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C Hartmann

Publications and source records attributed to C Hartmann.

At least 163 records · Page 9Linked to original sources
PubMed1987

Reductive trapping of substrate to bovine plasma amine oxidase.

Plasma amine oxidases catalyze the oxidative deamination of amines to aldehydes, followed by a 2e- reduction of O2 to H2O2. Pyrroloquinoline quinone (PQQ), previously believed to be restricted to prokaryotes, has recently been proposed to be the cofactor undergoing reduction in the first half-reaction of bovine plasma amine oxidase (Ameyama, M., Hayashi, U., Matsushita, K., Shinagawa, E., and Adachi, O. (1984) Agric. Biol. Chem. 48, 561-565; Lobenstein-Verbeek, C. L., Jongejan, J. A., Frank, J., and Duine, J. A. (1984) FEBS Lett. 170, 305-309). This result is unexpected, since model studies with PQQ implicate Schiff's base formation between a reactive carbonyl and substrates, whereas experiments with bovine plasma amine oxidase have failed to provide evidence for a carbonyl cofactor. We have, therefore, re-examined putative adducts between substrate and enzyme-bound cofactor, employing a combination of [14C]benzylamine and [3H]NaCNBH3. The use of the relatively weak reductant, NaCNBH3, affords Schiff's base specificity and permits the study of enzyme below pH 7.0. As we show, enzyme can only be inactivated by NaCNBH3 in the presence of substrate, leading to the incorporation of 1 mol of [14C]benzylamine/mol of enzyme subunit at complete inactivation. By contrast, we are unable to detect any labeling with [3H]NaCNBH3, analogous to an earlier study with [3H]NaCNBH4 (Suva, R. H., and Abeles, R. H. (1978) Biochemistry 17, 3538-3545). We conclude, first, that our inability to obtain adducts containing both carbon 14 and tritium rules out the reductive trapping either of amine substrate with pyridoxal phosphate or of aldehyde product with a lysyl side chain and, second, that the observed pattern of labeling is fully consistent with the presence of PQQ at the active site of bovine plasma amine oxidase.

Amine Oxidase (Copper-Containing)↗
PubMed1987

Diffuse epithelial ingrowth after perforating keratoplasty.

Diffuse epithelial ingrowth was observed in 2 patients after perforating keratoplasty. Both cases involved a corneal graft after perforating injury with aphakia. In the first patient, the epithelial invasion was probably stimulated by a spatula synecholysis. In this case, the diagnosis was only made by histological investigation after enucleation. In the second patient the epithelial ingrowth was observed 8 months after keratoplasty. The clinical diagnosis was made on the basis of the typical slitlamp findings. In this case, the epithelial invasion led to hypotension with high resistance of outflow measured by electrotonography. In a very close chronological relation to the probable fall of chamber fluid secretion, development of a band-shaped keratopathy was observed.

Adult↗
PubMed1987

Aromatase activity in monolayer cell cultures of human endometrium.

Monolayer cell cultures of proliferative human endometrial stromal cells were incubated with 100 nCi 3H-androstenedione or 100 nCi 3H-testosterone for 15 hours. After termination of the incubations 16% of the recovered radioactivity was identified as estrone by thin layer chromatography and subsequent recrystallization. 3H-testosterone was almost quantitatively converted to 3H-androstenedione. 3H-dihydrotestosterone remained unmetabolized. These findings indicate a highly active 17 beta-ol-dehydrogenase and a high aromatizing capacity of human endometrial cells.

Androstenedione↗
PubMed1986

Small tandemly repeated DNA sequences of higher plants likely originate from a tRNA gene ancestor.

Several monomers (177 bp) of a tandemly arranged repetitive nuclear DNA sequence of Brassica oleracea have been cloned and sequenced. They share up to 95% homology between one another and up to 80% with other satellite DNA sequences of Cruciferae, suggesting a common ancestor. Both strands of these monomers show more than 50% homology with many tRNA genes; the best homologies have been obtained with Lys and His yeast mitochondrial tRNA genes (respectively 64% and 60%). These results suggest that small tandemly repeated DNA sequences of plants may have evolved from a tRNA gene ancestor. These tandem repeats have probably arisen via a process involving reverse transcription of polymerase III RNA intermediates, as is the case for interspersed DNA sequences of mammalians. A model is proposed to explain the formation of such small tandemly repeated DNA sequences.

Base Sequence↗
PubMed1986

[Trypan blue and alizarin red S sequential staining with subsequent fixation. A modified technic for the study of the corneal endothelium].

