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M Pezzano

Publications and source records attributed to M Pezzano.

At least 19 recordsLinked to original sources
PubMed2001

Circulating macrophages as well as developing thymocytes are enclosed within thymic nurse cells.

Both thymic nurse cells (TNCs) and macrophages have been reported to function as antigen-presenting cells during the process of MHC restriction. Negative selection, which results in the apoptosis of potentially autoreactive thymocytes, is believed to be associated with both macrophages and TNCs in the cortex. Both cell types have also been reported to ingest thymocytes undergoing positive and negative selection. However, macrophages ingest apoptotic thymocytes, while TNCs have been shown to internalize viable cells. A subset of the TNC-engulfed population is allowed to mature and is released, while the remaining fraction becomes apoptotic and is absorbed within the TNC cytoplasm through lysosomal activity. A recent report described a subset of rat TNCs that contain macrophages as well as thymocytes within their cytoplasm. We examined freshly isolated TNCs from C57BL/6 mice and found that, of the TNC population recovered, 1.7% contained macrophages within its cytoplasm. There also were macrophages tightly bound but not internalized into the multicellular structure at a rate of 2.9%. The total association of macrophages with TNCs was approximately 4.6%. This unique association of macrophages with TNCs was also observed in vitro when freshly isolated thymocytes (containing macrophages) were added to cultures of cells from the TNC cell line tsTNC-1. The macrophage-TNC interaction was found to be dynamic, with macrophages moving rapidly into and out of TNCs containing cytoplasmic thymocytes. Macrophages within TNCs showed a close association with cytoplasmic thymocytes. We then labeled peritoneal macrophages with CFDA SE, a cell tracking dye, and returned them to the mouse peritoneum. Within 1 h, labeled macrophages were detectable in the thymus. This is the first investigation to show a direct interaction between peripheral macrophages and TNCs. These results suggest that TNCs and macrophages work together as antigen-presenting cells.

Animals↗
PubMed2001

Questionable thymic nurse cell.

Since their discovery in 1980, thymic nurse cells (TNCs) have been controversial. Questions pertaining to the existence of the TNC as a "unit" cell with thymocytes completely enclosed within its cytoplasm were the focus of initial debates. Early skeptics proposed the multicellular complex to be an artifact of the procedures used to isolate TNCs from the thymus. Since that time, TNCs have been found in fish, frogs, tadpoles, chickens, sheep, pigs, rats, mice, and humans. Their evolutionary conservation throughout the animal kingdom relieved most speculations about the existence of TNCs and at the same time demonstrated their apparent importance to the thymus and T-cell development. In this review we will discuss and debate reports that describe (i) the organization or structure of TNCs, (ii) the thymocyte subset(s) found within the cytoplasm of TNCs and their uptake and release, and (iii) the function of this fascinating multicellular interaction that occurs during the process of T-cell development. Discussions about the future of the field and experimental approaches that will lead to answers to remaining questions are also presented.

Animals↗
PubMed2001

TNF and Fas-induced apoptosis during negative selection in thymic nurse cells.

Apoptosis of thymocytes associated with thymic nurse cells (TNCs) has been well-documented. TNCs selectively bind and internalize immature alphabeta TCRlo CD4+ CD8+ thymocytes in vitro. A subset of the internalized population matures to the alphabeta TCRhi CD69hi stage of development while the fraction that remains within the cytoplasm dies through the process of apoptosis. Negative selection by thymic cortical epithelial cells has been reported, but little is known about the apoptotic pathway(s) employed to facilitate the death signal. Using the TNC line tsTNC-1 that was reported earlier to maintain the ability to internalize alphabeta TCRlo CD4+ CD8+ cells in vitro, we investigated the role of Fas and TNFalpha in TNC-induced apoptosis. Our initial studies revealed that tsTNC-1 cells express both FasL and TNFalpha apoptosis of triple positive cells was shown to be reduced approximately 50% in co-cultures of tsTNC-1 cells and thymocytes in the presence of either anti-TNFalpha or Fas-Fc. When maximum effective concentrations of both TNFalpha, and Fas-Fc were added to these co-cultures, apoptotic death was further reduced to approximately 68%. These results suggest that both TNFalpha and Fas apoptotic pathways are active during thymocyte selection by TNCs.

Apoptosis↗
PubMed2000

[Cardiac tamponade].

