Labilisierung einer Carboxylgruppe der koordinierten Triethylentetramin- N, N, N′,N″, N‴, N‴ -hexaessigsäure (H6ttha): Koordinationszahlen 10 für [La(H ttha)]2- und 9 für [Dy(Httha)]2- in ihren Guanidiniumsalzen / Labilizing of a Carboxyl Group o f the Coordinated Triethylenetetramine-N, N, N′ ,N″, N‴, N‴ - hexaacetic Acid (H6ttha): Coordination Numbers 10 for [La(Httha)]2- and 9 for [Dy(Httha)]2- in their Guanidinium Salts

The lanthanum(III) and dysprosium(III) complexes of triethylenetetramine-N, N, N′, N″, N‴, N‴-hexaacetic acid (H6ttha) were prepared and isolated as guanidinium salts:[C(NH2)3]2[La(Httha)] · 3 H2O and [C(NH2)3]2[Dy(Httha)] · 5 H2O. The X-ray crystal structure of both complexes was determined: In the La(III) complex (space group P1̄) all donor atoms (N4O6) are coordinated. The coordination number 10 is realized in a bicapped square antiprism (SAPRS-10). The bond length La to O of the protonated carboxylic group is ca. 0.3 Å longer than the other five La-O distances. The Dy(III) complex (space group P1̄) exhibits coordination number 9 in a monocapped square antiprism (SAPRS-9). The protonated carboxylic group is not coordinated.

Plasmafibronectin bei normaler Schwangerschaft und EPH-Gestose

Plasma fibronectin was determined during normal pregnancy after 15th week, post partum, in cord blood and in cases of EPH gestosis. Non-pregnant women of a comparable age group were examined for plasma fibronectin concentration. Fibronectin at the end of gestation was at about the same level as at the beginning of the second trimester and as in non-pregnant women. The amount of fibronectin remains post partum practically the same. Cord blood fibronectin was about half the concentration of that in adult plasma. In EPH gestosis, levels were significantly elevated.

Brief-tone frequency discrimination by children

This study investigated maturational changes in children's ability to discriminate the frequency of short-duration tone pulses. Frequency difference limens (DLs) were measured for digitally generated 1000-Hz tones with pulse durations of 200, 50, and 20 ms using a two-alternative, two-interval, forced-choice procedure. Participants were 16 5-year-old children; 10 children each in the age categories of 7, 9, and 11 years; and a control group of 10 young adults. Eleven of the 5-year-old children were unable to learn the experimental task. All children in the three older groups and the adults successfully completed the study. The five 5-year-old children who completed the task performed similarly to the 7-year-old children. All groups of participants showed an inverse relationship between duration of the signal and the size of the DL. The DLs at all three tone durations were significantly larger for the 7-year-old children than they were for the older children and adults. There were no significant differences in DL size among the 9-year-old, 11-year-old, and adult subjects at any tone duration. These findings suggest that the sensory and/or cognitive skills required to discriminate the frequency of brief-duration tones may not reach maturity until after age 7 years.

New gadolinium complexes as magnetic resonance imaging--contrast agents

We have investigated the physicochemical and paramagnetic properties of the new gadolinium complexes of N-(pyrid-2-yl-methyl)-ethylenediamine-N,N,N-triacetic acid (Gd-PEDTA) and N-tris(2-aminoethyl)amine-N,N,N,N,N,N+hexaacetic acid(Gd-TTAHA). The relaxivities as well as the thermodynamic and conditional stability constants of these complexes with respect to the physiological relevance were determined and discussed in comparison with the commercially available gadolinium (III) diethylenetriaminpentaacetic acid/gadopentate dimeglumine (Gd-DTPA, Magnevist). In case of Gd-TTAHA a twofold higher relaxivity and a complex stability similar to Gd-DTPA were determined. It is shown, that lower concentrations of Gd-TTAHA are sufficient for the same signal enhancement in the T1-weighted MR image compared with Gd-DTPA and, thus, the use of the new contrast agent Gd-TTAHA should diminish risks for health. Therefore, Gd-TTAHA might be used potentially as a new contrast agent for clinical MRI application.

Brief tone discrimination by children with histories of early otitis media

Twelve children, ranging in age from 8.9 to 12.4 years, with histories of severe otitis media with effusion (OME) before age 3, were compared to age-matched cohorts in their ability to discriminate the frequency of tone pulses of 20-, 50-, and 200-msec duration. An adaptive procedure was used in combination with a two-alternative forced-choice paradigm to measure difference limens (DLs) for digitally generated 1000-Hz tones. The OME group exhibited larger DLs than the non-OME group at all three stimulus durations. These results provide tentative evidence of possible long-term effects of early OME on brief tone frequency discrimination.