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K Brand

Publications and source records attributed to K Brand.

At least 73 records · Page 4Linked to original sources
PubMed1992

Characterization of a phospholipase A2 in human serum.

Elevated catalytic activities of serum phospholipase A2 were measured in patients with inflammatory diseases. In contrast to human pancreatic phospholipase A2, the enzyme in serum of patients with non-pancreatic diseases was rather heat labile and showed a broad pH-optimum in the neutral range. Molecular sieving experiments revealed the existence of macro-molecular forms of the enzyme in serum which were cleaved into monomers of M(r) 14,000 in the presence of high salt concentrations. More than 100-fold purification was achieved by gel filtration chromatography on Sephadex G-100 in the presence of 2 mol/l KCl. Whether this serum phospholipase A2 and a secretory liver and platelet isoenzyme are identical remains to be established.

Blood Platelets↗
PubMed1992

[Toxic oil syndrome--an example of an exogenously-induced autoimmune disease].

In 1981 epidemic poisoning with adulterated cooking oil occurred in Spain, affecting more than 20,000 people. The condition caused has since become known as the toxic oil syndrome (TOS). About 10-15% of the patients with acute symptoms developed a chronic disease with scleroderma-like skin manifestations, polyneuropathy and myositis. While the acute phase of the TOS was characterized by eosinophilia and elevated IgE, the chronic stage involved humoral autoimmune phenomena, such as antinuclear and antinucleolar antibodies, in many cases. In women with the chronic phase of TOS there was a possible prevalence of HLA-DR3 and HLA-DR4. The recently characterized eosinophilia-myalgia syndrome (EMS), which is thought to have been induced by contaminated L-tryptophan preparations, is similar to the TOS in some particulars. Understanding of the toxicological, immunological and genetic pathways leading to these diseases might give us some insight into the pathogenesis of spontaneously occurring autoimmune diseases, such as systemic scleroderma.

Animals↗
PubMed1991

Lipopolysaccharide-mediated transcriptional activation of the human tissue factor gene in THP-1 monocytic cells requires both activator protein 1 and nuclear factor kappa B binding sites.

Lipopolysaccharide (LPS) activation of cells of monocytic lineage leads to rapid and transient expression of a set of inflammatory gene products, including tissue factor (TF). This transmembrane receptor is the major cellular initiator of the blood coagulation cascades, and induced expression of TF is postulated to play a role in inflammation. Functional studies using transfected THP-1 monocytic cells revealed the presence of a 56-bp LPS response element (LRE) within the TF promoter that conferred LPS responsiveness to a heterologous promoter. LPS stimulation of these cells activated proteins that bound to nucleotide sequences within the LRE resembling consensus binding sites for activator protein 1 (AP-1) and nuclear factor kappa B (NF-kappa B). Induction of the TF gene may represent a prototypic example of gene activation in monocytic cells by assembly of transcription factor complexes, and may clarify the role of AP-1 and NF-kappa B in the regulation of other LPS-responsive genes.

Base Sequence↗
PubMed1991

The early induction of the actin-sequestering peptide thymosin beta 4 in thymocytes depends on the proliferative stimulus.

The expression of the actin-sequestering peptide, thymosin beta 4, was analyzed in proliferating rat thymocytes, activated by diverse stimuli, during the early G1 phase and the S phase. In the presence of concanavalin A a 6.3-fold increase of thymosin beta 4 occurred already after 1 h of stimulation without elevation of the corresponding mRNA level. In contrast, during the S phase the increase of thymosin beta 4 (2.5-fold) was accompanied by a higher mRNA level, but did not exceed the growth related increase of total protein. Stimulation with a crosslinked antibody against rat T cell antigen receptor or stimulation with phorbol 12-myristate 13-acetate (PMA) and Ca(2+)-ionophore A23187, separately or in combination, did not lead to the marked increase of the thymosin beta 4 concentration in the early G1 phase but resulted in elevated thymosin beta 4 peptide and mRNA levels during the S phase. It therefore appears that protein kinase C activation and a rise in cytoplasmic Ca(2+)-concentration are not exclusively responsible for the stimulation of thymosin beta 4 specific translation in thymocytes. This assumption was reinforced by the observation that inhibition of the protein kinase C activity by 1-(5-isoquinolinylsulfony)-2-methylpiperazine (H-7) did not affect the cellular thymosin beta 4 content 1 h and 48 h after concanavalin A (Con A) stimulation.

