Biomedical subjects
Publications and source records attributed to D Maassen.
Orcein was separated into 14 dyes by partition chromatography. Their constitutions were determined mainly by spectroscopy and led to formulae that are derived from 7-amino-2-phenoxazone, 7-hydroxy-2-phenoxazone, and 7-amino-2-phenoxazime, and that were confirmed by syntheses. The major constituent of litmus is assembled polymerically from 7-hydroxy-2-phenoxazone chromophores. The mechanism of formation is elucidated.
The crystal structure of human CG reveals that each subunit is a member of the superfamily of cystine-knot growth factors. Although the distribution of the cysteine residues in all the beta-subunits is conserved, the conformation of the human FSH dimer differs from that of the CG/LH dimers. This suggests that the function of the cystine bonded loops in the human FSHbeta-subunit may differ from that in the CGbeta-subunit. To address this issue, we deleted two disulfide bonds in the FSHbeta domain: cys 20-104 and cys 28-82, which correspond to the disulfide bonds 26-110 and 34-88, respectively, in the CGbeta-subunit. The cys 26-110 bond is associated with the "seat-belt" region and cys 34-88 is a bond in the cystine knot. Coexpression of the wild-type alpha-subunit with the FSHbeta cysteine mutants in CHO cells revealed no detectable heterodimer. The FSHbeta mutants were then incorporated into a single chain where the beta-subunit is genetically fused to the alpha-subunit. In such a model, the rate-limiting subunit assembly step is by-passed and mutations that otherwise block heterodimer formation can be evaluated in terms of biological activity. Compared with the nonmutated single chain, the single-chain 28-82 mutant is secreted more slowly and its recovery is substantially reduced, whereas secretion and recovery of the 20-104 mutant was not significantly affected. The receptor binding affinity of the cys 28-82 mutant did not differ from wild-type and binding of the cys 20-104 mutant was decreased only 2-fold. The signal transduction data parallel the binding affinities, although the maximal accumulation of cAMP is less for the cys 20-104 mutant than that seen for cys 28-82 and nonmutated single-chains variants. These data support the hypothesis that the determinants for intracellular behavior and bioactivity of the gonadotropins are not the same, and that the cystine knot is a critical determinant for the formation of a stable, assembly-competent subunit. In addition, the data imply that the "seat-belt" conformation does not play a prominent role in the bioactivity of FSH.
Lower-limb somatosensory evoked potentials (SEPs) of nerve-trunk (peroneal nerve, posterior tibial nerve) and dermatomal (L5 and S1) stimulation were recorded in 120 patients suffering from lumbosacral disk disease. Recordings were performed before surgery and on Days 4 and 50 after surgery. Electromyography was also performed before surgery. Dermatomal SEPs were shown to be sensitive (70%) and specific in both terms of their lateralizing value and their ability to identify the L5 or S1 level. Moreover, combining SEPs and EMG significantly increased the sensitivity of the electrophysiological testing when compared with each method alone. There was no relationship between SEPs performed before surgery and surgical outcome. Inversely, we demonstrated the prognostic value of SEPs performed on Day 4, SEP normalization at Day 4 was associated with a good outcome at Day 50 in 91.8% of examined cases, while the persistence of pathological SEPs at Day 4 was associated with poor outcome at Day 50 in 56% of the cases.
Proteus syndrome is a rare congenital disorder in which the major clinical manifestations are skeletal deformities and hamartomatous tumors. The case of a 42-year-old woman with right hemihypertrophy, macrodactyly of the right hallux, extreme kyphoscoliosis and bilateral plantar connective tissue naevi is reported. Proteus syndrome is reviewed with reference to this patient.