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Biomedical subjects

R Stoll

Publications and source records attributed to R Stoll.

At least 19 recordsLinked to original sources
PubMed1997

Conformation of thymosin beta 9 in water/fluoroalcohol solution determined by NMR spectroscopy.

The conformation of thymosin beta 9 in solution of 40% (v/v) 1,1,1,3,3,3-hexafluoro-2-propanol-d2 in water has been investigated by two-dimensional 1H-nmr spectroscopy. Under this condition thymosin beta 9 adopts an ordered structure. The determination of the conformation of the peptide was based on a set of 304 approximate interproton distance constraints derived from nuclear Overhauser enhancement measurements. The conformation of thymosin beta 9 includes two helical regions from residues 4 to 27 and 32 to 41. The two helices are separated by a poorly defined loop region between amino acids 28 and 31; the N-terminus of thymosin beta 9 shows random-coil structure only.

Amino Acid Sequence↗
PubMed1997

Synergistic effect of immunoregulatory cytokines on peripheral blood monocytes from patients with inflammatory bowel disease.

Active inflammatory bowel disease (IBD) is characterized by increased monocyte secretion of proinflammatory cytokines. Immunoregulatory cytokines such as Interleukin (IL)-4, IL-10, and IL-13 are capable of inhibiting the proinflammatory cytokine response of activated monocytes. The aim of our study was to determine the effect of different antiinflammatory cytokines under various culture conditions and to evaluate combinations of antiinflammatory cytokines in down-regulating monocyte response in IBD. Peripheral monocytes from patients with active IBD were isolated and stimulated with pokeweed mitogen (PWM). IL-4, IL-10, IL-13 and a combination of IL-4/IL-10 and IL-10/IL-13 were added at different concentrations and different times. Secretion of IL-1beta and TNF-alpha was assessed using sandwich ELISA systems. There was a diminished down-regulation of TNF-alpha by IL-4 and IL-13 in IBD when the cytokines were added at the time of stimulation, while there was a significantly higher down-regulation when monocytes were primed with these Th-2 cytokines 24 hr before activation. IL-10 plus IL-4 and IL-10 plus IL-13, respectively, inhibited the proinflammatory cytokine response of monocytes as well as matured macrophages much more than IL-4, IL-10, or IL-13 alone. Even at suboptimal concentrations for each cytokine alone, a combination of cytokines showed synergistic inhibitory effects. In summary, a combination of antiinflammatory cytokines is more effective in down-regulating the response of activated monocytes than using the cytokines alone and thus may have a potential therapeutic benefit for patients with IBD.

Cells, Cultured↗
PubMed1996

Immunoregulatory properties of IL-13 in patients with inflammatory bowel disease; comparison with IL-4 and IL-10.

Activated monocytes with increased expression of proinflammatory cytokines play a major role in inflammatory bowel disease (IBD). Immunoregulatory cytokines such as IL-4 and IL-10 can effectively suppress the proinflammatory response of activated monocytes. IL-13 is a recently described antiinflammatory agent in vitro. The aim of our study was to determine the in vitro immunosuppressive capacity of IL-13, IL-4 and IL-10 in patients with IBD. Peripheral blood monocytes were isolated from 27 patients with ulcerative colitis (UC), 27 patients with Crohn's disease (CD) and 16 healthy controls. Cells were stimulated with pokeweed mitogen (PWM) after treatment with IL-13, IL-4 and IL-10, and secretion of IL-1beta, tumour necrosis factor-alpha (TNF-alpha) and IL-6 was assessed using sandwich ELISA systems. Peripheral blood monocytes secreted significantly increased amounts of TNF-alpha and IL-6 under stimulation with PWM in patients with CD, while UC patients showed significantly elevated levels of IL-1beta. The antiinflammatory cytokines IL-13, IL-4 and IL-10 were all capable of inhibiting monocyte secretion of IL-1beta in a dose-dependent manner. With regard to IL-13 and IL-4, there was no significant suppression of TNF-alpha and IL-6 in patients with active IBD. By contrast, IL-10 was able to down-regulate all proinflammatory cytokines in active IBD as well as in controls. Proinflammatory cytokines from patients with inactive IBD could be significantly down-regulated by all three immunoregulatory cytokines. The inhibitory effect of IL-13 on TNF-alpha and IL-6 production in differentiated macrophages was diminished in IBD patients, as well as in controls. In disease controls we also observed a reduced inhibition of TNF-alpha and IL-6 after treatment with IL-13. In conclusion, the antiinflammatory activity of IL-13 is partially reduced in patients with active IBD. The hyporesponsiveness of activated and differentiated monocytes to IL-13 and IL-4 does not seem to be a disease-specific phenomenon.

