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M Meignan

Publications and source records attributed to M Meignan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Mucosal immunity in primary glomerulonephritis. III. Study of intestinal permeability.

To study the specificity of gut hyperpermeability in primary glomerulonephritis, we investigated intestinal permeability by means of 51Cr-EDTA testing in 20 healthy individuals and in 30 patients with Immunoglobulin A nephropathy (IgA GN), 25 with idiopathic nephrotic syndrome (INS) and 20 with immune complex glomerulonephritis (IC-GN; membranous+membranoproliferative glomerulonephritis). Gut permeability was statistically increased in each patient group versus the controls [controls: 2% (0.4-3.9); IgA GN: 3.25% (0.7-17.70); INS: 3.71% (0.82-10); IC-GN: 3.40% (0.30-16); results are median (range); p < 0.005, nonparametric Mann-Whitney test]. An increase in intestinal permeability exceeding the upper limit of control values (95th percentile) was observed in 36% of IgA GN, 60% of INS and 50% of IC-GN patients. We conclude that intestinal permeability is frequently increased in primary glomerulonephritis and may also be increased in types of glomerulonephritis other than IgA GN.

Adult↗
PubMed1993

The hot spot hepatobiliary scan in focal nodular hyperplasia.

A prospective study was performed on 14 patients with histologically proven focal nodular hyperplasia (FNH) using a hepatobiliary scan with trimethylbromoimino-diacetic acid (TBIDA) and a colloid scan with rhenium sulfur colloids. TBIDA uptake was relatively normal in the region of the tumor, but during the clearance phase 23/25 of the tumors were detected by a hot spot of radioactivity. Depending on the relative contrast achieved between the tumor and normal liver, this hot spot appeared early or later, but was always present at 60 min. In three tumors, a "doughnut" pattern was observed within the hot spot due to a central defect. Hypervascularization was observed during the perfusion phase in 76% of the tumoral sites and normal colloid uptake in only 64%. The detectability of FNH appears greater with TBIDA (92%) than with CT or MRI (84%). The high prevalence of hot spots may be due to careful technological conditions when obtaining hepatobiliary scans. Late images, overexposed films, multiple views and stimulation of gallbladder excretion increased tumor detectability. The hot spot sign may be a useful tool when combined with the results of other imaging modalities in the diagnosis of FNH. The peculiar pathology of FNH with fibrosis, hyperplastic hepatocytes and cholangiolar proliferation might explain this scintigraphic appearance.

Adult↗
PubMed1992

Technetium-99m-DTPA aerosol and gallium-67 scanning in pulmonary complications of human immunodeficiency virus infection.

We retrospectively compared the results of 67Ga chest scans and 99mTc-DTPA aerosol clearance measurements with those of fiberoptic bronchoscopy in 88 patients infected with the human immunodeficiency virus. Of 100 investigations, a pulmonary infection was diagnosed in 39, mainly Pneumocystis carinii pneumonia and a noninfectious disorder was found in 42, mainly Kaposi's sarcoma and lymphocytic alveolitis. Gallium scans and DTPA clearance were abnormal respectively in 74% and 92% of infectious complications, and in 12% and 60% of noninfectious disorders. In 10 cases, DTPA clearance was accelerated, while chest x-ray, arterial blood gases and even gallium scanning were normal. A value of DTPA clearance greater than 4.5%.min-1 was both sensitive and specific for the diagnosis of Pneumocystis carinii pneumonia. The gallium scan was always normal in bronchopulmonary Kaposi's sarcoma. We conclude that in symptomatic patients: (1) DTPA clearance measurements are useful for detecting lung disease when chest x-ray and/or PaO2 are normal and (2) a gallium scan is indicated to distinguish progressive Kaposi's sarcoma from a superimposed second process when radiological abnormalities of pulmonary Kaposi's sarcoma are present.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Effects of platelet-activating factor on lung epithelial permeability in the guinea-pig.

