Mechanism of mitogen-induced stimulation of glucose transport in human peripheral blood mononuclear cells. Evidence of an intracellular reserve pool of glucose carriers and their recruitment.

The present study examines the effects of phytohemagglutinin stimulation of a population of human (h) PBMC enriched in lymphocytes (hPBMC) on D-glucose displaceable cytochalasin B binding sites or medium-affinity sites (M-sites) in relation to glucose transport. Previously we have shown that M-sites are glucose transporters in hPBMC (Mookerjee, B.K., et al. 1981. J. Biol. Chem. 256:1290-1300). Equilibrium exchange of 3-O-methyl D-glucose in unstimulated cells revealed two populations with fast and slow flux rates. Phytohemagglutinin stimulates flux rates by converting part of the slow flux population to the fast flux population. M-sites occur in two distinct pools, one in plasma membrane and the other in microsomal fraction. Phytohemagglutinin treatment increases the plasma membrane pool size of M-sites with a concomitant reduction in the microsomal pool size without affecting the binding affinities or the total number of M-sites/cell. Data presented in this paper demonstrate that there are two pools of glucose transporters in these cells and phytohemagglutinin stimulation induces an energy-dependent net translocation of glucose transporters from an intracellular reserve pool to the plasma membrane, which accounts for greater than 60% of the increment in glucose transport.

Adrenergic mechanisms and the adenyl cyclase system in atopic dermatitis.

Patients with atopic dermatitis have abnormal autonomic responses of the arterioles, pilomotor smooth muscle, and sweat glands. Their lesions have been reported to contain increased amounts of the neurohumors, acetylcholine and norepinephrine, as well as increased activity of acetylcholinesterase and catechol-O-methyltransferase. In vitro studies of epidermis show that beta adrenergic agonists fail to evoke the normal inhibition of mitosis of basal cells of patients with atopic dermatitis. Epidermis removed not only from the lesions, but also from normal-appearing skin, responded abnormally. The increase in intracellular levels of cAMP after exposure to catecholamines was similar in normal and atopic epidermis. Lymphocytes and PMN leukocytes isolated from patients with atopic dermatitis show both a decreased physiologic response (glycogenolysis and inhibition of lysosome enzyme release) and a decreased rise in intracellular levels of cAMP upon incubation with beta agonists, but a normal response to PGE1. Cortisol increases the response of lymphocyte adenyl cyclase to both agonists and, in the case of the patients with atopic disease, more than overcomes the depressed response to beta agonists. Because the leukocytes respond normally to PGE1 and because others have reported normal activities of skin and adenyl cyclase, phosphodiesterase, and protein kinases, we conclude that the step responsible for the diminished beta adrenergic response lies antecedent to the catalytic site of adenyl cyclase.

Improvement in quality-of-life measures and stimulation of weight gain after treatment with megestrol acetate oral suspension in geriatric cachexia: results of a double-blind, placebo-controlled study.

BACKGROUND: Weight loss among older patients is a severe problem, associated with an increased incidence of infections, decubiti, and death. Megestrol acetate (MA) causes weight gain in cachectic cancer and AIDS patients, but its effects in older cachectic patients are unknown. OBJECTIVE: To compare the effects of MA oral suspension (O.S.), 800 mg/day, versus placebo on weight in geriatric nursing home patients with weight loss or low body weight. DESIGN: Twelve-week, randomized, double-blind, placebo-controlled trial with a 13-week follow-up period. SETTING: Veterans Administration Medical Center (VMAC) nursing home. PATIENTS: Nursing home patients with weight loss of > or =5% of usual body weight over the past 3 months, or body weight 20% below their ideal body weight. INTERVENTIONS: Patients were randomly assigned to receive placebo or MA 800 mg/day for 12 weeks and were then followed for 13 weeks off treatment. MEASUREMENTS: Primary outcome was measured by weight and appetite change. Secondary outcome measures included sense of well-being, enjoyment of life, change in depression scale, laboratory nutrition parameters, energy intake counts, body composition, and adverse events. RESULTS: At 12 weeks there were no significant differences in weight gain between treatment groups, whereas MA-treated patients reported significantly greater improvement in appetite, enjoyment of life, and well-being. Body composition was not statistically different between the two groups. At Week 25 (3 months after treatment), 61.9% of MA-treated patients had gained > or =1.82 kg (4 lbs) compared to 21.7% of placebo patients. CONCLUSIONS: In geriatric patients with weight loss or low body weight MA improves appetite and well-being after 12 weeks of treatment. During the 3 months of MA treatment, there was no statistically significant weight gain (> or =4 lbs). Three months after treatment, weight gain (> or =4 lbs) was significantly increased in MA-treated patients.

