On rat alpha-fetoprotein as a fatty acid carrier. Influence of the structure of fatty acids.

Fatty acids interfere with rat alpha-fetoprotein-estrogen interaction. We present here a quantitative study of the association constants for the binding to alpha-fetoprotein of different fatty acids. It can be concluded that fatty acids bind more strongly if the number of carbon atoms increases with the number of double bonds. The maximum binding ability occurred with the C20 fatty acids having three or four double bonds. As these fatty acids are the precursors in the synthesis of prostaglandins, we tested some compounds in this series and showed that prostaglandins presented no particular affinity for rat alpha-fetoprotein.

Oestrone binding properties of nine molecular variants of rat alpha-foetoprotein.

Rat alpha-foetoprotein was separated into nine molecular variants by electrophoresis and affinity chromatography on Ricinus communis agglutinin and concanavalin-A. The nine variants are able to bind oestrone with the same capacity of one binding site per alpha-foetoprotein molecule. The association constants seem to vary with the sialic acid composition of the iso-alpha-foetoprotein.

Inhibition of phosphatidylserine synthesis in Jurkat T cells by hydrogen peroxide.

Incubation of Jurkat cells in the presence of H2O2 either directly added to the culture medium or generated with glucose oxidase, menadione or the couple xanthine/xanthine oxidase induced a marked decrease of phosphatidylserine synthesis in the absence of changes in the synthesis of phosphatidylcholine and phosphatidylethanolamine. Concentration dependent response curves indicated that H2O2 induced inhibition of phosphatidylserine synthesis with an IC(50)=5 microM while both induction of tyrosine phosphorylation of proteins and Ca(2+) signals were obtained with an EC(50)=300 microM. The tyrosine kinase and Ca(2+) independent mechanism was confirmed by comparing the H2O2-induced and the CD3-induced inhibition of phosphatidylserine synthesis using several Jurkat clones differing in the expression of cell surface receptors such as CD3/TCR and CD45 and protein tyrosine kinase such as p72syk, ZAP-70 and p56lck. While CD3-induced inhibition of phosphatidylserine synthesis necessitates protein tyrosine phosphorylation and Ca(2+) signals, H2O2 provoked its effect in all the clones studied independently of the presence or absence of the proteins previously shown to be key elements in T cell signal transduction. Conversely, the antioxidant molecule, butylated hydroxanisole, generates an increased PtdSer synthesis, suggesting that the synthesis of this phospholipid is regulated by the redox status of the cells.

Modulation of insulin action on 2-deoxyglucose uptake by chloroquine in chick embryo fibroblasts.

Blazar et al. recently found that chloroquine therapy decreased intravenous insulin requirements in a case of extreme insulin resistance. However, no relationship has been shown to exist between insulin degradation and the stimulation of glucose uptake. In this study we investigate the action of insulin on glucose uptake by the ability of this hormone to stimulate 2-deoxyglucose. The effect on alpha-aminoisobutyrate uptake, which is known to be insulin sensitive, is also investigated. Cell-associated 125I-labeled insulin and trichloroacetic acid-soluble and -precipitable substances were measured in parallel. Chloroquine increased insulin-stimulated uptake of 2-deoxyglucose and alpha-aminoisobutyrate. Three hours were required for this effect to appear, and it did not depend on DNA synthesis. Chloroquine also increased cell-associated insulin and slightly decreased the percentage of trichloroacetic acid-soluble products. Methylamine affected neither nutrient uptake processes nor insulin binding and degradation; however, it did abolish the effect of chloroquine on these parameters. These data suggest that in chick embryo fibroblasts a relationship may exist between the increase in undegraded cell-associated insulin and the ability of the hormone to stimulate sugar and amino acid uptake.

Phospholipid metabolism and T cell activation: receptor triggering is associated with the inhibition of phosphatidylserine synthesis.

