Dany Brohée

Effect of Vitamin C Supplements on Cell-Mediated Immunity in Old People

Both ageing and vitamin C (VC) deficiency result in immune defect. Since low serum and tissue levels of VC are found in the elderly, we have in a placebo-controlled study, tested the effect of VC supplements (500 mg/day i.m. for 1 month) on various immune parameters. Indeed, VC enhances the proliferative response of T lymphocytes in vitro, and the tuberculin skin hypersensitivity in vivo. Neither the serum concentrations of IgA, IgG and IgM, nor the proportion of E-rosette-forming cells were modified. No significant change was observed in the placebo-treated group.

Sleep apnoea-hypopnoea index is an independent predictor of high-sensitivity C-reactive protein elevation.

Background: Recent reports have identified the apnoea and hypopnoea index (AHI) as an additional independent risk factor for cardiovascular morbidity and mortality. However, several studies reported contradictory results about the association between the serum C-reactive protein (CRP) level and the severity of apnoea. Objective: The purpose of this work is to study this association in patients referred to the sleep laboratory for clinical suspicion of sleep apnoea and presenting a wide range of AHI. Methods: Forty-nine consecutive patients were included in the study. The SigmaStat® software package (Jandle Scientific) was used. Multilinear regression analysis was tested using a stepwise backward selection of the explicative variables. The clinical characteristics (diabetes, hypertension, smoking habits, gender) were treated as dichotomous variables, while all other data (age, BMI, lipids, white blood cells) were continuous ones; high-sensitivity (hs)-CRP was the dependent variable. Results: In univariate analysis, AHI was correlated to hs-CRP: R = 0.43, p = 0.002. In multivariate analyses, we found an independent association between the AHI, adjusted for classical cardiovascular risk factors, and hs-CRP. Conclusion: In a sample of 49 patients, referred to the sleep laboratory for suspicion of sleep apnoea in routine practice, we observed an independent association between the AHI and hs-CRP.

Leukocyte and lymphocyte subsets after a short pharmacological stress by intravenous epinephrine and hydrocortisone in healthy humans.

Nine healthy volunteers received epinephrine and hydrocortisone intravenously in order to assess the typical acute response to a brief stress, of leukocyte and lymphocyte subsets, acute phase reactants and lymphocyte reactivity to T and B mitogens. At 10 min., all leukocyte subsets were increased, especially mononuclear cells. At 1 hour, moderate lymphopenia and monocytopenia occurred. At 6 hours, neutrophilia and eosinopenia were observed. During the lymphocytic early wave, all the lymphocyte subset counts increased, particularly T-suppressive/cytotoxic and natural killer cells. As a consequence, the percentage of T cells decreased and the CD4/CD8 ratio fell. No changes in acute phase reactants occurred over the 24 hours of the study. All leukocyte and lymphocyte subsets were normalized and mitogen reactivity was unchanged 24 hours after the stress. These typical shifts in leukocyte subsets could probe the adrenocortical and medullary response to an environmental stressor.

Sleep restriction increases white blood cells, mainly neutrophil count, in young healthy men: A pilot study

Objectives: This study examines the effects of sleep restricted to four hours for three consecutive nights on blood parameters, known to be associated with cardiovascular risk, in young healthy men. Material and methods: Eight young healthy men (age 24.5 ± 3.3 years) were studied in the sleep restricted group. Nine young healthy men (age 24 ± 2 years) were included in the control group and spent the days and nights in the sleep lab, while sleeping eight hours/night. One baseline night was followed by three nights of sleep restriction to four hours and by one recovery night of eight hours. Blood samplings were performed after the baseline night and after the third night of sleep restriction or without restriction for the control group. Results: A significant increase in white blood cells (WBC) (5.79 ± 1.05 vs. 6.89 ± 1.31 103 cell/μl, p = 0.03), and neutrophils (3.17 ± 0.69 vs 4.24 ± 0.97 103 cell/μl, p = 0.01) was observed after the third night of sleep restriction. Other blood parameters were not affected. No significant variation was observed in the control group. Conclusion: Sleep restriction affected WBC count, mainly neutrophils, considered as risk factor for cardiovascular disease. Stress induced by the short term sleep restriction could be involved in this observation.

