Computerized equipment for the delivery of inhaled doses of solid particles in specific bronchial challenge.

An apparatus to generate solid particles was tested for use in diagnosing occupational asthma. This equipment measures the inhaled dose of dry particles during specific inhalation challenge. It includes an aerosol generator, a cyclone type particle size selector, and an inhalation chamber to which a patient breathing at tidal volume can be connected for the test. It is fully controlled by a standard personal computer in automatic mode, acting on the flow rate and the aerosol generator to maintain the concentration at a fixed value, usually 3 mg/m3. The dose of aerosol delivered to the patient was calculated from the aerosol concentration, and the inhaled volume was calculated by integration of the corresponding signals. The coefficient of variation for this measurement was estimated to be 12%. The mass median aerodynamic diameter (MMAD) of aerosol inside the inhalation chamber was measured for three substances: lactose, wheat flour, and buckwheat flour. The MMAD of the aerosol inside the chamber was also estimated from the particle size distribution of the raw powder. The relative difference between the measured MMAD and the calculated value was less than 15%. The corresponding relative difference between the measured geometrical SD and the calculated value was found to be less than 26%.

Inducibility of the 70 kD heat shock protein in peripheral blood monocytes is decreased in human acute respiratory distress syndrome and recovers over time.

The heat shock/stress proteins (HSP), and, in particular, the inducible, cytosolic Hsp70, represent an extremely conserved response to many different cellular injuries, including reactive oxygen species (ROS). Hsp70 has been shown to confer to cells and tissues protection against the deleterious effects of ROS or cytokines, both in vitro and in animal models of acute respiratory distress syndrome (ARDS). We hypothesized that Hsp70 expression levels in peripheral blood monocytes (PBM) of patients with ARDS, would correlate with disease severity. We prospectively included 13 patients with previous ARDS (50 +/- 17 yr; range, 20 to 76 yr), nine ventilated patients with non-ARDS/ALI disease (45 +/- 20 yr; range, 19 to 76 yr), and 14 healthy volunteers (45 +/- 20 yr; range, 22 to 77 yr). PBM activation state was evaluated according to their membrane expression of CD16, and oxidative status according to plasma lipid peroxidation products. Both baseline expression and Hsp70 inducibility (after in vitro heat shock) were examined in PBM, using flow cytometric analysis. We found that basal expression of Hsp70 in PBM was similar for patients and control subjects, whereas Hsp70 inducibility- a reflection of the ability to mount a stress response-was significantly reduced in the patients with ARDS (p = 0. 02). Among all correlation analyses we considered between Hsp70 inducibility on the one hand, clinical and laboratory biomarkers for disease severity and outcome in the patients with ARDS on the other, only the duration of ventilatory support was significant (p < 0.003). As an approach to distinguish between disease and ventilation, we also analyzed a group of, ventilated patients without ARDS. Our results indicate that in patients with ARDS, Hsp70 inducibility in PBM is decreased, but it recovers over time with duration of ventilatory support.

HLA class II polymorphism in cystic fibrosis. A possible modifier of pulmonary phenotype.

Evolution of lung damage is highly variable in cystic fibrosis (CF) even in patients with the same cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The analysis of genetic factors other than CFTR may help our understanding of genotype-phenotype relationships in CF. As human leukocyte antigen (HLA) class II polymorphism has been associated with a number of diseases including autoimmune and inflammatory diseases, asthma, and allergy, we investigated the possibility that HLA polymorphism contributes to CF-associated pulmonary inflammation. Among the 98 adult CF patients tested, the genotypic frequencies of DR4 and DR7 alleles (serologic group DR53) and DR7/ DQA*0201 haplotype were higher than in 39 selected control subjects without atopy (p

[Occupational asthma caused by buckwheat flour]. / Asthme professionnel à la farine de sarrasin.

Buckwheat flour, mainly used for pancakes, may induce asthma following inhalation and anaphylactic reactions following ingestion. These allergic reactions are mediated by specific IgE and may be confirmed by skin test and radio-allergo-sorbent test. The occupational asthma of a patient working in pancake restaurant was confirmed by specific challenge test with a computerised device to generate particles. A very small amount of buckwheat flour (10 micrograms) induced an immediate fall of the FEV1 to 56% of the initial value. No bronchial reaction was observed with lactose nor with wheat flour. Specific bronchial challenge identifies the allergen responsible for asthma, measures the level of sensitization and thus can prevent the occupational exposure.