Animals↗
PubMed1991

Nucleotide and nucleic acid metabolism in rat thymocytes during cell cycle progression.

A complete cell cycle of mature, concanavalin A (Con A) stimulated rat thymocytes was documented by analyzing the cell number as well as the content and synthesis of DNA and RNA. Cell cycle progression is accompanied by an elevation of class I, II and III RNA polymerase activities (about 10-fold) in the S phase maximum, 48 h after stimulation. Moreover, maximal cellular contents of DNA, ATP, ADP and AMP were observed at this culture period, whereas the RNA level peaked at 60 h. The synthesis of purine and pyrimidine nucleotides de novo was detected by use of [14C]HCO3-. Maximal incorporation rates of [14C]HCO3- into nucleotides (de novo synthesis) and of [3H]adenine into adenylates ('salvage pathway') occur during the S phase. However, the de novo synthesis rates were markedly lower than those of the 'salvage pathway'. The highest cellular level of the nucleotide precursor 5-phosphoribosyl-1-pyrophosphate (8.4-fold increase) also coincided with the S phase.

Animals↗
PubMed1991

Cell-cycle-regulated expression of thymosin beta 4 in thymocytes.

Thymosin beta 4 belongs to a family of ubiquitous peptides present at a high cellular content but still with an unknown intracellular function. The expression of this peptide was studied in concanavalin-A-stimulated, proliferating rat thymocytes during cell cycle progression. An early, transient 10-fold increase of the peptide occurred 1 h after stimulation without elevation of the corresponding mRNA level. This increase coincided with that of thymosin beta 4 biosynthesis. The sharp decline of the thymosin beta 4 content was not due to a secretion of the peptide into the medium. During S phase and mitosis, the biosynthetic rates as well as mRNA content, but not the cellular thymosin beta 4 concentration, increased again. After 96 h of culture the values returned to those of quiescent cells.

Animals↗
PubMed1991

The structural biology of expression and function of tissue factor.

Analysis of the structural biology of TF provides insights into the both the expression of the gene and the function of this cell surface receptor in the initiation of the coagulation protease cascades. The advance of information may permit inferential hypotheses for the structural biology of other cofactor regulated catalytic steps in blood coagulation.

Amino Acid Sequence↗
PubMed1991

Role of ornithine decarboxylase for proliferation of mesangial cells in culture.

To elucidate the role of polyamine metabolism in the regulation of mesangial cell growth, we examined the involvement of ornithine decarboxylase (ODC), the rate limiting enzyme for polyamine synthesis, in the mitogenesis of cultured rat mesangial cells (MCs). Resting MCs, stimulated with fetal calf serum (FCS 10%), showed an induction of ODC activity from undetectable values in resting cells to mean = 5035 nmol CO2/10(10) cells.hr (range 3157 to 7154, N = 5), which is 25-fold above the detection limit. We found a single peak of ODC activity eight to ten hours after stimulation, declining to 22 to 34% of peak levels after 24 hours. 3H-thymidine (TdR) uptake, an S-phase marker of MC replication, peaked at 24 hours, reaching 10.7-fold values of resting MCs. ODC mRNA levels were low in resting cells. After serum stimulation there was a two- to 10-fold increase in ODC mRNA with a maximum after six hours. ODC activity with similar kinetics but lower peak levels was also induced by incubating MCs with mitogens, such as platelet-derived growth factor (PDGF-AB 20 ng/ml), arginine vasopressin (AVP 10(-7) M), phorbol myristate acetate (PMA 10(-7) M), interleukin 1 alpha and beta (IL-1 alpha 10 U/ml, IL-1 beta 10 U/ml). In the presence of alpha-difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ODC, the growth rate of MCs, assessed by cell counts and by 3H-TdR uptake, was markedly reduced by 62 to 100%. This antiproliferative effect of DFMO could be reversed by addition of putrescine, the reaction product of ODC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Tissue factor mRNA in THP-1 monocytic cells is regulated at both transcriptional and posttranscriptional levels in response to lipopolysaccharide.

