Biomedical subjects

A Kist

Publications and source records attributed to A Kist.

10 recordsLinked to original sources

PubMed1998

Antiviral potential of interferon-omega on hepatitis B virus replication in human hepatoma cells.

Interferon-alpha (IFN-alpha) and other cytokines are able to interfere with hepatitis B virus (HBV) replication. However, a sustained antiviral effect is achieved only in 25% to 40% of the patients with chronic HBV infection and clearance of the virus rarely occurs, stressing the need for developing therapeutic alternatives. In this study the antiviral potential of a new recombinant interferon, IFN-omega was investigated. IFN-omega was assessed in comparison with IFN-alpha 2c, IFN-gamma, and TNF-alpha with respect to production of HBV proteins and DNA in HepG2.2.15 cells, a HBV-DNA transfected hepatoma cell line which produces infectious viral particles. Cells were seeded at different states of confluence (20%-90%) and treated with increasing concentrations of interferons (5 to 5,000 U/ml), TNF-alpha (5 to 500 ng/ml), or combinations of both for one to three days. IFN-omega reduced the production of HBsAg down to 59% of the untreated controls, which was comparable to the reduction obtained by treatment with IFN-alpha (60%), the standard interferon used for the treatment of chronic HBV infections. The strongest inhibition, however, was achieved by treatment with 500 ng/ml TNF-alpha (42%). Likewise, production of HBeAg and synthesis of HBV DNA were inhibited to similar degrees by the different interferons. In non-replicating high-density cultures only TNF-alpha was effective. IFN-omega is of similar antiviral potential as IFN-alpha in this in vitro experimental system.

Animals↗

PubMed1996

HCC-1, a novel chemokine from human plasma.

A novel CC chemokine, HCC-1, was isolated from the hemofiltrate of patients with chronic renal failure. HCC-1 has a relative molecular mass of 8,673 and consists of 74 amino acids including four cysteines linked to disulfide bonds. HCC-1 cDNA was cloned from human bone marrow and shown to code for the mature protein plus a putative 19-residue leader sequence. Mature HCC-1 has sequence identity of 46% with macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta, and 29-37% with the other human CC chemokines. Unlike MIP-1 alpha and the other CC chemokines, HCC-1 is expressed constitutively in several normal tissues (spleen, liver, skeletal and heart muscle, gut, and bone marrow), and is present at high concentrations (1-80 nM) in plasma. HCC-1 has weak activities on human monocytes and acts via receptors that also recognize MIP-1 alpha. It induced intracellular Ca2+ changes and enzyme release, but no chemotaxis, at concentrations of 100-1,000 nM, and was inactive on T lymphocytes, neutrophils, and eosinophil leukocytes. In addition, HCC-1 enhanced the proliferation of CD34+ myeloid progenitor cells. It was as effective as MIP-1 alpha, but about 100-fold less potent.

Amino Acid Sequence↗

PubMed1996

Kinetics of soluble TNF-receptors and soluble adhesion molecules ICAM-1, E-selectin and VCAM-1 under systemic rhTNF alpha therapy.

Cytostatic as well as cytotoxic effects of tumour necrosis factor alpha (TNF-alpha) therapy have been shown in vitro and in experimental in vivo models. Nevertheless, the mechanism of anti-tumour activity in humans in vivo remains unclear. To determine the role of the vascular lining endothelial cells as important mediators of several immunological interactions, we investigated changes in the levels of the soluble endothelial cell adhesion molecules intercellular adhesion molecule 1, E-selectin and vascular cell adhesion molecule 1 as well as of soluble TNF receptors I and II during systemic therapy with recombinant human rhTNF-alpha (rhTNF-alpha). All tests were performed by enzyme-linked immunosorbent assays (ELISAs). The clinical efficacy of the intravenous rhTNF-alpha therapy was poor. Only one patient with isolated intraarterial limb perfusion had a delayed, marked, but only temporary necrosis of tumour cells. In contrast, we found a marked, significant and (during therapy) undulating augmented increase in the levels of soluble adhesion molecules as well as of the soluble TNF receptors. Taken together, these data support the hypothesis that a sufficient tumour-specific cellular immunity is required to achieve a clinically apparent efficacy of systemic rhTNF-alpha therapy in addition to cytokine-dependent inducible activation mechanisms. In this context, the vascular lining endothelial cells might play an important role as mediators of the complex immunological antitumoral activity.

Adult↗

PubMed1996

Urodilatin is involved in sodium homeostasis and exerts sodium-state-dependent natriuretic and diuretic effects.