We examined the effects of platelet-activating factor (PAF) on lung epithelial permeability by measuring the clearance of intratracheally administered 99m-technetium-labeled diethylene triamine penta-acetic acid (99mTc-DTPA) in guinea-pigs which were anaesthetised, paralysed and mechanically ventilated. The clearance of the radiolabeled tracer molecule 99mTc-DTPA from airways to the blood was expressed as changes in counts/min corrected for background. For each guinea-pig, 99mTc-DTPA clearance was assessed before and after i.v. PAF administration, when tracheal pressure had returned to near control values. Doses of 10, 50 and 100 ng/kg of PAF caused dose-dependent increases in 99mTc-DTPA clearance of 7 +/- 3%, 38 +/- 7% and 65 +/- 11% respectively. The respective effects of 0.5 mg/kg of the beta 2-adrenergic agonist salbutamol and 0.3 mg/kg of the alpha 1-adrenergic agonist methoxamine on the increase in lung epithelial permeability induced by 50 ng/kg PAF were also studied. Salbutamol significantly reduced the acute bronchoconstrictor effects of PAF, but did not affect the increase in lung epithelial permeability, which was 58 +/- 10%. Conversely, methoxamine significantly enhanced the bronchoconstrictor effects of PAF but inhibited the lung epithelial permeability increase, which was only 10 +/- 13%. In the absence of PAF, salbutamol significantly increased this permeability by 49 +/- 11%, whereas methoxamine alone slightly reduced, it by -11 +/- 4%. These results demonstrate that PAF increases lung epithelial permeability and suggest that vascular surface area recruitment may explain this increase.

Albuterol↗
PubMed1991

Changes in the distribution of ventilation and perfusion associated with separation from mechanical ventilation in patients with obstructive pulmonary disease.

A trial of separation from mechanical ventilation may induce an abnormal respiratory pattern and a maldistribution of ventilation-to-perfusion ratios (VA/Q), especially in patients with chronic obstructive pulmonary disease. This study was designed to assess the effects of three different modes of ventilation on the distribution of global and also regional VA/Q in eight patients with chronic obstructive pulmonary disease recovering from acute respiratory failure who remained dependent on mechanical ventilation after more than 5 days of attempted separation from the ventilator. VA/Q distribution was assessed using the multiple inert gas and isotopic scanning methods after 30 min each of controlled mechanical ventilation (CMV), 10 cmH2O inspiratory pressure support, and spontaneous breathing (SB). Controlled ventilation was provided at a respiratory rate ranging from 12 to 18 breaths per min and a tidal volume of 8 ml.kg-1. In comparison to CMV, SB resulted in a decrease in tidal volume (from 512 +/- 144 to 301 +/- 102 ml, P less than 0.01), and an increase in respiratory rate (from 15.5 +/- 3.2 to 27.3 +/- 15.0 breaths per min, P less than 0.05), which increased dead space (+7.1% of minute ventilation), cardiac output (+36%), and the perfusion to areas of low VA/Q (+8.9% of cardiac output) (P less than 0.05, P less than 0.001, and P less than 0.05, respectively). Isotopic scans revealed a horizontal craniocaudal difference of VA/Q in all modes, with the lowest VA/Q zones at the basal part of the lungs (mean basal VA/Q 0.58 in SB and 1.05 in CMV).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Increased lung epithelial permeability in HIV-infected patients with isolated cytotoxic T-lymphocytic alveolitis.

HIV-related lymphocytic alveolitis is common in HIV-seropositive patients without lung infection or tumor. In some of them a fraction of alveolar lymphocytes are HIV-specific cytotoxic T-lymphocytes (CTL) bearing the CD8 and D44 cell surface markers and capable of killing HIV-infected alveolar macrophages. In order to evaluate the in vivo effect of these CTL on lung function, we measured the pulmonary clearance of aerosolized 99mTc-diethylene triamine penta-acetate (DTPA-CI) on 24 occasions in 22 patients with lymphocytic alveolitis. DTPA-CI has been selected as a highly sensitive test to detect injury of the lung epithelium. In 13 of the patients, we found a high DTPA-CI of 4.56 +/- 2.54%.min-1 (mean +/- SD), suggesting an increase of the epithelial permeability. The lymphocytic alveolitis was then characterized by a high cellularity, a high proportion of lymphocytes (59 +/- 18%), mainly composed of CD8+D44+ T-lymphocytes (149 +/- 109 cells/mm3), which spontaneously exhibited a cytolytic activity against the autologous alveolar macrophages in a standard 51Cr release assay. In the remaining 11 patients, DTPA-CI was normal (less than 1.78%.min-1), lymphocytic alveolitis being characterized by a low number or an absence of CD8+D44+ alveolar lymphocytes (9 +/- 13 cells/mm3) with no significant cytolytic activity. In the whole group, a significant correlation (r = 0.74, p = 0.0004) was found between the DTPA-CI and the number of CD8+D44+ lymphocytes and their cytotoxic activity against alveolar macrophages. Altogether, these results suggest that an injury of the lung epithelium could result from a HIV-specific CTL-induced immunologic conflict.

