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C Büttner

Publications and source records attributed to C Büttner.

At least 37 records · Page 2Linked to original sources
PubMed1998

Identification of activating c-kit mutations in adult-, but not in childhood-onset indolent mastocytosis: a possible explanation for divergent clinical behavior.

Mastocytosis represents a mast cell proliferative disease that generally runs a benign clinical course, with spontaneous remissions mostly by puberty in childhood-onset disease, although rare forms, particularly in adult-onset disease, can be associated with (pre)malignant hematologic disorders and very rarely present as mast cell leukemia or malignant mastocytosis. Reasons for this divergent clinical behavior of childhood- versus adult-onset disease are unknown. Recently, two activating mutations in the intracellular domain of the proto-oncogene c-kit, which encodes a tyrosine kinase receptor for the mast cell growth factor stem cell factor, have been detected in the human leukemic mast cell line HMC-1. We have therefore studied lesional skin biopsies from patients with adult- and childhood-onset indolent mastocytosis for the presence of these codon 560 and 816 mutations. C-kit coding DNA sequences were amplified and analyzed by mutation-specific restriction analyses, and mutated polymerase chain reaction products were additionally cloned and sequenced. The codon 816 mutation was found in all six samples from adult patients, but not in any of the 11 specimens from children. In addition, the codon 560 mutation could be demonstrated for the first time in indolent mastocytosis, namely in two of four specimens from adult patients, but not in those from two children. These data thus provide a possible explanation for the divergent clinical behavior of adult- versus childhood-onset indolent mastocytosis, with the first being associated with an activating mutation, possibly as part of a neoplastic process, and the latter representing most likely a reactive process of an as yet unknown pathogenesis.

Adult↗
PubMed1998

Delayed low density lipoprotein (LDL) catabolism despite a functional intact LDL-apolipoprotein B particle and LDL-receptor in a subject with clinical homozygous familial hypercholesterolemia.

We identified a 38-yr-old male patient with the clinical expression of homozygous familial hypercholesterolemia presenting as severe coronary artery disease, tendon and skin xanthomas, arcus lipoides, and joint pain. The genetic trait seems to be autosomal recessive. Interestingly, serum concentrations of cholesterol responded well to diet and statins. We had no evidence of an abnormal low density lipoprotein (LDL)-apolipoprotein B (apoB) particle, which was isolated from the patient using the U937 proliferation assay as a functional test of the LDL-binding capacity. The apoB 3500 and apoB 3531 defects were ruled out by PCR. In addition, we found no evidence for a defect within the LDL-receptor by skin fibroblast analysis, linkage analysis, single-strand conformational polymorphism and Southern blot screening across the entire LDL-receptor gene. The in vivo kinetics of radioiodinated LDL-apoB were evaluated in the proband and three normal controls, subsequently. The LDL-apoB isolated from the patient showed a normal catabolism, confirming an intact LDL particle. In contrast the fractional catabolic rate (d-1) of autologous LDL in the subject and the normal controls revealed a remarkable delayed catabolism of the patient's LDL (0.15 vs. 0.33-0.43 d-1). In addition, the elevation of LDL-cholesterol in the patient resulted from an increased production rate with 22.8 mg/kg per day vs. 12.7-15.7 mg/kg per day. These data indicate that there is another catabolic defect beyond the apoB and LDL-receptor gene causing familial hypercholesterolemia.

Adult↗
PubMed1997

In vivo kinetics as a sensitive method for testing physiologically intact human recombinant apolipoprotein A-I: comparison of three different expression systems.

In order to assess the structural and functional integrity of recombinant human apoA-I, we expressed apoA-I using three different expression systems: Baculovirus transfected Spodoptera frugiperda (Sf9) cells, stably transfected Chinese hamster ovary (CHO) cells, and transformed Escherichia coli (E. coli). Purified apoA-I from the three expression systems was radioiodinated and their catabolism was compared in normolipemic rabbits. The kinetic turnover studies of radiolabelled apoA-I in normolipemic rabbits revealed that highly purified recombinant apoA-I had an identical decay curve compared to native apoA-I, regardless whether it was purified from Sf9 cells, CHO cells, or E. coli. We also determined the association of the three recombinant apoA-I forms with both rabbit and human HDL. All three recombinant apoA-I forms were associated with HDL2 and HDL3 after injection into the rabbits and after incubation with human serum using both a Superose 6 column separation system and density gradient ultracentrifugation. The addition of the pro-segment or the addition of methionine at the amino-terminal end of apoA-I did not alter its metabolism and association to HDL. In conclusion, all studied expression systems are capable of producing high levels of physiologically intact recombinant human apoA-I. The aminoterminal addition of the prosegment of apoA-I or methionine did not alter the in vivo metabolism of apoA-I or its association to HDL.