Activation of Jurkat T lymphocytes to produce IL2 is accompanied by a strong inhibition of phosphatidylserine (PS) synthesis. This inhibition was obtained either with the mitogenic lectin PHA, anti-CD3 monoclonal antibodies (mAb), anti-CD2 mAb or anti-Ti mAb. Bypassing membrane receptor signalling, by using a Ca2+ ionophore or a protein phosphatase inhibitor, sodium ortho-vanadate, also results in a marked inhibition of PS synthesis. Activators of phospholipid -Ca2+ dependent protein kinase C (PKC) did not significantly modify PS synthesis, suggesting that the observed changes only involve the transduction of the first activation signal. PS being a necessary cofactor for PKC, our results strongly suggest that the inhibition of PS synthesis induced by receptor triggering exerts a feed back control on PKC therefore leading to a transient activation of the enzyme upon full lymphocyte activation.

Diacylglycerol production in Jurkat T-cells: differences between CD3, CD2 and PHA activation pathways.

Diacylglycerol (DAG) production induced after stimulation with either CD3 mAb, a pair of CD2 mAbs or phytohaemagglutinin has been monitored in Jurkat T-cells prelabelled to isotopic equilibrium with seven [3H]- or [14C] fatty acids. It was found that CD3 induced a high production of arachidonic acid-labelled DAG and a modest production of oleic acid-DAG. The reverse was observed when using CD2 as activator. Phytohaemagglutinin induced a high production of these two DAG subspecies and in addition induced the production of linolenic acid-labelled DAG. Whatever the activator used no changes were observed in DAG production when cellular phospholipids were prelabelled with either myristic, palmitic, stearic or linoleic acids. All together our results strongly suggest that the three activation pathways previously described in T-lymphocytes might differ either at the level of the transduction mechanism or the phospholipid pools solicited during the activation process.

A chymotryptic-type protease inhibitor decreases interleukin 2 synthesis and induces prostaglandin production in Jurkat T cells.

TPCK (N-alpha-p-tosyl-L-phenylalanine chloromethylketone), a potent inhibitor of chymotryptic-type serine proteases, was found to decrease IL2 synthesis in Jurkat T cells. Conversely, the tryptic-type protease inhibitor, TLCK (N-alpha-p-tosyl-lysine chloromethylketone), which structurally is very similar to TPCK, had no effect on IL2 synthesis. Prostaglandin synthesis, a process that is known to reduce IL2 production in T cells, was increased by TPCK but not by TLCK, suggesting that this process could be, at least in part, responsible for the inhibition of IL2 production. Our results imply that a chymotryptic-type serine protease plays an active role in the regulation of IL2 synthesis and thus in the whole process of T-lymphocyte activation.

Is biolectrical impedance analysis a tool at bedside, during heat waves to assist geriatricians with discriminative diagnosis of hypertonic dehydration?

OBJECTIVES: To assess BIA data given by Analycor 3 and some bio-impedance equations to assist geriatricians with discriminative diagnosis of hypertonic dehydration, during heat waves. DESIGN: Prospective study: a dehydrated patients group has been compared with a randomised control group. SETTING: The study was carried out in a French geriatric department, in the Emile Roux geriatric hospital. PARTICIPANTS: 36: six men and twelve women in each group. MEASUREMENTS: The most valuable clinical indicators of dehydration severity were recorded and scored. BIA measurements were performed with an Analycor 3 analyzer; TBW was calculated from impedances at 50 and 100 kHz, ECW from impedance at 5 kHz; Calculations were made also with formula described in the literature, validated in healthy or in institutionalised elderly subjects. RESULTS: TBW and ECW values were always lower in dehydrated group than in control group, but without significance, whatever the applied formula; however ICW values calculated with "manufacturers equations" significantly decreased in dehydrated group. Data given by the analyzer used in this study, as well as BIA age specific equations discriminated the severely hypertonic dehydrated patients sub-group, but not the mildly hypertonic dehydrated patients sub-group. CONCLUSION: The BIA data given by the analyzer used in this study assist geriatricians at bedside with discriminative diagnosis of hypertonic dehydration, especially in severe hypertonic dehydration, but data given by the analyzer used in this study, as well as age specific equations are sometimes in poor agreement with clinical and biological parameters usually selected to assess dehydration, in mildly dehydrated patients.

