate complexes and mechanistic considerations based on semi-empirical calculations

Abstract The new complexes (η-4-cyclooctene-1-yl)(1,1,1,-trifluoro-2,4-pentane-dionato) nickel, Ib, and (η-4-cyclooctene-1-yl)(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) nickel, Ic, oligomerize α olefins such as ethylene, propylene, 1-butene, 1-hexene and 1-octene to predominantly linear products without a cocatalyst. The dimers of 1-butene show a linearity of > 80%. The rate of reactivity follows the order ethylene > propylene > 1-butene > 1-hexene > 1-octene. The experimental findings that complex Ic is more reactive than complex Ib are rationalized by preliminary semi-empirical calculations using the EHT method.