Woon-Seok Cho

Self-organizing map and species abundance distribution of stream benthic macroinvertebrates in revealing community patterns in different seasons

Abstract Benthic macroinvertebrates are considered to be one of the most representative taxa in assessing the ecological integrity of aquatic ecosystems. Data for benthic macroinvertebrates collected using the Surber sampler were used for analysis at different sampling sites across different levels of pollution. Species Abundance Distribution (SAD) and Self-Organizing Map (SOM) were utilized in combination to reveal both consistency and variability in community compositions under natural and anthropogenic conditions. According to the SOM benthic macroinvertebrates were clustered in different season groups (e.g., “summer”, “autumn–winter”) at the less polluted site. SADs of the sampled communities, however, were overall stable across different seasons except the period from late spring to summer (i.e., low level of abundance for the mid-ranked species in SADs) due to heavy rainfall in the Monsoon climate. Along with increase in degree of pollution, seasonality deceased for both SOMs and SADs. In all seasons, the SAD curves were fitted to a lognormal distribution for the less polluted site while the polluted site was in accordance with a geometric series. The parameters in the SAD models were not significantly different across different seasons. Species in the highest ranks in the SADs were persistently dominant regardless of seasons, while densities of the mid-ranked species were variable in different seasons at the less and intermediately polluted sites. At the severely polluted site a few selected tolerant species showed high densities persistently and variability of densities in different seasons was minimized. Species groups clustered using the SOM also presented stronger persistence in SADs, and were feasible in addressing diverse patterns of species composition and in outlining species associations presented in different sampling sites through ordination and clustering. The combined use of SOM and SAD is highly be suitable in presenting community properties and ecological integrity in stream ecosystems in response to natural variability and anthropogenic disturbances.

Inferring community properties of benthic macroinvertebrates in streams using Shannon index and exergy

Definition of ecological integrity based on community analysis has long been a critical issue in risk assessment for sustainable ecosystem management. In this work, two indices (i.e., Shannon index and exergy) were selected for the analysis of community properties of benthic macroinvertebrate community in streams in Korea. For this purpose, the means and variances of both indices were analyzed. The results found an extra scope of structural and functional properties in communities in response to environmental variabilities and anthropogenic disturbances. The combination of these two parameters (four indices) was feasible in identification of disturbance agents (e.g., industrial pollution or organic pollution) and specifying states of communities. The four-aforementioned parameters (means and variances of Shannon index and exergy) were further used as input data in a self-organizing map for the characterization of water quality. Our results suggested that Shannon index and exergy in combination could be utilized as a suitable reference system and would be an efficient tool for assessment of the health of aquatic ecosystems exposed to environmental disturbances.

Isolated Acute Appendicitis Caused by Aspergillu s in a Patient Who Underwent Lung Transplantation: A Case Report

Invasive aspergillosis is an important cause of morbidity and mortality in patients who have undergone lung transplantation. Aspergillus infections usually involve the respiratory tract, with vascular invasion and subsequent dissemination. However, acute appendicitis associated with localized aspergillosis is rare, especially among patients who have undergone prophylaxis with voriconazole. We present a case of primary Aspergillus appendicitis diagnosed by histologic examination in a patient who underwent lung transplantation. A 51-year-old woman with dermatomyositis underwent lung transplantation for acute interstitial pneumonitis. According to our institutions protocol, the patient was treated with immunosuppressive therapy and prophylaxis with voriconazole, ganciclovir, and trimethoprim sulfamethoxazole during the post-transplantation period. Twenty-eight days after transplantation, the patient developed mild abdominal pain and paralytic ileus. There was no apparent infection sign. Abdominal computerized tomography indicated a wall defect of the appendix with multifocal fluid collection, mesenteric leave thickening, and pneumoperitoneum. These findings were consistent with perforated appendicitis, and the patient underwent an appendectomy. The histopathology examination of the resected appendix showed inflammation and abscess. Periodic acid-Schiff-positive and Grocott-Gomori methenamine silver-positive fungal hyphae with acute-angle branching were observed, demonstrating muscular invasion. A galactomannan antigen test obtained on the same day had negative results. The trough level of voriconazole was well maintained and was subsequently adjusted through monitoring of circulating drug concentration. Simultaneously, other potential sites of disseminated Aspergillus were considered and examined, but no other site of systemic Aspergillus infection was detected. Voriconazole treatment was maintained for 3 months, and no aspergillosis relapse or other invasive fungal infections were observed.