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Biomedical subjects

G Dupuis

Publications and source records attributed to G Dupuis.

At least 37 records · Page 2Linked to original sources
PubMed1999

Long term vascular complications of Coxiella burnetii infection in Switzerland: cohort study.

OBJECTIVE: To evaluate the range of long term vascular manifestations of Coxiella burnetii infection. DESIGN: Cohort study in Switzerland of people affected in 1983 by the largest reported outbreak of Q fever and who were followed up 12 years later. Follow up information about possible vascular disease and endocarditis was obtained through a mailed questionnaire and death certificates. SETTING: Val de Bagnes, a rural Alpine valley in Switzerland. PARTICIPANTS: 2044 (87%) of 2355 people who had serum testing for Coxiella burnetii infection in 1983: 1247 were classed as not having been infected, 411 were classed as having been acutely infected, and 386 were classed as having been infected before 1983. MAIN OUTCOME MEASURES: Relative risk controlled for age and sex and 12 year risk of vascular diseases and endocarditis among infected participants as compared with those who had never been infected. RESULTS: The 12 year risk of endocarditis or venous thromboembolic disease was not increased among those who had been acutely infected. The 12 year risk of arterial disease was significantly higher among those who had been acutely infected (7%) as compared with those who had never been infected (4%) (relative risk 2.2, 95% confidence interval 1.4 to 3.6). Specifically, there was an increased risk of developing a cerebrovascular accident (relative risk 3.7, 1.6 to 8.4) and cardiac ischaemia (relative risk 1.9, 1.04 to 3.4). 12 year mortality was significantly higher among the 411 people who had been acutely infected in 1983 (9.7%; age adjusted relative risk 1.8, 1.2 to 2.6) when compared with the 1247 participants who had remained serologically negative in 1983 (7.0%). CONCLUSIONS: Coxiella burnetii infection may cause long term complications including vascular disease.

Adult↗
PubMed1999

Age-related impairment of p56lck and ZAP-70 activities in human T lymphocytes activated through the TcR/CD3 complex.

Cellular immune responses decrease with aging. Lymphocytes of aged individuals do not perform as well as cells from young subjects in a number of in vitro assays including cell proliferation, cytokine production, and protection against apoptosis. Here, we have tested the hypothesis that a decrease in T cell responses in tymphocytes from elderly subjects could parallel a decrease in the activity of protein tyrosine kinases (PTK) associated with signal transduction in T lymphocytes. We report that anti-CD3-triggered T lymphocyte proliferation was significantly decreased in T lymphocytes from elderly subjects, but the decrease was not due to an alteration of the percentage or mean fluorescence intensities of CD3, CD4, and CD45. Of significance, the activities of p56lck and ZAP-70 in vitro were significantly decreased in T lymphocytes from elderly subjects compared to young individuals. However, the level of expression of the two kinases did not change with aging. The activity of p59fyn did not show changes with aging, suggesting that p59fyn did not compensate for the decreased activity of p56lck. We also found that the extent of tyrosine phosphorylation of the adaptor protein p95vav was similar in activated T lymphocytes from elderly and young subjects. Our results suggest that the altered cellular immune responses observed in T lymphocytes with aging may be the result, at least in part, of an alteration in early events associated with signal transduction through the TcR/CD3 complex that translates into decreased activities of p56lck and ZAP-70. Impairment in the activities of these twokey components of T cell signaling may contribute to reduced immune functions associated with aging.

Adult↗
PubMed1998

The sensitivity of the human Kv1.3 (hKv1.3) lymphocyte K+ channel to regulation by PKA and PKC is partially lost in HEK 293 host cells.

