Biomedical subjects

H Fleischer

Publications and source records attributed to H Fleischer.

At least 19 recordsLinked to original sources

PubMed2001

Molecular structure of Te(OMe)4.ClTe(OMe)3, a model for ligand exchange between Te(IV) centers.

ClTe(OiPr)3 could be prepared from stoichiometric amounts of TeCl4 and Te(OiPr)4, a reaction that requires the exchange of ligands between different Te centers. Ligand redistribution between telluranes was studied, and rapid exchange of -Cl and -OR (R = Me, iPr) ligands in solutions of several binary mixtures of Te(OMe)4, Te(OiPr)4, ClTe(OMe)3, and ClTe(OMe)3, and ClTe(OiPr)3 was established by multinuclear NMR spectroscopy. The solid-state structure of Te(OMe)4.ClTe(OMe)3, the first structurally characterized adduct between different telluranes, was investigated by single-crystal X-ray diffraction. It exhibits a very short Te-O...Te bridge between the two Te centers and additional Te...O and Te...Cl contacts between different adduct molecules. Selected structural parameters of Te(OMe)4.ClTe(OMe)3 are Te1-Cl1 274.6(3), Te1-O13 191.0(5), Te1-O12 194.9(6), Te1-O11 200.9(7), Te1...O24 226.8(5), Te1...O11a 314.2(8), Te2-O21 191.6(5), Te2-O22 198.7(5), Te2-O23 190.1(5), Te2-O24 225.3(5), Te2...O13 307.8(6), and Te2...O22b 269.2(6) pm and Te2-O24...Te1 126.1(2) degrees. Ab initio (MP2/LANL2DZP) geometry optimization of the model compound Te(OH)4.ClTe(OH)3 revealed that the central Te-O...Te bridge is less symmetric and hence weaker in the isolated adduct molecule than in the solid state. The stability of Te(OMe)4.ClTe(OMe)3 toward decomposition in Te(OMe)4 and ClTe(OMe)3 is attributed to the strengths of the short Te-O...Te bridge between Te(OMe)4 and ClTe(OMe)3. On the basis of the molecular structures of Te(OH)4.ClTe(OH)3 and Te(OMe)4.ClTe(OMe)3, a mechanism for the exchange of -OR groups between Te(IV) centers is proposed.

Journal Article↗

PubMed2001

Reduced release of DNA from streptococcus pneumoniae after treatment with rifampin in comparison to spontaneous growth and ceftriaxone treatment.

In order to study the release of DNA from Streptococcus pneumoniae in vitro during spontaneous growth and treatment with ceftriaxone or rifampin, a semiquantitative polymerase chain reaction was used. During spontaneous growth, high concentrations of bacterial DNA were released. Exposure to 10 microg/ml of ceftriaxone decreased the DNA release, in median, by 19 times (P=0.03 vs. spontaneous growth). Treatment with 10 microg/ml of rifampin led to a reduction of DNA release, in median, by a factor of 49 (P=0.03 vs. ceftriaxone; six experiments performed on different days).

Base Sequence↗

PubMed2000

Functionalized Tellurium(II) Thiolates: Tellurium Bis(2-hydroxyethanethiolate) Hydrate, the First H(2)O-Te(II) Complex This work was supported by the Fonds der Chemischen Industrie.

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Journal Article↗

PubMed2000

Assessment of hemispheric language lateralization: a comparison between fMRI and fTCD.

The cerebral blood flow velocity (CBFV) in the basal arteries during a word-generation task was assessed by functional transcranial Doppler ultrasonography (fTCD) and by functional magnetic resonance imaging (fMRI). The study investigates how event-related CBFV modulations in the middle cerebral artery (MCA) relate to regional cerebral blood flow (rCBF) changes. Both fMRI and fTCD were used in 13 subjects (7 men, 6 women, aged 21 to 44 years). The maximum difference of relative CBFV changes between the left and right MCA during the word-generation task was used as the language laterality index (LIfTCD). For the fMRI examination during the nearly identical language task, the corresponding index was defined by LIfMRI = 100(N(L) - N(R))/(N(L) + N(R)), where N(L) and N(R) refer to the numbers of voxels activated in the left and right hemisphere, respectively. The evoked CBFV changes expressed by LIfTCD and the corresponding laterality index, LIfMRI, estimated by fMRI showed a close linear relation (regression analysis: r = 0.95, p < 0.0001). The results of this study demonstrate that language-related velocity changes in the MCAs relate to rCBF increases in a linear fashion. Since the laterality indices assessed by fMRI and fTCD are in such close agreement both techniques can therefore be used in a complementary way.

Adult↗

PubMed1995