A sequential corneal endothelium staining technique with trypan blue (TB)--alizarin red S (ARS)--ethanol-trypan blue is described which can be performed in a few minutes. The first step permits the TB exclusion to be determined as a criterion of normal endothelial cell function. The two following steps permit intercellular staining by ARS and nuclear staining by TB. After each staining procedure, fixation can be performed by methanol or ethanol, both with full-thickness corneal preparations or endothelial flat mounts. In flat preparations, the focussing problems and optical artifacts of full-thickness mounts can be avoided. These modifications render simple sequential staining with subsequent fixation a complement and alternative to specular microscopy and to the customary complicated silver staining of corneal endothelium.

Animals↗
PubMed1985

Gene conversion as a mechanism for divergence of a chloroplast tRNA gene inserted in the mitochondrial genome of Brassica oleracea.

We have characterized a 1.7 kb sequence, containing a tRNA Leu2 gene shared by the ct and mt genomes of Brassica oleracea. The two sequences are completely homologous except in two short regions where two distinct gene conversion events have occurred between two sets of direct repeats leading to the insertion of 5 bp in the T loop of the mt copy of the ct gene. This is the first evidence that gene conversion represents the initial evolutionary step in inactivation of transferred ct genes in the mt genome. We also indicate that organelle DNA transfer by organelle fusion is an ongoing process which could be useful in genetic engineering.

Brassica↗
PubMed1985

Possible effect of the cell synchronization method on the pattern of 5-bromodeoxyuridine incorporation into early synthesized DNA.

Synchronously and asynchronously growing chick embryo fibroblasts have been used to study the pattern of 5-bromodeoxyuridine (BrdU) incorporation into DNA. In the synchronous cell system, the density of unifilarly substituted DNA is about 0.010 g/ml higher during first half of S phase than during second half of S phase. The density of unifilarly substituted DNA isolated from asynchronously growing cells is similar to that of DNA synthesized during the second half of S phase of synchronously growing cells for a given concentration of analogue in culture medium. Reassociation kinetics experiments have shown the oversubstitution to occur at the level of early synthesized repeated and/or intermediate DNA sequences. It is then assumed that the oversubstitution is due to some metabolic changes caused by the synchronization procedure itself. As BrdU incorporation into early replicating DNA is known to induce alterations of the cell metabolism, the implication of this phenomenon is discussed at the level of the inhibition of transformation which takes place when chick embryo fibroblasts are infected with Rous sarcoma virus during G1 and subsequently treated with BrdU during early S phase.

Animals↗
PubMed1985

Follow-up study of 100 malignant pleural mesotheliomas.

One hundred malignant pleural mesotheliomas have been treated in our hospital since 1955. Clinical and autopsy findings are analyzed and compared to X-ray changes. The most common symptoms were dyspnea (49%), pain (40%) and cough (36%). The main initial X-ray signs were pleural effusion (62%), pleural thickening (29%) and solitary nodules (6%). Prior to death a combination of effusion and pleural thickening was the usual finding. Histologically there were 49 biphasic, 32 mesenchymal and 18 epithelial malignant pleural mesotheliomas. At autopsy 82% of the cases had distant metastases, most of which had not been expected clinically. The median survival time was 7.3 months following the first clinical symptoms, and only 4 months after the first radiological signs.

Adult↗
PubMed1985

[Clinical specular microscopy. Technic, organization and simple calculator morphometry].

The use of specular microscopy (SM) as a routine clinical method for qualitative morphological and quantitative morphometric analysis of the corneal endothelium requires a standardized examination technique. Organizational and apparative means are necessary for the analysis, documentation and storage of the data. The results of the immediate analysis are documented on a result form. The morphological changes are classified in 4 different groups (endothelial, pre-endothelial, retro-endothelial, and non-endothelial changes). The morphometric analysis is performed immediately: the mean cell density (mcd) is estimated by comparing the endothelial mosaic in the camera viewfinder with 3 standardized specular micrographs with known cellular density. The good correlation between the results of estimation and definite counting allows this rapid method to be used as a simple clinical screening techniques. The definitive morphometric analysis is carried out directly from the photographic negative using the fixed frame principle. The mcd and mean cell area (mca), m +/- sd, are determined by a simple method which saves time and money, using a scientific pocket calculator programmed in Basic. A specially designed slide rule serves to define the frame. The calculator may also be used for statistical analyses. This is demonstrated in a group of 127 patients (aged 51-87) before IOL implantation. The mcd and mca of the examined population is 2249 +/- 290 cells/mm2 and 444 +/- 57 microns 2. There is no statistically significant difference in mcd between the right and left eye (t-test: p = 0.93). Although statistically mcd decreases significantly with advancing age (p = 0.05), there is a large range of results in this population.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