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Biomedical subjects

B Wiedenmann

Publications and source records attributed to B Wiedenmann.

At least 163 records · Page 9Linked to original sources
PubMed1991

Effect of intraperitoneal recombinant human tumour necrosis factor alpha on malignant ascites.

29 patients with refractory malignant ascites due to metastatic peritoneal spread of adenocarcinomas originating from the ovary, gastrointestinal tract, liver, breast and uterus were treated in a phase I trial of intraperitoneal infusions of recombinant human tumour necrosis factor alpha (rhTNF-alpha). Patients received 40-350 micrograms/m2 rhTNF-alpha intraperitoneally once weekly for 2 months or for a shorter period in case of early resolution of ascites. Systemic side-effects resembled those reported for rhTNF-alpha given intravenously. No dose-limiting toxicities were found and thus a maximum tolerated dose of intraperitoneal rhTNF-alpha was not established. Out of 29 patients, 22 responded with a complete (16) or partial (6) resolution of their ascites. There was a less than 50% reduction in 4, and no increase in ascites in 1. 1 patient showed progressive ascites formation, and another patient was not eligible because of early death unrelated to treatment. Trials in patients with smaller tumour burden are warranted.

Adenocarcinoma↗
PubMed1991

Subcellular localization of secretogranin II and synaptophysin by immunoelectron microscopy in differentiated hypothalamic neurons in culture.

Secretogranin II (SgII), a tyrosine-sulfated secretory protein, is a widespread component of endocrine and neuronal cells. In the present study we used mouse hypothalamic neurons differentiated in culture and studied the subcellular localization of SgII by two methods, i.e., by the use of immunoperoxidase or immunogold electron microscopy. By immunoperoxidase labeling, SgII was mainly detected in the matrix of large dense-core vesicles (LDCVs). In addition, usually in nerve terminals containing LDCVs, peroxidase reaction product was also found in association with the membrane of small synaptic vesicles (SSVs). By immunogold labeling, SgII was detected only in the matrix of LDCVs. We also compared the localization of SgII and synaptophysin (SY), an integral membrane protein of SSVs, by double labeling, using a combination of pre-embedding immunogold and -peroxidase techniques for SgII and SY, respectively. In perikarya, SgII-positive LDCVs were observed in the vicinity of the Golgi complex and scattered in the cytoplasm. In contrast, SY labeling was restricted to electron-translucent vesicles and tubular membranes in the Golgi area. Moreover, membrane structures positive for both SgII and SY were not found either in the Golgi zone or in other regions of the cytoplasm. In synaptic boutons, immunolabeling of LDCVs and SSVs with anti-SgII and anti-SY, respectively, was mutually exclusive. In summary, within the limitation of the methods used, our data are consistent with the notion that SgII and SY are segregated from each other on exit from the trans-Golgi network, than follow two distinct membrane traffic pathways, and that the presence of SgII on the membrane of some SSVs is due to endocytosis.

Animals↗
PubMed1991

Synaptophysin. A widespread constituent of small neuroendocrine vesicles and a new tool in tumor diagnosis.

Synaptophysin, a vesicular integral membrane protein, is specifically expressed in neuroendocrine tissues. According to cDNA cloning studies, it has a molecular weight of 33,300 Dalton, one potential N-glycosylation site at the vesicle inside, four major hydrophobic domains as well as a C-terminus containing approximately 90 amino acids. The C- and N-termini of synaptophysin are located on the cytoplasmic side of the vesicle membrane. No signal sequence is found. Transfection of non-neuroendocrine cells with synaptophysin cDNA leads to the synthesis of synaptophysin-containing vesicles, which contain this protein in highly enriched form and have biophysical properties similar to presynaptic vesicles of neurons. So far, the vesicular content has only been determined in rat neurons, where classical neurotransmitters such as biogenic amines and transmitter-active amino acids were found. Reconstitution of the purified protein in liposomes suggests a possible channel function of synaptophysin. Using mono- and polyvalent antibodies against synaptophysin, a considerable number of studies in several laboratories have shown that this protein is a reliable marker molecule for neuroendocrine tumors of various degrees of differentiation.