Tissue factor (TF) is transiently expressed in human monocytes exposed to the inflammatory agonist bacterial lipopolysaccharide (LPS). Since TF is the major cellular initiator of the coagulation protease cascades, it is inferred that its expression within the vasculature is strictly regulated. In this study, we investigated mechanisms which control TF mRNA expression in the human monocytic cell line THP-1. LPS induced a rapid and transient accumulation of the mature 2.2-kb TF mRNA, which was maximal at 2 h. After stimulation, the rate of transcription of the TF gene was increased (3.3 +/- 1.3)fold. In addition, we observed a significant change in TF mRNA stability: at 1 h after LPS stimulation, TF mRNA was stable during a 60-min period and had a half-life of greater than 120 min, whereas at 2 h, the half-life had declined to 25 +/- 5 min. Furthermore, a larger (3.4-kb) TF RNA species was induced in these cells; the size of this species and data from selective hybridizations with intron-specific probes are consistent with the presence of an unspliced copy of intron 1. These results demonstrate that the LPS-induced accumulation of TF mRNA levels in these monocytic cells is accomplished by both transcriptional and posttranscriptional control mechanisms.

Cycloheximide↗
PubMed1990

Rapid induction of thymosin beta 4 in concanavalin A-stimulated thymocytes by translational control.

The expression of thymosin beta 4, an ubiquitous peptide of high cellular content, was studied in concanavalin A-stimulated rat thymocytes within the first 3 h after activation of the cells. An early 6.3-fold increase of the peptide occurred after 1 h of stimulation amounting to 0.4% of the total cellular protein. This increase coincided with that of thymosin beta 4 biosynthesis measured by [35S]methionine incorporation. The share of thymosin beta 4 synthesis in total protein synthesis 1 h after addition of concanavalin A amounts to 1% but no elevation of the corresponding mRNA was observed. These data suggest that a translational control mechanism is involved in this rapid induction. Consequently, actinomycin D did not inhibit thymosin beta 4 induction in contrast to cycloheximide. The peaks of maximal thymosin beta 4 levels and biosynthesis were followed by rapid decreases of these parameters suggesting a function of thymosin beta 4 in the early phase of T cell activation.

Animals↗
PubMed1990

Prostatic acid phosphatase in the serially transplantable human prostatic tumor lines PC-82 and PC-EW.

The correlation between tumor volume of untreated tumor-bearing nude mice and serum concentration of prostatic acid phosphatase (PAP/RIA) was studied in the hormone-dependent serially transplantable human prostatic tumor models PC-82 and PC-EW. The normal serum level of PAP in control male nude mice without tumor was found to be 0.9 +/- 0.3 ng/ml. Elevated PAP serum concentrations were never found in animals without tumor (a highly specific diagnostic technique). A close correlation was observed between the concentration of PAP in the serum (range 0.3 to 154 ng/ml) and the tumor volume (range 10.0 to 6,530 mm3) of 104 untreated mice bearing a PC-82 or PC-EW human prostatic tumor. This correlation was comparable in both tumor lines (p less than 0.001). The positive effect of endocrine manipulation which resulted in tumor diameter decrease or growth arrest with regressive histological patterns, showed the normal PAP serum level, too. After successful treatment PAP was found to be normal, independent from the residual tumor mass. By contrast, in the event of only retarded tumor growth, the PAP level still correlated with the tumor burden.