cDNA encoding the full-length hKv1.3 lymphocyte channel and a C-terminal truncated (delta 459-523) form that lacks the putative PKA Ser468 phosphorylation site were stably transfected in human embryonic kidney (HEK) 293 cells. Immunostaining of the transfected cells revealed a distribution at the plasma membrane that was uniform in the case of the full-length channel whereas clustering was observed in the case of the truncated channel. Some straining within the cell cytoplasm was found in both instances, suggesting an active process of biosynthesis. Analyses of the K+ current by the patch-clamp technique in the whole cell configuration showed that depolarizing steps to 40 mV from a holding potential (HP) of -80 mV elicited an outward current of 2 to 10 nA. The current threshold was positive to -40 mV and the current amplitude increased in a voltage-dependent manner. The parameters of activation were -5.7 and -9.9 mV (slope factor) and -35 mV (half activation, V0.5) in the case of the full-length and truncated channels, respectively. The characteristics of the inactivation were 14.2 and 24.6 mV (slope factor) and -17.3 and -39.0 mV (V0.5) for the full-length and truncated channels, respectively. The activation time constant of the full-length channel for potentials ranging from -30 to 40 mV decreased from 18 to 12 msec whereas the inactivation time constant decreased from 6600 msec at -30 mV to 1800 msec at 40 mV. The unit current amplitude measured in cells bathing in 140 mM KCl was 1.3 +/- 0.1 pA at 40 mV, the unit conductance, 34.5 pS and the zero current voltage, 0 mV. Both forms of the channels were inhibited by TEA, 4-AP, Ni2+ and charybdotoxin. In contrast to the native (Jurkat) lymphocyte Kv1.3 channel that is fully inhibited by PKA and PKC, the addition of TPA resulted in 34.6 +/- 7.3% and 38.7 +/- 9.4% inhibition of the full-length and the truncated channels, respectively, 8-BrcAMP induced a 39.4 +/- 5.4% inhibition of the full-length channel but had no effect (8.6 +/- 8.3%) on the truncated channel. Cell dialysis with alkaline phosphatase had no effects, suggesting that the decreased sensitivity of the transfected channels to PKA and PKC was not due to an already phosphorylated channel. Patch extract experiments suggested that the hKv1.3 channel was partially sensitive to PKA and PKC. Cotransfecting the Kv beta 1.2 subunit resulted in a decrease in the value of the time constant of inactivation of the full-length channel but did not modify its sensitivity to PKA and PKC. The cotransfected Kv beta 2 subunit had no effects. Our results indicate that the hKv1.3 lymphocyte channel retains its electrophysiological characteristics when transfected in the Kv beta-negative HEK 293 cell line but its sensitivity to modulation by PKA and PKC is significantly reduced.

Cell Line↗
PubMed1998

VCAM-1 is internalized by a clathrin-related pathway in human endothelial cells but its alpha 4 beta 1 integrin counter-receptor remains associated with the plasma membrane in human T lymphocytes.

Lymphocyte extravasation involves a step(s) of de-adhesion to allow trans- and subendothelial migration in response to inflammatory signals. We show here that ligated VCAM-1 was rapidly internalized (t1/2 14.5 min) in ECV 304 endothelial cells and in TNF-alpha-primed human umbilical vein-derived endothelial cells (t1/2 11.2 min). The process required energy (ATP), intracellular Ca2+, an intact cytoskeletal network and active protein kinases. The internalization of VCAM-1 involved a clathrin-dependent pathway based on the observations that 1) it was inhibited in cells treated with lysosomotropic agents or with a hypertonic concentration of sucrose, and 2) internalized VCAM-1 colocalized with clathrin. In contrast, the cross-linked alpha 4 beta 1 integrin counter-receptor of VCAM-1 remained associated with the plasma membrane of purified peripheral T and Jurkat cells. Our results suggest a model where VCAM-1 would initially participate in the retention of T cells to the endothelium by binding alpha 4 beta 1 integrin. Lymphocyte de-adhesion would be facilitated as a result of the internalization of VCAM-1. The persistent cell surface expression of alpha 4 beta 1 integrin would allow the migrating T cells to interact with and receive signal(s) from its fibronectin ligand of the extracellular matrix.

Cell Line↗
PubMed1998

Panic disorder in coronary artery disease patients with noncardiac chest pain.

In this study we address the following questions: (1) What percentage of coronary artery disease (CAD) patients that present with chest pain, but whose symptoms cannot be fully explained by their cardiac status, suffer from panic disorder (PD)? (2) How do patients with both CAD and PD compare to patients without CAD and to patients without either PD or CAD in terms of psychological distress? Four hundred forty-one consecutive walk-in emergency department patients with chest pain underwent a structured psychiatric interview (ADIS-R) and completed psychological scales. Fifty-seven percent (250 of 441) of these patients were diagnosed as having noncardiac chest pain and constituted this study's sample. A total of 30% (74 of 250) of noncardiac chest pain patients had a documented history of CAD. Thirty-four percent (25 of 74) of CAD patients met criteria for PD. Patients with both PD and CAD displayed significantly more psychological distress than CAD patients without PD and patients with neither CAD nor PD. However, they did not differ from non-CAD patients with PD. PD is highly prevalent in patients with CAD that are discharged with noncardiac diagnoses. The psychological distress in these patients appears to be related to the panic syndrome and not to the presence of the cardiac condition.