Cardiac tamponade is an emergency situation. Diagnosis is to be suspected when an elevation of systemic venous pressure, a decline in systemic arterial pressure and a clinical context of neoplasia or recent acute pericarditis are associated. Transthoracic echocardiogram is the gold-standard of diagnosis, and allows the accurate diagnosis of a large pericardial effusion: precise localisation and haemodynamic evaluation are needed before therapeutic decision. Pericardiocentesis is the only appropriate treatment. Surgical procedure, or less traumatic echo-guided pericardiocentesis, provide rapid haemodynamic relief of symptoms. Prognosis is determined by aetiology.

Cardiac Tamponade↗
PubMed2000

A single point mutation in HIV-1 V3 loop alters the immunogenic properties of rgp120.

The results of the study presented in this report show that clones of env derived from genetically divergent HIV-1 field isolates fall into two major subsets based on the predicted secondary structure of the V3 region in gp120. One subset exemplified by the clones A-UG06c, B-RT3.12 and C-UG045 is predicted to assume a beta-turn conformation in the V3 loop and comprises the GPGX residues. The other subset exemplified by the clones D-UG23c and D-UG042 (GXGX) are deficient in the expression of the beta-turn in the loop. Since secondary conformations are highly likely to confer antigenic properties in a protein backbone at least for B cells, we have used nucleic acid immunization to test the effect of the beta-turn deficiency on the immunogenic potential of rgp120 encoded in these field isolates. As hypothesized, inoculation of BALB/c mice with the env plasmid encoding the beta-turn expressing rgp120 molecules resulted in the development of a vigorous antibody response to the homologous V3 loop peptides. In contrast, immunization with an rgp120 clone deficient in the beta-turn in the V3 loop showed no evidence of antibody development to the V3 loop. Instead, the latter clones triggered T cell proliferative responses and markedly increased the level of IL-2 and IFN-gamma production by T cells. Significantly, reconstitution of the beta-turn conformation by site-directed mutagenesis of a single V3 loop residue yielded rgp120 molecules which restored antibody production while diminishing the cell-mediated immune (CMI) responses to the V3 residue. These observations demonstrate the marked impact of a single amino acid substitution on the immunogenic properties of V3 region in gp120 encoded by divergent HIV-1 field isolates.

Amino Acid Sequence↗
PubMed2000

Subxiphoid pericardiocentesis guided by contrast two-dimensional echocardiography in cardiac tamponade: experience of 110 consecutive patients.

AIMS: We evaluated echo-guided pericardiocentesis with contrast study in cardiac tamponade management. PATIENTS AND METHODS: From 1982 to 1998 we performed pericardiocentesis in 110 patients (56 +/- 14 years old). Subxiphoid approach was used in 109. Cardiac tamponade was idiopathic (n = 16), secondary to malignant disease (n = 50) and miscellaneous disorders (n = 44). RESULTS: Pericardial fluid was bloody (n=75), serous (n = 29) or turbid (n = 6). Mean volume of fluid removed was 585 +/- 370 ml. When prolonged drainage (60 +/- 26 h) was used (n = 41), total effusion volume was 850 +/- 340 ml. Eleven deaths were observed during the early period following pericardiocentesis. No relation with procedure was demonstrated by autopsy in 10, and death always occurred in critically-ill patients (five malignant diseases, five cardiac ruptures and one septic shock). Other complications were: right ventricular puncture (n = 11) with deleterious effect in one, vasovagal hypotension (n = 6) and paroxysmal arrhythmia (n = 6). Surgical drainage was mandatory in 19 patients. It had to be done as an emergency (within 6 h), because of failure of the procedure in four patients. In 14 patients without prolonged drainage a delayed surgical evacuation was indicated, because of persistent (n = 3) or recurrent (n = 11) cardiac tamponade. Only one surgical procedure was required after prolonged drainage. CONCLUSIONS: Echo-guided pericardiocentesis with contrast study is an effective technique which reduces the risk of cardiac tamponade management. It should be considered in patients with critical haemodynamic condition or advanced malignancy, and in patients with poor short-term prognosis.

Adult↗
PubMed2000

[Aneurysm of the sinus of Valsalva. Apropos of a case of right intra-atrial rupture].

An unusual systolo-diastolic heart murmur was discovered fortuitously in a 39-year-old man undergoing a routine check-up. Transesophageal echocardiography gave the diagnosis of Valsalva sinus aneurysm ruptured into the right atrium. Cardiac surgery was successful. We reviewed the literature on this unusual condition, focusing on the pathophysiological, clinical, diagnostic and therapeutic aspects. Transesophageal echocardiography provides the diagnosis.