Acid Phosphatase↗
PubMed1990

Alternative fuels for platelet storage: a metabolic study.

We have studied the metabolism of platelets in vitro using washed platelets. Oxygen uptake and fuel utilization were measured. It was found that glucose is never oxidized to any significant extent and is always converted to lactate, regardless of oxygen availability. Oxidative metabolism fuels 70-100% of the ATP turnover, and oxygen uptake is the same whether the platelet is consuming glucose, acetate or only an unidentified endogenous fuel. When acetate is the added fuel, no endogenous fuel is oxidized, whereas the addition of glucose results in sparing of only 8% of endogenous fuel. Preliminary storage experiments using plasma-free media show that an acetate-containing buffered salt solution provided excellent storage conditions and that a medium without any exogenous fuel is better than one containing glucose. Thus we conclude that a successful storage medium should contain minimal amounts of glucose, and an oxidizable fuel such as acetate, in order to supplement the endogenous one.

Acetates↗
PubMed1990

The diagnostic validity of the serum tumor marker phosphohexose isomerase (PHI) in patients with gastrointestinal, kidney, and breast cancer.

The diagnostic validity of the glycolytic enzyme phosphohexose isomerase (PHI) as a serum tumor marker was evaluated. For this purpose the sensitivity of PHI was determined in 435 patients with histopathologically defined, malignant gastrointestinal, kidney, and mammary tumors prior to primary treatment. To assess the specificity, PHI serum activities were measured in 181 patients with benign diseases and disorders from an internal practice. In gastrointestinal and kidney cancer, PHI reached an overall diagnostic sensitivity of about 70%, and a specificity of 92% was obtained. Even in early stages without metastasis, elevated PHI serum levels were found in about 60% of the patients. In mammary cancer, however, a sensitivity of only 40% was observed. PHI activity can be measured without the need for highly technical skills and equipment, in a short time and at low cost. These data suggest that serum PHI can be a useful indicator in the preventive checkup of gastrointestinal and renal cancer in medical practice.

Biomarkers, Tumor↗
PubMed1989

Effects of warm and cold ischemia on mitochondrial functions in brain, liver and kidney.

The purpose of this work was to study the effects of warm (37 degrees C) and cold (4 degrees C) ischemia on different mitochondrial functions in rat brain, liver and kidney. After 10 to 60 minutes of ischemia at 37 degrees C the energy coupled respiration as well as the ADP-induced malate-aspartate shuttle activity in brain and liver mitochondria or the rate of mitochondrial ATP synthesis in kidney were significantly decreased. However, the respiratory rates and the shuttle activity in the absence of ADP remained unchanged. These data suggest that ischemia primarily affects electron transport in the respiratory chain rather than the hydrogen shuttle and the energy coupling system. When the temperature during the indicated ischemic periods was decreased to 4 degrees C, in brain and liver no significant alterations of these mitochondrial functions were found in comparison with the non-ischemic controls. When rat kidneys were stored for 36 hours at 4 degrees C according to Collins mimicking transplantation conditions, the mitochondrial respiration and ATP synthesis were only slightly decreased. It therefore appears that hypothermia can prevent effectively mitochondrial dysfunction due to ischemia.

Adenosine Triphosphate↗
PubMed1989

Metabolism of glutamine in lymphocytes.

