Improving the accuracy of nitrogen estimates from nonpoint source in a river catchment with multi-isotope tracers.

Climate change can affect precipitation patterns, temperature, and the hydrological cycle, consequently influencing the dynamics of nitrogen (N) within aquatic ecosystems. In this study, multiple stable isotopes (15N-NO3/18O-NO3 and 2H-H2O/18O-H2O) were used to investigate the N sources and flowpath within the Bogang stream in South Korea. Within the vicinity of the stream with complex land use where various N sources were present, four end-members (rainfall, soil, sewage, and livestock) were sampled and examined. Consequently, spatial-temporal variations of the N sources were observed dependent on the type of land use. During the dry season, sewage accounted for the dominant N source, ranging from 62.2 % to 80.2 %. In contrast, nonpoint sources increased significantly across most sites during the wet season (10.3-41.6 % for soil; 6.3-35.2 % for livestock) compared to the dry season (7.7-28.5 % for soil; 6-13.2 % for livestock). However, sewage (78.7 %) remains dominant, representing the largest ratio at the site downstream of the wastewater treatment plant during the wet season. This ratio showed a notable difference from the calculated N loading ratio of 52.2 %, especially for livestock. This suggests that a significant potential for N legacy effects, given that groundwater flow is likely to be the primary hydrological pathway delivering N to rivers. This study will help to develop water resource management strategies by understanding how the interaction between N sources and hydrological process responds to climate change within sub-basins.

Identification of nitrate sources in tap water sources across South Korea using multiple stable isotopes: Implications for land use and water management.

Stable nitrate isotopes (δ15N-NO3 and δ18O-NO3) in conjunction with stable water isotopes (δ18O-H2O and δD-H2O) were used to identify nitrogen (N) sources and N-biogeochemical transformation in tap water sources sampled from 11 water purification plants across South Korea. The raw water sources are taken from rivers within the water supply basins, which indicates the quality of tap water is highly dependent on surrounding the land use type. We estimated the proportional contribution of the various N sources (AD: atmospheric deposition; SN: soil nitrogen; CF: chemical fertilizer; M&S: manure/sewage) using Bayesian Mixing Model. As a result, the contribution of N sources exhibited large seasonal and spatial differences, which were related to the type of land use in the water supply basins. Commonly, the M&S and SN were the dominant N source during the dry and wet seasons in almost regions, respectively. However, in the regions with high N loading ratios from urban and industrial sources, the M&S was the dominant N source during both the wet and dry seasons. In addition, the regions were characterized by high NO3- concentrations due to the decreased dilution effect of precipitation during the dry seasons. In contrast, the SN was the dominant N source in the regions with high N loading ratios from agricultural areas during both the wet and dry seasons. The NO3--N concentration during the wet season was significantly higher than those during the dry season in these regions due to the input of non-point sources with high concentrations. Meanwhile, denitrification and nitrification were observed in the watersheds. It is important to understand the isotope fractionation due to N-biogeochemical transformation for considering the potential misinterpretations of the origin and fate NO3-. Collectively, our findings provide a basis on N source control strategies to ensure tap water quality in complex land use areas.

A case report of ovarian granulosa cell tumor in patient with polycystic ovarian syndrome.

