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B Beutler

Publications and source records attributed to B Beutler.

At least 91 records · Page 5Linked to original sources
PubMed1990

Endotoxin-responsive sequences control cachectin/tumor necrosis factor biosynthesis at the translational level.

The biosynthesis of cachectin/TNF is largely regulated at a post-transcriptional level. Bacterial endotoxin, which strongly induces cachectin/TNF production, thus seems to elicit at least some of its effects by altering the macrophage cytoplasmic milieu. It has previously been shown that the 3'-untranslated TTATTTAT element present in numerous cytokines and proto-oncogenes is capable of repressing the translation of mRNA molecules in which it is represented. Using constructs in which the CAT coding sequence is followed by varying segments of the cachectin/TNF 3'-untranslated region, we now demonstrate that downstream sequences present in the cachectin/TNF mRNA are sufficient to mediate greater than 200-fold induction of CAT synthesis in response to activation by endotoxin. Induction of CAT activity is not attributable to a change in cytoplasmic mRNA concentration, but to a marked enhancement of translational efficiency. The response to endotoxin represents "derepression," and is conferred chiefly by the translationally repressive TTATTTAT element, acting in concert with essential flanking sequences.

Base Sequence↗
PubMed1990

Detection of interleukin 1 beta but not tumor necrosis factor-alpha in cerebrospinal fluid of children with aseptic meningitis.

Tumor necrosis factor-alpha and interleukin 1 beta have been shown to be mediators of meningeal inflammation in animal models of bacterial meningitis. The presence of both cytokines in cerebrospinal fluid (CSF) of patients with bacterial meningitis has been documented recently. In this study, we measured concentrations of interleukin 1 beta and tumor necrosis factor-alpha in CSF samples from 36 patients with nonbacterial (aseptic) meningitis, 13 of whom had culture-proved enteroviral meningitis, and from 14 control patients. None of the samples from patients with aseptic meningitis and from the controls had detectable tumor necrosis factor activity in CSF. Thirty-two (89%) of 36 patients with aseptic meningitis had detectable interleukin 1 beta in CSF (mean +/- SEM, 48 +/- 11 pg/mL). These concentrations were significantly smaller than those previously reported in patients with bacterial meningitis (944 +/- 128 pg/mL). Only 2 of the 14 control patients had detectable CSF interleukin 1 beta concentrations of 21 and 42 pg/mL. A significant correlation was evident between interleukin-1 beta concentrations and white blood cell counts in the CSF of patients with aseptic meningitis. Our data suggest that the initial events of CSF inflammation in children with aseptic meningitis are different than those in patients with bacterial meningitis, and the participation of these two cytokines, especially tumor necrosis factor-alpha, is less critical to the process.

Adolescent↗
PubMed1990

Tumor necrosis factor alpha and interleukin 1 beta in synovial fluid of infants and children with suppurative arthritis.

Tumor necrosis factor alpha and interleukin 1 beta concentrations were measured in synovial fluid of 24 infants and children with diagnoses of suppurative arthritis (n = 16) and other kinds of arthritis (n = 8). Large concentrations of tumor necrosis factor alpha (range, 100 to 85,000 pg/mL) were found in 12 (75%) of 16 patients with bacterial infection and in none of the patients with noninfectious origins. Large concentrations of interleukin 1 beta (greater than 200 pg/mL) were found in 15 (94%) of 16 patients with bacterial infection and in none of the other patients. In the latter group, small concentrations of interleukin 1 (range, 40 to 120 pg/mL) were present in 5 (63%) of 8 patients. Serum samples obtained simultaneously were negative for both cytokines. Tumor necrosis factor alpha and interleukin 1 beta concentrations correlated significantly and with leukocyte counts in synovial fluid. We conclude that large concentrations of tumor necrosis factor alpha and interleukin 1 beta are produced locally in patients with suppurative arthritis and they may be potentially useful in differentiating this condition from other kinds of arthritis.

Adolescent↗
PubMed1990

Mapping of the human ribonuclease inhibitor gene (RNH) to chromosome 11p15 by in situ hybridization.

