Enhancement of IL-2-induced T cell proliferation by a novel factor(s) present in murine spleen dendritic cell-T cell culture supernatants

The mechanism(s) underlying the potent accessory cell function of dendritic cells (DC) remains unclear. The possibility was considered that a soluble factor(s) released during the interaction of DC and T cells might contribute to the potent T cell activating function of DC. Culture supernatants were generated from mixtures of murine spleen DC and periodate-treated spleen T cells and were examined for the presence of known cytokine activities and factors capable of enhancing T cell responsiveness to IL-2. Serum-free supernatants from 24 h DC-T cell co-cultures exhibited high levels of IL-2, detectable levels of IL-3, and negligible levels of IL-1, -4, -5, -6, and TNF. A factor(s) was also identified with an apparent Mr of 12.5 to 17.0 kDa, henceforth designated IL-2 enhancing factor (IL-2EF), which enhanced the IL-2-induced proliferation of murine thymocytes, CTLL, and HT-2 cells by approximately three- to fourfold. This enhancement was also observed in the presence of neutralizing antibodies to murine IL-1 alpha, -1 beta, -3, -4, -5, -6, granulocyte-macrophage (GM)-CSF, TNF, and IFN-gamma. However, IL-2EF failed to enhance: 1) the activity of IL-1, -3, -4, -5, or -6 on cells responsive to these cytokines; 2) IL-2-augmented, IL-5-induced BCL1 proliferation; and 3) either PHA- or Con A-stimulated thymocyte proliferation. Moreover, neither IFN-gamma nor GM-CSF exhibited IL-2EF activity. When DC and T cells were cultured separately (after an initial 12 h co-culture period), IL-2EF activity resided predominantly in the T cell-derived supernatants. These and other data indicate that IL-2EF, a heat-labile T cell-derived 12.5 to 17.0 kDa protein, is distinct from IL-1 alpha, -1 beta, -2, -3, -4, -5, -6, TNF, IFN-gamma, GM-CSF, and previously described factors that co-stimulate thymocyte proliferation in the presence of Con A or PHA. It is suggested that IL-2EF functions to specifically enhance IL-2-driven T cell proliferation and contributes to the potent activation of T cells induced by DC.     

Contraceptive steroids increase cholesterol in bile: mechanisms of action

Contraceptive steroids increase the risk of acquiring cholesterol gallstones. The factors responsible include an increase in cholesterol saturation of bile and an increase in rate of secretion of cholesterol into bile. The goal of this study was to investigate the mechanism(s) of these increases in biliary cholesterol. During the use of contraceptive steroids, cholesterol saturation of gallbladder bile and the amount of cholesterol secreted per mole of bile acid increased (P less than 0.05 and P less than 0.02, respectively). Cholesterol absorption, cholesterol synthesis, chylomicron remnant clearance, and the concentration of plasma and lipoprotein lipids were not altered by contraceptive steroids. Despite this apparent lack of effect, important correlations were present during steroid use. LDL (low density lipoprotein) cholesterol increased as dietary cholesterol increased (r = 0.58, P less than 0.025). Cholesterol synthesis correlated directly with VLDL cholesterol concentration (r = 0.64, P less than 0.01), biliary cholesterol secretion (r = 0.68, P less than 0.01) and with molar percent cholesterol in bile (r = 0.49, P = 0.06). Chylomicron remnant clearance also correlated with cholesterol secretion (r = 0.85, P less than 0.001). As either remnant uptake or synthesis increased, the effect of the other source of hepatic cholesterol on biliary cholesterol secretion diminished. These relationships were not observed in the same subjects when they were not taking the hormones. The findings suggest that both newly synthesized and dietary cholesterol contribute to the cholesterol secreted in bile. This is consistent with the hypothesis that cholesterol for secretion into bile and VLDL is derived from a common metabolic pool of free cholesterol. It is proposed that contraceptive steroids exert their effect on biliary cholesterol by increasing cholesterol entering the pool and/or by inhibiting hepatic ACAT (acylcoenzyme A:cholesterol acyltransferase) activity, a known effect of progesterone, so that an increase in free cholesterol entering the pool leads to an increase in output.     