Inhibition of phosphatidylserine synthesis induced by triggering CD2 or the CD3-TCR complex in a human T cell line. Relationships with G proteins and receptors modulation.

Activation of Jurkat T cells with phytohemagglutinin, CD3 or CD2 mAbs results in a marked inhibition of phosphatidylserine (PS) synthesis. Monitoring PS synthesis in T cells shows that: (i) after modulation of CD3 molecules the cells become refractory to further treatment with CD3 mAbs as well as to a further challenge with CD2 mAbs; and (ii) treatment of T cells with fluoride ions and cholera toxin, two known effectors of guanosine triphosphate-binding proteins, also resulted in a strong inhibition of the synthesis of this phospholipid. The inhibition of PS synthesis thus appears to be regulated similarly to the other activation events, suggesting that transmembrane signalling mechanisms leading to PS inhibition are the same as those previously proposed for increasing phosphatidylinositides turnover and subsequent rise in the intracellular calcium concn in lymphocytes.

Effect of indinavir on HIV-related wasting.

OBJECTIVE: To study the effect of the protease inhibitor indinavir on body weight and body composition of subjects with HIV-related wasting. DESIGN: Prospective measurement of body weight in patients who had wasting and were treated with indinavir. A subgroup of 16 representative patients also underwent a metabolic study that included measurements of body composition (skinfolds and bioelectrical impedance) and food intake. Seven from this subgroup who did not have chronic diarrhoea also underwent indirect calorimetry for measurement of resting energy expenditure; the nine patients with wasting and chronic diarrhoea had measurements of faecal losses and intestinal permeability using the lactulose-mannitol test. SETTING: A tertiary care university hospital. PATIENTS: Two hundred and fourteen HIV-infected patients with wasting (less than 95% of usual body weight) had their body weight measured at day 0; 186 patients had a second body weight measurement within the first 100 days of treatment, and 160 patients were weighed a third time, at a median of 176 days. RESULTS: Body weight increased significantly (P < 0.0001) during treatment, whatever the degree of weight loss at baseline. After a median of 176 days on treatment, body weight had increased in 119 out of the 160 patients followed (74.4%; mean weight gain, 6.3+/-SD 3.8 kg; range, 1-18 kg), had not changed in 13 (8.1%) and had fallen in 28 (17.5%; mean weight loss, 4.2+/-3.0 kg; range, 1-12 kg), relative to baseline. Overall, 119 out of the 214 patients (55.6%) from the initial population gained weight. Fat mass, fat-free mass and body cell mass increased significantly in the 16 patients who underwent metabolic studies, together with energy, protein and lipid intake. In the patients with chronic diarrhoea, intestinal permeability improved but there was no change in intestinal losses. In patients who had wasting but not chronic diarrhoea, resting energy expenditure did not change significantly. Body weight changes correlated with changes in the CD4+ cell count (r = 0.882; P = 0.00001) and, to a lesser extent, with changes in the viral load (r = -0.466; P = 0.047). CONCLUSION: Indinavir significantly improved the nutritional status of these patients with HIV-related wasting.

Oleylamine and stearylamine increase phosphatidylserine synthesis in T cells by synergy with calcium ions.

Oleylamine and stearylamine, two cationic amphiphilic drugs, strongly increase phosphatidylserine synthesis in human T cells. The two compounds had little effect on either phosphatidylcholine or phosphatidylethanolamine synthesis. A decrease in the formation of phosphatidylethanolamine through decarboxylation of phosphatidylserine was observed, but this effect is only marginally involved in increased phosphatidylserine synthesis. The high incorporation of [3H]-serine into phosphatidylserine is a protein kinase C independent process and is due to a synergy of either oleyamine or stearylamine with calcium ions.

Effects of antiarrhythmic drugs on phospholipid metabolism in Jurkat T cells. The potassium channel blocker, clofilium, specifically increases phosphatidylserine synthesis.