Animals↗
PubMed1997

Expression and purification of recombinant human apolipoprotein A-I in Chinese hamster ovary cells.

The expression of apolipoprotein A-I (apoA-I) has been shown to be very difficult due to its amphiphilic character, autoaggregation, and degradation. We have expressed apoA-I using CHO cells, Baculovirus, and Escherichia coli [Schmidt et al., J. Biol. Chem. (1995) 270, 469-475]. Here we report about optimized conditions for the expression of proapoA-I in CHO cells, testing various serum-free media. We were able to yield apoA-I expression up to 80 micrograms/ml, by far the highest ever reported. However, immunoblot analysis revealed degraded apoA-I. The best apoA-I expression testing various conditions was about 20-30 micrograms/ml without any evidence of degradation. Interestingly, the apoA-I expression resulted in reproducible apoA-I fragments of 26 and 14 kDa. These fragments are consistent with already reported in vivo findings, in which carboxy-terminal proteolysis was suggested. The use of the protease inhibitors pepstatin and chymostatin, both carboxy-peptidase inhibitors, did result in contrast to other studied protease inhibitors in increased apoA-I yield. Therefore, limited carboxy-terminal proteolysis contributes to the degradation of CHO cell-secreted apoA-I. In addition, we evaluated various purification methods for the preparative isolation of recombinant apoA-I. In our hands we obtained the best recovery and no degradation with reversed-phase chromatography using a FPLC system.

Animals↗
PubMed1997

Local production of interleukin-4 during radiation-induced pneumonitis and pulmonary fibrosis in rats: macrophages as a prominent source of interleukin-4.

Fibrosis of lung tissue is a frequent and serious consequence of radiotherapy of mammary carcinoma. The pathogenesis of radiation-induced pulmonary fibrosis remains unclear. Cytokines such as transforming growth factor beta (TGFbeta) and interleukin-4 (IL-4) have been reported to stimulate collagen synthesis in fibroblasts in vitro. The aim of this study was to document the presence of IL-4 during the development of post-irradiation lung fibrosis. Right lungs of male Fischer rats were irradiated with a single dose of 20 Gy and IL-4 expression in the irradiated lungs was monitored for a period of three months. IL-4 gene transcription as determined by ribonuclease protection assay (RPA) as well as IL-4 synthesis as shown by Western blotting increased in the irradiated lungs reaching a plateau concentration within 3 weeks after irradiation. Enhanced IL-4 production was still detected at day 84 after irradiation. The cellular origin of IL-4 was analyzed by in situ hybridization and two-color immunofluorescence on lung tissue sections and on cytospin preparations of leukocytes obtained from bronchoalveolar lavages. These experiments revealed a substantial IL-4 production by macrophages during development of post-irradiation lung fibrosis.

Animals↗
PubMed1995

Molecular and structural characterization of the heat-resistant thyroxine-binding globulin-Chicago.

Thyroxine-binding globulin (TBG) is the main transport protein for thyroxine (T4) in blood. It shares considerable sequence homology with alpha 1-antitrypsin (AT) and other members of the serine proteinase inhibitor (serpin) superfamily of proteins. The crystallographic structure of AT has been determined and was found to represent the archetype of the serpins. This model has been used for structure-function correlations of TBG. Sequence analysis of the heat-resistant variant TBG-Chicago (TBG-CH) revealed a substitution of the normal tyrosine 309 with phenylalanine. For further analysis, vectors containing the coding regions of normal TBG (TBG-N) and TBG-CH were constructed, transcribed in vitro, and expressed in Xenopus oocytes. Both TBGs were secreted into the culture medium and could not be distinguished by gel electrophoresis. Scatchard analysis of T4 binding to TBG-N and -CH revealed no significant differences in binding affinity. The rate of heat denaturation of TBGs was determined by measurement of residual T4 binding capacity after incubation at 60 degrees C for various periods of time. The half-life values of denaturation of TBG-N and -CH were 7 and 132 min, respectively. The tyrosine 309 to phenylalanine substitution of TBG-CH involves a highly conserved phenylalanine residue of the serpins. The respective phenylalanine 312 of AT ties the alpha-helix hI1 to the molecule, thus stabilizing the tertiary structure. A substitution with tyrosine would disrupt this interaction. Accordingly, stabilization of the TBG molecule by replacement of tyrosine with phenylalanine in position 309 causes the increased heat stability of TBG-CH.

