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H Taube

Publications and source records attributed to H Taube.

17 recordsLinked to original sources
PubMed2004

Comparison of four different in vitro systems to study the reservoir capacity of the stratum corneum.

Four in vitro test systems were used to study the reservoir capacity of porcine stratum corneum (SC) for flufenamic acid and its drainage via penetration into the deeper skin layers: Franz diffusion cell using full thickness skin and split skin of 300 mum; Saarbruecken penetration model (SB) and intact porcine tissue (IP). Each skin sample was segmented 1, 4 and 21 h after application of an 'infinite dose' of flufenamic acid. The lipophilic drug was extracted from the SC and the deeper skin layers (viable epidermis and dermis) and determined using high-performance liquid chromatography (HPLC). For each test system, an increase in the drug amount in the deeper skin layers and the acceptor fluid, respectively, was observed in combination with a decreased amount in the SC with increasing time after application. The drainage of the SC reservoir was only reflected by a linear correlation of the drug amount in the SC with the amount in the deeper skin layers in the case of IP. The absolute drug concentrations previously detected in human skin in vivo and in vitro were compared with the present data, affording the best accordance in the case of IP.

Animals↗
PubMed2001

Tmtacn, tacn, and triammine complexes of (eta 6-arene)OsII: syntheses, characterizations, and photosubstitution reactions (tmtacn = 1,4,7-trimethyl-1,4,7-triazacyclononane; tacn = 1,4,7-triazacyclononane).

A series of (eta 6-arene)OsII complexes containing the saturated nitrogen donor ligands tmtacn, tacn, and NH3 are prepared and characterized. The electrochemical properties and photochemical reactions of these complexes are studied, and the solid-state structures for [(eta 6-p-cymene)Os(tacn)](PF6)2 (1) and [(eta 6-p-cymene)Os(tmtacn)](PF6)2 (2) are determined. Single-crystal X-ray data: 1, orthorhombic, space group Pbca-D2h15 (No. 61), with a = 14.716(3) A, b = 17.844(3) A, c = 18.350(4) A, V = 4819(2) A3, and Z = 8; 2, monoclinic, space group C2-C2(3) (No. 5), with a = 17.322(4) A, b = 10.481(3) A, c = 15.049(4) A, beta = 98.72 degrees, V = 2701(1) A3, and Z = 4.

Electrochemistry↗
PubMed1998

Platinum catalysts for the high-yield oxidation of methane to a methanol derivative

Platinum catalysts are reported for the direct, low-temperature, oxidative conversion of methane to a methanol derivative at greater than 70 percent one-pass yield based on methane. The catalysts are platinum complexes derived from the bidiazine ligand family that are stable, active, and selective for the oxidation of a carbon-hydrogen bond of methane to produce methyl esters. Mechanistic studies show that platinum(II) is the most active oxidation state of platinum for reaction with methane, and are consistent with reaction proceeding through carbon-hydrogen bond activation of methane to generate a platinum-methyl intermediate that is oxidized to generate the methyl ester product.

Journal Article↗
PubMed1994

Oligoclonality and skewed T cell receptor V beta gene segment expression in in vivo activated human intestinal intraepithelial T lymphocytes.

