First Observation of Electron Scattering from Online-Produced Radioactive Target.

We successfully performed electron scattering off unstable nuclei which were produced online from the photofission of uranium. The target ^{137}Cs ions were trapped with a new target-forming technique that makes a high-density stationary target from a small number of ions by confining them in an electron storage ring. After developments of target generation and transportation systems and the beam stacking method to increase the ion beam intensity up to approximately 2×10^{7} ions per pulse beam, an average luminosity of 0.9×10^{26} cm^{-2} s^{-1} was achieved for ^{137}Cs. The obtained angular distribution of elastically scattered electrons is consistent with a calculation. This success marks the realization of the anticipated femtoscope which clarifies the structures of exotic and short-lived unstable nuclei.

Mechanisms of hyperinflation in asthma.

We studied 11 mild asthmatics to verify whether the mechanisms of hyperinflation in asthma could be inhibited or overcome by passively changing lung volumes. On day 1, we induced a fall in forced expiratory volume in one second (FEV1) of 30-60% by methacholine inhalation and measured the resulting increase in FRC (delta FRC). The delta FRC was 729 +/- 378 ml (mean +/- SD). On day 2, with the subject supine in an iron lung, we measured oesophageal (Poes), gastric (Pgas) and transdiaphragmatic (Pdi) pressures, and changes in functional residual capacity (FRC) (delta V) induced by extrathoracic pressures from -20 to +20 cmH2O before and after bronchoprovocation. With positive pressures, the FRC decreased and reached a plateau at 10 cmH2O pressure or higher. This plateau was at a mean FRC of 839 ml higher after the bronchoprovocation than before. Pdi at FRC varied in the same direction as the extrathoracic pressure and was not modified by the bronchospasm. Peak inspiratory Pdi, without pressure applied in the iron lung, increased from 13.6 +/- 5.4 to 28.1 +/- 13.5 cmH2O after methacholine; extrathoracic pressure of -20 cmH2O decreased this latter value to 15.4 +/- 7.3 cmH2O (p less than 0.01). The increased lung volume and the displaced chest wall recoil curve after provocation were not inhibited by positive or negative extrathoracic pressures. Our data show that the mechanisms of hyperinflation are not eliminated or overcome by passively changing lung volumes and support the hypothesis that persisting activity of inspiratory muscles other than the diaphragm during expiration and perhaps a prolonged expiratory time constant are responsible for hyperinflation in asthma.

Bronchial responsiveness to histamine after repeated exercise-induced bronchospasm.

The effects of repeated exercise-induced bronchospasm on nonspecific (nonallergenic) bronchial responsiveness (NSBR) to histamine were studied in 12 asthmatic patients (6 F, 6 M). Baseline NSBR, determined by the provocative concentration of histamine giving a 20% fall in FEV1 (PC20), ranged from 0.41 to 10.2 mg/ml (geometric mean +/- SD: 2.6 +/- 2.5). Each subject performed three consecutive exercises on the ergometer for 6 min at 70% of their VO2 max. Each test was preceded and followed by a histamine inhalation test (HIT). On a control day, 4 HIT were done at 1 h interval, without intercurrent exercise. A significant reduction in histamine responsiveness was observed on control day from the first to the fourth HIT. On exercise day, a mean percent fall in FEV1 of 19.4 +/- 12.9, 16.2 +/- 12.2 and 15.8 +/- 12.7 was observed after the three consecutive exercises but no significant difference could be found between the four PC20 measurements. Four subjects showed refractoriness to the second exercise and no change in the bronchial response to histamine was observed during the refractory period. In conclusion, (1) repeated exercises do not change NSBR; (2) the refractory period after exercise is not due to a change in NSBR, and (3) a tachyphylaxis to histamine occurs in some subjects after repeated inhalations of histamine.

Comparative bronchial responses to hyperosmolar saline and methacholine in asthma.

