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Biomedical subjects

H Winkler

Publications and source records attributed to H Winkler.

At least 91 records · Page 5Linked to original sources
PubMed1996

Presence and distribution of a new neuropeptide, secretoneurin, in human retina.

Secretoneurin (SN) is a neuropeptide formed by endoproteolytic processing of secretogranin II (chromogranin C). Chromatographic analysis revealed that the human retina contains significant concentrations (14.2 fmol/mg wet weight) of this peptide. Its cellular localization in the retina was characterized by immunohistochemistry. SN-immunoreactive (IR) fibers showed a distinct distribution in central and peripheral retinal regions. Immunopositive somata were found in the ganglion cell layer and in the inner nuclear layer. The localization was similar to that of substance P. The physiological role of SN in the human retina is at present unknown. However, its presence in ganglion cells and/or amacrine cells suggests that it may play a role in visual processing.

Aged↗
PubMed1996

Three-dimensional distortion correction applied to tomographic reconstructions of sectioned crystals.

Unaveraged tomograms of embedded and sectioned insect flight muscle show not only structural variation within the individual unit cells but also defects in the filament lattice such as lack of straightness of the filaments and wrinkling of the sections. Adaptation of conventional 2D crystal image processing methods usually average out these structural variations and lattice defects thereby reducing the resolution and information content of the 3D reconstructions. We present here a computational method to correct the reconstructed 3D object for these distortions to make it suitable for further analysis. The correction is an extension of conventional 2D cross-correlation techniques applied to a 3D image. These procedures determine the unit cell positions of the distorted crystal and use a spline-fitting approach to calculate a mapping function from the observed positions that is subsequently used to reinterpolate the image onto a regular grid. The resulting reinterpolated image is corrected for both filament straightening as well as section wrinkling.

Animals↗
PubMed1996

Co-localization of secretoneurin immunoreactivity and macrophage infiltration in the lesions of experimental autoimmune encephalomyelitis.

Secretoneurin, a novel neuropeptide, has recently been shown to attract monocytes. In our present study we have tested whether the local presence of secretoneurin within the CNS of the rat may influence the topographical distribution of inflammatory infiltrates in acute T-cell mediated encephalomyelitis. Experimental allergic encephalomyelitis was induced by passive transfer of myelin basic protein-reactive T-lymphocytes and the distribution of T-cells and macrophages was studied at day 3, 4 and 7 after transfer. In the same sections secretoneurin immunoreactivity was visualized by immunohistochemistry. A clustering of macrophages, but not of T-lymphocytes, was seen at sites of secretoneurin immunoreactivity in all stages of experimental autoimmune encephalomyelitis. Our data indicate for the first time that local neuropeptides may play a role in leucocyte recruitment into inflammatory lesions of the CNS.

Animals↗
PubMed1996

Secretogranin II: relative amounts and processing to secretoneurin in various rat tissues.

Secretoneurin is a 33-amino-acid peptide produced in vivo from secretogranin II. An antiserum raised against this peptide recognizes both the free peptide and its precursors. By HPLC and radioimmunoassay we characterized the immunoreactive molecules and determined the levels of immunoreactivity in various rat organs. In adrenal medulla and to a lesser degree in the anterior pituitary processing of secretogranin II to secretoneurin was very limited, whereas in all other organs studied (brain, intestine, endocrine pancreas, thyroid gland, and posterior pituitary) a high degree of processing was apparent. Thus, practically all of the immunoreactivity was present as free secretoneurin. This was also true for serum. When the total amount of secretoneurin immunoreactivity was calculated for the various organs, the largest pools in descending order were in the intestine, CNS, anterior pituitary, pancreas, and adrenal gland. This makes it likely that secretoneurin in serum is mainly derived from the intestine. The high degree of processing of secretogranin II in most organs is consistent with the concept that this protein acts as a precursor of a functional peptide, i.e., secretoneurin.

Animals↗
PubMed1996

Microfilarial clearance in loiasis involves elevation of Th1 and Th2 products and emergence of a specific pattern of T-cell populations.

Diethylcarbamazine (DEC) induced clearance of microfilaraemia in loiasis is associated with severe posttreatment reactions. To define the switch from hypo- to hyper-responsiveness associated with DEC treatment, phenotypic alterations of T-lymphocytes, characterized by flow cytometry, and cytokines, determined by enzyme linked immunosorbent assay, were monitored in a microfilaraemic patient. In contrast to reports on onchocerciasis and lymphatic filariases, no elevation of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha was observed. The most severe side effects coincided with an elevation of interferon (IFN)-gamma on day 3, followed by IL-10, transforming growth factor (TGF)-beta 2 and macrophage inflammatory protein-1 alpha (MIP-1 alpha) peaking on day 5. Phenotypically, T-cell activation markers CD38, CD54 and CD25 were significantly expressed before treatment, with high CD38 expression still existing one year after clearance of microfilaraemia. Treatment-related increases were observed with anti-CD122, anti-HLA-DR and anti-CD69. CD28 was expressed before treatment on almost 100% of CD4+ and CD8+ T cells and dropped to 20% by day 5, reaching again baseline levels on day 21. Furthermore, there emerged 20% TCR alpha beta+/CD3+ T cells and 10% anti-beta V5(c)+ T cells, altogether indicating a specific pattern of T-helper (Th) 1 and Th2 cytokines as well as expansion of certain pauciclonal T-cell populations in response to microfilarial clearance.