Pathways of glutamine metabolism in resting and proliferating rat thymocytes and established human T- and B-lymphoblastoid cell lines were evaluated by in vitro incubations of freshly prepared or cultured cells for one to two hours with [U14C]glutamine. Complete recovery of glutamine carbons utilized in products allowed quantification of the pathways of glutamine metabolism under the experimental conditions. Partial oxidation of glutamine via 2-oxoglutarate in a truncated citric acid cycle to CO2 and oxaloacetate, which then was converted to aspartate, accounted for 76% and 69%, respectively, of the glutamine metabolized beyond the stage of glutamate by resting and proliferating thymocytes. Similar results were obtained with the lymphoblastoid T- and B-cell lines. Complete oxidation to CO2 in the citric acid cycle via 2-oxoglutarate dehydrogenase and isocitrate dehydrogenase accounted for only 25% and 7%, respectively. In proliferating cells a substantial amount of glutamine carbons was also recovered in pyruvate, alanine, and especially lactate. The main route of glutamine and glutamate entrance into the citric acid cycle via 2-oxoglutarate in lymphocytes appears to be transamination by aspartate aminotransferase rather than oxidative deamination by glutamate dehydrogenase. In the presence of glucose as a second substrate, glutamine utilization and aspartate formation markedly decreased, but complete oxidation of glutamine carbons to CO2 increased to 37% and 23%, respectively, in resting and proliferating cells. The dipeptide, glycyl-L-glutamine, which is more stable than free glutamine, can substitute for glutamine in thymocyte cultures at higher concentrations.

Ammonia↗
PubMed1989

Sequential effects of interleukin 2-diphtheria toxin fusion protein on T-cell activation.

The interleukin 2-diphtheria toxin-related fusion protein (IL-2-toxin) rapidly inhibits protein synthesis in IL-2 receptor (IL-2R)-bearing phytohemagglutinin-activated T cells but transiently stimulates DNA synthesis. At 7 hr after interaction with IL-2R+ phytohemagglutinin-activated T cells, IL-2-toxin-treated cells bear augmented steady-state levels of c-myc, interferon gamma, and IL-2R mRNA; these effects are indistinguishable from those produced by recombinant IL-2. Amplification of IL-2 sequences by the polymerase chain reaction reveals an increased level of IL-2 mRNA in cell cultures treated with recombinant IL-2, IL-2-toxin, and cycloheximide. These results suggest that IL-2-toxin can affect de novo IL-2 gene transcription/mRNA stabilization through independent mechanisms exerted by both the IL-2R binding domain and ADP-ribosyltransferase activity of the fusion protein. After 20 hr of culture, IL-2R mRNA was markedly decreased in both IL-2-toxin- and cycloheximide-treated phytohemagglutinin-activated T cells. Although interaction of IL-2-toxin with IL-2R+ T cells initially mimics the stimulatory effects of IL-2 upon c-myc, interferon gamma, IL-2R, and IL-2 gene expression, the consequences of inhibition of protein synthesis mediated by the ADP-ribosyltransferase activity of the toxin dominate after 7 hr and are indistinguishable from those effects mediated by cycloheximide.

Base Sequence↗
PubMed1988

Purification and characterization of phosphohexose isomerase from human gastrointestinal carcinoma and its potential relationship to neuroleukin.

Phosphohexose isomerase (PHI) derived from human gastrointestinal tumor tissue was isolated by specific elution from a cation exchanger. The identity of three PHI variants in the purified preparation could be demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing analysis. By preparative IEF the variants could be resolved to high homogeneity. The monomer of the common major variant with a pI of 9.1 revealed a molecular weight of 60,000, whereas for the cancer-associated variants with a pI of 8.9 and 8.6, a molecular weight of 57,000 and 56,000, respectively, was determined. The results obtained support the hypothesis that those variants are due to a specific intracellular cleavage of the enzyme in the malignant cells. Since it has been shown that the Mr 56,000 protein neuroleukin exhibits a strikingly high degree of homology with PHI (M. Chaput et al., Nature (Lond.), 332: 454-455, 1988; P. Faik et al., Nature (Lond.), 332: 455-456, 1988), the described specific cleavage of PHI might be responsible for the conversion of an enzyme to a trophic factor.

Electrophoresis, Polyacrylamide Gel↗