Adenoma, Islet Cell↗
PubMed1989

Topogenesis and sorting of synaptophysin: synthesis of a synaptic vesicle protein from a gene transfected into nonneuroendocrine cells.

Diverse nonneuroendocrine (non-NE) cells were forced to express synaptophysin (SY), the major and typical transmembrane glycoprotein of small (30-80 nm) neurotransmitter vesicles of NE cells, using microinjection of RNA synthesized in vitro from cDNA or transient and stable transfections with cDNA brought under SV40 promoter control. The glycoprotein synthesized in non-NE cells is indistinguishable from SY of NE cells and is integrated with similar, if not identical, orientation in the membranes of a specific, novel type of small cytoplasmic vesicle that structurally resembles synaptic vesicles and in which SY is the only major protein detected. A non-N-glycosylated form of SY generated by site-directed mutagenesis showed the same behavior and specific distribution in small vesicles. The results show that the information contained in this protein alone is sufficient to secure its sorting into a special type of vesicle in a heterotypic context, i.e., in the absence of other NE-specific components.

Animals↗
PubMed1989

Phase-I trial of intravenous continuous infusion of tumor necrosis factor in advanced metastatic carcinomas.

Fifteen patients with advanced metastatic adenocarcinomas were treated in a phase-I study with continuous intravenous 24 h infusion of recombinant tumor necrosis factor alpha (TNF-alpha) in order to determine the maximum tolerated dose (MTD) and associated side-effects. Patients received 40-400 micrograms/m2 TNF-alpha once (arm A) or twice (arm B) weekly for a scheduled treatment period of 2 months. The observed systemic side-effects resembled those reported for interferons and included fever, chills, fatigue, headaches, myalgias, thrombocytopenia, prostration, and malaise. Dose-limiting toxicities, resulting in a median MTD of 200 micrograms/m2 for 24 h, were fever, chills, fatigue, myalgias, and thrombocytopenia. Out of 15 patients, 11 showed tumor progression, and 3 sustained in no change for over 2 months of treatment. A minor response was seen in 1 patient with a colorectal carcinoma and liver metastases. To reduce side-effects, patients were treated either with paracetamol or indomethacin. Higher MTDs were observed in patients treated with indomethacin. No detectable plasma TNF-alpha levels or TNF antibodies were measured under therapy (plasma TNF-alpha less than 20 pg/ml). We conclude that TNF-alpha appears to have some antineoplastic activity in patients with adenocarcinomas since 4 patients remained in no change or showed a minor response.

Antibodies↗
PubMed1989

Synaptophysin and chromogranins/secretogranins--widespread constituents of distinct types of neuroendocrine vesicles and new tools in tumor diagnosis.

Normal and neoplastic neuroendocrine (NE) cells have been identified for many years by morphological criteria only. With the advent of immunocytochemistry, antibodies against NE-specific polypeptides have been used to identify NE cells that had been missed by conventional techniques, thus improving the diagnosis of NE cells. In this review article we discuss (i) the biochemical, cell biological and molecular biological data obtained so far for two major types of NE markers, synaptophysin, which is characteristic of the small "transparent-looking" neurosecretory vesicles, and the chromogranins/secretogranins, which are widespread constituents of the larger "dense-cored" secretory granules; (ii) the immunohistochemical data obtained for these marker proteins in normal and neoplastic human NE cells and tissues; and (iii) future possible developments involving these as well as other proteins that are associated with these two distinct secretory organelles of NE cells and may serve as potential markers in NE cell diagnosis.

Animals↗
PubMed1989

Tumour necrosis factor production and natural killer cell activity in peripheral blood during treatment with recombinant tumour necrosis factor.

Tumour necrosis factor (TNF) has been found to be an important immunomodulator. Among other functions TNF activates natural killer (NK) cells and stimulates monocytes/macrophages in an autocrine fashion. TNF production and NK activity in peripheral blood mononuclear cells were determined in a clinical phase I study in which recombinant human (rh) TNF was administered as a continuous infusion weekly for a period of 8 weeks. Even though TNF production and NK activity were significantly reduced directly after rhTNF infusion the effect proved to be transient and most pronounced at the first rhTNF administration. One day after completion of the rhTNF infusion the peripheral cells released more TNF into the supernatant compared to TNF activity immediately before the rhTNF infusion. This effect was conspicuous in non-stimulated cultures. After repeated rhTNF infusions both stimulated and non-stimulated TNF production of the peripheral blood mononuclear cells was increased. NK cell activity was also enhanced after repeated cycles of rhTNF administration as compared to early rhTNF treatment. Thus, repeated rhTNF infusions lead to a stimulatory effect on TNF production and NK activity of peripheral blood cells.

