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Biomedical subjects

D Brohee

Publications and source records attributed to D Brohee.

At least 19 recordsLinked to original sources
PubMed1995

[Comparison of 2 techniques for measuring lymphocyte proliferation: tritiated methyl-thymidine incorporation and propidium iodide fluorometry].

In vitro lymphocyte mitogenic stimulation by phytohemagglutinin A was determined in 20 subjects, comparing tritiated thymidine incorporation and nuclear propidium iodide fluorescence. Unexpectedly, no correlation could be found between the two measures. The pitfalls of both methods are reviewed and discussed. The inability to validate one test by the other restricts the interpretation of the results obtained with one method and prevents their generalization. Without another gold-standard at the present time, specific and limited method-dependent norms should be defined.

Fluorometry↗
PubMed1994

Thiobarbiturate and fructosamine assays: significance and interest of the borohydride blank.

The acute-phase reaction (APR) induces the production by the liver of short-lived glycoproteins. The carbohydrate moiety of these proteins is thought to interfere with the thiobarbiturate (TBA) and nitroblue tetrazolium colorimetric tests which are used for assaying non-enzymatic glycosylation (NEG) of serum proteins. The aim of the present study was to assess the effect of the APR on the specificity of the colorimetric tests in non-diabetic and diabetic subjects. A positive correlation was found between C-reactive protein (CRP), an APR glycoprotein, and non-specific TBA reactivity as determined after borohydride reduction (BH4-resistant TBA, BR-TBA), both in non-diabetics (r = 0.61; P < 0.01) and diabetics (r = 0.68; P < 0.01). The BH4-sensitive specific TBA (SP-TBA) was not influenced by glycoproteins, and its increase in diabetics was correlated with the nitroblue tetrazolium assay (r = 0.89; P < 0.01). An independent effect of diabetes and APR on non-specific TBA was also demonstrated, suggesting an effect of hyperglycaemia on both protein glycation and glycosylation. TBA with borohydride reduction is an attractive tool for the study of complex glycoproteins in diabetes.

Acute-Phase Reaction↗
PubMed1992

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.

Adrenal Cortex Diseases↗
PubMed1991

Changing pattern of CD5+ CD20+ double positive lymphocytes with ageing and cytotoxic chemotherapy.

In this cross-sectional clinical study, it was found that two subtypes of CD5+ B-lymphocytes existed either with CD5-high and CD20-low or CD5-low and CD20-high expression, as determined by dual fluorescence analysis with fluorochrome-labeled monoclonal antibodies on a FACScan flowcytometer. In the normal healthy subjects (n = 20), the CD20 positive cells could be broken down into 3 subsets: CD5(2+) CD20+, 25.4 +/- 3.0% (mean +/- S.E.M.), CD5+ CD20(2+), 18.4 +/- 2.4% and CD5- CD20(2+), 56.2 +/- 2.7%. Similar values were observed in a group of patients (n = 29) suffering from a wide variety of benign or untreated malignant disorders. The CD5(2+) CD20+ subset was typically related to age (Spearman coefficient of correlation rho = 0.77, P less than 0.001 in healthy subjects and rho = 0.46, P = 0.02 in pathological cases). The CD5+ CD20(2+) subpopulation was a salient feature of newborns and little infants (n = 6, 75.4 +/- 2.4%, P less than 0.01). The CD5- CD20(2+) subset was characteristically depressed in patients treated with cytotoxics (n = 21, 41.2 +/- 3.6%, P = 0.001). As far as cytotoxic chemotherapy may represent a model of accelerated ageing, it is worth noting that, in patients treated with cytotoxics, the CD5 CD20 pattern was frequently disturbed in a hyperyoung or hyperaged picture. That age and cytotoxics can affect CD5 expression on CD20+ lymphocytes, suggests some specific B-dysregulation and should be put together with the known emergence of autoantibodies, paraproteinemias and lympho-plasmocytic tumors with age and chemotherapy.

Adult↗
PubMed1990

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.

Acute-Phase Proteins↗
PubMed1989

[The gold standard and optimalization of diagnostic choice: the pulmonary nodule and transthoracic pulmonary puncture-biopsy].

In this review of the literature, it is emphasized that the published results about the transthoracic pulmonary needle biopsy (TPNB) cannot be readily evaluated due to the inconsistency of the reference tests, the methods and the investigated subjects. Gold-standards for evaluation of lung tumors have been described and are recalled. The limits of the TPNB are pointed out in the diagnosis of solitary pulmonary nodules and benign lesions. In a bayesian approach, it is shown that the TPNB is only useful in confirming an a-priori diagnosis of cancer.

Bayes Theorem↗
PubMed1988

Hepatic telangiectasia and cirrhosis.