Chest Pain↗
PubMed1997

Comparison of preoperative characteristics of men and women undergoing coronary artery bypass grafting (the Post Coronary Artery Bypass Graft [CABG] Biobehavioral Study).

A cohort of 759 coronary artery bypass grafting (CABG) patients (269 women and 490 men) was enrolled in the prospective POST CABG Biobehavioral Study at 5 clinical centers in the United States and Canada. Sociodemographic and medical data were obtained by interview and from medical charts. Health-related quality of life and psychosocial data were ascertained preoperatively by interview and questionnaire for those patients whose condition allowed preoperative assessment and was compared among patients from hospitals enrolling both male and female patients (143 women and 267 men). Women enrolled in the Biobehavioral Study were older than men (65.4 +/- 9.0 vs 61.8 +/- 9.7 years, p < 0.001) and more likely to have a preoperative medical condition which precluded biobehavioral evaluation (47% vs 34%, p < 0.001). Women were less likely to be high school graduates (59% vs 74%, p < 0.001), were less likely to be earning > or = $25,000 per year (39% vs 69%, p < 0.001), and were married less often at the time of surgery (59% vs 85%, p < 0.001). Fewer women than men were able to perform basic self-care activities (p < 0.001) and social activities (p < 0.001). Women were also less able to perform the more demanding activities required for independent living, recreation, and maintaining a household (p < 0.001). Women were also more anxious (p = 0.01) and reported more depressive symptoms (p < 0.001) than men. These data suggest that plans for perioperative and convalescent care for women undergoing CABG should take into account their less favorable medical and psychosocial status relative to men.

Activities of Daily Living↗
PubMed1997

Clustering the adhesion molecules VLA-4 (CD49d/CD29) in Jurkat T cells or VCAM-1 (CD106) in endothelial (ECV 304) cells activates the phosphoinositide pathway and triggers Ca2+ mobilization.

Ligation of very late antigen (VLA)-4 (alpha 4 beta 1 integrin) with a cross-linked anti-alpha 4 subunit monoclonal antibody (mAb) triggered a biphasic Ca2+ response in Jurkat cell populations and in peripheral human lymphocytes. Cross-linking vascular cell adhesion molecule (VCAM)-1 (the counter-receptor of VLA-4) in ECV 304 endothelial cells generated a biphasic Ca2+ response. Tumor necrosis factor-alpha-primed human umbilical cord vascular endothelial cells also responded to the cross-linked mAb with a biphasic Ca2+ profile. Ligated VLA-4 (Jurkat cells) or VCAM-1 (ECV 304) stimulated the production of myo-inositol 1,4,5-trisphosphate. ECV 304 cells induced a biphasic Ca2+ response in Fura2-loaded Jurkat cells, whereas a transient response was observed when Jurkat cells were added to Fura2-loaded ECV 304 cells. The Ca2+ responses in these experiments involved VLA-4/VCAM-1 interactions since they were significantly reduced (approximately 80%) by prior treatment of the target cells with the relevant noncross-linked mAb. Close contact between the cells triggered mutual Ca2+ signaling as shown by spectrofluorimetric and confocal microscopy time-dependent recordings. Fibronectin and its CS-1 fragment (V25) triggered a sustained Ca2+ response in Jurkat cells (confocal microscopy). Our results suggest that the VLA-4 and VCAM-1 adhesion molecules can transduce a signal that involves activation of the phosphoinositide pathway and the mobilization of Ca2+.

Calcium↗
PubMed1997

Signal transduction in Jurkat T lymphocytes. Evidence for early Ca2+ movements between the cytoplasm and the nucleoplasm in activated cells.