Amino Acid Sequence↗
PubMed1993

[Chronic lipogranuloma (paraffin granuloma) of the eyelids and orbits after endonasal paranasal sinus operation].

During the last five years 10 patients received surgical treatment in our eye clinic for tumours of the eyelids and the orbit that had developed after endonasal sinus surgery. In most patients the first signs of lid or orbital involvement had occurred 4 weeks after ENT surgery and after a unilateral or bilateral postoperative haematoma had subsided. The histological examination of the surgical specimens showed chronic sclerosing lipogranuloma containing large vacuoles surrounded by epithelioid and giant cells, typical of a so-called paraffin granuloma. MR-spectroscopy detected high concentrations of paraffin in the specimens of 3 patients. Since paraffin is a constituent of many ointments, we assume that the granulomatous reaction was elicited by the ointment tampons routinely applied to the wound area following sinus surgery. The bleeding acted as a vehicle to distribute the paraffin into the surrounding tissues.

Adult↗
PubMed1991

[Chronic lipogranuloma of the eyelids after paranasal sinus operations].

Over a period of about 1 year we observed five patients who developed tumors of their eyelids a few days to 3 weeks after surgery on the paranasal sinuses through the nasal passage. One patient noticed a swelling of his ipsilateral eyelid during an irrigation procedure for the maxillary sinus, which was also followed by endonasal surgery. After surgery each patient developed an ipsilateral periorbital hematoma and subsequently solid indolent tumors of the eyelid without a tendency to regress over a period of 3 to 14 months. Therefore, surgical treatment was necessary. The histological examination showed lipogranulomas with giant cells and many lipid vacuoles of different size. Exploring the origin of these lipids, we performed a magnetic-resonance-spectrum analysis of one tumor sample. We predominantly found signals for linear hydrocarbons, which are the main components in paraffin-liquids. We presume that our patients developed lipogranulomas of their eyelids due to the paraffin introduced into the tissue by the ointment used to tampon the paranasal sinus after endonasal surgery.

Adult↗
PubMed1989

[Embolization by the wall components after the PTA of pelvic arterial stenoses].

Quality and frequency of embolisation caused by angioplasty of stenoses of iliac arteries were investigated in 50 patients. In 18% emboli were found. They mostly consisted of atheromatous material and were visible by macroscopic view in 10% of the patients. Complications caused by embolisation during angioplasty of iliac artery stenosis however are very rare.

Aged↗
PubMed1989

Sensitivity of the adenine nucleotide metabolism of platelets from malignant hyperthermia patients to halothane.

Blood platelets from malignant hyperthermia patients share the same defect as skeletal muscle. This could be verified by the effect of halothane on the energy metabolism of blood platelets under optimal experimental conditions. The sensitivity of changes in adenine nucleotide metabolization to halothane was significantly higher in platelets from malignant hyperthermia patients than in controls. The enhanced sensitivity is not caused by an adenylate kinase deficiency.

Adenine Nucleotides↗
PubMed1988

Immunological reaction of guinea-pigs following intranasal Mycoplasma pneumoniae infection and immunization with the 168 kDa adherence protein.

Humoral responses to Mycoplasma pneumoniae proteins, especially the 168 kDa protein, were demonstrated by Western blotting in sera and bronchial washings of all groups of infected or immunized guinea-pigs. However, infection was not prevented by these local and systemic antibodies. Hilar lymphocytes of infected and immunized guinea-pigs were stimulated in vitro by sonicated M. pneumoniae antigen and by the 168 kDa protein. Stimulation was significantly lower in animals which had been infected twice or had been preimmunized and challenged by infection. Histologically the most severe lesions were seen in the twice-infected group followed by the preimmunized group which was subsequently infected.

Animals↗
PubMed1983

[Pancreas tail pseudotumor--CT for the detection of position variants of the pancreas tail as a cause for pathologic findings in conventional radiographic and ultrasound studies].

Four cases are presented, in whom conventional radiography of the abdomen including tomography and ultrasound raised high suspicion of a left suprarenal tumor. Abdominal CT explained the finding in each case as being produced by a normal anatomic variation of the pancreatic tail, which was found in a paraspinal and suprarenal location. The statistical incidence of such a variation is discussed.

Adrenal Gland Neoplasms↗