In a woman with hereditary hemorrhagic telangiectasia (HHT) (Osler-Weber-Rendu disease) who died of fulminant hepatitis B, autopsy revealed cirrhosis of the liver and diffuse hepatic telangiectasia. Her daughter and grandson also suffered from the hepatic involvement of HHT. Sufficient laboratory investigations were available to exclude known causes of cirrhosis. We review the relationship between Osler-Weber-Rendu disease and liver cirrhosis or fibrosis.

Aged↗
PubMed1987

Effect of age, sex and health status on human lymphocyte functions: demonstration of a sex-related defect in suppressor cell function.

The mitogenic response of human lymphocytes and the short-lived suppressor cell function on concanavalin A response were studied as dependent variables in 194 patients using multiple regression analysis, with health status and sex as dummy variables, and age as an explicative one. This study confirms a decrease of the lymphocyte functional response to mitogens with aging. A sex-related defect in suppressor cell function is put forward in females independently of age. An inverse linear relationship is found between the functional response to pokeweed mitogen (T and B mitogen) and suppressor cell function in males but not in females. No such relationship is found with the pure T mitogens (Con A and phytohemagglutinin-A). The present study suggests that a defect in short-lived suppressor cells can play some role in the greater incidence and prevalence of autoimmune diseases in women while the depressed lymphocyte response of old people cannot be explained by modifications of the activity of these suppressor cells.

Adult↗
PubMed1983

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.

Aged↗
PubMed1982

Increased stability of E-rosettes and restricted capping of sheep erythrocytes by lymphocytes of aged humans.

The processes of E-rosette dissociation and sheep red blood cell (SRBC) capping provide simple assays for studying age-related changes in membrane dynamics of T-lymphocytes. After incubation at 4 degrees C, no significant difference is observed between young-adult and elderly subjects, either in the number of rosette-forming-cells (E-RFC) or in the distribution of SRBC at the lymphocyte surface. However, when the E-RFC are incubated at 22 or 37 degrees C after resuspension, the rosettes disintegrate to a larger extent forming fewer morula-like structures and more caps in young donors. An inverse relationship is noted between the number of E-RFC and the percentage of capping cells, suggesting a role for the lateral movement of the SRBC receptors in the dissociation process. In the elderly, rosette disintegration seems to be related only to the random release of SRBC. It is speculated that this increased stability of the E-rosettes represents some locking of the T-lymphocyte membrane receptors, which could alter the transduction of cell-cell signals.

Adult↗
PubMed1982

E rosette dissociation: evidence for a role of the cytoskeleton.

When put into 37 degrees C incubation, the E rosettes dissociate spontaneously and the sheep erythrocytes (SRBC) form caps at one pole of the lymphocytes. This process is associated with changes in cell morphology such as uropod formation or membrane budding. The disintegration of E rosettes and the capping of SRBC can be retarded by addition of cytochalasin B plus colchicine, chlorpromazine or sodium azide. These findings suggest a pivotal role of the cytoskeleton in the dissociation process of E rosettes. However, other mechanisms of disintegration are to be considered since none of the drugs can prevent the dissociation of E rosette entirely.

Adolescent↗
PubMed1981

Early biochemical events associated with lymphocyte activation in ageing. I. Evidence that Ca2+ dependent processes induced by PHA are impaired.

The requirement for Ca2+, a divalent ion which plays a fundamental role in cell activation, has been analysed in cultures of PHA-stimulated human peripheral blood lymphocytes (PHA-PBL) from adult (range: 20-35 years) and old (over 70 years) subjects. For this purpose, increasing concentrations of Ca2+ chelators (EGTA and EDTA) were added to cultures in order to compare the effect of progressive extracellular Ca2+ (Ca2+EC) depletion on [3H]-Tdr incorporation by PHA-PBL. Kinetic analysis showed that Ca2+EC requirement was restricted to the first 24 h after culture initiation. At optimal doses of PHA, the PHA-PBL from old subjects were more sensitive than those from adult subjects to increasing concentrations of both chelators. They also required larger amounts of Ca2+ supplements to restore their normal response after total inhibition by EGTA. Furthermore, the PHA-PBL from the elderly were hypersensitive to verapamil (Isoptin), a drug which instigates a reversible inhibition of Ca2+-dependent processes associated with lymphocyte transformation, by a quite similar reaction to that induced by chelators. We conclude that the Ca2+-dependent processes in lymphocyte activation are impaired with ageing. Following further experiments and recent work suggesting that lymphocytes need more than one signal to proliferate, the authors speculate on a deficiency of a late activation signal requiring cell-cell interactions in the elderly.

Adult↗