Spatial analyses of the distribution of Ca2+ in resting and activated T and B lymphocytes have shown that the bulk of increased [Ca2+]i appears to be associated with the nuclear region. These observations suggest that Ca2+ is released from the perinuclear space or that it diffuses to the nucleoplasm, or both. We have used laser scanning confocal microscopy to assess whether cytoplasmic diffusion of Ca2+ could contribute to the rise in nuclear Ca2+. We found that the activation of individual Jurkat cells by use of an anti-Ti (beta-subunit) mAb induced a nucleus-associated increase in [Ca2+]i. In cells loaded with the InsP3 receptor antagonist heparin, the nuclear Ca2+ response was abolished but not the response to thapsigargin. Evidence for a cytoplasmic Ca2+ response was obtained by loading Jurkat cells with a cytoplasm-restricted Ca2+ probe (Calcium Green-1-Dextran). These observations suggested that a process of diffusion of cytoplasmic Ca2+ contributed to the rise of nuclear Ca2+ in Jurkat T cells. This interpretation was supported by the findings (1) that rapid scanning of thapsigargin-released Ca2+ showed an inverse relationship between the levels of cytoplasmic and nuclear Ca2+ and (2) that modulation of the external concentration of Ca2+ in thapsigargin-treated Jurkat cells showed a time-dependent decrease of fluorescence from the nucleoplasm that was reversed by raising the concentration of external Ca2+. We conclude that Ca2+ can rapidly diffuse between the cytoplasm and the nucleoplasm in activated Jurkat T lymphocytes and that hydrophilic Ca2+ probes largely partition to the nucleoplasm, thus giving rise to distorted nucleus-to-cytoplasm fluorescence ratios.

Calcium↗
PubMed1997

Detecting panic disorder in emergency department chest pain patients: a validated model to improve recognition.

OBJECTIVE: To develop and validate a detection model to improve the probability of recognizing panic disorder in patients consulting the emergency department for chest pain. METHODS: Through logistic regression analysis, demographic, self-report psychological, and pain variables were explored as factors predictive of the presence of panic disorder in 180 consecutive patients consulting an emergency department with a chief complaint of chest pain. The detection model was then prospectively validated on a sample of 212 patients recruited following the same procedure. RESULTS: Panic-agoraphobia (Agoraphobia Cognitions Questionnaire, Mobility Inventory for Agoraphobia), chest pain quality (Short Form McGill Pain Questionnaire), pain loci, and gender variables were the best predictors of the presence of panic disorder. These variables correctly classified 84% of chest pain subjects in panic and non-panic disorder categories. Model properties: sensitivity 59%; specificity 93%; positive predictive power 75%; negative predictive power 87% at a panic disorder sample prevalence of 26%. The model correctly classified 73% of subjects in the validation phase. CONCLUSION: The scales in this model take approximately ten minutes to complete and score. It may improve upon current physician recognition of panic disorder in patients consulting for chest pain.

Adult↗
PubMed1997

Changes in apoptosis of human polymorphonuclear granulocytes with aging.

Many alterations with aging occur at the cellular and organic levels in the immune system ultimately leading to a decrease in the immune response. Our aim in the present work was to study apoptosis of polymorphonuclear granulocytes (PMN) with aging under various stimulations since apoptosis might play an important role in several pathologies encountered with aging. The PMN of healthy young (20-25 years) and elderly (65-85 years) subjects were examined after 24 h of sterile culture with and without stimulation. The stimulating agents included: phorbol myristate acetate (PMA), hydrogen peroxide (H2O2), N-formyl-methionyl-leucyl phenylalanine (FMLP), granulocyte-macrophage colony stimulating factor (GM-CSF), reduced glutathione (GSH), lipopolysaccharide (LPS) and interleukin 2 (IL-2). Apoptosis was assessed by traditional staining of the plates, by flow cytometric staining and DNA gel electrophoresis. It was found that without stimulation the susceptibility of PMN to apoptosis was slightly increased with aging. Under various stimulations, such as PMA. H2O2, apoptosis was almost 100%, while the treatment by FMLP, oxLDL and GSH did not change its extent in PMN obtained either from young or elderly subjects. Marked age-related changes were observed in the extent of apoptosis under stimulation with GM-CSF, IL-2 and LPS. These agents were able to significantly prevent apoptosis in PMN of young subjects, while only the GM-CSF was able to slightly modulate it in neutrophils of elderly subjects. From these results, we suggest that changes in apoptosis of PMN with aging could play a role in the increased incidence of certain immune system related pathologies of aging, such as cancer, infections and autoimmune disorders.