Adult↗
PubMed2000

[Hemostasis disturbances in myocardial ischemia].

In this article, a description has been given of the close connection between coronary atherosclerosis and the onset of thrombosis. The hemostatic factors examined in this study are implicated both in the pathology of acute coronary syndromes and in the prognosis of ischemic heart disease. Amongst other factors, the role of the following has been investigated: platelets, thromboxane A2 and prostacyclin, von Willebrand factor, factor VII and tissue factor, thrombin, fibrinogen tissue plasminogen activator and plasminogen activator inhibitor. It is concluded that endothelial dysfunction in coronary atherosclerosis is the most frequent cause of disturbances in hemostatic function.

Blood Coagulation Factors↗
PubMed1999

Lysosomal-mediated degradation of apoptotic thymocytes within thymic nurse cells.

A thymic epithelial cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature alphabetaTCR(lo)CD4(+)CD8(+) thymocytes in vitro was used in long-term coincubation experiments to determine the ultimate fate of thymocytes that remained within intracytoplasmic vacuoles of thymic nurse cells (TNCs). In an earlier report, a subset of the population released from the TNC interaction was shown to mature to the alphabetaTCR(hi)CD69(hi) stage of development, while thymocytes that bided within the TNC cytoplasm died through the process of apoptosis. Here, we show the presence of both apoptotic and nonapoptotic thymocytes within the cytoplasm of freshly isolated TNCs as well as in tsTNC-1 cells in culture. A microscopic analysis revealed total degradation of the cytoplasmic apoptotic thymocyte population that remained in tsTNC-1 cells after an 8- to 10-h incubation period. A quantitative analysis showed an increase of cytoplasmic thymocyte degradation over time to almost 80% after 9 h of incubation. However, in the presence of bafilomycin A1, which is used to inhibit acidification of lysosomal vesicles, degradation of apoptotic thymocytes never reached 10%. These data suggest that lysosomes within TNCs play a role in the degradation of apoptotic thymocytes. We examined tsTNC-1 cells before the addition of thymocytes to cultures and found lysosomes to be clustered around the nucleus in the cytoplasm of TNCs. Shortly after the internalization event, apoptotic thymocytes move to the area of the cytoplasm containing lysosomes. Using the confocal microscope, we obtained evidence that shows the degradation event to be facilitated through the fusion of lysosomes with the specialized vacuoles within TNCs containing apoptotic cells.

Animals↗
PubMed1999

[Thoracic radiodermatitis in interventional cardiology. Apropos of 6 cases].

The aim of this study is to describe thoracic radiodermatitis, a rare but not to be forgotten complication of interventional cardiology. The appearances are variable, from often oval-shaped erythema to cutaneous necrosis, with risk of chronic ulceration and malignant degeneration. The authors report 6 cases observed in 1997 after coronary angioplasty. Complex and long procedures are the main causes of this complication. Prevention requires a contribution from all the medical cardiological team, for the diagnosis, determining the indication of the type of revascularisation and for limiting the dose of X-radiation administered.

Aged↗
PubMed1999

[Immediate collateral coronary circulation after a methylergometrin test].

The development of a collateral coronary circulation has been well studied by angiography in two main clinical situations: myocardial infarction (by durable coronary occlusion) and angina (due to significant coronary artery stenosis), but only rarely in spastic angina. The authors report the case of severe spasm at the site of non-significant stenosis after a methylergometrine test, with immediate contro-lateral collateral circulation in a patient with a short history of spastic angina without myocardial infarction. This observation demonstrates that collateral circulation may develop very rapidly in spastic angina (without basal ischaemia in the absence of significant coronary stenosis), because this patient only had seven ten-minute episodes of clinical ischaemia. As collateral circulation may mask clinical and electrical signs in spastic angina, this case suggests that angiographic control should be systematic during the methylergometrine test.

Collateral Circulation↗
PubMed1999

Feasibility of routine transradial coronary angiography: a single operator's experience.