Adult↗
PubMed1988

Fractionation of synaptophysin-containing vesicles from rat brain and cultured PC12 pheochromocytoma cells.

Synaptophysin is a transmembrane glycoprotein of neuroendocrine vesicles. Its content and distribution in subcellular fractions from cultured PC12 cells, rat brain and bovine adrenal medulla were determined by a sensitive dot immunoassay. Synaptophysin-containing fractions appeared as monodispersed populations similar to synaptic vesicles in density and size distribution. Membranes from synaptic vesicles contained approximately 100-times more synaptophysin than chromaffin granules. In conclusion, synaptophysin is located almost exclusively in vesicles of brain and PC12 cells which are distinct from dense core granules.

Adrenal Medulla↗
PubMed1988

Identification of gastroenteropancreatic neuroendocrine cells in normal and neoplastic human tissue with antibodies against synaptophysin, chromogranin A, secretogranin I (chromogranin B), and secretogranin II.

Gastroenteropancreatic human neuroendocrine (NE) cells (normal and neoplastic) were investigated for the expression of the neuroendocrine-specific polypeptides synaptophysin, chromogranin A, secretogranin I (chromogranin B), and secretogranin II, using immunohistochemistry and immunoblotting. Monoclonal antibody against synaptophysin stained most, and possibly all, of the neuroendocrine cells in both normal and neoplastic tissue. Monoclonal antibody against chromogranin A also stained a high proportion of normal and neoplastic neuroendocrine cells. Immunostaining with polyclonal antisecretogranin I and antisecretogranin II antibodies was detectable in almost all of the normal and neoplastic tissue sections that were analyzed, and it was confined to a smaller population of neuroendocrine cells than that observed for synaptophysin and chromogranin A. Consistent with the immunohistochemical observations, immunoblotting revealed the presence of all four antigens in various tumors. The data show that synaptophysin and chromogranin A, for which monoclonal antibodies are commercially available, may be used as diagnostic markers for human gastroenteropancreatic tumors. Our results also suggest that the development of monoclonal antibodies against human secretogranins I and II will provide additional tools for a refined diagnosis of such tumors.

Antibodies, Neoplasm↗
PubMed1988

Immunoelectron microscopic localization of synaptophysin in a Golgi subcompartment of developing hypothalamic neurons.

Synaptophysin, previously identified as an integral membrane glycoprotein (mol. wt 38,000) characteristic of presynaptic vesicles of mature neurons, provides a molecular marker to study the origin, formation and traffic of synaptic vesicles. Using the monoclonal antibody SY38 against this polypeptide we have localized synaptophysin by immunofluorescence and electron microscope immunoperoxidase methods in cultured mouse hypothalamic neurons taken from 16-day-old fetuses which achieve synaptogenesis after 10-12 days in vitro. We have compared the localization of synaptophysin in perikarya and nerve endings as a function of age (2-19 days in vitro) and of treatment of mature neurons with nocodazole. Using immunofluorescence microscopy, synaptophysin was already detected in neuronal soma at 2 days in vitro, where the initiation of neurite development is observed. At the electron microscope level, virtually all mature synaptic boutons and varicosities showed an extensive synaptophysin labeling of synaptic vesicles at 12-13 days in culture whereas neurites showed only very few labeled vesicles. In neuronal soma taken before synapse formation (6 days in vitro), synaptophysin was selectively localized in membranes of the innermost cisternae of the Golgi zone and in vesicles of variable size and shape in the core of the Golgi zone. In contrast, after synapse formation, synaptophysin labeling was barely detected in the Golgi zone of neurons but a very strong labeling of synaptic vesicles in synaptic boutons was observed. Treatment of mature neurons (12 days in vitro) with nocodazole (10(-5) M) resulted in a conspicuous synaptophysin staining of the innermost trans-Golgi cisternae and numerous vesicles in the cytoplasm. Furthermore, an accumulation of labeled synaptic vesicles on the presynaptic membrane of nerve terminals was found. The data suggest that synaptophysin is released from the Golgi apparatus in a vesicular form, after glycosylation, and is then transported to nerve endings by a mechanism which requires integrity of microtubules.