Adult↗
PubMed1997

The MRD1 (P-glycoprotein) and MRP (P-190) transporters do not play a major role in the intrinsic multiple drug resistance of Jurkat T lymphocytes.

The response of T cells in relation to the cell cycle has not been extensively studied. We have attempted to address this question using Jurkat T cells treated with cytostatic drugs known to arrest cells at various transition points of their cycle. We tested various concentrations of drugs that act at G1/S (hydroxyurea, lovastatin, thymidine), early S [aphidicolin, cyclosporin A (CsA), rapamycin] or G2 + M (colchicine, nocodazole) in 24 h cultures. Cytofluorimetric analyses showed that cycling Jurkat cells were equally distributed between the G1 (44.9 +/- 6.5%) and S (42.3 +/- 8.0%) phases. Cell distribution in G2 + M was 12.7 +/- 2.8%. Hydroxyurea but not lovastatin increased the percentage of cells in S phase to ca 60-70% and both drugs decreased it to ca 30% in G1. Thymidine had no effects. Aphidicolin increased the distribution in S phase to ca 70% with a decrease in G1 to ca 30%. CsA and rapamycin increased the percentage of the cells in G1 to ca 70% and decreased it to ca 25% in S phase. Nocodazole increased cell distribution in G2 + M to ca 60% and induced a decrease in G1 to ca 10%. The effects of the drugs were not related to their toxicity and their limited efficiency raised the possibility that Jurkat cells possessed an intrinsic resistance to these xenobiotics. Time-course analysis showed (scanning electron microscopy) that the early morphological changes induced by colchicine were reversible. Drug efflux experiments (vinblastine) suggested that an ATP-dependent process could be involved. However, Northern blot analyses showed a weak signal for MDR1 (MDR, multiple drug resistance). In contrast, a probe for multidrug resistance-associated protein (P-190; MRP) showed a strong signal in Jurkat and peripheral lymphocytes. The presence of drugs (CsA, nocodazole, thymidine) (24 h) did not up-regulate its message and cell treatment with BSO only moderately affected the efficiency of the glutathione S-conjugate MRP transporter. Our data suggest that the intrinsic multidrug resistance of leukemic Jurkat T cells does not appear to involve the MDR1 and MRP members of the ABC family of reverse drug transporters and these observations raise the possibility of the involvement of multi-faceted mechanisms.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Suicidal ideation in emergency department chest pain patients: panic disorder a risk factor.

Most patients who present to the emergency department (ED) for chest pain do not have a cardiac disorder. Approximately 30% of noncardiac chest pain patients suffer from panic disorder (PD), a disabling, treatable, yet rarely detected psychiatric condition. Although still controversial, PD may be a risk factor for suicidal ideation and attempts. The prevalence of recent suicidal ideation (ie, past week) was studied in 441 consecutive ED chest pain patients who underwent a structured psychiatric interview. To examine the controversial link between panic and suicidal behavior, logistic regression analyses were conducted in which current psychiatric diagnoses (Axis I) as well as pertinent medical and demographic information were assessed as risk factors for suicidal ideation. Participants were interviewed with the Anxiety Disorders Interview Schedule-Revised to establish psychiatric diagnoses. Recent suicidal ideation (ie, past week) was assessed with question 9 of the Beck Depression Inventory. Ten percent of patients had recent suicidal ideation. Sixty percent of patients with suicidal thoughts met criteria for PD. In the patients with PD, suicidal ideation could not be explained by the presence of comorbid psychiatric or medical conditions or medication. In the total sample, only diagnoses of PD (odds ratio [OR] = 4.3; 95%, confidence interval [CI], 2.09-8.82; P = .0001) and dysthymia (OR = 9.98; 95% CI, 4.00-24.8; P = .00001) were significant and independent risk factors for suicidal ideation. PD, the most common psychiatric condition in ED chest pain patients, may be an independent risk factor for suicidal ideation, further supporting the need for recognition and treatment of these patients.

Adult↗
PubMed1997

A caffeine/ryanodine-sensitive Ca2+ pool is involved in triggering spontaneous variations of Ca2+ in Jurkat T lymphocytes by a Ca(2+)-induced Ca2+ release (CICR) mechanism.