Ribonuclease inhibitor (RNH) is a protein that binds tightly to ribonucleases in cells and may be essential in the control of mRNA degradation and gene expression. The human RNH gene has been regionally localized to chromosome band 11p15 by in situ hybridization. A human placental cDNA was used to construct a 600-bp probe, which was then radiolabeled with tritium for in situ hybridization to human metaphase chromosomes. Localization of the RNH gene to 11p15, and possibly to 11p15.5, adds to a large number of genes assigned to this band, including 10 structural genes. This chromosomal region also represents an evolutionarily conserved syntenic group in the owl monkey, mouse, rat, and cow. Thus, regional assignment of RNH could facilitate the understanding of this gene and its association with ribonucleases, and perhaps extend a conserved syntenic region in mammalian genomes.

Chromosome Mapping↗
PubMed1990

Translational control mediated by UA-rich sequences.

Several messenger RNAs coding for cytokines, growth factors or oncoproteins contain a conserved UA-rich sequence in their 3' untranslated regions. This sequence, which is composed of several interspersed repeats of the octanucleotide UUAUUUAU, is a key element in the posttranscriptional regulation of these mRNAs. Previously shown to be involved in mRNA destabilization, these UA-rich elements can also strongly influence mRNA translation. A translation inhibition mediated by these sequences has indeed been observed in vitro as well as in frog oocyte or in somatic cells.

Animals↗
PubMed1990

The complex regulation and biology of TNF (cachectin).

Cachectin (tumor necrosis factor) and lymphotoxin have been studied intensively over the past 3 years and have been shown to initiate a broad spectrum of biological responses. In addition to their ability to induce hemorrhagic necrosis of certain transplantable animal tumors, these molecules have been shown to be highly toxic and to mediate many aspects of the host inflammatory response. When produced in large quantities, cachectin is capable of inducing a shock state that closely resembles endotoxin-induced shock; when chronically secreted, cachectin causes a wasting syndrome very similar to that observed in infectious and neoplastic diseases. Both cachectin and lymphotoxin may play a critical role in a variety of human disease states.

Animals↗
PubMed1989

Multiple splice forms of ribonuclease-inhibitor mRNA differ in the 5'-untranslated region.

We report the sequence of the cDNAs representing five independent splice forms of human placental RNase inhibitor (RI) mRNA. RI mRNAs differ principally in the 5'-untranslated region, which may include or lack a 68-nucleotide (nt) exon inserted at a splice site located only 20 nt upstream from the initiator AUG. At least three other exons may also abut the same splice site. This unusual and variable feature of the mRNA would suggest that secondary structure in the region of the start codon may differ among RI messages. A single copy of the RI gene exists in the human genome.

Amino Acid Sequence↗
PubMed1989

Alternative cleavage of the cachectin/tumor necrosis factor propeptide results in a larger, inactive form of secreted protein.

Cachectin/tumor necrosis factor is initially synthesized as a 26 kilodalton prohormone. This molecule is 76 (human) or 79 (mouse) amino acids longer than the mature protein, as a result of additional residues present at the amino terminus. A short hydrophobic stretch of amino acids serves to anchor the prohormone in lipid bilayers; the mature protein, as well as a partially processed form of the hormone, are secreted after cleavage of the propeptide. We have analyzed the cleavage of the murine propeptide as it occurs in RAW 264.7 cells and now report that scission occurs at a site within the propeptide fragment, 10 residues before the amino-terminal leucine of the mature protein. This incompletely processed form of the molecule also begins with a leucine residue. Although secreted as a soluble product, it is biologically inactive in the L-929 cell cytotoxicity assay.

Amino Acid Sequence↗
PubMed1989

Porcine tumor necrosis factor alpha: cloning with the polymerase chain reaction and determination of the nucleotide sequence.

We have cloned the gene for the porcine tumor necrosis factor alpha (TNF-alpha) utilizing the polymerase chain reaction (PCR). Total RNA from stimulated monocytes was used to generate TNF-alpha-specific single-stranded cDNA, with reverse transcriptase and a conserved consensus primer, starting at the TNF-alpha translation stop codon. After adding a second conserved consensus primer to the propeptide region, we amplified the cDNA between the two primers. The isolated fragment was cloned and sequenced. Comparison of the nucleotide sequence indicated an 85% sequence similarity to the human TNF-alpha gene. Eighteen amino acids of the deduced mature peptide sequence of porcine TNF-alpha were different from those in the sequence of man. The technique used in this work allows rapid cloning of specific genes from total RNA, and, additionally, screens for full-length transcripts during the amplification procedure.