The aims of this study were to assess the feasibility of routine transradial coronary angiography in a standard population of patients with presumed coronary artery disease over a period of time long enough to allow for technical evolution and evaluation of a single operator's learning curve, and to provide data for a randomized comparison versus the femoral approach. Between June 1994 and March 1997, transradial angiography was attempted in 1,000 patients. Approximately 25% of these patients were excluded because of an abnormal Allen test. Except in the case of acute myocardial infarction, there was no selection based on symptoms, age, sex, weight or size in the absence of double internal mammary artery bypass graft operation or simultaneous right heart catheterization. Symptoms and angiographic results were typical of a standard population. The right radial approach was used in 95% of the cases for ease of handling and comfort of a right-handed operator. Radial artery puncture and catheterization success was obtained in 97.6% of the cases; the left coronary artery was selectively catheterized in 100%, right coronary artery in 98%, left ventricle in 96.9%, mammary artery grafts in 100% and saphenous grafts in 97.2%. Average procedure duration was 18 +/- 9 minutes, and decreased progressively with experience and catheter strategies. The optimal catheter selection would seem to be a single catheter, either left Amplatz or Champ, for both coronary arteries. Two coronary complications and 3 transient neurological complications occurred, but no clinically significant vascular complications requiring surgery or transfusion were reported. Transradial angiography seems to be a routine approach that should now be compared with the femoral approach and supersede the brachial approach whenever possible.

Aged↗
PubMed1998

A thymic nurse cell-specific monoclonal antibody.

A thymic epithelial cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature alpha beta TCRloCD4+CD8+ thymocytes in vitro was used in the development of a monoclonal antibody that is specific to the cell surface of thymic nurse cells (TNCs) in the thymus. The rat monoclonal antibody ph91 showed specificity to cells of the subcapsular region of the thymic cortex. Upon mechanical dispersion of the thymus in vitro, ph91 recognized cells displaying the multicellular morphology unique to TNCs. Ph91 staining was not detected on fresh thymocytes, stromal cells of the inner thymic cortex, thymic medullary cells, B cells or fibroblasts. Ph91 recognized a 43-kDa protein on the surface of TNCs. Exposure of tsTNC-1 cells to ph91 in tissue culture significantly reduced the percentage of binding of the alpha beta TCRloCD4+CD8+ thymocyte subset previously shown to target TNCs. In organ culture, ph91 reduced the viability of developing thymocytes by 70%. The largest reduction was found in the alpha beta TCR+CD4+CD8+ thymocyte subset. These results represent the first report of a TNC-specific monoclonal antibody. Further, the antigen to which ph91 binds may play a role in the process of thymocyte binding and their subsequent internalization which is unique to TNCs and important to the T cell developmental process.

Animals↗
PubMed1998

[Tamponade in patients with systolic left ventricular dysfunction. An atypical presentation].

BACKGROUND: Left ventricular failure has been described following surgery due to localized compression of the left ventricle and in case of diastolic left ventricular dysfunction after pericardiotomy or pericardiocentesis. CASE REPORTS: Global heart failure was observed in 3 patients with dilated cardiopathy who developed tamponade. Systolic left ventricular dysfunction was caused by ischemic heart disease in one patient and secondary to anthracyclin chemotherapy in the two others. The effusion was successfully removed with pericardiocentesis in all three cases. No specific complications were observed. DISCUSSION: Although exceptional, tamponade may occur in patients with signs of left ventricular failure.

Adult↗
PubMed1998

[Coronary angiography by a radial artery approach: feasibility, learning curve. One operator's experience].

The aim of this study was to assess the feasibility of the radial artery approach for coronary angiography in a standard population of presumed coronary patients and to continue the assessment for a sufficiently long period of time to perfect the technique, evaluate the learning curve and prepare a randomised comparison with the femoral approach. The radial artery was used for coronary angiography in 800 patients after exclusion of about 25% of patients, mainly because of a negative Allen's maneuver. With the exception of acute myocardial infarction, there was no selection based on symptoms and transradial catheterisation was attempted irrespective of age, sex, weight or height. The representative nature of the study population was confirmed by the results of the procedure (normal: 20%, single vessel disease: 30%, double vessel disease: 26%, triple vessel disease: 18% and left main disease: 5.4%). The right radial artery was used in 94% of cases. Successful radial puncture/catheterisation was obtained in 97% of cases: 100% of left coronary arteries and 99% of right coronary arteries were catheterised, the left ventricle in 98% of cases, the internal mammary arteries in 100%, and venous bypass grafts in 95%. The average duration of the whole procedure was 19 +/- 9 minutes. This decreased regularly with operator experience and judicious choice of catheters. The best choice seemed to be a single catheter for both coronary arteries, either an Amplatz or a Champ catheter. There were two probably avoidable coronary complications and two transient neurological events but no clinically significant vascular complication. The radial artery seemed to be a good approach for routine coronary angiography and may now be compared with the femoral approach. It should help expand the practice of ambulatory coronary angiography.

