PubMed Health⌕ Search

Biomedical subjects

R Christ

Publications and source records attributed to R Christ.

At least 19 recordsLinked to original sources
PubMed2005

Mutational and functional analyses of xylosyltransferases and their implication in osteoarthritis.

OBJECTIVE: The hallmark in osteoarthritis (OA) is the loss of proteoglycans (PGs) in articular cartilage (AC). Xylosyltransferase I (XT-I) catalyzes the transfer of xylose to serine residues in the core protein and initiates the biosynthesis of PGs in AC. The XYLT-II gene encodes a highly homologous protein but its biological function is not yet known. Here we investigate for the first time genetic variations in the XYLT-genes and serum XT-I activities and their implication in OA. METHODS: Denaturing high-performance liquid chromatography (DHPLC) was used for the screening of the XYLT-genes in 49 OA patients. For a detailed characterization of XT-I amino acid exchanges we performed recombinant expression of XT-I mutants in insect cells. Furthermore, the XT activity was measured in the patients' serum. RESULTS: The variation c.1569C>T (XYLT-II) occurs with a significantly higher frequency in younger OA patients in comparison with the older ones (P<0.001) and the controls (P<0.02). Furthermore, significantly higher serum XT activities were found in patients with a long disease duration of OA (P<0.04). The recombinant XT-I mutants p.P385L and p.I552S had reduced enzymatic activity (85% and 74%) compared with the wildtype (wt). CONCLUSIONS: Our findings indicate a correlation of the c.1569 T-allele in XYLT-II with an earlier manifestation of OA and that the serum XT activity is a potential biochemical marker for staging and monitoring the progression of AC damage in OA. Comparison of XT-I activity in mutant enzymes in vivo and in vitro revealed that heterozygous mutations are not involved in OA.

Aged↗
PubMed1999

Phylogeny and polyphasic taxonomy of Caulobacter species. Proposal of Maricaulis gen. nov. with Maricaulis maris (Poindexter) comb. nov. as the type species, and emended description of the genera Brevundimonas and Caulobacter.

The genus Caulobacter is composed of prosthecate bacteria often specialized for oligotrophic environments. The taxonomy of Caulobacter has relied primarily upon morphological criteria: a strain that visually appeared to be a member of the Caulobacter has generally been called one without challenge. A polyphasic approach, comprising 16S rDNA sequencing, profiling restriction fragments of 16S-23S rDNA interspacer regions, lipid analysis, immunological profiling and salt tolerance characterizations, was used to clarify the taxonomy of 76 strains of the genera Caulobacter. Brevundimonas, Hyphomonas and Mycoplana. The described species of the genus Caulobacter formed a paraphyletic group with Caulobacter henricii, Caulobacter fusiformis, Caulobacter vibrioides and Mycoplana segnis (Caulobacter segnis comb. nov.) belonging to Caulobacter sensu stricto. Caulobacter bacteroides (Brevundimonas bacteroides comb. nov.), C. henricii subsp. aurantiacus (Brevundimonas aurantiaca comb. nov.), Caulobacter intermedius (Brevundimonas intermedia comb. nov.), Caulobacter subvibrioides (Brevundimonas subvibrioides comb. nov.), C. subvibrioides subsp. albus (Brevundimonas alba comb. nov.), Caulobacter variabilis (Brevundimonas variabilis comb. nov.) and Mycoplana bullata belong to the genus Brevundimonas. The halophilic species Caulobacter maris and Caulobacter halobacteroides are different from these two genera and form the genus Maricaulis gen. nov. with Maricaulis maris as the type species. Caulobacter leidyia was observed to cluster with species of the genus Sphingomonas. Caulobacter crescentus is synonymous with C. vibrioides and C. halobacteroides is synonymous with Maricaulis maris as determined by these analyses and DNA-DNA hybridization. Biomarkers discerning these different genera were determined. The necessary recombinations have been proposed and a description of Maricaulis is presented.

Antigens, Bacterial↗
PubMed1994

PCR-RFLP-based DQA1 typing of rhesus monkeys: sequence analysis of a new allele.