Amino Acid Sequence↗
PubMed1989

Correlation of interleukin-1 beta and cachectin concentrations in cerebrospinal fluid and outcome from bacterial meningitis.

Because interleukin-1 beta (IL-1 beta) and cachectin (tumor necrosis factor) are thought to mediate the body's response to microbial invasion, we measured IL-1 beta and tumor necrosis factor concentrations in paired cerebrospinal fluid (CSF) samples (on admission to the hospital, CSF1; 18 to 30 hours later, CSF2) from 106 infants and children with bacterial meningitis. In CSF1, IL-1 beta was detected in 95% of samples; the mean (+/- 1 SD) concentration was 944 +/- 1293 pg/ml. Patients with CSF1 IL-1 beta concentrations greater than or equal to 500 pg/ml were more likely to have neurologic sequelae (p = 0.001). Tumor necrosis factor was present in 75% of CSF1 samples; the mean concentration was 787 +/- 3358 pg/ml. In CSF2 the mean IL-1 beta concentration was 135 +/- 343 pg/ml, and IL-1 beta concentrations correlated significantly with CSF2 leukocyte count, with glucose, lactate, protein, and tumor necrosis factor concentrations, and with neurologic sequelae. Tumor necrosis factor was detected in CSF2 specimens of 53 of 106 patients, with a mean concentration of 21 +/- 65 pg/ml. Of the 106 patients, 47 received dexamethasone therapy at the time of diagnosis. These patients had significantly lower concentrations of IL-1 beta and higher glucose and lower lactate concentrations in CSF2, and they had a significantly shorter duration of fever compared with the values in patients not treated with steroids (p less than or equal to 0.002). Our data suggest a possible role of IL-1 beta and tumor necrosis factor as mediators of meningeal inflammation in patients with bacterial meningitis, and might explain, in part, the beneficial effect of dexamethasone as adjunctive treatment in this disease.

Bacterial Infections↗
PubMed1989

Evolution of the genome and the genetic code: selection at the dinucleotide level by methylation and polyribonucleotide cleavage.

Noting the scarcity of CpG dinucleotide in total genomic DNA derived from higher organisms and the scarcity of TpA dinucleotide in total genomic DNA derived from most life forms, we examined the distribution of these dinucleotides in sequences derived from functionally distinct types of human DNA, including mitochondrial DNA, intergenic DNA, intron DNA, and DNA destined to be represented in the cytoplasm as mRNA, tRNA, or rRNA. While CpG frequency has fallen to its lowest levels in DNA that is transcriptionally silent, TpA is most stringently excluded in DNA destined to be expressed as mRNA in the cytosol. This observation suggests that the selective pressures leading to the removal of CpG and TpA operate at different levels. With respect to TpA, dinucleotide scarcity may reflect a requirement for mRNA stability and may indicate the action of UpA-selective ribonucleases. We propose that, by reason of its instability, UpA must have been very rare in primordial RNA. Therefore, tRNA with the anticodon for this dinucleotide may have failed to evolve, making UpA the primordial doublet "stop" codon. The modern triplet code has faithfully conserved this arrangement in the two universal stop codons, UAA and UAG.

Base Sequence↗
PubMed1989

Cachectin alters anterior pituitary hormone release by a direct action in vitro.