Volatile production by Aspergillus versicolor as a possible cause of odor in houses affected by fungi

Aspergillus versicolor, which has been isolated from several mould affected houses was shown by laboratory studies under axenic conditions to produce several specific volatile compounds on water agar. These compounds were not produced by the fungus when grown on a rich malt extract medium or on several synthetic media. The volatile compounds were analysed by GC-MS. The majority of the peaks represented aromatic compounds. A non-aromatic substance which previously has been revealed by us among prominent volatile compounds sampled from building materials from so-called mould houses was produced only on water agar. According to a comparison with the mass spectrum and retention time of pure reference compound this compound is ethylhexanol, a compound not previously reported as a mould metabolite. The presence of this compound was correlated with pungent odor in the cultures.     

Interaction of workplace demands and cardiovascular reactivity in progression of carotid atherosclerosis: population based study.

OBJECTIVE: To examine the combined influence of workplace demands and changes in blood pressure induced by stress on the progression of carotid atherosclerosis. DESIGN: Population based follow up study of unestablished as well as traditional risk factors for carotid atherosclerosis, ischaemic heart disease, and other outcomes. SETTING: Eastern Finland. SUBJECTS: 591 men aged 42-60 who were fully employed at baseline and had complete data on the measures of carotid atherosclerosis, job demands, blood pressure reactivity, and covariates. MAIN OUTCOME MEASURES: Change in ultrasonographically assessed intima-media thickness of the right and left common carotid arteries from baseline to 4 year follow up. RESULTS: Significant interactions between workplace demands and stress induced reactivity were observed for all measures of progression (P < 0.04). Men with large changes in systolic blood pressure (20 mm Hg or greater) in anticipation of a maximal exercise test and with high job demands had 10-40% greater progression of mean (0.138 v 0.123 mm) and maximum (0.320 v 0.261 mm) intima-media thickness and plaque height (0.347 v 0.264) than men who were less reactive and had fewer job demands. Similar results were obtained after excluding men with prevalent ischaemic heart disease at baseline. Findings were strongest among men with at least 20% stenosis or non-stenotic plaque at baseline. In this subgroup reactive men with high job demands had more than 46% greater atherosclerotic progression than the others. Adjustment for atherosclerotic risk factors did not alter the results. CONCLUSIONS: Men who showed stress induced blood pressure reactivity and who reported high job demands experienced the greatest atherosclerotic progression, showing the association between dispositional risk characteristics and contextual determinants of disease and suggesting that behaviourally evoked cardiovascular reactivity may have a role in atherogenesis.     

Proton-induced membrane fusion role of phospholipid composition and protein-mediated intermembrane contact

Glycolipid-phospholipid vesicles containing phosphatidate and phosphatidylethanolamine were found to undergo proton-induced fusion upon acidification of the suspending medium from pH 7.4 to pH 6.5 or lower, as determined by an assay for lipid intermixing based on fluorescence resonance energy transfer. Lectinmediated contact between the vesicles was required for fusion. Incorporation of phosphatidylcholine in the vesicles inhibited proton-induced fusion. Vesicles in which phosphatidate was replaced by phosphatidylserine underwent fusion only when pH was reduced below 4.5, while no significant fusion occured (pH ? 3.5) when the anionic phospholipid was phosphatidylinositol. It is suggested that partial protonation of the polar headgroup of phosphatidate and phosphatidylserine, respectively, causes a sufficient reduction in the polarity and hydration of the vesicle surface to trigger fusion at sites of intermembrane contact.     

Effects of specific inhibition of sterol biosynthesis on the uptake and utilization of low density lipoprotein cholesterol by HepG2 cells.

