Biomedical subjects

R J Dandurand

Publications and source records attributed to R J Dandurand.

11 recordsLinked to original sources

PubMed1998

Differential responses of pulmonary arteries and veins to histamine and 5-HT in lung explants of guinea-pigs.

1. The mechanisms by which histamine and 5-HT differentially contract pulmonary arteries and veins are unclear. In lung explants from 26 guinea-pigs, we compared responses of pulmonary arteries and vein to histamine, 5-HT and KCI, and examined potential determinants for the differential responses. Lungs were filled with agarose, sectioned into approximately 1 mm thick slices, and vascular luminal areas measured by image analysis. 2. Histamine and 5-HT produced a concentration-dependent constriction in arteries and veins, greater in the latter. KCl constricted arteries and veins equally. 3. The histamine H1 antagonist chlorpheniramine (10(-4) M) abolished contractions to histamine; the H2 antagonist cimetidine enhanced maximal responses and sensitivity of arteries and veins to histamine, and diminished the differences between their maximal responses; the NO synthase inhibitor Nomega-nitro-L-arginine (L-NOARG) increased the maximal responses of arteries and veins, and the differences between their responses; indomethacin had no effect. 4. Contractions to 5-HT were abolished in arteries and markedly reduced in veins by the 5-HT2 antagonist ketanserin (10(-4) M); L-NOARG potentiated the maximal responses of arteries but not of veins; indomethacin increased the maximal responses of arteries but reduced them in veins. 5. By morphometry, arteries had a greater medial thickness and luminal diameter than veins. 6. The data suggest that in guinea-pigs, H2 receptors are responsible for the differential contractile responses of pulmonary arteries and veins to histamine, whereas endothelium-derived vasoactive substances are responsible for their differential contractile responses to 5-HT.

Animals↗

PubMed1998

Local cytokine messenger ribonucleic acid expression and in vitro allergic late phase responses in Brown-Norway rats.

The events subsequent to antigen challenge in allergic asthmatics involve the synthesis of pro-inflammatory cytokines. However, little is known how cytokine gene activation prior to allergen challenge may influence this series of events, nor how cytokine gene expression is related to antigen-induced alterations in lung function. Using a novel in vitro explant technique, we hypothesized that the local expression of cytokines influenced the development of antigen-induced late-onset airway responses, and that alterations in cytokine messenger ribonucleic acid (mRNA) expression were associated with antigen-induced changes in airway luminal area. Explants were prepared from excised lungs of ovalbumin-sensitized Brown-Norway rats. Airways were challenged by direct application of ovalbumin or an irrelevant control antigen. Cryostat sections of explants were used for in situ hybridization and mRNA for interleukin (IL)-2, IL-4 and interferon (IFN)-gamma were detected using radiolabelled probes. We found that the presence of high numbers of cells expressing IFN-gamma and IL-2 mRNA within the airways attenuated the development of antigen-induced late airway responses in sensitized rat lung explants. Furthermore, we observed that cytokine mRNA for IL-4 was significantly increased following allergen exposure in sensitized lung explants exhibiting late airway responses. This study implicates the local expression of interferon-gamma and interleukin-2 messenger ribonucleic acid in the failure of sensitized rat lung explants to exhibit late airway responses, and provides evidence linking local interleukin-4 messenger ribonucleic acid expression to the sequelae of events occurring as a result of antigen exposure within the airways.

Animals↗

PubMed1997

In vitro bronchial responsiveness in two highly inbred rat strains.

We investigated methacholine (MCh)-induced bronchoconstriction in explanted airways from Fischer and Lewis rats. Lung explants, 0.5- to 1.0-mm thick, were prepared from agarose-inflated lungs of anesthetized 8- to 12-wk-old male rats. After overnight culture, videomicroscopy was used to record baseline images of the individual airways. Dose-response curves to MCh were then constructed by repeated administration of MCh; airways were reimaged 10 min after each MCh administration. Airway internal luminal area (Ai) was measured at successive MCh concentrations from 10(-9) to 10(-1) M. In addition to the effective concentration leading to 50% of the achieved maximal response, we also determined the effective concentration leading to a 40% reduction in Ai. Both the effective concentration leading to 50% of the achieved maximal response and the concentration leading to a 40% reduction in Ai were significantly lower among Fischer rat airways (P < 0.05). Airway closure was more common among Fischer rat airways (17%) than among those of Lewis rats (7.5%). Responsiveness of Fischer rat airways was more heterogeneous than among Lewis airways; a larger number of Fischer rat airways exhibited high sensitivity to MCh. There was no relationship between responsiveness and baseline Ai in either strain. In a second experiment, we measured the rate of contraction of explanted airways from lungs inflated to 50, 75, and 100% of total lung capacity. The average rate of contraction in the first 15 s was higher in Fischer rat airways at each inflation volume. These data indicate that the hyperresponsiveness of the Fischer rat reflects the responsiveness of individual airways throughout the airway tree and are consistent with the notion that in this model hyperresponsiveness is an intrinsic property of airway smooth muscle.

