Insulin and ischemia stimulate glycolysis by acting on the same targets through different and opposing signaling pathways.

The stimulation of heart glycolysis by insulin and ischemia involves the recruitment of the glucose transporter GLUT4 to the plasma membrane and the activation of 6-phosphofructo-2-kinase (PFK-2), which in turn increases the concentration of fructose 2,6-bisphosphate, a well-known stimulator of glycolysis. This review focuses on the mechanisms responsible for PFK-2 activation by insulin and ischemia in heart. Heart PFK-2 is phosphorylated by various protein kinases, including protein kinase B (PKB), thought to mediate most, if not all, short-term effects of insulin, and the AMP-activated protein kinase (AMPK), known to be activated under anaerobic conditions.

Control of p70 ribosomal protein S6 kinase and acetyl-CoA carboxylase by AMP-activated protein kinase and protein phosphatases in isolated hepatocytes.

Certain amino acids, like glutamine and leucine, induce an anabolic response in liver. They activate p70 ribosomal protein S6 kinase (p70S6K) and acetyl-CoA carboxylase (ACC) involved in protein and fatty acids synthesis, respectively. In contrast, the AMP-activated protein kinase (AMPK), which senses the energy state of the cell and becomes activated under metabolic stress, inactivates by phosphorylation key enzymes in biosynthetic pathways thereby conserving ATP.

Signalling pathways and combinatory effects of insulin and amino acids in isolated rat hepatocytes.

Liver metabolism is influenced by hormones and nutrients. Amino acids such as glutamine or leucine induce an anabolic response, which resembles that of insulin in muscle and adipose tissue. In this work, the signalling pathways and the effects of insulin were compared to those of glutamine and leucine in isolated hepatocytes from normal and streptozotocin-diabetic rats.

The stimulation of glycolysis by hypoxia in activated monocytes is mediated by AMP-activated protein kinase and inducible 6-phosphofructo-2-kinase.

The activation of monocytes involves a stimulation of glycolysis, release of potent inflammatory mediators, and alterations in gene expression. All of these processes are known to be further increased under hypoxic conditions. The activated monocytes express inducible 6-phosphofructo-2-kinase (iPFK-2), which synthesizes fructose 2,6-bisphosphate, a stimulator of glycolysis.

Phagocytosis and killing of intracellular pathogens: interaction between cytokines and antibiotics.

Phagocytosis and bacterial killing are the primary functions of macrophages. Among the mechanisms involved in the phagocytic process, cytokines, especially those of T-helper 1 profile, appear to influence considerably the internalization and the intracellular fate of the pathogen within the macrophage. In particular, the evidence for a cooperation of cytokines with antibiotics in intracellular infection could provide new therapeutic approaches to intracellular infectious diseases in the future.

The matrix metalloproteinase-1 (MMP-1) expression in the human endometrium is inversely regulated by interleukin-1 alpha and sex steroids.

Objective: To investigate the regulation of perimenstrual MMP-1 expression in human endometrium.

Design: In vitro study utilizing epithelial-stromal co-cultures.

Setting: Cell Biology Unit, International Institute of Cellular and Molecular Pathology, and Departments of Pathology and Gynecology, Saint-Luc University Clinics, Louvain University Medical School, Brussels, Belgium.

Treatment with calcitonin suppresses the responses of bone, cartilage, and synovium in the early stages of canine experimental osteoarthritis and significantly reduces the severity of the cartilage lesions.

Objective: To relate the rate of bone resorption to serum levels of both hyaluronan (HA) and antigenic keratan sulfate (KS) in canine experimental osteoarthritis (OA) and to evaluate the effects of calcitonin on these parameters and the OA lesions of the unstable knee.

Methods: Twenty-two dogs underwent anterior cruciate ligament transection (ACLT) and 6 dogs underwent sham operation. Urinary pyridinium crosslinks were quantified by high-performance liquid chromatography.

Human immunodeficiency virus type 2 produces a defect in CD3-gamma gene transcripts similar to that observed for human immunodeficiency virus type 1.

T cells are central players in the immune response to infectious disease, with the specificity of their responses controlled by the T-cell receptor (TCR)/CD3 complex on the cell surface. Impairment of TCR/CD3-directed CD4(+) T-cell immune responses is frequently observed in individuals infected with human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Virus replication is also regulated by T-cell activation factors, with HIV-1 and HIV-2 responding to different TCR/CD3-directed cellular pathways.

Absence of internal ribosome entry site-mediated tissue specificity in the translation of a bicistronic transgene.

The 5' noncoding regions of the genomes of picornaviruses form a complex structure that directs cap-independent initiation of translation. This structure has been termed the internal ribosome entry site (IRES). The efficiency of translation initiation was shown, in vitro, to be influenced by the binding of cellular factors to the IRES.

The Yersinia Yop virulon, a bacterial system to subvert cells of the primary host defense.

The Yop virulon enables yersinias (Yersinia pestis, Y. pseudotuberculosis and Y. enterocolitica) to survive and multiply in the lymphoid tissues of their host.

Mutagenesis of the fructose-6-phosphate-binding site in the 2-kinase domain of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

Multiple alignment of several isozyme sequences of the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase revealed conserved residues in the 2-kinase domain. Among these residues, three asparagine residues (Asn76, Asn97 and Asn133; numbering refers to the liver isozyme sequence) and three threonine residues (Thr132, Thr134 and Thr135) are located near the fructose 6-phosphate-binding site in the crystal structure of the bifunctional enzyme. The role of these residues in substrate binding and catalysis in the 6-phosphofructo-2-kinase domain has been studied by mutagenesis to alanine.