Treatment of HepG2 cells in lipoprotein-deficient media with 4,4,10 beta-trimethyl-trans-decal-3 beta-ol (TMD) abolished the incorporation of [3H]acetate into cholesterol with concomitant accumulation of squalene 2,3(S)-oxide and squalene 2,3(S):22(S),23-dioxide, indicating a specific inhibition of oxidosqualene cyclase. The activity of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase was affected in a biphasic manner, being inhibited by 30% at low concentrations of TMD and stimulated by 30% at concentrations that completely shut down oxidosqualene cyclase. Treatment with TMD (greater than 20 micrograms/ml) doubled the specific binding and internalization of low density lipoproteins (LDL) and also enhanced their degradation to a degree comparable to that produced by lovastatin, a well-known inhibitor of HMG-CoA reductase. The enhanced binding of LDL to HepG2 cells appeared to occur as a result of an increase in the number of binding sites with no change in their binding affinity for the lipoprotein. At concentrations that completely inhibited cholesterol biosynthesis, TMD did not affect the ability of LDL-derived cholesterol to stimulate cholesterol esterification by seven- to tenfold or to stimulate bile acid secretion to a lesser degree. However, TMD treatment inhibited overall bile acid secretion by 75-85%. The compound had no inhibitory effect on the rates of secretion of either apolipoprotein B or of cholesterol by HepG2 cells into the culture medium. These data demonstrate that a specific inhibition of the sterol branch of isoprenoid biosynthetic pathway in hepatic cells by TMD is sufficient to induce the expression of LDL receptors and that the cholesterol delivered by LDL is available for normal metabolic purposes of the cell.     

Effect of anti-pilus antisera on virulence of variants of Neisseria gonorrhoeae for cultured epithelial cells

Variants of Neisseria gonorrhoeae P9 possessing a, gamma or delta pili were shown to vary in their toxicity and virulence for human epithelial cells. Studies with antisera raised against purified pili showed that attachment and virulence were reduced to a significant degree in the presence of antisera to homologous pili. Heterologous antisera, while capable of agglutinating whole organisms, were largely ineffective in reducing attachment and cytotoxicity. Using an enzyme-linked immunosorbent assay (ELISA) system, the cross-reactivity between pili and heterologous antisera was estimated to be no more than 10-20%.     

Failure of acetylmethadol in treatment of narcotic addicts due to nonpharmacologic factors.

Acetylmethadol, a new narcotic substitute, has a longer duration of action than methadone. Seventeen subjects, former heroin users currently under methadone treatment, entered a study of the toxicity and efficacy of this drug. Only nine subjects completed the assessment phase of the study and began the acetylmethadol phase, and only one completed the 8-week study phase. Hence, no conclusions can be drawn about acetylmethadol''s efficacy. The high attrition rate was unrelated to pharmacologic factors; the subjects were concerned that if this drug was effective there would be no methadone to take home and hence no opportunity to trade, sell or "play with" (that is, combine with other drugs) the latter. This study emphasizes the difficulty in determining the efficacy of specific drug treatments for opiate-dependent patients.     

Juvenile hormone regulation of CYCLIC AMP and cAMP phosphodiesterase activity in Oncopeltus fasciatus.

The fifth instar large milkweed bug, Oncopeltus fasciatus, exhibits fluctuation in both cyclic AMP titre and cyclic AMP phosphodiesterase activity. Cyclic AMP titres are lowest very early in the instar, increase rapidly to peak at 14% of the instar, and decrease throughout the remainder of the instar. The juvenile hormone (JH) mimic (Law-Williams mixture) treated bugs exhibit a similar pattern for cyclic AMP titres except the peak titre is at 20% of the instar. Phosphodiesterase activity is the greatest at 5% of the instar, decreases during the middle of the instar, and increases again at approximately 90% of the instar. One day corresponds to 14% of the instar in these bugs. Treatment with JH shifts the period of greatest activity to 11% of the instar. One day corresponds to 20% of the instar for JH treated bugs. It is proposed that these findings are due to a stimulatory effect of JH on phosphodiesterase activity.