Airway responsiveness to inhaled methacholine and to ultrasonically nebulised hyperosmolar saline was compared in 20 asthmatic subjects. Each subject had two hyperosmolar inhalation tests and a methacholine challenge in random order at least 48 hours apart over a period of two weeks. Hyperosmolar challenge, carried out with doubling concentrations of saline from 0.9% to 14.4% to obtain a dose-response curve, was well tolerated by all subjects. The response to hyperosmolar saline--expressed as the PO20, the osmolarity inducing a 20% fall in forced expiratory volume in one second (FEV1) was obtained in 16 of the 20 subjects and in each was repeatable to within one doubling concentration of saline. The peak bronchoconstrictor effect of hyperosmolar saline inhalation occurred at 3 minutes and its mean total duration (FEV1 less than 90% of baseline) was 50 minutes. There was no significant correlation between the PO20 and the PC20 methacholine (the concentration inducing a 20% fall in FEV1). Thus by using a new method to obtain a quantitative airway response to inhaled hyperosmolar saline we found that the airway response to hyperosmolar inhalation differs from the airway response to methacholine.

Prevalence and characteristics of late asthmatic responses to exercise.

The prevalence and characteristics of late asthmatic responses to exercise were studied in an adult asthmatic population. Twenty-four subjects (eight male and 16 female), aged 17 to 39 years (mean, 23.7 years), performed a 6-minute exercise on a bicycle ergometer at 75% of their maximum oxygen intake. FEV1 was measured at regular time intervals up to 8 hours after exercise. Seven subjects demonstrated a late asthmatic reaction defined as a fall in FEV1 greater than 10% between 2 to 8 hours. Bronchial reactivity to histamine was unchanged 24 hours after the exercise, compared to baseline. On a control day, a fall in FEV1 similar to the one observed after exercise was induced by methacholine inhalation. Measurements of FEV1 were done at the same time intervals as on exercise day. Neutrophil chemotactic activity was measured in the serum of 15 subjects, on exercise day for early responders, and on the 3 test days for subjects with a dual response. There was no difference between subjects with an isolated early or late response for age, sex, or atopic status. Baseline expiratory flows and nonspecific bronchial reactivity to histamine were similar in both groups. These results demonstrate the occurrence of a late asthmatic response in 30.4% of the population studied. There was no significant change of nonspecific bronchial responsiveness after the late asthmatic response to exercise. No significant increase in neutrophil chemotactic activity could be observed.

Correlation between substratum roughness and wettability, cell adhesion, and cell migration.

Cell adhesion and spreading of chick embryo vascular and corneal explants grown on rough and smooth poly (methyl methacrylate) (PMMA) were analyzed to test the cell response specificity to substratum surface properties. Different degrees of roughness were obtained by sand-blasting PMMA with alumina grains. Hydrophilic and hydrophobic components of the surface free energy (SFE) were calculated according to Good-van Oss's model. Contact angles were determined using a computerized angle meter. The apolar component of the SFE gamma s(LW), increased with a slight roughness whereas the basic component, gamma s-, decreased. The acido-basic properties disappeared as roughness increased. Incubation of PMMA in culture medium, performed to test the influence if the biological environment, allowed surface adsorption of medium proteins which annihilated roughness effect and restored hydrophilic properties. An organotypic culture assay was carried out in an attempt to relate the biocompatibility to substratum surface state. Cell migration was calculated from the area of cell layer. Cellular adhesion was determined by measuring the kinetic of release of enzymatically dissociated cells. A slight roughness raised the migration are to an upper extent no matter which cell type. Enhancement of the cell adhesion potential was related to the degree of roughness and the hydrophobicity.

Tetracycline-inducible gene expression in cultured rat renal CD cells and in intact CD from transgenic mice.

The renal collecting duct (CD) plays a key role in the control of ion and fluid homeostasis. Several genetic diseases that involve mutations in genes encoding for ion transporters or hormone receptors specifically expressed in CD have been described. Suitable cellular or transgenic animal models expressing such mutated genes in an inducible manner should represent attractive systems for structure-function relationship analyses and the generation of appropriate physiopathological models of related diseases. Our first goal was to develop a CD cell line that allows inducible gene expression using the tetracycline-inducible system (Tet-On). We designed several strategies aimed at the development of a tight and highly inducible system in RCCD1 cells, a rat cortical collecting duct (CCD) cell line exhibiting several properties of the native CCD. Analysis of reporter gene expression demonstrated that the Tet-On system is suitable for inducible gene expression in these cells. In a second step, we have tested whether transgenic Tet-On mice expressing the tetracycline transactivator under the control of the human cytomegalovirus promoter were suitable for inducible gene expression in tubule epithelial cells. The results indicate that, in vivo, the inducible expression of the lacZ reporter gene appeared to be restricted to the CD. This particular strain of transgenic mice may therefore be useful for the expression of genes of interest in an inducible manner in the collecting duct.