Caffeine and ryanodine triggered an increase in [Ca2+]i (73 +/- 22 and 61 +/- 18 nM, respectively) in Jurkat cell populations that was independent of external Ca2+. In individual cells, caffeine and ryanodine induced Ca2+ spikes. Jurkat cell populations initially exposed to caffeine did not respond further to ryanodine and vice versa, suggesting an overlap of the Ca2+ pool that was contained within the thapsigargin-sensitive Ca2+ reserve. [3H]ryanodine bound to a single class of sites of Jurkat microsomes (KD, 18.4 +/- 5.7 nM; Bmax, 24.3 +/- 7.7 fmol/mg protein). Photolytic release (Nitr5) of caged Ca2+ induced a time-dependent increase of Ca2+ in individual Jurkat cells. The profile of the release of Ca2+ was characterized, 1) by a kinetic (0.55 +/- 0.07 nM s-1) slower than the Ca2+ response to caffeine (3.93 +/- 0.66 nM s-1) or to ryanodine (3.96 +/- 0.94 nM s-1), 2) by a release of Ca2+ (131 +/- 43 nM) that slowly returned to baseline and during which low amplitude oscillations were present (room temperature) or Ca2+ spikes (37 degrees C) and, 3) by a lack of dependency on an influx of Ca2+. Inhibitors of CICR (ruthenium red and 1-octanol) prevented the photolysis-dependent increase in [Ca2+]i but not the InsP3-dependent Ca2+ response. Our data suggest that Jurkat T cells possess at least two Ca2+ pools, one that is sensitive to InsP3 and one that is insensitive. These two Ca2+ pools may be involved in a CICR that generates spontaneous Ca2+ spikes and oscillations in these cells.

1-Octanol↗
PubMed1996

Panic disorder in emergency department chest pain patients: prevalence, comorbidity, suicidal ideation, and physician recognition.

PURPOSE: To establish the prevalence of panic disorder in emergency department (ED) chest pain patients; compare psychological distress and recent suicidal ideation in panic and non-panic disorder patients; assess psychiatric and cardiac comorbidity; and examine physician recognition of this disorder. DESIGN: Cross-sectional survey (for psychiatric data). Prospective evaluation of patient discharge diagnoses and physician recognition of panic disorder. SETTING: The ambulatory ED of a major teaching hospital specializing in cardiac care located in Montreal, Canada. SUBJECTS: Four hundred and forty-one consenting, consecutive patients consulting the ED with a chief complaint of chest pain. PRIMARY OUTCOME MEASURE: Psychiatric diagnoses (AXIS I). Psychological and pain test scores, discharge diagnoses, and cardiac history. RESULTS: Approximately 25% (108/441) of chest pain patients met DSM-III-R criteria for panic disorder. Panic disorder patients displayed significantly higher panic-agoraphobia, anxiety, depression, and pain scores than non-panic disorder patients (P < 0.01). Twenty-five percent of panic disorder patients had thoughts of killing themselves in the week preceding their ED visit compared with 5% of the patients without this disorder (P = 0.0001) even when controlling for co-existing major depression. Fifty-seven percent (62/108) panic disorder patients also met criteria for one or more current AXIS I disorder. Although 44% (47/108) of the panic disorder patients had a prior documented history of coronary artery disease (CAD), 80% had atypical or nonanginal chest pain and 75% were discharged with a "noncardiac pain" diagnosis. Ninety-eight percent of the panic patients were not recognized by attending ED cardiologists. CONCLUSIONS: Panic disorder is a significantly distressful condition highly prevalent in ED chest pain patients that is rarely recognized by physicians. Nonrecognition may lead to mismanagement of a significant group of distressed patients with or without coronary artery disease.

Chest Pain↗
PubMed1996

Effects of staurosporine on the capacitative regulation of the state of the Ca2+ reserves in activated Jurkat T lymphocytes.