Adult↗
PubMed1989

Intravenous digital subtraction angiography and lung imaging: compared value in the diagnosis of pulmonary embolism.

In a prospective study, 42 consecutive patients with clinically suspected pulmonary embolism underwent ventilation-perfusion (V-Q) lung imaging and digital subtraction angiography (DSA) concurrently with selective conventional pulmonary angiography (CPA). Thirty-eight studies achieved within 24 hours were reviewed independently by two pairs of observers. The findings were compared using CPA as the gold standard. V-Q lung imaging had a high percentage of indeterminate results, but none were false negative nor false positive. DSA had a lower percentage of indeterminate results but missed four of the 25 positive cases and erroneously affirmed the presence of pulmonary embolism in three cases. Therefore, the authors think that V-Q lung imaging should remain the screening examination of choice for evaluating patients with suspected pulmonary embolism.

Angiography↗
PubMed1989

Zones of increased perfusion (hot spots) on perfusion lung scans: correlation with pulmonary arteriograms.

Perfusion lung scans are occasionally characterized by focal zones of apparent hyperperfusion ("hot spots"). To investigate the frequency and significance of this phenomenon, ventilation-perfusion lung scans and pulmonary arteriograms were reviewed in 72 patients who underwent both procedures for the evaluation of suspected pulmonary embolism. Hot spots were present in the scans of 13 patients and usually occupied less than one pulmonary segment. Most hot spots were detected within a region of atelectasis identified on chest radiographs (38%). A substantial number of the remaining hot spots were located in the lung adjacent to regions of embolus. In patients with massive embolus, hot spots actually represented normally preserved perfusion in the presence of globally reduced perfusion elsewhere.

Adult↗
PubMed1989

Effects of sustained exercise on pulmonary clearance of aerosolized 99mTc-DTPA.

The effects of intensive prolonged exercise on the pulmonary clearance rate of aerosolized 99mTc-labeled diethylenetriaminepentaacetate (99mTc-DTPA) and pulmonary mechanics were studied in seven healthy nonsmoking volunteers. 99mTc-DTPA clearance and pulmonary mechanics (lung volumes and compliance) were assessed before and after 75 min of constant-load exercise performed on a treadmill, corresponding to 75% of maximal O2 uptake. Because both clearance measurements were made in similar conditions of pulmonary blood flow, respiratory rate, and tidal volume, changes in clearance rate can be assumed to represent changes of alveolar epithelial permeability. After exercise, total, apical, and basal clearance were significantly increased (P less than 0.01, 0.05, and 0.05, respectively) and the increases in total clearance and tidal volume observed during exercise were significantly correlated (P less than 0.05). In contrast, no significant change was found in pulmonary mechanics. These results show that prolonged intensive exercise induces an increase in epithelial permeability, which appears to be related to the mechanical effects of sustained increased ventilation. Because no change was evidenced in pulmonary volumes or in lung elasticity, our results suggest that this increase may result from alteration of the intercellular tight junctions rather than from a surfactant deficiency.

Adolescent↗
PubMed1989

Chronic thromboembolic occlusion of main pulmonary artery does not reduce the lung clearance of 99mTc-DTPA.

In two patients with chronic unilateral massive pulmonary embolism, we studied the pulmonary epithelial permeability by measuring the clearance of inhaled and deposited 99mTc-DTPA aerosol. The clearances from the embolized lungs with complete or almost complete occlusion of a main pulmonary artery were more rapid than the clearances from the normal lung, which had an increased blood flow. This suggests that in chronic, embolized lung (1) the bronchial flow clears the inhaled solutes, and (2) there is an increase of epithelial permeability.

Adult↗
PubMed1988

Inhaled soluble aerosols insolubilised by lysosomes of alveolar cells. Application to some toxic compounds; electron microprobe and ion microprobe studies.