Animals↗

PubMed1996

Evidence for major basic protein immunoreactivity and interleukin 5 gene activation during the late phase response in explanted airways.

Current evidence suggests that the events subsequent to antigen challenge in allergic asthmatics involve eosinophil activation and the synthesis of proinflammatory cytokines, in particular interleukin 5 (IL-5). However, little is known about how local inflammatory cell infiltration and activation are related to the changes in lung function following allergen exposure. We have developed a novel technique to investigate the local inflammatory events during late-onset allergic bronchoconstriction in lung explants from sensitized Brown-Norway (BN) rats. In this study we tested the hypothesis that the in vitro late airway response involves IL-5 gene activation and recruitment and activation of eosinophils. Explants were prepared from excised lungs of BN rats (n = 9) sensitized 2 wk previously to ovalbumin (OVA). Lungs were inflated with liquid agarose solution (2% wt/vol, 48 ml/kg) following perfusion with cold Ca2+/Mg(2+)-free Hanks' solution, and refrigerated briefly to gel the agarose, and 0.5- to 1.0-mm slices were prepared and cultured overnight at 37 degrees C. Airways were identified and challenged by direct application of OVA (20 micrograms). Cryostat sections of explants were immunostained for major basic protein (MBP) and IL-5 mRNA was detected by a 35S-uridine triphosphate-labeled probe and in situ hybridization. Explants harvested immediately prior to challenge showed little evidence of MBP and IL-5 mRNA expression. Explants harvested at 6 h which exhibited evidence of bronchoconstriction showed strong cell-associated immunostaining for MBP and high expression of IL-5 mRNA in the bronchial mucosa. colocalization studies performed in lung explants demonstrating late-onset airway responses suggested that the majority of IL-5 mRNA expression was not found in MBP-positive cells. When compared with explants from sham-sensitized rats (n = 4), there was a significant increase in MBP-positive and IL-5 mRNA-positive cells per millimeter of basement membrane of the airway. The presence of MBP immunoreactivity and IL-5 gene expression was not observed in explants taken from sensitized BN rats which did not undergo late-onset airway responses, indicating an association between inflammatory cell activation and airway constriction. The increase in MBP-positive cells several hours after OVA suggests activation, local recruitment, and/or differentiation of eosinophils. This study provides direct evidence for a temporal association between IL-5 expression, eosinophil infiltration, and the late response in individual cultured airways.

Allergens↗

PubMed1995

Mucociliary function in the mouse measured in explanted lung tissue.

To develop a method for the study of mucociliary clearance in small-caliber airways, we investigated ciliary function in an in vitro lung tissue culture technique in mice. Lungs were excised from 45 anesthetized mice [weight 30.9 +/- 6.2 (SD) g] and inflated with 2% liquid agarose at 37 degrees C via the trachea. After cooling to 4 degrees C, the lungs were cut into 0.5- to 1.0-mm thick slices and cultured overnight. Ciliary beat frequency (CBF) was measured in airways cut in cross section using a computerized image processing system. In some experiments, charcoal particle transport (PT) in tangentially cut airways was also measured. Airway diameter ranged from 0.3 to 0.8 mm. In this preparation CBF was stable over a 3-h period and unaffected by minor pH changes. Both CBF and PT exhibited a linear dependency on temperature. CBF and PT were significantly correlated with each other. CBF at 37 degrees C (18.7 +/- 2.93 Hz) was almost twofold higher than values at 22 degrees C (9.74 +/- 3.11 Hz). Isoproterenol increased CBF in a dose-dependent fashion (50% effective concentration of 10(-6.75) M); the effect of isoproterenol could be blocked by propranolol. Administration of forskolin (10 microM) also increased both CBF and PT significantly. These findings demonstrate the feasibility of measuring the major aspects of mucociliary clearance in this system. This approach holds promise as a technique suitable to the investigation of both the small airways of humans and other large animals as well as of airways in murine genetic models of respiratory disease.