Adult↗
PubMed1996

Rat brain: distribution of immunoreactivity of PE-11, a peptide derived from chromogranin B.

An antiserum was raised against the peptide PE-11 whose sequence is present in the chromogranin B molecule. The antiserum reacts only with the free C-terminal end of this peptide. PE-11 immunoreactivity in brain was characterized by molecular size exclusion high performance liquid chromatography. Only the free peptide and a N-terminally elongated peptide were detected, indicating that proteolytic processing of chromagranin B in brain is quite extensive. In immunohistochemistry PE-11 immunoreactivity was found in varicosities, fibres and perikarya throughout the brain. Strong staining was detected in the shell sector of the nucleus accumbens, in the lateral septum, in subregions of the extended amygdala, in some areas of the hippocampus and of the hypothalamus, in the locus coeruleus, in the Purkinje cells of the cerebellum and in the dorsal horn of the spinal cord. Our results, which demonstrate significant processing of chromogranin B in brain and its widespread distribution, can be taken as an indication that chromogranin B represents a precursor of peptides with functional relevance for this organ.

Animals↗
PubMed1996

Genetic engineering of endothelial cells to ameliorate xenograft rejection.

The prospect of clinical xenotransplantation using pigs as donors (a discordant combination) holds out a potential solution to the shortage of human organs, as well as potentially widening the spectrum of patients who might benefit from a transplant procedure. While generalized clinical trials of pig to human organ transplantation (of immediately vascularized organs, such as the heart or kidney) will probably not occur in the very near future, there are reasons for optimism that this approach, deemed impossible a few decades ago, may find its way to the bedside. This optimism is based on two factors: First, a great increase in our understanding of the probable underlying causes of rejection and, second, the development of a number of important therapeutic approaches, including genetic manipulation of the donor animal, to tackle the manifold problems inherent in rejection of such a transplanted organ.

Animals↗
PubMed1996

[C6 fatal trans-vertebral dislocation fracture with tracheal lesion in Bechterew disease. A case presentation].

A fracture of the cervical spine is a dangerous and life-threatening injury in patients suffering from ankylosing spondylitis. A 71-year-old motorist with a long history of ankylosing spondylitis was injured during a car accident. A rare transverse fracture through the body of C6 occurred and in addition a lesion of the trachea was found. This combination of injuries is described for the first time. Special problems relating to the initial rescue, diagnosis and treatment are discussed according to the literature. The necessity of handling the cervical spine with extreme caution during all medical procedures, taking into account the kyphotic deformity is stressed.

Aged↗
PubMed1996

[Medical expert assessment in social rights lawsuits].

Diseases and their effects are characteristics of legal evidence in a number of claims regarding social welfare. The courts frequently use medical expert assessment to clarify the important facts of the case. The medical assessment has to be formulated thoroughly and clearly as well as understandable for the layman as it is of decisive importance for the lawsuit.

Disability Evaluation↗
PubMed1995

Inhibition of NF-kappa B by pyrrolidine dithiocarbamate blocks endothelial cell activation.

Endothelial cell activation is achieved by the rapid, protein synthesis-independent induction of a characteristic set of genes. Because of the abundance of binding sites for the transcription factor NF-kappa B in the regulatory region of the aforementioned genes, we hypothesized that this factor might play a key role. Reactive oxygen intermediates act as second messengers in the activation of NF-kappa B. We have used the antioxidant pyrrolidine dithiocarbamate to analyze the effect of NF-kappa B inhibition on TNF alpha-induced EC activation in vitro. We show that pyrrolidine dithiocarbamate strongly reduces the TNF alpha-mediated induction of E-selectin, VCAM-1, ICAM-1, PAI-1, tissue factor, IL-8 and I kappa B-alpha. We present evidence identifying NF-kappa B as a central of EC activation. Therefore, this factor may represent a prime target for therapeutic intervention in pathologic conditions associated with EC activation such as allo- and xenograft rejection, atherosclerosis, ischemic reperfusion injury and vasculitis.

Animals↗
PubMed1995

Large variations in the proteolytic formation of a chromogranin A-derived peptide (GE-25) in neuroendocrine tissues.