Five antiarrhythmic drugs (bretylium, clofilium, propranolol, N-acetylprocainamide and amiodarone) were tested for their ability to modify phospholipid metabolism in Jurkat T lymphocytes. The five drugs, decreased in a dose-dependent mode the biosynthesis of both phosphatidylcholine and phosphatidylethanolamine, this effect was essentially due to impairment of either choline or ethanolamine uptake by the cells. The efficiency of the drugs to inhibit phosphatidylcholine and phosphatidylethanolamine synthesis was in the order: clofilium greater than amiodarone much greater than propranolol = bretylium much greater than N-acetylprocainamide. The IC50 varied from 3-5 microM for clofilium to greater than 200 microM for N-acetylprocainamide. In contrast, only clofilium, a voltage-gated K(+)-channel blocker, was able to increase phosphatidylserine synthesis with an EC50 = 50 microM. The effect of clofilium on phosphatidylserine synthesis thus mimics the effect of three other K(+)-channel blockers, quinine, 4-aminopyridine and tetraethylammonium, suggesting close relationships between phosphatidylserine synthesis and K+ channel activity.

Imidazole antimycotics inhibitors of cytochrome P450 increase phosphatidylserine synthesis similarly to K(+)-channel blockers in Jurkat T cells.

The imidazole antimycotics, miconazole, econazole and triclomazole as well as alpha-naphtoflavone, known as powerful inhibitors of cytochrome P450 and previously recognized as K+ channel blockers are shown to be potent activators of the base exchange enzyme system responsible for the biosynthesis of phosphatidylserine in Jurkat T cells. The inhibition of CD3-induced Ca2+ influx by antimycotics but not by K+ channel blockers, demonstrated that the rise in phosphatidylserine synthesis caused by the two classes of drugs, was independent of Ca2+ influx in the cells. In addition, we show that the action of these drugs on phosphatidylserine synthesis was not mimicked by modifications of membrane potential. The regulation of both K+ channels and the base exchange enzyme system thus occurs through a similar (or common) pathway that is independent of Ca(2+)-influx and membrane potential.

CD95 (Fas/APO-1) induces an increased phosphatidylserine synthesis that precedes its externalization during programmed cell death.

CD95 (Fas, APO-1)-induced programmed cell death (apoptosis) in T cell lines is accompanied by a rapid flip-flop of phosphatidylserine (PtdSer). Externalization of this phospholipid has been previously recognized as one of the early detectable events of cells undergoing apoptosis. We show here that CD95 induces a rapid (detectable at time < 15 min), strong (2.5-fold) but transitory neosynthesis of PtdSer in the Jurkat cell line that precedes its externalization. PtdSer decarboxylation, a mitochondrial specific process, was strongly inhibited by CD95 suggesting that changes in mitochondrial activity take place in the early events of Fas-induced apoptosis and participate in the increased PtdSer synthesis observed. In cells undergoing apoptosis, newly synthesized PtdSer first exposed at the cell surface was in part shed with CD95-induced plasma membrane vesicles, a process that likely explains the transitory effect observed.

Effect of insulin on aminoisobutyric acid uptake by human non-rheumatoid and rheumatoid synovial cells.

The biological sensitivity of cultured non-rheumatoid human synovial cells (NRSCs) and rheumatoid synovial cells (RSCs) was examined in terms of the ability of insulin to stimulate the uptake of alpha-aminoisobutyrate (AIB). NRSCs, like numerous fibroblastic lines, were sensitive to physiological concentrations of the hormone: half-maximal stimulation was obtained with (4 X 10(-10) M) insulin, while maximum transport was found with a 60-90 min association time. On the contrary, although the basal transport was similar in RSCs, insulin was totally unable to accelerate AIB transport in these cells. Inflammatory processes lead to an insulin resistance which most likely involves a post-receptor step at the cellular level.

IL-1 beta, a strong mediator for glucose uptake by rheumatoid and non-rheumatoid cultured human synoviocytes.