Urodilatin is involved in sodium homeostasis exerts sodium-state-dependent natriuretic and diuretic cts. Eight male volunteers participated in a study consisting of three consecutive phases of 7 days each. The volunteers a sodium diet with 52, 172.6, and 347.8 mmol um/day. Sodium excretion increased from 57.4 +/- 3.7 via .8 +/- 4.6 (P < 0.001) to 322.5 +/- 10.2 mmol/24 h (P < 0.001) at the end of each sodium diet. Urinary urodilatin excretion increased from 24.8 +/- 3.0 via 35.5 +/- 9.0 (P = 0.07) to 49.0 = mol/min (P < 0.01). At the end of each diet, urodilatin was infused for 2 h at 20 ng.kg body wt-1.min-1. Natriuresis increased after low- (4.1 to 52.9 mmol/h, P < 0.001), normal (6.9 to 44.9 mmol/h, P < 0.05), and high-sodium diet (20.1 to 102.9 mmol/h, P < 0.001). Diuresis increased from 174 to 709 (P < 0.001), 395 to 1,026 (P < 0.05), and 266 to 1,339 ml/h < 0.001). The present results indicate that endogenous urodilatin plays an important role in sodium homeostasis and that renal response to exogenous urodilatin is modulated by sodium balance.

Adaptation, Physiological↗

PubMed1993

Lack of intrathyroidal tumor necrosis factor alpha in Graves' disease.

In vitro tumor necrosis factor alpha (TNF alpha) exerts a synergistic action on HLA class II expression and a cytotoxic action in FRTL-5 cells. Therefore, a role for TNF alpha as a local mediator of cell destruction in thyroid autoimmunity has been postulated. To elucidate the in vivo significance of these and other in vitro findings for the pathophysiology of Graves' disease we investigated 11 thyroid glands of patients suffering from Graves' disease for TNF alpha. In situ hybridization was done with a TNF alpha probe synthesized with T7 polymerase on a 750-base pair EcoRI fragment of the coding region. Primers at positions 152 and 854 in the TNF alpha copy DNA sequence were used for reverse polymerase chain reaction (PCR) amplification of TNF alpha in 5 patients. Immunohistological staining for TNF alpha was done with a mouse monoclonal antibody. We could not detect any TNF alpha and TNF alpha messenger RNA in thyroid tissue of 11 patients suffering mostly from relapsing Graves' disease by immunohistology and in situ hybridization as well as reverse PCR, respectively. A faint signal could be detected by reverse PCR in control thyroid tissue from a patient with recurrent goiter. This lack of intrathyroidal TNF alpha in relapsing Graves' disease is in accordance with a lack of increased TNF alpha production by T cell clones isolated from Graves' disease thyroid glands and contrasts with previous in vitro results. Since protective TNF actions have been demonstrated in other autoimmune diseases it could therefore be envisaged that the lack of intrathyroidal TNF alpha may be associated with the relapse of Graves' disease in our patients.

Actins↗

PubMed1991

Induction of tumor necrosis factor expression by a lectin from Viscum album.

A purified lectin (MLI) from Viscum album was used to test whether peripheral monocytes from human blood can be activated for the production of tumour necrosis factor (TNF). Cytotoxic activity was detected in the supernatant of MLI-stimulated monocyte cultures. This cytotoxic activity was completely inhibited by monoclonal antibodies to TNF alpha. Small amounts of soluble TNF protein were measured in a TNF alpha-specific enzyme-linked immunospecific assay system. Strong expression of TNF alpha mRNA was induced in human monocytes as well as in macrophage cultures from C3H/HeJ mice having a low response to endotoxin after 2 h of stimulation. Both chains of the MLI were found to induce TNF mRNA equally well in human monocytes. In macrophages of endotoxin-low-responder mice the toxic A chain was a better inducer of TNF mRNA than the galactose-specific lectin B chain. Thus, MLI has immunomodulating effects in activating monocytes/macrophages for inflammatory responses.

Animals↗

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↗

PubMed1990

Tumor-induced tumor necrosis factor production in macrophages.

Tumor-associated tumor necrosis factor (TNF) production in patients as well as a TNF-inducing membrane constituent of tumor cells have been reported. In a murine fibrosarcoma model we analyzed TNF production during growth of a tumor transplant. In situ hybridization showed that a gradually increasing number of cells within the tumor tissue became positive for TNFmRNA. Also, in spleen cells of tumor-bearing mice TNFmRNA became more abundant in later stages of tumor growth compared to early stages. In plasma of these animals, however, TNF activity was not detected at any time even after stimulation with bacterial endotoxin. Neutralization with monoclonal antibodies of endogenous TNF during tumor growth did not affect the growth rate of the tumor, indicating that either the antibodies did not reach the relevant TNF production and action sites or that endogenously produced TNF did not play a significant role in this tumor model.

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

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↗