Stability of brain content of magnesium in experimental hypomagnesemia.

Magnesium is important in cerebral function. If there is a deficiency and neurological symptoms accrue, we hypothesised that Mg2+ deficiency causes neurological symptoms by decreasing the level of Mg2+ in cerebral tissue. The content of magnesium was determined in 12 brain structures in magnesium-deficient rats. Experiments were carried out for 40 days in two groups of Wistar male rats made magnesium-deficient (MD) by a well-controlled diet (50 mg of Mg2+/kg of food), and a control group (CG) rats fed normal diet (1 g of Mg2+/kg of food). At the end of the 40 days, the clinical signs of hypomagnesemia were sought in the MD rats and Mg2+ concentration levels were measured in the blood and brain. The results showed variable distribution of Mg2+ in the different brain structures, both in CG and MD rats; in the MD rats there is an important stability of global Mg2+ content of the brain. Although the global values for Mg2+ in the brain did not decline in MD rats, there was a significant decrease in Mg2+ in the brainstem. We conclude that the brain is able to maintain a stable concentration of Mg2+ during chronic hypomagnesemia, but its topographic variations could account for some of neurological signs accompanying this condition.

Reproducibility of thermodilution cardiac output determination in critically ill patients: comparison between bolus and continuous method.

OBJECTIVE: A semi-continuous thermodilution method (CCO) was recently developed to measure cardiac output with less risk of bacterial contamination, fluid overload, and user-induced errors than the classical bolus technique (BCO). Previous comparison between these two methods showed negligible bias. However, large limits of agreement suggest that the two methods are not interchangeable. We hypothesized that this poor agreement may be due to differences in reproducibility. METHODS: In 23 critically ill patients, 369 paired measurements of CCO and BCO were compared (range of cardiac outputs: 2.8 to 16 L/min). The reproducibility of BCO and CCO methods was evaluated on a sample of 205 and 209 determinations, respectively. RESULTS: The comparison between the CCO and the BCO methods confirmed previous results: i.e., small bias (-0.39 L/min) and large limits of agreement (-2.06 to +1.28 L/min). Reproducibility showed no bias for either the CCO or the BCO method. Limits of reproducibility agreement between repeated determinations were approximately 50% less for CCO than for BCO method: respectively -0.87 to +0.82 L/min for the CCO method and -1.56 to +1.37 L/min for the BCO method. Consequently, the threshold necessary to ascertain that the difference between two measurements was not due to the internal variability of the method (3 x SEM) was 0.39 for the CCO method and 0.75 L/min for the BCO method. CONCLUSION: Differences in reproducibility may explain the poor agreement between the CCO and BCO methods. The better reproducibility of the CCO method allows the detection of smaller variations in cardiac output and suggests the superiority of this new method.

[Maximal ventilatory pressure through the mouth in adults: normal values and explanatory variables]. / Les pressions ventilatoires maximales à la bouche chez l'adulte: valeurs normales et variables explicatives.

Mouth pressure measured during maximal inspiratory or expiratory efforts depends on the force exerted by ventilatory muscles. Normal values and anthropometric factors accounting for maximal inspiratory and expiratory pressures (MIP, MEP) are not fully agreed upon to date. We measured MIP and MEP in 253 normal subjects (135 females and 118 males, age 15-59 years) using a digital transducer (163 Sibelmed). All subjects had normal forced vital capacity (FVC) and one second forced expiratory volume (FEV1). Sex, age, height and weight were recorded for all subjects and were entered as independent variables in computation of linear multiple regressions with MEP or MIP the dependent variables. MEP and MIP were greater in males than in females (p less than 0.01) with MIP lower than MEP in both sexes (p less than 0.01). In both males and females, FVC and FEV1 depend on age and height (p less than 0.01). In the entire group, we found a correlation of MIP in females and MEP in males with age (p less than 0.01) and of both MIP and MEP in females with weight (p less than 0.01). However, in subjects aged 20-59 years, there was no significant dependence of MIP and MEP on age, and when the weight of subjects was normal (n = 170), MIP and MEP were independent of weight. We conclude that in adults aged 20-59 years and with normal weight, maximal ventilatory pressures depend solely on sex. In this subgroup mean (+/- SD) values of MEP and MIP were 111 +/- 25 cmH2O and 79 +/- 19 cmH2O respectively in females and 192 +/- 42 cmH2O and 117 +/- 25 cmH2O in males.