Higher basal 2-deoxy-D-glucose uptake in rheumatoid synovial cells than in non-rheumatoid synovial cells, was found to be associated with an increased interleukin-1 beta (IL-1 beta) secretion (respectively 850 +/- 238 vs. 8.3 +/- 2.4 pg/24 h/10(5) cells, mean +/- S.E.M.). When exogenous human recombinant IL-1 beta was added to cultures, a marked stimulation of 2-deoxy-D-glucose uptake was performed by both human synovial cultured cells, in a time-dependent and dose-dependent manner (IL-1 beta 0-100 ng/ml). In non-rheumatoid synoviocytes, stimulation occurred 1-3 h following the addition of 1 ng/ml interleukin-1 beta and increased up to 24 hours (respectively +150% and +261.4% after 6 and 24 hours association time). Rheumatoid synovial cells were less sensitive to 1 ng/ml IL-1 beta (respectively +80% and +146.4%). IL-1 beta increased significantly the Vmax for 2-deoxy-D-glucose uptake by synovial cells, with no change in the Km. This effect was protein synthesis-dependent, and not secondary to prostaglandin E2 synthesis or cell growth. IL-1 beta possesses an important effect on glucose homeostasis in synovial cells, which could be indirect and/or regulated by the presence of natural inhibitors.

The protein tyrosine kinase p56(lck) regulates the serine-base exchange activity in Jurkat T cells.

Different classes of protein kinase inhibitors for protein kinase C, cAMP-dependent protein kinase or protein tyrosine kinases have been studied for their effect on phospholipid metabolism. The results show that among the compounds studied, only 4'-aminohydroxyflavone (AHF), previously described as a specific inhibitor of the protein tyrosine kinase p56(lck), markedly increased phosphatidylserine synthesis in Jurkat T cells. The biosyntheses of phosphatidylcholine and phosphatidylethanolamine were not affected. Also, the synthesis of phospholipids from tritium-labeled fatty acid as precursor was left unchanged by the p56(lck) inhibitor. The decreased phosphatidylserine synthesis induced when triggering the CD3-TCR complex was impaired by AHF, suggesting that p56(lck) could be implicated in the regulation of the serine-base exchange enzyme system. Direct evidence for the participation of p56(lck) in the regulation of the serine-base exchange enzyme system was obtained by using p56(lck)-deficient Jurkat cells (J.CaM 1.6) in which the basal base exchange activity was markedly increased and on the other hand AHF had no effect. In addition, transfection of J.Cam 1.6 cells with p56(lck)-cDNA allowed recovery of the AHF activity.

Plasma branched-chain keto acids in burn patients.

Plasma branched-chain keto acids (BCKA) and glucose-alanine cycle-related substances were measured in venous and arterial blood following burn injury. It was found that the three BCKA diminished with a minimum on day 7 while pyruvate increased. Alanine and glutamate + glutamine also decreased but plasma branched-chain amino acids (BCAA) did not vary. BCKA and gluconeogenic amino acids were liberated by peripheral tissues whereas BCAA were not. By analogy with the fate of alanine, a reduction in plasma BCKA associated with a high release by peripheral tissues might involve an increase in their hepatic metabolism. The BCKA would then give rise to ketone bodies used by the peripheral tissue. This step would complete the glucose-alanine cycle described by Cahill in hypercatabolic states where energy requirements are intense and similar to those found in burn injuries.

Alpha-foetoprotein and oestrogen metabolism. I. -Influence of alpha-foetoprotein on the metabolism of steroids by rat liver microsomes in vitro.

Rat alpha-foetoprotein (AFP) was shown to inhibit the formation of water soluble metabolities of oestrone and oestradiol by incubation with microsomes from rat liver in the presence of NADPH. The results support the proposal that in young animals the low activity of enzymes responsible of oestradiol metabolism may be due in part to the presence of AFP and not only to the low level of these enzymes.

Purification and characterization of an estrogen-binding peroxidase from human fetuses.

A peroxidase found under two forms with a molecular weight of 220,000 and 170,000 respectively, was purified from human fetuses. The purification procedure included ammonium sulfate precipitation, ion exchange chromatography, gel filtration and hydrophobic interaction chromatography. The purification factor approximated 400. These two forms of peroxidase were found to be immunologically identical as shown when utilizing immunodiffusion. They were able to bind estradiol in the presence of H2O2. This bond resisted to denaturation and solvent extraction therefore suggesting a covalent binding of estradiol to the enzyme.