Staurosporine (Stp) is an inhibitor of protein kinase C (PKC) that has been used to address the role of this enzyme in a variety of cells. However, Stp can also inhibit protein tyrosine kinases (PTK). We have investigated the effects of Stp on the InsP3-(using mAb C305 directed against the beta chain of the T cell receptor (TcR/CD3 complex) and the thapsigargin (Tg)-dependent release and influx of Ca2+ in human (Jurkat) T cells. The addition of Stp (200 nM) during the sustained phase of the TcR-dependent Ca2+ response resulted in a rapid inhibition of the influx of Ca2+ that was not seen when Ca2+ mobilization was triggered by Tg (1 microM). When the cells were preincubated with Stp (200 nM), there was an inhibition of the mAb C305- but not the Tg-dependent Ca2+ response. The effect of Stp was not the result of the inhibition of PKC as shown by down-regulation of PKC and with the use of the specific PKC inhibitor bis-indolyl maleimide GF 109203X. The effect of Stp on the entry of Ca2+ in activated (mAb C305) Jurkat lymphocytes was dose-related and was not the result of a direct inhibition of plasma membrane Ca2+ channels based on an absence of effect on the Tg-dependent entry of Ca2+ and the use of Ca2+ channel blockers (econazole and Ni2+). These blockers terminated the influx of Ca2+ but the Tg-sensitive Ca2+ reserves were not refilled in marked contrast to the effect of Stp. Quantification of InsP3 revealed that the addition of Stp resulted in an approximate 40% reduction in mAb C305-activated Jurkat cells. The effects of Stp can be explained as follows. Stp decreases the mAb C305-induced production of InsP3 by inhibiting the TcR/CD3-dependent activation of PTK associated with the stimulation of phospholipase C-gamma 1. A decrease in [InsP3] without a return to baseline is sufficient to close the InsP3 Ca2+ channel, endoplasmic Ca2+ ATPases use the incoming Ca2+ to refill the Ca2+ pools and that terminates the capacitative entry of Ca2+. A simple kinetic model reproduced the experimental data.

Antibodies, Monoclonal↗
PubMed1995

Cellular distribution of protein kinase C isozymes in CD3-mediated stimulation of human T lymphocytes with aging.

Protein kinase C (PKC) is involved in a variety of cellular responses, such as the expression and secretion of IL-2, the regulation of cytotoxic killing and cell proliferation. It is known that these immune functions are altered with aging. Here, we show that anti-CD3-triggered T cell proliferation is significantly decreased with aging and that H7, an inhibitor of PKC, impairs the anti-CD3-induced T cell proliferation in a differential manner, lymphocytes of healthy young subjects being more sensitive to the PKC inhibitor than those of elderly subjects. We examined (Western blot) the presence and the cellular distribution of PKC isozymes in T lymphocytes of healthy young and elderly subjects in the resting state and after anti-CD3 mAb stimulation using antibodies directed against PKC alpha, beta, delta, epsilon and zeta isoforms in the cytosol and the plasma membrane fractions. These five PKC isotypes were present in human T cells of young and elderly subjects. However, their distribution between the cytosolic and membrane fractions varied according to the isozymes and the age of the subjects. In resting lymphocytes of young subjects, all the PKC isozymes were found in the cytosolic fraction, except PKC-zeta. In resting lymphocytes of elderly subjects PKC-zeta and -epsilon were almost equally distributed between the cytosolic and the membrane fractions, whereas PKC-alpha and -zeta were mainly found in the membrane fraction and PKC-beta was almost exclusively located in the cytosolic fraction. The translocation of PKC-alpha, -beta, -delta and -epsilon could be observed under anti-CD3 mAb stimulation in lymphocytes of young subjects, while in the case of elderly subjects only the PKC beta isoform was translocated. Our results suggest tha the decreased availability of cytosolic PKC may contribute to the diminished PKC-dependent responses to CD3-triggered stimulation of human T lymphocytes with aging.

Adult↗
PubMed1995

[Nodular or pseudo-nodular Hashimoto thyroiditis. Value of cytologic examination].

OBJECTIVES: Nodular or pseudo-nodular aspects of Hashimoto's thyroiditis raise the problem of the association with a differentiated carcinoma or a non Hodgkin's lymphoma. METHODS: We looked for patients needing surgery in 165 cases of Hashimoto's thyroiditis. For this purpose, we used fine needle aspiration cytology. RESULTS: We found a differentiated carcinoma in 4% of cases and a non Hodgkin's lymphoma in 1% of cases. CONCLUSION: In nodular or pseudo-nodular aspects of Hashimoto's thyroiditis, fine needle aspiration cytology is helpful for the nodule diagnosis and for the selection of suspicious nodules only to be referred to surgery.

Adenoma↗