Lymphocyte activation in human ageing: V. Acquisition of response to T cell growth factor and production of growth factors by mitogen-stimulated lymphocytes.

In order to ascertain why the T cell proliferative response declines with ageing, the age-related quality of the interleukin II (Il-2)-mediated signal during lymphocyte activation was investigated in mitogen-stimulated peripheral blood mononuclear cells (PBMC) from old (over 70 years) and adult (20-40 years) subjects. Both the Il-2 properties of supernatants produced by phytohaemagglutinin (PHA)-stimulated PBMC on Il-2 sensitive cells and the PHA-induced transformation in Il-2 sensitive T cells were decreased in the old subjects. Supplements with human Il-2 enhanced the DNA synthesis by PHA-, concanavalin-A-, or pokeweed-mitogen-activated lymphocytes in the two groups of subjects. The addition of Il-2 to old cultures restored a response similar to that observed in adults cells cultured without exogenous Il-2. The similarity of the dose-response curves to interleukin II indicated the unaltered affinity of the specific membrane receptors to the humoral factors. These findings strongly suggest that the immune deficiency commonly found in the elderly results principally from a selective alteration of the hormonal step of lymphocyte activation.

Temporal dissociation between myeloperoxidase (MPO)-modified LDL and MPO elevations during chronic sleep restriction and recovery in healthy young men.

Objectives Many studies have evaluated the ways in which sleep disturbances may influence inflammation and the possible links of this effect to cardiovascular risk. Our objective was to investigate the effects of chronic sleep restriction and recovery on several blood cardiovascular biomarkers. Methods and Results Nine healthy male non-smokers, aged 22–29 years, were admitted to the Sleep Laboratory for 11 days and nights under continuous electroencephalogram polysomnography. The study consisted of three baseline nights of 8 hours sleep (from 11 pm to 7 am), five sleep-restricted nights, during which sleep was allowed only between 1 am and 6 am, and three recovery nights of 8 hours sleep (11 pm to 7 am). Myeloperoxidase-modified low-density lipoprotein levels increased during the sleep-restricted period indicating an oxidative stress. A significant increase in the quantity of slow-wave sleep was measured during the first recovery night. After this first recovery night, insulin-like growth factor-1 levels increased and myeloperoxidase concentration peaked. Conclusions We observed for the first time that sleep restriction and the recovery process are associated with differential changes in blood biomarkers of cardiovascular disease.

Relationship between CRP and hypofibrinolysis: Is this a possible mechanism to explain the association between CRP and outcome in critically ill patients?

Background-Endothelial cell dysfunction may be implicated in the development of multiple organ failure (MOF) by a number of mechanisms. Among these, altered fibrinolysis promotes fibrin deposition, which may create microvascular alterations during inflammation. Elevated concentrations of C-reactive protein (CRP), especially when these persist over time, are correlated with an increased risk of MOF and death. CRP may inhibit fibrinolysis by inducing plasminogen activator inhibitor-1 (PAI-1) release from human aortic endothelial cells. Moreover, the administration of recombinant CRP in volunteers may increase circulating PAI-1 levels.In this study, we tested the hypothesis that CRP is associated with hypofibrinolysis in intensive care patients with and without sepsis.Methods-We studied the association of inflammation and abnormal fibrinolysis in intensive care unit (ICU) patients with (n = 11) and without (n = 21) sepsis. The inflammatory response was assessed by serum concentration of C-reactive protein (CRP), a marker of the acute phase reaction, which increase rapidly in the inflammatory response, and the plasma fibrinolytic capacity was evaluated by the Euglobulin Clot Lysis Time (ECLT), determined by a new semi-automatic method.Results-ECLT was significantly higher in septic than non-septic patients (1104 ± 439 vs 665 ± 275 min; p = 0.002) and was significantly correlated with CRP concentration (R2 = 0.45; p < 0.001). In a multivariate analysis, CRP was the strongest predictor of ECLT (R2 = 0.51, F = 25.6, p < 0.001). In addition, the overall ICU length of stay was significantly correlated with CRP (R2 = 0.264, p = 0.003) and ECLT (R2 = 0.259, p = 0.003).Conclusion-In critically ill patients a significant correlation thus exists between plasma fibrinolytic capacity and serum CRP levels. Our data were obtained in the first 24 hours of ICU admission or of sepsis, thus, the relation between CRP and hypofibrinolysis appeared very quickly. This finding is compatible with a link between inflammation and abnormal fibrinolysis, and may explain the negative prognostic value of CRP in critically ill patients.