Adaptation of Theiler's virus to L929 cells: mutations in the putative receptor binding site on the capsid map to neutralization sites and modulate viral persistence.

Persistent strains of Theiler's virus, a murine picornavirus, produce a life-long infection of the central nervous system of the mouse and induce a chronic demyelinating disease. Strain DA1, a molecular clone of such a persistent strain, produces a prominent cytopathic effect in BHK-21 cells but is less efficient at infecting L929 cells. We cloned the cDNA of a derivative of virus DA1, adapted to promote a rapid cytopathic effect in L929 cells.

In vivo stimulation of polymeric Ig receptor transcytosis by circulating polymeric IgA in rat liver.

Binding of human polymeric IgA ligand to its epithelial cell polymeric Ig receptor, pIgR, has been shown to stimulate pIgR apical transcytosis in an in vitro system, based on polarized confluent MDCK cells expressing rabbit pIgR. The present study aimed at testing whether such a stimulation also occurs in vivo. Transcytosis of pIgR was monitored by rat liver output of total secretory component (SC) into bile, measured by radial immunodiffusion as the sum of free SC and pIgA-bound SC.

Novel evidence for an ecto-phospholipid methyltransferase in isolated rat hepatocytes.

Phospholipids of isolated rat hepatocytes were labelled by preincubation with either 2 microM -methyl-14C-S-adenosylmethionine (AdoMet) or 2 microM [methyl-14C]methionine. Subsequent addition of phospholipase C to the suspension removed 95% of the radioactivity from phospholipids methylated by [methyl-14C]AdoMet within a few minutes, but was without effect on phospholipids methylated by [methyl-14C]methionine radioactivity from the latter could, nevertheless, be removed by phospholipase C after permeabilization of the cells with digitonin. The results clearly show that the methyl group of exogenous AdoMet, contrary to that of methionine, is transferred on to phospholipids located on the external face of the plasma membrane.

Organization, sequence and stage-specific expression of the phosphoglycerate kinase genes of Leishmania mexicana mexicana.

In Leishmania mexicana two genes were detected coding for different isoforms of the glycolytic enzyme phosphoglycerate kinase. This situation contrasts with that observed in other Trypanosomatidae (Trypanosoma brucei, Trypanosoma congolense, Crithidia fasciculata) analyzed previously, which all contain three different genes coding for isoenzymes A, B and C, respectively. All attempts to detect in L.

The Yersinia Yop virulon: LcrV is required for extrusion of the translocators YopB and YopD.

LcrV, an essential piece of the Yop virulon, is encoded by the large lcrGVsycDyopBD operon. In spite of repeated efforts, the role of LcrV in the Yop virulon remains elusive. In an attempt to clarify this, we engineered a complete deletion of lcrV in the pYV plasmid of Yersinia enterocolitica E40 and characterized the phenotype of the mutant.

Enzymes of the purine nucleotide cycle in muscle of patients with exercise intolerance.

The activities of adenylosuccinate synthetase, adenylosuccinate lyase, and adenosine monophosphate deaminase were measured in muscle from patients suffering from fatigue and cramps following exercise. Results denote the existence of secondary deficiencies of adenylosuccinate synthetase and/or adenylosuccinate lyase in subjects with congenital or acquired myopathies. They also suggest that searches are warranted for primary deficiencies of adenylosuccinate synthetase as a cause of exercise intolerance.

Heparin interferes with translocation of Yop proteins into HeLa cells and binds to LcrG, a regulatory component of the Yersinia Yop apparatus.

Yersiniae are equipped with the Yop virulon, an apparatus that allows extracellular bacteria to deliver toxic Yop proteins inside the host cell cytosol in order to sabotage the communication networks of the host cell or even to cause cell death. LcrG is a component of the Yop virulon involved in the regulation of secretion of the Yops. In this paper, we show that LcrG can bind HeLa cells, and we analyse the role of proteoglycans in this phenomenon.

The glycosomal ATP-dependent phosphofructokinase of Trypanosoma brucei must have evolved from an ancestral pyrophosphate-dependent enzyme.

Trypanosoma brucei contains an ATP-dependent phosphofructokinase (PFK), located in its glycosomes, which are peroxisome-like organelles sequestering the majority of its glycolytic enzymes. In this paper, we report the cloning and sequencing of the single-copy gene encoding this enzyme. Its amino-acid sequence is more similar to pyrophosphate (PPi)-dependent PFKs than to other ATP-dependent PFKs.

Species-specific plasmid sequences for PCR identification of the three species of Borrelia burgdorferi sensu lato involved in Lyme disease.

Species-specific sequences were shown to be carried by plasmids of the three main species of Borrelia burgdorferi sensu lato involved in Lyme disease. Libraries of the 16-, 33-, and 25-kb plasmids of B. burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii, respectively, were then built and used to isolate species-specific sequences.

Cyclic AMP suppresses the inhibition of glycolysis by alternative oxidizable substrates in the heart.

In normoxic conditions, myocardial glucose utilization is inhibited when alternative oxidizable substrates are available. In this work we show that this inhibition is relieved in the presence of cAMP, and we studied the mechanism of this effect. Working rat hearts were perfused with 5.

Role of interleukin-10 in the lung response to silica in mice.

There is evidence that, following exposure to crystalline silica, the release of several proinflammatory cytokines contributes to the induction of unbalanced inflammatory reaction leading to lung fibrosis. We have examined the potential contribution of interleukin-10 (IL-10), an anti-inflammatory cytokine, in the development of silicosis. In a mouse model of inflammatory lung reaction induced by intratracheal instillation of silica (0.