Aged↗
PubMed1998

[Evaluation of echo-guided pericardiocentesis in cardiac tamponade].

Between April 1982 and December 1995, 78 consecutive patients with an average age of 57 +/- 13 years underwent echo-guided pericardiocentesis in the intensive care unit for poorly tolerated pericardial effusions. The patients were admitted to the cardiology departments of Ambroise-Paré Hospital at Boulogne (n = 44). Gilles-de-Corbeil Hospital at Corbeil-Essonnes (n = 31) and Val-de-Grâce Hospital in Paris (n = 3). The underlying aetiologies were malignant disease (n = 31), idiopathic (n = 13), post-surgery (n = 7), infection (n = 7), autoimmune (n = 6), post-radiotherapy (n = 6), post-myocardial infarction (n = 3), chronic renal failure (n = 3) and coagulation defects (n = 2). Pericardial puncture was undertaken by the subxiphoid (n = 77) or left parasternal (n = 1) approaches under guidance of echocardiography. Intra-pericardial contrast was used to verify the position of the catheter. The average volume of liquid drained was 580 +/- 390 mL. After pericardiocentesis, continuous drainage was continued in 17 patients for an average duration of 63 +/- 29 hours. The total average volume was 750 +/- 330 mL. The major complications were a) three deaths during the puncture, not caused by the procedure after post-mortem study, b) ten right ventricular punctures with no consequences in 9 cases, c) two cases of shock, one of which was due to a pre-existing septicaemia of pulmonary origin, d) two non-sustained ventricular arrhythmias. The minor incidents were six vasovagal syndromes during the procedure and four paroxysmal supraventricular arrhythmias. Emergency surgical drainage was required (n = 3) for a failed procedure and late surgical drainage (n = 12) for persistence or recurrence of the effusion. No surgical drainage was required in the 17 patients placed under continuous aspiration. Echo-guided pericardiocentesis is a simple procedure and provides rapid haemodynamic relief in subjects generally in serious condition. Continuous aspiration may help avoid the need for surgical drainage for persistence or recurrence of the effusion.

Aged↗
PubMed1997

[Ultrasound-guided pericardial drainage. Experience in 34 consecutive patients].

OBJECTIVES: Transthoracic echoguided puncture of the pericardium can be an alternative to surgical drainage. We report our experience with this technique acquired over the last 11 years. PATIENTS AND METHODS: From January 1984 to September 1995, 34 consecutive patients in the cardiology intensive care unit (mean age 56.5 +/- 13 years) underwent echoguided pericardial puncture for poorly tolerated pericardial effusion. The underlying cause was neoplasia (n = 22), idiopathic disease (n = 5), autoimmune disease (n = 2), post-surgical complication (n = 2 including 1 on hemodialysis), infection (n = 1), antivitamin K therapy (n = 1) and disseminated vascular coagulation (n = 1). The subxyphoid (n = 33) or left parasternal (n = 1) route was used under echographic guidance. Intrapericardial contrast allowed verification of the catheter position. The mean quantity of fluid removed was 585 +/- 390 ml. The fluid was hemorrhagic (n = 19), clear (n = 10) or serohematic (n = 4). Aspiration was continued in 16 patients after the initial puncture for a mean 64 hours. The mean total volume of fluid was 750 +/- 330 ml. RESULTS: There was one death during puncture which was found to be unrelated to the procedure after anatomic verification. In two cases, the left ventride was punctured without any consequence. Collapsus occurred during puncture in 2 patients with pulmonary sepsis. Minor incidents were: 6 vasovagal syndromes at puncture with paroxysmal supraventricular rhythm disorder during aspiration. Prior to 1988, surgical drainage was required in 5 patients for persistent or recurrent effusion. Since that time, continuous aspiration has been used in all patients and no surgical drainage has been required. Short-term prognosis depends on the underlying cause (6 deaths at 1 month). CONCLUSION: Echoguided pericardial puncture is a simple procedure which rapidly improves cardiac hemodynamics in these particularly fracle patients. Continuous aspiration avoids subsequent surgical drainage for persistent or recurrent effusion.

Drainage↗