Adolescent↗
PubMed1996

Crohn's disease (CD) patients suffering from peripheral arthritis or ankylosing spondylitis reveal restricted T cell receptor V beta regions in different temporal phases of disease.

Little is known about the mechanisms triggering and controlling both the development and perpetuation of extraintestinal complications in CD. The aim of the present study was to test the hypothesis that the T cell immune response in CD patients with joint complications may be altered when compared with patients without extraintestinal manifestations. We used a semiquantitative polymerase chain reaction assay to analyse the T cell antigen receptor repertoire in peripheral blood T cells from eight CD patients suffering from peripheral arthritis and ankylosing spondylitis, 12 CD patients without extraintestinal manifestations, and from seven non-CD patients with ankylosing spondylitis showing typical changes on joint radiographs. Being concerned that different patterns may be seen in different phases of the inflammatory disease process, we have also taken care to analyse sequential samples at various time points of the disease. Expression of all 22 V beta genes was found in each healthy control and in each CD patient without extraintestinal manifestations and showed no major variation over time. Southern hybridization analysis of amplified products revealed a highly restricted V beta repertoire in all CD patients suffering from peripheral arthritis and ankylosing spondylitis. In contrast, non-CD patients with ankylosing spondylitis without signs or symptoms of gastrointestinal problems demonstrated the presence of the entire V beta repertoire. Our longitudinal studies confirmed variable V beta usage over time, as certain transcripts were found only in distinct temporal phases of disease. Our data are not directly suggestive of a common superantigen model of CD, but instead emphasize a specific decrease in signals throughout the T cell receptor V beta repertoire in CD patients suffering from joint complications.

Adult↗
PubMed1996

Cytochrome c550 expression in Paracoccus denitrificans strongly depends on growth condition: identification of promoter region for cycA by transcription start analysis.

The periplasmic cytochrome c550 content of Paracoccus denitrificans has been shown by immunological detection to be strongly dependent on the mode of growth. Cells grown under anaerobic, denitrifying conditions or methylotrophically in the presence of oxygen contained substantially more cytochrome c550 than cells grown aerobically on multicarbon substrates. A similar pattern was observed when expression of the cycA gene (encoding cytochrome c550), was monitored using an Escherichia coli alkaline phosphatase gene (phoA) fusion as a reporter of cycA promoter activity. The increase in cycA expression observed during growth on C1 substrates was substantially diminished if succinate was also present. These results reveal that expression of cycA is subject to multiple regulatory controls and suggest that cytochrome c550 has a general role in electron transfer to periplasmic reductases required for anaerobic denitrifying growth and from dehydrogenases required for aerobic growth on C1 compounds. Two major transcriptional initiation start points for the cycA gene have been identified.

Base Sequence↗
PubMed1996

Alteration of haem-attachment and signal-cleavage sites for Paracoccus denitrificans cytochrome C550 probes pathway of c-type cytochrome biogenesis in Escherichia coli.

Paracoccus denitrificans cytochrome C550 is expressed as a periplasmic holo-protein in Escherichia coli; amino acid substitutions of cysteine residues in the haem-binding motif (Cys-X-X-Cys-His), either together or singly, prevented covalent attachment of haem but not polypeptide translocation into the periplasm. When the three alanine residues at positions -3 to -1 in the native signal-cleavage site were deleted, or alanine at -1 was changed to glutamine, signal cleavage was at alternative sites (after only ten residues in the latter case), but haem attachment still occurred. When the same three alanines were changed to Asp-Glu-Asp, a membrane-associated apo product that had retained the complete signal sequence was detected. These and other results presented here indicate that (i) haem attachment is not required for the apo-cytochrome C550 export to the periplasm; (ii) haem cannot attach to apo-cytochrome C550 when attached to the cytoplasmic membrane, suggesting that signal-sequence cleavage precedes periplasmic haem attachment, which can occur at as few as six residues from the mature N-terminus; and (iii) two cysteines are required for haem attachment, possibly because a disulphide bond is an intermediate. The gene for Saccharomyces cerevisiae mitochondrial iso-1-cytochrome c was expressed as a holo-protein in E. coli when fused with the signal sequence plus the first 10 residues of the mature cytochrome C550, indicating that the E. coli cellular apparatus for the c-type cytochrome biogenesis has a broad substrate specificity.

