Fractal analysis of alveolarization in hyperoxia-induced rat models of bronchopulmonary dysplasia

Abstract

No papers are available about potentiality of fractal analysis in quantitative assessment of alveolarization in bronchopulmonary dysplasia (BPD). Thus, we here performed a comparative analysis between fractal [fractal dimension (D) and lacunarity] and stereological [mean linear intercept (Lm), total volume of alveolar air spaces, total number of alveoli, mean alveolar volume, total volume and surface area of alveolar septa, and mean alveolar septal thickness] parameters in experimental hyperoxia-induced models of BPD. At birth, rats were distributed between the following groups: 1) rats raised in ambient air for 2 wk; 2) rats exposed to 60% oxygen for 2 wk; 3) rats raised in normoxia for 6 wk; and 4) rats exposed to 60% hyperoxia for 2 wk and to room air for further 4 wk. Normoxic 6-wk rats showed increased D and decreased lacunarity with respect to normoxic 2-wk rats, together with changes in all stereological parameters except for mean alveolar volume. Hyperoxia-exposed 2-wk rats showed significant changes only in total number of alveoli, mean alveolar volume, and lacunarity with respect to equal-in-age normoxic rats. In the comparison between 6-wk rats, the hyperoxia-exposed group showed decreased D and increased lacunarity, together with changes in all stereological parameters except for septal thickness. Analysis of receiver operating characteristic curves showed a comparable discriminatory power of D, lacunarity, and total number of alveoli; Lm and mean alveolar volume were less discriminative. D and lacunarity did not show significant changes when different segmentation thresholds were applied, suggesting that the fractal approach may be fit to automatic image analysis.

Proximal Tubular Development Is Impaired with Downregulation of MAPK/ERK Signaling, HIF-1α, and Catalase by Hyperoxia Exposure in Neonatal Rats

“…Neonatal hyperoxia can cause bronchopulmonary dysplasia [27]. To test the hypothesis that neonatal hyperoxia may disrupt kidney development, a histologic examination was undertaken of kidney samples from the normoxia and hyperoxia groups.…”

IL-17A both initiates (via IFNγ suppression) and limits the pulmonary type-2 immune response to nematode infection

“…Histological sections demonstrated infection-induced injury at d2pi in isotype-treated WT 320 mice, an effect that is almost absent in infected mice depleted of neutrophils. Using lacunarity [33] as an indicator of acute lung injury [34], we show that neutrophil depleted mice show no significant signs of damage ( Fig. 3C).…”

Present and Future of Bronchopulmonary Dysplasia

“…That is why the latest standards for quantitatively assessing lung structure (such as those of the American Thoracic Society/European Respiratory Society) stress the importance of using unbiased stereological methods [115]. The main stereological parameters for assessing alveolarization are: total volume of alveolar air spaces; total number of alveoli; mean alveolar volume; total volume and surface area of alveolar septa; and mean alveolar septal thickness [116][117][118]. Recently, automatically derived parameters have been evaluated in comparison with stereological analysis, demonstrating a comparable efficiency in detecting changes in alveolarization [119], with a fractal approach that may be fit to this automatic analysis [118].…”