Effect of quercetin on human polymorphonuclear leukocyte lysosomal enzyme release and phospholipid metabolism.

Quercetin inhibited in a concentration-dependent manner the release of beta-glucuronidase from human polymorphonuclear leukocytes stimulated with zymosan-activated serum. 3H-arachidonic acid-prelabelled polymorphonuclear leukocytes released 3H-arachidonic acid upon stimulation with zymosan-activated serum and this was associated with a decrease of radioactivity in the phospholipid fraction as determined by thin layer chromatography. Quercetin inhibited the release of 3H-arachidonic acid. These observations suggest that the zymosan-activated serum stimulus activates phospholipase A2 and that phospholipase A2 is inhibited by quercetin. Thus, quercetin alters polymorphonuclear leukocyte phospholipid metabolism and responses to stimulation.

Regulation of beta-adrenergic response in human lymphocytes: agonist induced subsensitivity.

The concentration of intracellular cAMP in lymphocytes is regulated by isoproterenol and PGE1. Preincubation of lymphocytes with isoproterenol leads to a loss of the response to beta-adrenergic agents but not to PGE1. Preincubation of lymphocytes with PGE1, however, affects the sensitivities both to isoproterenol and PGE1. A decrease of beta-adrenergic receptors was found in cells preincubated with isoproterenol but not with PGE1. Part of the abnormalities associated with PGE1-preincubated cells can be restored by treating the cells with theophylline.

Virus exposure diminishes beta-adrenergic response in human leukocytes.

We used Ficoll-Hypaque isolated peripheral lymphocytes and PMNs to investigate the relationship between viral exposure and beta-adrenergic responses in target cells. Lymphocyte E-rosette formation with sheep red blood cells and PMN beta-glucuronidase release in response to opsonized zymosan particles are two cell activities regulated by beta-adrenergic agonists. After incubation with influenza or measles virus, the treated cells have decreased response to isoproterenol, a beta-adrenergic agonist. The in vitro viral exposure causes a decreased beta-adrenergic response in target cells.

Effects of histamine-sensitizing factor and cortisol on lymphocyte adenyl cyclase responses.

Levels of cyclic adenosime monophosphate (cAMP) in lymphocytes are regulated by beta-adrenergic agonists and PGE1. The effect of these agonists is potentiated by cortisol. Incubation of lymphocytes with histamine-sensitizing factor (HSF) leads to loss of response to epinephrine and PGE1. The response can be partially restored by cortisol. Incubation of lymphocytes with beta-adrenergic antagonists such as propranolol leads to the loss of beta-adrenergic agents but not PGE1. The inhibition by propranolol is not reversed by cortisol. These results suggest that the action of HSF and Bordetella pertussis vaccine is not mediated through the inhibition of beta-adrenergic receptors alone.

Effect of Aroclor 1254 on leukocyte glucose uptake.

Uptake of glucose in human leukocytes was estimated by measuring incorporation of 14C-labeled 2-deoxyglucose (2-DG) into the cells. Exposure of lymphocytes and monocytes, but not neutrophils, to Aroclor 1254 (10 microM) caused a decreased 2-DG uptake. This method of measuring glucose uptake may be useful for detecting potential polychlorinated biphenyl (PCB) target cells.

Absence of the effect of ephedrine on levels of cyclic adenosine monophosphate in human lymphocytes.