Animals↗
PubMed1988

Expression of neuroendocrine markers (neuronspecific enolase, synaptophysin and bombesin) in carcinoma of the lung.

The value of immunoreactivity of antibodies against neuronspecific enolase (NSE), bombesin (GRP), and synaptophysin (SY 38) as markers for various human lung carcinoma has been assessed. One hundred-forty-two primary bronchus carcinomas (small cell anaplastic carcinoma, epidermoid carcinoma, adeno carcinoma, and large cell anaplastic carcinoma) were studied by the indirect immunoperoxidase method (PAP). SY 38 was found to react positively in 49/68 (79%) of the small cell anaplastic carcinoma (SCCL) and in 6/74 (8%) of the non-small cell carcinoma of the lung (NSCCL). Positive immunohistochemical data with antibody SY 38 showed in some cases an immunoreactive polypeptide of Mr = 40.000 obtained by immunoblotting similar in molecular weight as described for synaptophysin in other tumours. Reactivity of NSE was observed in 41/68 (61%) of the SCCL and in 8/74 (10%) of the NSCCL. Positive reactivity to GRP was similar to NSE in 42/68 (62%) of SCCL and in 7/74 (10%) of NSCCL. All cases of NSCCL reacting positively to SY 38 were found to react positively to NSE, and to GRP. Prognostic value of SY 38 was calculated vp = 0.71 for positive prediction and vn = 0.91 for negative prediction. The data indicate that SY 38 represents the broadest marker for neuroendocrine carcinoma of the lung since in addition to the majority of SCCL about 10% of NSCCL are recognized by the antibody SY 38.

Antibodies, Monoclonal↗
PubMed1988

Differentiation markers as an aid in the histological diagnosis of small-cell carcinoma of the lung: synopsis of intermediate filament protein and synaptophysin expression.

Small-cell carcinomas of the lung (SCLCs) are frequent tumors of the bronchopulmonary tract which are distinguished by their neuroendocrine (NE) features, indicative of a derivation from the sparse neuroendocrine cells present in the normal epithelium. Because of the lack of marked morphological details, the differential diagnosis of this tumor is very difficult. We show that the epithelial nature and origin of SCLCs can be demonstrated, biochemically and immunocytochemically, by the expression of cytokeratins, notably cytokeratins 8 and 18, often together with desmosomal proteins as another independent differentiation marker. The NE character of SCLCs, on the other hand, is revealed by antibodies to certain NE-specific components, notably the broad range NE marker, the membrane protein synaptophysin. Both kinds of differentiation markers are also expressed in a number of SCLC-derived cultured cell lines which therefore may serve as valuable biological model systems to study the biology of SCLC.

Biomarkers, Tumor↗
PubMed1988

Decrease of natural killer cell activity and monokine production in peripheral blood of patients treated with recombinant tumor necrosis factor.

Tumor necrosis factor (TNF), a protein predominantly produced by activated macrophages/monocytes, is presently available in recombinant, purified form for clinical trials. Intensive studies in many laboratories have shown that besides the tumorcytotoxic effects, TNF acts on a large array of different cells and has potent immunomodulatory activities. In a clinical phase I study, some immunologic functional parameters of blood cells from patients who received 24-hour infusions of recombinant human TNF (rhTNF) were analyzed. Natural killer (NK) cell activity, TNF production, interleukin-1 (IL-1) production and mitogen-induced proliferation were measured either in whole blood samples or in cultures of peripheral mononuclear leukocytes of the patients directly before and after rhTNF infusion. NK cell activity, TNF and IL-1 production capacity and proliferative responses to concanavalin A (Con A) were significantly reduced after rhTNF application. We conclude from these observations that rhTNF in vivo acts directly or indirectly on NK cells and monocytes by either inactivating their functional capacity or by absorbing the relevant cells to the endothelial cell layer, thus removing them from circulation.