Amino Acid Sequence↗
PubMed1996

13C-urea breath test for detection of Helicobacter pylori and its correlation with endoscopic and histologic findings.

The urea breath test (UBT) reflects the intragastric urease activity and thus the extent of H. pylori (H.p.) burden of the mucosa. We compared UBT results with gastroscopic and histologic findings in 174 patients. H.p.density, grade and activity of the chronic gastritis type B were semiquantitatively assessed. 46% of patients were H.p.-positive. A type B gastritis was significantly (p < 0.01) associated with H.p. colonization. UBT-results significantly correlated with the grade (r = 0.53) and the activity (r = 0.45) of gastritis. They correlated better with grade and activity of the inflammation than did the H.p.-density in histology (r = 0.38 and r = 0.37). There is a considerable interindividual variability in UBT-results for the same degree of gastritis indicating that besides the number of bacteria other factors must be of significance for the severity of inflammation. Endoscopic findings apart from ulcers do not predict the presence of H.p.

Breath Tests↗
PubMed1995

Chromosome polymorphisms close to the cm-ADE1 locus of candida maltosa.

The imperfect yeast Candida maltosa has an ill-defined genetic constitution; it is nominally diploid, but probably highly aneuploid, in nature. We report on polymorphisms specifically affecting those chromosomes which bear the cm-ADE1 gene. This gene encodes phosphoribosylaminoimidazole-succino-carboxamide synthetase, an enzyme in the adenine biosynthetic pathway. By electrophoretic karyotype analysis, three differently sized chromosomes were demonstrated to carry cm-ADE1; the size (but not the number) of these chromosomes was also found to vary, both between strains and during the mitotic growth of a single strain. Four different alleles of cm-ADE1 have been cloned and sequenced from one prototrophic strain. DNA sequence divergence between these different alleles is as high as 8%, with the greatest divergence being found in the upstream region. Mitotic recombination events that led to changes in the karyotype were followed by using cm-ADE1 DNA as an hybridization probe. A recombination hot-spot in the neighbourhood of the gene appears to be responsible for the instability of the chromosomes on which it residues.

Alleles↗
PubMed1995

Action of testosterone on the estradiol-induced feminization of the male chick embryo.

The early treatment of male chick embryos with estradiol induces the feminization of their sex tract, i.e. both their gonads and müllerian tract exhibit female features. The additional treatment of estrogenized male embryos with testosterone propionate antagonizes the effects of estradiol on both gonads and müllerian ducts. Our data give further support to the view that testosterone and estrogens act respectively as agonist and antagonist modulators of the secretion of the anti-müllerian hormone.

Androgen-Insensitivity Syndrome↗
PubMed1995

Immunohistochemical demonstration of the calcium-binding proteins MRP8 and MRP14 and their heterodimer (27E10 antigen) in Crohn's disease.

Monospecific antibodies against the calcium-binding proteins MRP8 and MRP14 and their heterodimer MRP8/14 (epitope 27E10) were used to investigate immunohistochemically the distribution of these proteins in routinely processed small and large bowel tissues from patients with Crohn's disease. MRP8, MRP14, and complex MRP8/14 were demonstrated in most granulocytes and macrophages in active Crohn's disease. Additionally, a strong complex MRP8/14 immunoreactivity was present in epithelial cells of the terminal ileum adjacent to ulcerative and fissuring lesions, whereas epithelial cells in large bowel tissues were consistently negative. Our results morphologically confirm the clinical finding of increased MRP8/14 serum levels in patients with active Crohn's disease; there is evidence that the serum MRP8/14 increase is caused by active secretion from granulocytes, monocytes, and epithelial cells.

Antibodies, Monoclonal↗
PubMed1995

Elevated levels of activities of beta-hexosaminidase and alpha-mannosidase in human immunodeficiency virus-infected patients.

To determine their value as markers of the clinical stage of human immunodeficiency virus (HIV) disease, plasma activities of lysosomal glycosidases were determined in the plasma of 97 HIV-infected patients: molecular forms of cathepsin D were characterized by Western blot to examine the mode of enzyme release. In patients with Centers for Disease Control and Prevention stage II and III of HIV disease, plasma activity of beta-hexosaminidase was significantly increased. In patients with stage III infection, alpha-mannosidase activity was also significantly increased and cathepsin D was elevated and present only in its premature form. Thus, determination of plasma activities of beta-hexosaminidase and alpha-mannosidase in HIV-positive persons may be useful for distinguishing the clinical stage of disease. The elevation of precursors of cathepsin D in patients with stage III HIV disease indicates that secretion of lysosomal enzymes rather than leakage of enzymes from damaged cells is markedly elevated.