In spite of the widespread use of rhesus monkeys (Macaca mulatta) in biomedical research, MHC typing of this species is not yet routine. Since suitable antibodies are lacking, serological typing of Mamu-DQA1 is not feasible. We developed a typing protocol for MhcMamu-DQA1 from published sequences of the second exon of Mamu-DQA1. This protocol is based on the amplification of the second exon of Mamu-DQA1 with one specific primer pair followed by a "diagnostic" digestion of the PCR products with, at most, 5 different restriction endonucleases. This modified PCR-RFLP permits the rapid identification of 11 out of 13 Mamu-DQA1 alleles in homozygous and heterozygous combinations. The protocol was validated by cloning and sequencing the PCR-products of several animals of different geographic origin. In addition, an as yet unknown allele was detected by PCR-RFLP and was subsequently cloned and its nucleotide sequence determined. All examined sequences except the new allele were identical to those previously published. Therefore, we assume that many of the Mamu-DQA1 alleles of rhesus monkeys have been identified molecularly and that the typing technique presented here can reliably identify Mamu-DQA1 alleles.

Alleles↗
PubMed1994

Complex polar lipids of a hot spring cyanobacterial mat and its cultivated inhabitants.

The complex polar lipids of the hot spring cyanobacterial mat in the 50 to 55 degrees C region of Octopus Spring, Yellowstone National Park, and of thermophilic bacteria cultivated from this or similar habitats, were compared in an attempt to understand the microbial sources of the major lipid biomarkers in this community. Intact complex lipids were analyzed directly by fast atom bombardment mass spectrometry (FAB-MS), two-dimensional thin-layer chromatography (TLC), and combined TLC-FAB-MS. FAB-MS and TLC gave qualitatively similar results, suggesting that the mat contains major lipids most like those of the cyanobacterial isolate we studied, Synechococcus sp. strain Y-7c-s. These include monoglycosyl, diglycosyl, and sulfoquinosovyl diglycerides (MG, DG, and SQ, respectively) and phosphatidyl glycerol (PG). Though Chloroflexus aurantiacus also contains MG, DG, and PG, the fatty acid chain lengths of mat MGs, DGs, and PGs resemble more those of cyanobacterial than green nonsulfur bacterial lipids. FAB-MS spectra of the lipids of nonphototrophic bacterial isolates were distinctively different from those of the mat and phototrophic isolates. The lipids of these nonphototrophic isolates were not detected in the mat, but most could be detected when added to mat samples. The mat also contains major glycolipids and aminophospholipids of unknown structure and origin. FAB-MS and TLC did not always give quantitatively similar results. In particular, PG and SQ may give disproportionately high FAB-MS responses.

Chlorobi↗
PubMed1991

Proliferative capacity of mononuclear cells in the human lung.

In pulmonary sarcoidosis, a chronic granulomatous disorder with different stages of activity, the proliferative capacity of the alveolar mononuclear cells is unknown. To get a closer look at this proliferation we combined pulse labeling (by means of tritium thymidine incorporation and autoradiography) with an immunocytochemical staining assay. This assay revealed on one single slide simultaneously blue CD4+ lymphocytes, brown CD8+ lymphocytes and red macrophages. We were able to show that CD4+ as well as CD8+ lymphocytes were radiolabeled only in the active state of the disease. But macrophage proliferation occurred independently of the activity of the disease. In other words with this combination of techniques, it is possible to differentiate, on a single slide, three subsets of mononuclear cells, in combination with their proliferative behavior.

Autoradiography↗
PubMed1991

[Immunohistochemically detected activity of lysozyme in sarcoidosis granulomas--a parameter for the activity of the illness process?].

In 30 patients with sarcoidosis we estimated immunohistochemically the activity of lysozyme in correlation to the activity of ACE in serum and found a positive correlation between these two parameters. We conclude, that the lysozyme content of sarcoidotic granulomas, estimated immunohistochemically, may be a useful morphological parameter of the activity of the disease, applicable on formol fixed and paraffin embedded bioptical material.

Adult↗
PubMed1991

[Serum reactivity of antigen fractions of atypical mycobacteria in patients with lung diseases].

In connection with studies on the pathogenesis of sarcoidosis antigen fractions were isolated from 8 mycobacteria species, three out of each strain. These fractions were tested for their reactivity to serum antibodies by means of RIA-technique, using 40 selected sera from controls, and patients with sarcoidosis, tuberculosis and asthma. Comparing the results (average titer steps) sera from asthmatics showed the lowest and those from sarcoidosis patients the highest reactivities to the mycobacterial antigen fractions. The reactivities clearly differed in dependence on the mycobacteria species. The highest mean reactivity in sarcoidosis patients was found with the HIP-antigen fraction of M. xenopi. It was 8 times higher compared to the control sera as well as the tuberculosis sera and 32 times higher than that of the asthma sera. There were also clear differences in the reactivities within the sarcoidosis sera tested. In sera from patients with clinically inactive sarcoidosis there were found nearly the same or only slightly higher titer steps than in control sera as well as tuberculosis sera, however in clinically active sarcoidosis the titer steps were clearly elevated. The findings are seen in connection with the role of atypical mycobacteria (MOTT) in the pathogenesis of sarcoidosis. The potential applications of the HIP- and Triton X-100 antigen fractions for in vitro diagnostics are discussed.