Animals↗

PubMed1995

Mitochondrial disease. Pulmonary function, exercise performance, and blood lactate levels.

Mitochondrial diseases are a heterogeneous group of disorders in which it has been suggested that genetic defects in oxidative phosphorylation lead to specific alterations in exercise performance and lactate metabolism during exercise. To investigate this possibility, we evaluated pulmonary function tests, incremental exercise testing, and serial blood lactate levels in a group of subjects with mitochondrial disease (M) and compared them with a group of patients with nonmitochondrial (N) myopathies and healthy subjects (H). The two groups were demographically comparable and had no significant differences in pulmonary function. Both groups showed similar degrees of reduced exercise tolerance compared with a group of healthy subjects (M: 61.08% predicted VO2max +/- 19.58 SD, n = 13; N: 62.14 +/- 28.89, n = 7; H: 115.17 +/- 19.35, n = 12; p < 0.001). The mitochondrial disease group more frequently showed abnormalities in cardiac response to exercise than did the nonmitochondrial myopathy subjects (M: 12/13, N: 3/7, H: 3/12, p = 0.002). Minute ventilation greater than predicted occurred with similar frequency in both groups. Although resting lactate level was increased in some subjects with mitochondrial myopathy compared with disease controls, there were no differences between groups for peak venous lactate level normalized for oxygen uptake or the rate of lactate clearance. These findings, while confirming the presence of some specific abnormalities in mitochondrial disease, are against the notion that exercise limitation in this condition directly results from specific abnormalities in oxidative metabolism.

Adolescent↗

PubMed1994

In vitro allergic bronchoconstriction in the brown Norway rat.

The ovalbumin (OA)-sensitized Brown Norway rat (BN) demonstrates early-response (ER) and late-response (LR) allergic bronchoconstriction. To determine whether these responses could be replicated in vitro, we studied lung explants from 8-wk-old male BN rats (wt: 239 +/- 28 g), of which 19 were sensitized to OA (test) and 16 served as controls. Two weeks after sensitization, the animals' lungs were removed, filled with a 1% (wt/vol) agarose-containing solution at 37 degrees C, and cooled to 4 degrees C. Transverse slices (0.5 to 1.0 mm thick) were cut and cultured overnight. Airways were visualized with an inverted microscope and baseline images were obtained with a video camera. To study the ER, 40 airways from 15 test rats and 29 airways from 10 control rats were challenged with 2 micrograms OA and imaged each minute for 10 min. To study the LR, 40 airways from 12 test rats and 44 airways from 12 control rats were challenged with 2 micrograms OA and imaged each hour for 8 h. The maximal response (MR) for each airway was defined as the percent of airway closure. The ER and LR were both defined as an MR > or = mean + 2 SD of the controls. An ER occurred in 38 of 40 test and 2 of 29 control airways (mean MR: 42 +/- 24% versus 4 +/- 3%, p < 0.001), and was completely blocked by methysergide pretreatment in 13 airways.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗

PubMed1993

Airway hyperresponsiveness in cigarette smoke-exposed rats.

To investigate the possibility that altered airway-parenchymal interaction may account for bronchial hyperresponsiveness induced by cigarette smoke exposure, we tested the effect of administration of cigarette smoke (SM), elastase (EL), and both SM and EL on airway responsiveness in 41 Long-Evans male rats. Twelve were exposed to 30 puffs of SM for 15 weeks; 8 received a single intratracheal injection of EL (250 IU/kg); 9 received both EL and SM exposure (SE); 12 control rats were exposed to room air (CO). After 15 weeks, animals were anesthetized and mechanically ventilated (Vt = 2.5 ml, f = 80/min). Methacholine (MCh) dose-response curves (DRCs) were constructed by calculating pulmonary resistance (RL) after ultrasonic nebulization of saline followed by doubling concentrations of MCh (0.0625-256 mg/ml). Exposure to cigarette smoking, with or without elastase, led to a significant reduction in body weight and increased total lung capacity (TLC) compared to exposure to CO. However, there was no significant change in static compliance in the experimental groups, despite increased lung volume. The concentration resulting in a doubling of RL (EC200RL) was significantly lower in rats treated with SM (n = 7) than CO (n = 8) (3.3 vs. 56.1 mg/ml, geometric mean, p < 0.01). The concentration at which a maximal RL was achieved was lower in SM than CO, EL, and SE (p < 0.05). To assess the possible influence of airway-parenchymal interaction on responsiveness, we measured RL both at functional residual capacity (FRC) and at a volume above FRC equivalent to 1 tidal volume. RL changed similarly in all groups. Despite similar effects on mechanics of both cigarette smoke exposure and elastase administration, only cigarette smoke-exposed animals exhibited evidence of hyperresponsiveness. In this model cigarette smoke-induced hyperresponsiveness is unrelated to changes in either lung elasticity or airway-parenchymal interaction.