Cathepsin D↗
PubMed1995

Circulating antiinflammatory cytokine IL-10 in patients with inflammatory bowel disease (IBD).

IBD is characterized by increased serum concentrations of different cytokines. IL-10 inhibits the production of proinflammatory cytokines such as IL-1, tumour necrosis factor-alpha (TNF-a), interferon-gamma (IFN-gamma) and IL-6 through inhibitory action on Th1 cells and macrophages, and it is thought to be a suppressor type cytokine. In the present study we determined serum concentrations of IL-10 in patients with ulcerative colitis (UC) and Crohn's disease (CD). We measured human IL-10 by our own newly established ELISA system using PharMingen antibodies. Serum antibodies were assessed in 44 patients with UC, 40 patients with CD, and in 30 healthy controls. Human IL-10 serum levels were significantly increased in patients with active UC (144 +/- 34 pg/ml (mean +/- s.e.m.), P < 0.001) and in active CD (132 +/- 32 pg/ml, P < 0.001) compared with healthy controls (44 +/- 9.5 pg/ml). Only patients with active CD and active UC presented with significantly increased IL-10 serum levels, while patients with inactive disease did not show any significant increase. There was no statistically significant difference between IL-10 serum levels in patients with CD or UC. Compared with clinical disease activity indices there was a significant correlation between IL-10 serum concentration and CDAI in patients with CD (r = 0.45, P < 0.01) and CAI in UC patients (r = 0.39, P < 0.05). Comparing IL-10 serum levels with serum concentrations of other proinflammatory cytokines there was a significant correlation to serum levels of sIL-2R (r = 0.417, P < 0.05) and IL-6 (r = 0.387, P < 0.05) in patients with CD. Serum cytokine levels in patients with UC did not show any significant correlation to IL-10 serum concentration. IL-10 is elevated in serum of patients with active CD and UC, suggesting that IL-10 acts as a naturally occurring damper in the acute inflammatory process of IBD.

Acute Disease↗
PubMed1995

Serum 27E10 antigen: a new potential marker for staging HIV disease.

MRP8 and MRP14 are myeloic related proteins expressed by most circulating and emigrated neutrophils and monocytes. Their composite molecule MRP8/14 (27E10 antigen) was shown to exhibit striking antimicrobial properties. The aim of the present study was to assess the value of MRPs as markers for detection of the different stages of HIV infection (Centres for Disease Control and Prevention, 1993). By employing the ELISA technique we measured serum concentrations of these proteins in samples from 122 HIV patients at the various stages of disease, and the results were compared with those for healthy controls. Serum levels of the heterodimeric molecule 27E10 were significantly increased (P < 0.001) in patients with CDC stages II and III, with the highest levels being in patients with stage III and acute ongoing opportunistic infections. For the single component MRP14, significantly raised levels (P < 0.05) were only found in HIV stage III individuals with acute clinical events. Similar associations were not found for MRP8 alone. Increase was not related to CD4+ cell count. There was a significant correlation between 27E10 antigen serum concentrations and levels of neopterin in patients with HIV stages II and III without acute concurrent illness. Patients being treated with Zidovudine showed no statistically significant variation in levels of 27E10 and its single components MRP8 and MRP14 compared with untreated patients. These findings suggest that elevation of MRP14 levels occurs in HIV+ individuals at later stages post-HIV infection, after the onset of opportunistic infections. 27E10 antigen is concluded to be a potential marker for the different stages of HIV disease.

AIDS-Related Opportunistic Infections↗
PubMed1995

The myeloic related protein MRP8/14 (27E10 antigen)--usefulness as a potential marker for disease activity in ulcerative colitis and putative biological function.

MRP8, MRP14 and their heterodimer MRP8/14 (27E10 antigen) are myeloic related proteins which have been shown to have a major role in inflammatory and immunological responses. In the present study monospecific antibodies against MRPs were used to investigate immunohistochemically the distribution of these proteins in routinely processed bowel tissues from 23 patients with ulcerative colitis (UC). MRP8, MRP14 and their heterocomplex MRP8/14 were demonstrated in the majority of granulocytes and macrophages in tissues of patients with active UC. Furthermore by employing the ELISA technique we measured MRP8/14 serum levels in 62 patients with UC and the results were compared with those for healthy controls. Disease activities were determined by established clinical activity indices. Serum MRP8/14 concentrations were significantly (P < 0.0001) increased in patients with active ulcerative colitis. No enhancement of serum levels were found for MRP14 and MRP8 alone, respectively. The follow-up of individual patients with initially active disease showed a decrease of MRP8/14 serum levels in parallel with clinical improvement following the start of therapy. It is thus concluded that MRP8/14 accurately reflects the degree of disease activity in UC. Further, possible biological function of MRPs seems to be associated with the heterodimeric form (27E10 antigen) rather than with individual proteins. Our morphological results confirm the finding of enhanced MRP8/14 serum levels in patients with active UC.