Neuraminidase alters red blood cells in sepsis.

Objective: To investigate the influence of neuraminidase, an enzyme that cleaves sialic acid from the red blood cell (RBC) membrane, on RBC shape and biochemistry in critically ill patients. Design: Prospective, observational study and in vitro laboratory study. Setting: A 31-bed medico-surgical department of intensive care and a university-affiliated cell biology laboratory. Subjects: Acutely ill patients with and without sepsis and healthy volunteers. Interventions: Blood sampling in volunteers. Measurements and Main Results: Neuraminidase activity was measured using a fluorescent assay. RBC shape was assessed by the second coefficient of dissymmetry of Pearson using a flow cytometry technique at 25°C. Intraerythrocytic 2,3-diphosphoglycerate and lactate contents were also measured. Neuraminidase activity was significantly higher in septic patients compared with nonseptic patients and healthy volunteers (5.42 [4.85–6.00] vs. 4.53 [4.23–5.23] and 1.26 [0.83–1.83] mU/mL; all p < 0.05). Neuraminidase treatment modified the RBC shape in vitro in a dose–response fashion, and most of these alterations were present after 10 hours of incubation. Incubation of RBCs with phosphatidylinositol phospholipase C modified RBC shape and increased sialic acid concentrations in the supernatant, suggesting a leakage of neuraminidase from the RBC membrane. Alterations in shape were associated with increased 2,3-diphosphoglycerate (0.46 ± 0.25 vs. 0.19 ± 0.05 &mgr;mol/mL; p = 0.006) and lactate content (0.81 ± 0.07 vs. 0.66 ± 0.05 mmoL/L; p = 0.002). Conclusions: In sepsis, desialylation under the influence of increased neuraminidase activity may contribute to the alterations in RBC rheology. Inhibition of neuraminidase may represent a new therapeutic option to ameliorate RBC rheology and perhaps oxygen delivery to the cells.

Lymphocyte subsets in major depressive patients. Influence of anxiety and corticoadrenal overdrive.

We studied 26 inpatients (17 females; mean age +/- SD: 41.2 +/- 14.3 years) who met the DSM III criteria for a major depressive episode and had a mean (+/- SD) Hamilton Depression Score of 19.3 +/- 8.0. All patients were drug free and medically healthy at the time of experimentation. We found a significant correlation between the CD4/CD8 ratio and the Hamilton Anxiety Score (r = 0.57, p less than 0.005). When splitting our sample in dexamethasone suppression test suppressors (DST-S) and nonsuppressors (DST-NS), this relationship appeared only in DST-NS (DST-NS: r = 0.81, p less than 0.005; DST-S: r = 0.20, p = NS). These results are discussed in terms of heterogeneity among major depressive disorders and possible relationships between catecholaminergic activity and the immune system.

Nifedipine-induced hyporeactivity in delayed hypersensitivity skin tests

Four patients and three healthy volunteers were submitted to delayed hypersensitivity skin tests to candidin, tuberculin, streptokinase/streptodornase (SK/SD) and mumps antigen before and after a 1 week treatment with nifedipine 10 mg q. 8h. A decrease in the scores of induration and erythema was observed, especially in response to SK/SD antigen challenge. We conclude that nifedipine may induce an anergy status in delayed hypersensitivity skin tests.