Cachectin (tumor necrosis factor) is a powerful macrophage hormone released during infection, which circulates in blood to produce diverse effects in the organism. We examined the effect of cachectin on release of anterior pituitary hormones from either hemipituitaries or dispersed pituitary cells incubated in vitro. The action of cachectin on dispersed cells was demonstrable only after 2 hr of incubation. With this incubation time, the protein produced a dose-related stimulation of release of adrenocorticotropin (ACTH), growth hormone (GH), and thyrotropin (TSH), but not of prolactin (Prl), from both hemipituitaries and dispersed cells. The doses required for stimulation were low in the case of hemipituitaries, usually of the order of 10(-12) M, whereas they were higher by one or two orders of magnitude with the dispersed pituitary cells. This may be related either to loss of receptors for the protein during the dispersion procedure or to the fact that in the hemipituitary system cell interactions are facilitated because the cells are close to each other. In the dispersed cell system cachectin evoked a dose-related decrease in cyclic AMP content. Incubation with somatostatin lowered the cyclic AMP content of the cells and depressed GH output without altering output of TSH or Prl. When somatostatin and cachectin were incubated together with the cells, the suppression of cyclic AMP production was abolished; TSH and Prl release were stimulated, but the action of cachectin to stimulate GH release was blocked. The stimulation of Prl release by cachectin in the presence of somatostatin may be related to the elevation of cyclic AMP, a known stimulator of Prl release. The cyclooxygenase inhibitor indomethacin nearly completely blocked the stimulatory effect of cachectin on release of GH and TSH from dispersed pituitary cells but had only a slight and nonsignificant attenuating effect on its ACTH-releasing action. These results suggest that at least part of the stimulatory action of the peptide on pituitary hormone release is brought about by prostaglandins. The failure of indomethacin to block the release of ACTH induced by cachectin suggests that other mechanisms may be involved in the release of ACTH induced by this peptide. Since the concentrations of cachectin required to stimulate pituitary hormone release are similar to those that are encountered in plasma during infection, it is likely that this direct pituitary action has pathophysiological significance.

Adrenocorticotropic Hormone↗
PubMed1989

Modulation of inflammation and cachectin activity in relation to treatment of experimental Hemophilus influenzae type b meningitis.

By use of an experimental lapin model, the effect of ceftriaxone therapy on inflammation during Hemophilus influenzae type b (Hib) meningitis was evaluated. Meningitis was induced by intracisternal inoculation of 2 x 10(4) to 2 x 10(5) colony-forming units of Hib. Administration of ceftriaxone 6 h after infection provoked rapid bacterial lysis associated with greatly increased concentrations of bacteria-free endotoxin (lipooligosaccharide) and tumor necrosis factor alpha (TNF) in the cerebrospinal fluid (CSF). CSF TNF activity peaked 2 h after initiation of antibiotic therapy (24.4 +/- 2 ng/ml), was significantly higher than that in untreated controls (1.4 +/- 1.1 ng/ml; P less than .05), and was associated with a substantially increased inflammatory response as reflected by higher CSF white blood cell count (24,500 +/- 8,151 vs. 1,920 +/- 644 in untreated controls; P less than .05), lower glucose, and higher protein and lactate concentrations. Simultaneous administration of dexamethasone with antibiotic therapy resulted in a significant reduction in CSF TNF activity that was associated with a substantial reduction in CSF white blood cell count. These data suggest that initiation of ceftriaxone therapy in experimental Hib meningitis exacerbates the meningeal inflammatory response, which can be modulated by concurrent dexamethasone administration.

Animals↗
PubMed1989

Diphosphoryl lipid A from Rhodopseudomonas sphaeroides ATCC 17023 blocks induction of cachectin in macrophages by lipopolysaccharide.

Purified diphosphoryl lipid A (DPLA) obtained from the nontoxic lipopolysaccharide of Rhodopseudomonas sphaeroides ATCC 17023 was shown to block the induction of cachectin (tumor necrosis factor) in the RAW 264.7 macrophage cell line by toxic deep-rough-chemotype lipopolysaccharide (ReLPS) of Escherichia coli in a concentration-dependent manner. The ReLPS-to-DPLA mass ratios of 1:10 and 1:100 (when 1.0 ng of ReLPS per ml was used) gave 55 and 95% inhibitions, respectively, of the induction of cachectin. Since the structure of the DPLA from R. sphaeroides is so similar to that of the lipid A moiety of the toxic ReLPS from E. coli, we suggest that this inhibition could have been due to competitive binding by DPLA to the active sites on the macrophage. This DPLA could become a useful reagent to study the nature of lipopolysaccharide/lipid A binding in macrophages and perhaps other responding cells.

Animals↗