Intraepithelial intestinal T lymphocytes (IEL) bearing alpha beta or gamma delta T cell receptors (TCR) are positioned to serve as a first line of defense against enteric pathogens. To investigate whether intestinal IEL are subject to antigenic selective forces distinct from that influencing (xp T cells in the peripheral blood (PBL), we performed a comparative analysis of V beta gene segment usage in IEL and PBL of immunologically normal donors by quantitative PCR. Primers for 22 different human TCR V beta gene segments of V beta gene segments families were used to analyze the repertoire of TCR beta chain transcripts in colonic IEL (c-IEL), in corresponding colonic lamina propria lymphocytes (c-LPL), and in peripheral blood lymphocytes. In each of the three individuals examined, a limited number (1-4 out of 22) of TCR V beta families predominated and accounted for more than 50% of the total beta chain transcripts from c-IEL, whereas in PBL and c-LPL a more even distribution of V beta gene families was observed. The dominating V beta gene families were V beta 2, V beta 3, V beta 6, V beta 8 and V beta 14. In one individual, V beta 3 comprised more than 40% of the entire repertoire of c-IEL beta chain transcripts. Sequence analysis of the predominant V beta 3 family in this individual revealed identical sequences in 13 of 17 clones analyzed. Human alpha beta TCR+ c-IEL could not be driven to proliferate or exhibit cytotoxic function in vitro however, PCR analysis for detection of lymphokine mRNA revealed constitutive production of several lymphokines known to exert trophic effects on intestinal epithelial cells and pro-inflammatory activities. Taken together, the striking degree of oligoclonality may indicate that the intraepithelial intestinal immune system is targeted to a limited set of hitherto unknown self- or foreign antigens present in the intestine and orchestrates intramucosal inflammatory and regenerative processes.

Base Sequence↗
PubMed1993

Analysis of T cell receptor V beta regions expressed by rheumatoid synovial T lymphocytes.

The T cell receptor (TCR) V beta gene segment repertoire of T lymphocytes derived from peripheral blood of two healthy individuals and synovial tissue, synovial fluid and peripheral blood of three rheumatoid arthritis (RA) patients was analyzed. A sensitive assay based on the amplification of cDNA by the polymerase chain reaction (PCR) was used to analyze the levels of expression of 20 TCR V beta gene segment families. The relative expression of V beta gene segments in lymphocytes derived from peripheral blood, synovial tissue and synovial fluid was conserved over 155 days in one patient. V beta 9 transcripts were undetectable in the cells of this individual. In the two other patients the frequency of V beta 2 transcripts in synovial T cells of affected joints was significantly higher than in their peripheral blood lymphocytes. Dominance of distinct rearrangements among the V beta 2 transcripts from the synovial cells of these patients support the idea that the synovial T cell response is driven by antigen.

Amino Acid Sequence↗
PubMed1992

Use of a dihydrogen osmium complex as a versatile 1H NMR recognition probe.

A new recognition probe for biomolecules, [en2Os(eta 2-H2)]2+ (1; en, ethylenediamine), is reported. In aqueous solution, 1 binds readily to a variety of biomolecules, including nucleotides, RNA, amino acids, peptides, and phospholipids. In each case, binding leads to a characteristic proton nuclear magnetic resonance (1H NMR) for the dihydrogen that appears in a spectral window in the range delta = 0 to -20 parts per million, and as well to characteristic values of the coupling JHD and of the relaxation time T1. Small structural differences in molecules such as DGMP (2'-deoxyguanosine 5'-monophosphate) and IMP (inosine 5'-monophosphate) or Asp and Glu can readily be distinguished, such as when 1 binds to the N-7 position of the nucleobase of DGMP or IMP and when 1 binds to the carboxylate of Asp or Glu. Upon one-electron oxidation of the metal center, diamagnetic 1 is converted to a paramagnetic probe.

Amino Acids↗
PubMed1991

Biased T cell receptor V alpha region repertoire in the synovial fluid of rheumatoid arthritis patients.

Synovial T lymphocytes seem to contribute to the pathogenesis of rheumatoid arthritis (RA). Since very little is known about the structural heterogeneity of their T cell antigen receptors (TcR), we analyzed TcR alpha chain mRNA of synovial fluid T cells from two RA patients. TcR alpha chain cDNA was amplified by the polymerase chain reaction with single-sided specificity for the alpha chain constant (C alpha) gene segment, and the nucleotide sequences of 51 functionally rearranged cDNA clones were determined. Twenty different V alpha genes and 26 different J alpha gene segments were utilized in these cDNA clones. Three of the V alpha gene segments which are frequently (8%-17% total) expressed in synovial fluid T cells have rarely been found in the TcR repertoire of peripheral blood T cells from healthy individuals. The T cell responses in the rheumatic synovia analyzed here are not oligoclonal, but the usage of TcR V alpha genes is biased.