Airway Resistance↗

PubMed1993

Airway-parenchymal interdependence and bronchial responsiveness in two highly inbred rat strains.

To investigate if airway-parenchymal interdependence may account for differing bronchial responsiveness between inbred rat strains, Fisher and Lewis 12-wk-old male rats were anesthetized, tracheostomized, and placed in a pressure plethysmograph. Functional residual capacity, total lung capacity [lung volume at transpulmonary pressure (PL) of 30 cmH2O], and specific compliance were determined and were found to be similar. Rats were paralyzed and mechanically ventilated. Concentration-response curves were constructed by calculating lung resistance (RL) and lung elastance (EL) after nebulization of saline and then doubling doses of methacholine (0.0625-512 mg/ml). In Fisher (n = 8) and Lewis (n = 7) rats RL and EL were again determined at a lung volume corresponding to 2 cmH2O PL above FRC. The doubling, maximal, and half-maximal effective concentrations were determined for RL and EL. The doubling of effective concentrations of RL and EL were significantly less for Fisher rats. Other groups of Fisher (n = 5) and Lewis (n = 5) rats were similarly exposed to three concentrations of methacholine (64, 128, and 256 mg/ml), and determinations of RL and EL were made at lung volume corresponding to PL of 0, 2, 4, and 8 cmH2O. In both groups, Lewis rats exhibited a significant effect of volume on maximal RL and EL, whereas Fisher rats did not. The absence of volume effect on bronchoconstriction in the hyperresponsive Fisher strain is consistent with the hypothesis that altered airway-parenchymal interdependence contributes to bronchial hyperresponsiveness.

Administration, Inhalation↗

PubMed1993

Responsiveness of individual airways to methacholine in adult rat lung explants.

We used a modified adult lung explant technique to directly measure the area of individual airways before and after methacholine (MCh) administration. Lungs were removed from 12-wk-old male Lewis rats under sterile conditions, filled with an agarose-containing solution at 37 degrees C, and cooled to 4 degrees C. Transverse slices (0.5-1.0 mm thick) were cut and cultured overnight. Concentration-response curves to MCh were determined for explant airways from lungs inflated to 25, 50, 75, and 100% total lung capacity (TLC) with a 1.0% agarose solution and to 75% TLC with 0.5 and 2.0% agarose solutions. MCh was added to the medium to achieve final concentrations ranging from 10(-9) to 10(-2) M. Airways were imaged before and 10 min after each increase in MCh concentration with an inverted microscope and video camera, and airway area was determined by computerized image processing. The maximal response (MR) ([1-(minimal area/baseline area)] x 100) and concentration of MCh resulting in 50% MR (EC50) were determined. A total of 217 airways from 3-12 explants per rat constricted in a concentration-dependent manner. Baseline area was larger with both higher lung volumes and agarose concentrations. MR was greatest in the airways from the 25% TLC and 0.5% agarose explants. Although there was considerable heterogeneity toward MCh within rats (EC50 varied up to 5.46 x 10(5)-fold), the median EC50 was similar among all rats (range 1.96 x 10(-6)-5.87 x 10(-4) M). Lung inflation volume and agarose concentration affected baseline area and MR, suggesting that airway-parenchymal interdependence mechanisms are operative in this preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Coenzyme Q10 with multiple vitamins is generally ineffective in treatment of mitochondrial disease.

We followed 16 patients with a variety of mitochondrial diseases over one to four periods of treatment (2 months each) with coenzyme Q10 plus vitamins K3 and C, riboflavin, thiamine, and niacin, using independent measures of oxidative metabolism to assess efficacy. There were large (> threefold) increases in serum coenzyme Q10 concentrations with treatment, but no measure of oxidative metabolism showed significant improvement with treatment for the group, nor did any individual patient show significant, reproducible, objective clinical improvement. The results suggest that coenzyme Q10 plus vitamin therapy does not significantly improve mitochondrial oxidative metabolism in patients with mitochondrial disease in general. Any clinical benefit that may follow from short-term administration appears slight.

Adenosine Triphosphate↗