Our previous investigations have shown that, after systemic injection, certain toxic aluminium, chromium, uranium, and cerium salts are reabsorbed and eliminated by the renal cells by an identical process in which lysosomes play a special role. The elements are precipitated in these organelles in the form of insoluble phosphate due to the activity of acid phosphatase. In this work we have studied the disposition of the same elements after aerosol inhalation of water-soluble particles. The microanalytic methods used, electronic probe and ionic microanalysis, enable the chemical composition of mineral intracellular inclusions and the distribution of elements in the tissues to be determined. The elements studied are precipitated in the lysosomes of alveolar cells (macrophages and type 1 pneumocytes) in the form of insoluble phosphate due to the action of acid phosphatase. These toxic elements do not cross the alveolar-capillary barrier and do not cause any lesion in the organism. Thus a new mechanism for the elimination of hydrosoluble particles has been demonstrated that is of great interest in the overall process of defensive reactions of the organism.

Aerosols↗
PubMed1988

[Aerosol pulmonary scintigraphy. A new test in the diagnostic strategy of pneumocystis carinii pneumonia in patients with acquired immunodeficiency syndrome].

In eleven patients with AIDS and suspected Pneumocystis carinii pneumonia we measured the pulmonary clearance and half-life of aerosolized 99m Tc-DTPA (diethylenetriamine pentaacetate). We correlated the half-life with gallium scans and bronchoalveolar lavages. In all nine patients with Pneumocystis, this half-life was shorter than normal value, documenting a significant increase of lung epithelial permeability (p less than 0.001). Six of these 9 patients had abnormal gallium scans. However, in two patients with normal chest X-rays, PaO2 and gallium scans, only the reduced half-life of 99mTc-DTPA evidenced acute lung disease. After treatment, the results of the DTPA half-life correlated with the presence or absence of Pneumocystis. This method is, therefore, a sensitive initial diagnostic test in patients with suspected Pneumocystis pneumonia. A short half-life should prompt bronchoalveolar lavage even when PaO2 and/or chest X-rays and gallium scans are normal.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Interpretation of the krypton-81m dynamic series: the distribution of a tidal breath.

Lung scans during cyclic breathing of krypton-81m, an isotope with a 13-s half-life, were acquired in "list mode," where both temporal and spatial information are preserved. Subjects in the left lateral decubitus position breathed with two tidal volumes at each of two frequencies. Profiles of total activity over the acquisition period were examined. They showed little effect of frequency or tidal volume on the distribution of air between dependent and non-dependent regions. Dynamic series for ensemble-averaged breaths were constructed. The regional flow per unit volume was shown to correspond to the time derivative of the regional activity of the dynamic series divided by the corresponding activity. Both the relative timing of the gas flow to different lung regions and the flow per unit volume as a function of time were obtained from the dynamic series. The dependent lung was seen to be better ventilated throughout the respiratory cycle except for brief periods at the start of inspiration and the end of expiration. Most of the dead-space gas can be construed to enter and leave the dependent lung.

Female↗
PubMed1987

[Calculation of the ventilation-perfusion ratio in the scintigraphic diagnosis of pulmonary embolism].

Ventilation perfusion scanning fails to diagnose pulmonary embolism in matched defects. In 61 patients (19 with pulmonary embolism proved by angiography, 32 with chronic obstructive lung disease and 10 with acute bacterial pneumonia) we computed the ventilation perfusion ratio (V/Q) in these matched defects, using Krypton 81 m. This analysis demonstrated that the diagnosis of pulmonary embolism could be made with a specificity of 100% when the V/Q ratio was greater than 1.2 in the matched defects. Pulmonary embolism was characterized by a perfusion defect with a high V/Q ratio, even in Laennec infarction. In contrast, the analysis excluded the diagnosis of pulmonary embolism and suggested another disease when the V/Q was less than 0.95 with a specificity of 95%. Perfusion defects in acute pneumonia always had a V/Q less than 1. The diagnosis remained difficult in chronic obstructive lung disease when pulmonary embolism was suspected on subsegmental defects. Nevertheless this could be solved in about 50% of the cases by quantitative analysis. We feel, therefore, that ventilation perfusion scanning should be quantified by V/Q analysis to improve the diagnosis of pulmonary embolism.

Adult↗