Adult↗
PubMed1987

Synaptophysin: a reliable marker for medulloblastomas.

Synaptophysin is an acidic, integral membrane glycoprotein (Mr 38,000) of presynaptic vesicles in various neurons and neuroendocrine cells, and in tumours derived from such cells. By indirect immunofluorescence microscopy of cryostat sections, using the monoclonal antibody SY 38 to synaptophysin, a consistent positive immunoreactivity was observed in all medulloblastomas (n = 6) and neuroblastomas (n = 3) as well as a ganglioneuroma and a glioneuronal hamartoma. The presence of synaptophysin in medulloblastomas was confirmed biochemically by immunoblotting experiments. For purpose of comparison, the expression of intermediate-sized filament (IF) proteins was also examined. While neurofilament proteins were consistently expressed in the neuroblastomas (3/3), the ganglioneuroma and the glioneuronal hamartoma, IF distribution in medulloblastomas was variable. A neurofilament-positive type of tumour (1/6) could be distinguished from vimentin-expressing neoplasms (4/6) by immunocytochemistry. These data indicate that synaptophysin is a reliable marker for medulloblastomas as well as other differentiated and undifferentiated neuronal tumours and in this respect is superior to the more heterogeneous expression patterns of IF proteins in these tumours.

Adult↗
PubMed1987

Synaptophysin identified in metastases of neuroendocrine tumors by immunocytochemistry and immunoblotting.

Synaptophysin, an Mr 38,000 integral membrane glycoprotein of neurotransmitter vesicles, has been identified in diverse primary neuroendocrine (NE) tumors of both neural and epithelial origin (Wiedenmann and co-workers, Proc Natl Acad Sci USA 1986; 83: 3500-3504). In the present study, metastases of several types of NE tumors, including medullary thyroid carcinoma, gastrinoma, insulinoma, small (oat) cell carcinoma of the lung, gastrointestinal carcinoid, and neuroblastoma, were examined for the presence of synaptophysin by immunocytochemistry, with the use of tissue sections as well as centrifuged cell suspensions and by immunoblotting of tumor proteins. The results show that expression of synaptophysin can be maintained during formation of metastases. Therefore, the authors propose that synaptophysin antibodies be used for the positive identification of metastatic NE tumors, notably in differential diagnosis. The possible implications of these findings for tumor diagnosis are discussed.

Endocrine System Diseases↗
PubMed1987

Synaptophysin expressed in the bronchopulmonary tract: neuroendocrine cells, neuroepithelial bodies, and neuroendocrine neoplasms.

Synaptophysin is an integral membrane glycoprotein with an Mr of 38,000 that occurs in the small, clear vesicles present in neuronal cells and tumors as well as in pancreatic islet cells and various neuroendocrine (NE) carcinomas. We found that synaptophysin is also expressed in normal NE cells of the lungs of newborn rabbits and mice as well as of human fetuses. In bronchial ganglion cells and in nerves, synaptophysin is coexpressed with neurofilament proteins (NFPs), whereas in solitary NE cells and in at least some of the neuroepithelial bodies (NEBs) of the bronchial mucosal lining, synaptophysin coexists with cytokeratins. We also studied a series of NE neoplasms of the lung covering the entire spectrum of differentiation (i.e., from carcinoids to small-cell NE carcinomas), and found that synpatophysin was present in the majority of them. In these tumors, synaptophysin was invariably coexpressed with cytokeratin filaments and desmoplakin, as well as, occasionally, with NFP. Synaptophysin was identified throughout, the whole range of these NE neoplasms, i.e., from benign to low-grade to aggressive and rapidly metastasizing carcinomas; its presence was unaffected by the highly variable expression of serotonin and/or neuropeptides in these neoplasms, and was unrelated to the presence or absence of associated endocrine syndromes. Our findings indicate that synaptophysin occurs in the neural as well as in the epithelial components of the dispered NE system of the lung as well as in the majority of NE neoplasms of this organ, and that the expression of this protein is therefore independent of the cytoskeletal characteristics and other differentiation features of both normal and transformed NE cells of the lung. We emphasize the value of synaptophysin as an immunocytochemical marker of NE differentiation.

Animals↗