Antibodies, Bacterial↗
PubMed1991

[Splenectomy in sarcoidosis].

It is reported about 6 patients suffering from sarcoidosis with splenomegaly. In these cases indication for splenectomy was given by symptoms of hypersplenism, abdominal pain and ineffective cortisone therapy. In general after operation activity of sarcoidosis is unchanged. Different markers of activity were used after a time interval of 2-11 years. In one case it has to be discussed an overwhelming postsplenectomy infection (OPSI).

Adult↗
PubMed1989

Evaluation of the biocompatibility and fixation of a new silicone intraocular lens in the feline model.

The biocompatibility and fixation of a new silicone intraocular lens was evaluated in the cat eye. Following extracapsular lens extraction, 14 cats were implanted with a silicone lens (SLM 2/UV type) with polypropylene modified J loops in one eye and a poly(methyl methacrylate) (PMMA) lens (Perspex CQ) of a similar design in the fellow eye. Half the lenses were placed in the ciliary sulcus and half in the capsular bag. The eyes were evaluated for up to one year. Neither lens material showed any signs of toxicity clinically or histopathologically. Both lenses achieved stable fixation in the capsular bag; however, some inflammatory reaction and lens dislocation were noted with sulcus placement of both lens types. The amount of proteinaceous and cellular debris on the explanted silicone lenses was significantly less than that on the PMMA lenses as assessed with methylene blue staining. All retrieved lenses were optically clear and no significant change in the lens surface morphology, clarity and/or optical properties was observed.

Animals↗
PubMed1988

[Problems in anesthesia of drug addicts].

This review attempts to provide an inside view of the current state of knowledge on the anesthetic management of the drug addict intra- and postoperatively. The summary of the numerous publications on this subject demonstrates that neither a unanimous opinion nor a uniform anesthetic procedure exists. The choice of procedure depends on the medical history as well as the physical and psychological status of the patient.

Anesthesia↗
PubMed1987

[Value of bronchoalveolar lavage in assessing the activity of sarcoidosis].

BAL was performed in different courses of sarcoidosis in order to evaluate the importance of this examination. We found a higher degree of lymphocytosis in Löfgren's syndrome and in relapses than in the others. Probably there is a direct connection between high intensity alveolitis and reduction of diffusing capacity. There could not be found any correlation to other markers of activity (lung function, SACE, 67-Gallium-Scan).

Bronchoalveolar Lavage Fluid↗
PubMed1987

[Value of gallium-67 scintigraphy in the diagnosis and assessment of activity in sarcoidosis].

Gallium-67 scan has an increased importance in the examination of activity in sarcoidosis. Compared with other markers of activity only gallium-67 can give an information about the localization of active granulomas in the body. It is profitable to distinguish between the accumulation of 67-gallium in the region of hilus and of lung parenchyma. SACE and gallium-67 scan complement each other. There is a good correlation between SACE and gallium-67 score, especially if there is an involvement of lung parenchyma.

Gallium Radioisotopes↗
PubMed1987

[Chemiluminescent measurements of alveolar macrophages in sarcoidosis patients].

The phagocytic activity of alveolar macrophages (AM) in a group of patients with stage I, stage II and stage III pulmonary sarcoidosis (gradation according to Wurm) has been investigated. Additionally a classification in different forms of the course of sarcoidosis was made (acute = Loefgren's syndrome, latent = primary-chronic, and relapses). Patients with other lung diseases and healthy subjects were recruited as control group. The phagocytic activity (stimulation with opsonized yeast cell wall particles) of AM, which were isolated by bronchoalveolar lavage, was determined by means of chemiluminescence (CL)-measuring using lucigenin and luminol, respectively, as amplifiers. The investigations showed that the lucigenin-dependent yeast cell wall-induced CL of AM in patients with sarcoidosis is significantly increased in comparison to the control group. No significant changes of the luminol-dependent CL of AM from sarcoidosis patients could be detected. The lucigenin-dependent CL-response of AM is obviously an indicator of the intensity of the alveolitis and thus of the activity of the pathological process in sarcoidosis. The results suggest that in pulmonary sarcoidosis there is a hyperreactive AM/lymphocytes-system.

Acridines↗