We have established a radioimmunoassay for GE-25, a peptide present in the C-terminal end of the primary amino acid sequence of chromogranin A where it is flanked by typical proteolytic cleavage sites. Gel-filtration HPLC was used to characterize the molecular sizes of the immunoreactive molecules. The antiserum recognized not only the free peptide but also larger precursors including the proprotein chromogranin A. The tissues with the highest levels of GE-25 immunoreactivity were in decreasing order: the adrenal medulla, the three lobes of the pituitary gland, intestinal mucosa, pancreas and various brain regions. In adrenal medulla and parathyroid gland most of the immunoreactivity was found to be present as intact chromogranin A and some intermediate-sized peptides, without significant amounts of the free peptide. In anterior pituitary, and even more so in intestine, a shift to smaller peptides was seen. In the posterior and intermediate pituitary and in pancreas the predominant immunoreactive material was apparently represented by the free peptide GE-25. In reverse-phase chromatography this peptide eluted exactly like the synthetic standard, which allows a tentative identification as GE-25. In brain tissue the processing of chromogranin A was intermediate, with significant amounts of immunoreactivity corresponding to GE-25 as well as precursor proteins being present. We suggest that in those organs (endocrine pancreas, intermediate and posterior pituitary) where the major hormones are proteolytically processed there is also a concomitant proteolysis of further susceptible peptides. Since GE-25 is apparently formed in vivo and is well conserved between species it seems a good candidate for having specific physiological functions.

Amino Acid Sequence↗
PubMed1995

Processing of secretogranin II by prohormone convertases: importance of PC1 in generation of secretoneurin.

Secretoneurin is a recently characterized neuropeptide present in the primary amino acid sequence of secretogranin II. We investigated the proteolytic processing of secretogranin II by prohormone convertases in vivo in a cellular system using the vaccinia virus system. Both PC1 and PC2 can cleave the secretogranin II precursor at sites of pairs of basic amino acids to yield intermediate-sized fragments. Other convertases like PACE4, PC5 and furin were not active. For the formation of the free neuropeptide secretoneurin a different pattern was found. Only PC1 but none of the other convertases tested including PC2 were capable of generating secretoneurin. Our results demonstrate that the prohormone convertases PC1 and PC2 are involved in proteolytic processing of secretogranin II. The neuropeptide secretoneurin can only be generated by PC1 suggesting tissue-specific processing of secretogranin II in neurons expressing different subsets of the prohormone convertases.

Adrenal Medulla↗
PubMed1995

Regulation of the tissue factor promoter in endothelial cells. Binding of NF kappa B-, AP-1-, and Sp1-like transcription factors.

Tissue factor is up-regulated on endothelial cells and monocytes in response to cytokines and endotoxin and is the main trigger of the extrinsic pathway of the coagulation cascade. We have isolated the porcine tissue factor gene and studied the regulation of the promoter, which has not been investigated previously in endothelial cells. Comparison of the promoter sequences with the respective human and murine genes reveals short stretches of homology, which encompass potential binding sites for AP-1, NF kappa B, and Sp1 transcription factors. Using DNase I footprinting, we detect binding of nuclear factors to these promoter elements. Transfection experiments demonstrate that a 300-base pair fragment containing the conserved elements can mediate induced transcription and that the NF kappa B-like element is essential. In accordance, electrophoretic mobility shift assays show a strong increase in the binding of factors to the NF kappa B-like site following induction. We further provide evidence that RelA (p65), c-Rel, and possibly novel polypeptides bind to the tissue factor NF kappa B element. In addition, we show constitutive binding of members of the Fos/Jun and Sp1 families to the AP-1 and Sp1 sites, respectively. We propose a concerted action of AP-1-, NF kappa B-, and Sp1-like factors in transcription from the tissue factor promoter in endothelial cells.

Animals↗
PubMed1995

Secretoneurin: a new peptide in the human enteric nervous system.

Secretoneurin is a functional neuropeptide derived from secretogranin II (chromogranin C). This proprotein is processed to varying degrees in neuroendocrine tissues. In the present study we established by gel filtration high performance liquid chromatography that in human intestinal wall and mucosa an antiserum against secretoneurin detects as the major immunoreactive moiety the free peptide secretoneurin. In the mucosa some larger immunoreactive peptides were also present, however, a significant amount of the intact proprotein secretogranin II could not be detected. By immunohistochemistry we studied the distribution of secretoneurin within the gut. Antibodies to protein gene product 9.5 and chromogranin A were used to identify all neurons and endocrine cells, respectively, whilst those to the peptides substance P, CGRP and somatostatin were used for the further characterization of individual secretoneurin-positive structures. Secretoneurin immunoreactivity was found in nerve fibres in all layers of the gut wall. In both myenteric and submucous plexuses, nerve fibres and the majority of ganglion cells were secretoneurin-immunoreactive. In the mucosa, some secretoneurin-positive nerve processes ran parallel to the basal membrane of epithelial cells, occasionally invading the epithelial layer. Secretoneurin immunoreactivity was found in endocrine cells, mostly D cells, in the following regions in descending order of density: stomach/duodenum; rectum; colon; ileum. Thus, secretoneurin is a new major peptide within the human enteric neuroendocrine system. Its presence in abundant myenteric ganglion cells may imply a role in the modulation of gastrointestinal motility. The chemotactic properties of secretoneurin and its possible localization in sensory fibres suggest that this peptide may be involved in the genesis of intestinal inflammation.

Adult↗