Concentrations of 10(-6) to 10(-3) M ephedrine did not increase cyclic adenosine monophosphate (cAMP) levels of normal human lymphocytes even in the presence of theophylline or cortisol, which enhance the response to isoproterenol or prostaglandin E1. Preincubation for 2 hr with ephedrine did not reduce the subsequent effect of isoproterenol, although preincubation with isoproterenol itself did. Therefore, ephedrine is not a direct beta-adrenergic agonist on human peripheral blood lymphocytes.

Decreased adrenergic responses in lymphocytes and granulocytes in atopic eczema.

The physiologic and cyclic adenosine monophosphate (cAMP) response to beta adrenergic stimulation in lymphocytes and granulocytes was examined in atopic eczema. These cells were isolated by Ficoll-Hypaque gradient from 10 patients with atopic eczema, and their responses were compared to 10 normal subjects. In eczema, basal concentrations of cAMP were normal in both lymphocytes and granulocytes. Lymphocyte cAMP response in eczema was decreased both to epinephrine (10-5 M) and to isoproterenol (10-5 M) but normal to prostaglandin E1 (PGE1). It was also noted that the glycogenolysis response to isoproterenol was significantly less at 10-5 M in eczema, but the fall in glycogen was normal with PGE (10-5 M and 10-7 M). The inhibition of lysosomal enzyme release from granulocytes after zymosan stimulation was significantly less (p less than 0.01) in eczema with all concentrations of isoproterenol tested. There was also a decrease in cyclic AMP response to isoproterenol in the polymorphonuclear leukocytes. PGE1 inhibited lysosomal enzyme release and stimulated cAMP normally. In eczema, both lymphocytes and polymorphonuclear leukocytes have a decreased beta adrenergic response.

Effects of DNP on rat thymocyte uptake of 2-deoxyglucose: effects of nutrients.

Rat thymocyte glucose transport activity was measured by the uptake of 3H-2-deoxyglucose. In the presence of 5mM glucose, DNP stimulated the uptake of 2-deoxyglucose. In the absence of glucose, DNP inhibited the uptake of 2-deoxyglucose. Both stimulatory and inhibitor effects of DNP were DNP concentration dependent. The incubation of thymocytes with nutrients which are metabolized through mitochondrial oxidation, such as beta-hydroxybutyrate, pyruvate, alanine and glutamine, did not support the stimulatory effects of DNP on 2-deoxyglucose uptake. The incubation of thymocytes with a nutrient which can support glycolysis, such as adenosine, supported the stimulatory effect of DNP on 2-deoxyglucose uptake. Iodoacetate, an inhibitor of glycolysis, inhibited 2-deoxyglucose uptake even in the presence of glucose. The present data suggested that the stimulatory effect of DNP on thymocyte 2-deoxyglucose uptake required intact glycolysis activity.

A direct radioimmunoassay for aldosterone in unextracted serum and plasma.

We describe a novel radioimmunoassay procedure for the direct estimation of aldosterone in unextracted plasma and serum samples, in which interfering binding proteins are digested by Proteinase K (Tritirachium alkaline proteinase, EC 3.4.21.14), a powerful proteolytic enzyme. Heating at 75 degrees C for 15 min inactivates the enzyme before radioimmunoassay. Alternatively, EDTA may be used to inactivate the enzyme. The antibody-bound fraction is then precipitated with polyethylene glycol and isolated by centrifugation. This easy method eliminates extraction and purification and gives accurate and reliable results. The total time required for 100 estimations, including counting time, is about 6 h.

Biochemical basis of aroclor 1254 and pesticide toxicity in vitro. 1. Effects on intracellular ATP concentration.

Aroclor 1254 and op'-DDT inhibit lymphocyte mitogenic response to PHA. We use petri dish purified lymphocytes for studying the biochemical basis of chemical toxicity. Aroclor 1254 and DDT decrease lymphocyte intracellular ATP concentration. The inhibitory effect on ATP production is due to the suppression of mitochondrial respiration as judged by decreased oxygen consumption. Lymphocyte glycolysis measured by lactate production is not inhibited by Aroclor 1254 to any significant extent. ATP is required for various biosynthetic reactions following mitogenic stimulation. The inhibition of mitochondrial respiration which leads to decreased ATP concentration may be responsible for Aroclor inhibition of lymphocyte mitogenic response to PHA.