RATIONALE: Granulosa cell tumors (GCTs) account for less than 2% of all ovarian malignancies and are the second most common ovarian sex cord stromal tumors after fibroma/thecomas.GCTs occur most frequently in postmenopausal women with a peak age of 50 to 55, are usually diagnosed in their early stages, and have a good prognosis. GCTs usually present with features of hyperestrogenism, with an average size is 10 to 15 cm. PATIENT CONCERNS: A 31-year-old nulligravida diagnosed with polycystic ovarian syndrome (PCOS) 10 years prior, had a 20-mm mass in her right ovary found on ultrasonography 2 years ago. She had been taking dienogest 2 mg for 2 years for a misdiagnosed endometrioma, but over a 2-year course, the mass increased to 50 mm. DIAGNOSES: An ultrasound scan revealed a 47 × 37-mm round solid mass in the right ovary with a spongiform appearance and little vascularity. The pathologic findings showed an adult-type granulosa cell tumor with necrosis and hemorrhage. The tissue stained positive for inhibin-α, Wilms' tumor-1, CD56, and negative for cytokeratin 7. INTERVENTIONS: We finally performed right salpingo-oophorectomy, endometrial biopsy, peritoneal biopsy, and partial omentectomy. The pathological findings were adult-type granulosa cell tumor. The International Federation of Gynecology and Obstetrics staging was IA. The patient did not require additional treatment. OUTCOMES: Surprisingly, her normal menstruation returned 2 weeks after the operation, and she had a normal pregnancy and parturition. The patient had been followed-up regularly for 3 years following the surgery. The patient has not experienced any complications and has remained disease-free. LESSONS: GCTs should be considered in the differential diagnosis if a female patient with PCOS and amenorrhea shows a unilateral small solid mass. They are extremely rare malignant ovarian tumors that must be differentiated from other benign ovarian tumors, especially endometriomas and dermoid cysts. It was difficult for us to suspect a granulosa cell tumor because the patient already had PCOS symptoms such as mild hirsutism and amenorrhea. This case highlights the importance of physicians being aware of and suspicious for GCTs in similar cases, along with knowing their characteristics in considering possible differential diagnoses.

Diagnostic performance of interferon-gamma release assay for diagnosis of tuberculous pericarditis: A meta-analysis.

BACKGROUND: The diagnosis of tuberculous pericarditis is difficult to set, not only for its non-specific clinical presentation, but also for the lack of useful diagnostic tests. We comprehensively evaluate the overall diagnostic accuracy of Interferon-gamma release assays (IGRA) upon tuberculous pericarditis by meta-analysis. METHODS: We searched PubMed, Embase and Cochrane Library database from the earliest available date of indexing through April 30, 2019. The study quality was evaluated using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS2) checklist. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-) and constructed summary receiver operating characteristic curves parameters. RESULTS: Across six results from five studies (415 patients), the pooled sensitivity for IGRA methods was 0.94 (95% confidence interval [CI]; 0.87-0.98) with heterogeneity (χ2  = 69.9, P = .01) and a pooled specificity of 0.94 (95% CI; 0.75-0.94) without heterogeneity (χ2  = 41.1, P = .13). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 16.8 (95% CI; 8.0-35.4) and negative likelihood ratio (LR-) of 0.06 (95% CI; 0.03-0.13). The pooled diagnostic odds ratio was 278 (95% CI; 114-6806). CONCLUSIONS: Interferon-gamma release assays demonstrated good sensitivity and specificity for diagnosis of tuberculous pericarditis. At present, the literature regarding remains the use of IGRA for diagnosis of tuberculous pericarditis still limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of IGRA test for the diagnosis of tuberculous pericarditis.

Presence, molecular characteristics and geosmin producing ability of actinomycetes isolated from South Korean terrestrial and aquatic environments.

The unpleasant odor of drinking water is one of the major problems in many water utilities in the world. Actinomycetes have long been associated with odorous compounds. Considering the paucity of research on Actinomycetes producing odorous compounds in South Korea, presence of Actinomycetes, their molecular characteristics and ability to produce odorous compounds were investigated in this study. Findings confirmed the presence of Actinomycetes in surface soil, sediment, and water samples from four sites: two artificial lakes [Paldang and Cheongpyeong (CP)], and two streams [Gyeongan (GA) and Yangpyeong]. Surface soil and sediment from CP area had the greatest concentration of Actinomycetes (8.2 x 10(7) and 6.8 x 10(6) colony forming units (CFUs)/gram, dry weight, respectively). When water samples are considered, samples from GA had the highest concentration (1.9 x 10(2) CFU/mL). 16S rRNA sequencing and molecular phylogenetic analysis showed that Streptomyces was the dominant genus (64.1%). In addition, the isolated Actinomycetes synthesized 5.4 ng/L geosmin as demonstrated by thermal desorption unit-gas chromatograph/mass spectrometry analysis.