Adrenal Cortex Hormones↗
PubMed1995

Immunohistochemical distribution and serum levels of the Ca(2+)-binding proteins MRP8, MRP14 and their heterodimeric form MRP8/14 in Crohn's disease.

In previous histochemical studies the distribution of the two Ca(2+)-binding proteins MRP8 and MRP14 as well as their heterocomplex MRP8/14 has been demonstrated in different inflammatory diseases. Monoclonal antibodies against MRP8 and MRP14 and their heterodimer MRP8/14 (27E10 epitope) were used to investigate immunohistochemically the distribution of these proteins in routinely processed small and large bowel tissues from patients with Crohn's disease (CD). Furthermore, we used a sandwich immunoassay to measure serum concentrations of MRPs in 62 patients were simultaneously assessed by the Crohn's disease activity index (CDAI) and the severity activity index of Goebell (SAI). In our immunohistochemical study, MRP8, MRP14 and heterocomplex MRP8/14 were demonstrated in the majority of granulocytes and macrophages in active CD. Additionally, a strong complex MRP8/14 immunoreactivity was present in epithelial cells adjacent to ulcerative and fissuring lesions in the bowel. Serum MRP8/14 concentrations were significantly (p < 0.0001) increased in patients with active CD (CDAI > 150, SAI > 120). No correlations were found for level of MRP14 and MRP8 alone, respectively. The follow-up of individual patients with initially active CD showed a further increase in MRP8/14 levels during acute attacks of the inflammatory process. We suggest that our assay for MRP8/14 discriminates well between active and inactive CD and may have considerable potential in the analysis of clinical disease activity in CD patients. Our morphological results confirm the finding of increased MRP8/14 serum levels in patients with active CD.

Acute-Phase Proteins↗
PubMed1995

Monoclonal antibody 1F10 immunoreactivity in inflammatory bowel disease: a new marker specific only for continuous endothelial cells.

OBJECTIVE: To investigate in detail the immunohistochemical properties of the two endothelial-specific markers 1F10 (continuous endothelia) and MS-1 (discontinuous endothelia) in bowel tissues of patients suffering from chronic inflammatory bowel disease (IBD). METHOD: Immunohistochemical techniques were employed to study the morphology and phenotypic expression of these two proteins in routinely processed bowel tissues from 27 patients with Crohn's disease, 18 patients with ulcerative colitis, and 20 normal controls. RESULTS: All patients with IBD and controls showed a low to moderate 1F10 immunohistochemical staining restricted to the lamina propria and submucosa. In contrast to ulcerative colitis patients and healthy controls, 1F10 immunoreactivity was strongly upregulated in the muscularis propria of the small and large bowel in Crohn's disease patients regardless of the histological severity of the inflammatory process. We did not observe immunoreactivity for MS-1 on endothelial surfaces in either Crohn's disease or ulcerative colitis. CONCLUSIONS: We conclude that endothelia in patients with IBD do not undergo metaplasia. The high immunoreactivity of 1F10 antigen in the muscularis propria in Crohn's disease indicates a state of tropical immunological activation and may be important in the maintenance of chronic inflammation by facilitating leukocyte migration into sites of Crohn's disease involvement. Further studies of the factors controlling endothelial cell differentiation in the bowel of Crohn's disease patients may help to explain the features observed in this study.

Adolescent↗
PubMed1994

Stimulus-secretion coupling in rat parietal cells is affected by extracellular magnesium.

We investigated the effects of extracellular magnesium on stimulus-secretion coupling in isolated rat parietal cells. A high concentration of extracellular magnesium (10 mM) decreased basal and carbachol-stimulated calcium levels, whereas low magnesium levels (0.2 mM) had the opposite effect. The calcium-triggered acid secretion was influenced in the same manner. Basal and carbachol-stimulated acid secretion could be enhanced by incubation in a buffer of low magnesium concentration, whereas a high magnesium concentration totally suppressed the carbachol-induced acid secretion. These results demonstrate that magnesium plays a modulative role in calcium-dependent stimulus-secretion coupling in rat parietal cells.

Aminopyrine↗