Antibody Diversity↗
PubMed1977

[Immunostimulation in the treatment of chronic joint rheumatism (author's transl)].

Results of a Double Blind Study: In a randomized double blind study, 22 patients were treated with levamisole. The intention was to find out whether immunostimulation would have a favorable influence on rheumatic complaints in patients with rheumatoid arthritis and whether an objectifiable improvement of the synovial reaction can be obtained. The course was monitored with an extensive laboratory diagnostic program in 13 patients treated with levamisole and 9 patients with placebo. The medicament did not cause a pseudo-LE syndrome. In the overall result, 84.6% of the patients were significantly improved compared to 33.3% of the placebo group. Gastric complaints were occasionally seen as side effects. In one patient, the treatment had to be interrupted several times because of recurrent leukopenia and was prematurely ended in the 21st week.

Adult↗
PubMed1975

Crystal structure of a compound featuring caffeine bound at C8 to ruthenium (III).

The structure of a novel ruthenium purine compound, trans-chloro-8-caffeinechlorotriamminruthenium(III) chloride monohydrate, has been determined using single-crystal x-ray techniques. This compound crystallizes in space group Pbca (D152h) with cell dimensions a equal to 11.341 (3)A, b equal to 11.606 (5) A, c equal to 26.673 (7) A, Z equals to 8. The observed and calculated densities are 1.79 plus or minus 0.01 and 1.781 g/cm3, respectively. The structure has been refined using full-matrix least-squares methods to R equal to 0.059 based on 1314 independent observed reflections. The coordination geometry at the ruthenium atom is distorted octahedral. The carbon-ruthenium bond length is 2.03 (1) A. The chloride-ruthenium bond lengths are 2.350 (4) A and 2.427 (3) A for the cis and trans forms respectively suggesting a strong trans-influence due to the caffeine.

Caffeine↗
PubMed1968

Binuclear ion containing nitrogen as a bridging group.

A binuclear ion ([NH(3))5RuN(2)Ru(NH(3))(5)](5)+ is formed by the direct reaction of N(2) with an aqueous solution of (NH(3))(5)RuOH(2)(2+) at room temperature. The binuclear ion is also formed by the reversible reaction of (NH(3))5RuOH(2)(2+) with (NH(3))(5)RuN(2)(2+). Solid [(NH(3))(5)RuN(2)Ru(NH(3))(5)] (BF(4))(4) has been prepared, and its ultraviolet and infrared spectra are reported.

Chemical Phenomena↗
PubMed1965

Mechanisms of oxidation with oxygen.

SEVERAL TOPICS ARE DEALT WITH IN DISCUSSING THE REACTIONS OF MOLECULAR OXYGEN, BUT A COMMON GOAL IS PURSUED IN EACH: to try to understand the reactions in terms of the fundamental properties of the oxygen molecule, and of the other reactants. The paper first describes the electronic structure of oxygen and of two low-lying electronically excited states. Concern with the low-lying electronically excited states is no longer the sole property of spectroscopists; recently, evidence has been presented for the participation of such activated molecules in chemical reactions. The chemistry of oxygen is dominated by the fact that the molecule in the ground state has two unpaired electrons, whereas the products of oxidation in many important reactions have zero spin. In its reactions with transition metal ions the restrictions imposed by the spin state of the oxygen molecule are easily circumvented. A number of reactions of oxygen with metal ions have been studied in considerable detail; conclusions on basic aspects of the reaction mechanism are outlined. Among the most interesting reactions of oxygen are those in which it is reversibly absorbed by reducing agents. Reversible absorption to form a peroxide in the bound state is possible; some of the conditions which must be fulfilled by a reducing system to qualify as storing oxygen in this way are reasonably well understood and are here enunciated. Little has been done on the formation of oxygen from water; some factors involved in this process are discussed.

Ammonia↗