Enzyme-linked immunosorbent assay, single radial immunodiffusion, and indirect methods for the detection of failure of transfer of passive immunity in dairy calves

BACKGROUND: Confirmatory tests for failure of transfer of passive immunity (FTPI) in dairy calves require direct measurements of the serum immunoglobulin G concentration. Enzyme-linked immunosorbent assay (ELISA) has advantages over single radial immunodiffusion (SRID) in terms of cost and time. OBJECTIVES: To evaluate the agreement between ELISA and SRID, and to compare the diagnostic performance of ELISA with indirect methods, in the detection of FTPI in calves. ANIMALS: One hundred and fifteen dairy calves (aged 0-10 days) from 23 calf-rearing facilities. METHODS: Prospective, observational study. The agreement between SRID and ELISA was determined by the Bland-Altman method. Fixed bias (SRID - ELISA) was calculated. For comparison of the diagnostic performance of ELISA with indirect methods, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated at cut-off values of 500 and 1,000 mg/dL. RESULTS: The agreement between SRID and ELISA was 94%. Fixed bias (SRID - ELISA) was 140 +/- 364 mg/dL. The AUC and sensitivity of ELISA at the cut-off value of 1,000 mg/dL were higher than those of indirect methods (P<.004). The specificity of ELISA at the cut-off value of 1,000 mg/dL was not higher than that of indirect methods, except for serum total protein concentration assay. CONCLUSION AND CLINICAL IMPORTANCE: ELISA exhibited good diagnostic performance and good agreement with SRID. ELISA is an adequate method for both screening and confirmatory tests for FTPI in dairy calves at the cut-off value of 500 mg/dL.     

Physical and Chemical Properties of a Winter-Time Yellow Sand Event in Northeast Asia

The long range transport of mineral dust such as Yellow Sand (YS) is not restricted to the springtime periods in Northeast Asia. A YS phenomenon was observed during 25～27 January 1999, which was a remarkably distinctive episode in the occurrence time and intensity that had ever been observed in the wintertime in Korea. This YS event had a bi-modal temporal structure with the daily average concentrations of 210～349 µg m^?3. The long-lasted second one followed the first arriving short and strong dust pulse. The dominant ion components were SO₄ ^2?, NO₃ ^?, Ca²⁺ and Na⁺ with the concentration of 11.3, 7.6, 6.1 and 4.2 µg m^?3, respectively during the passage of YS, compared to the corresponding concentrations of 4.1, 4.6, 0.4, and 1.2 µg m^?3 after the passage of YS (AYS) over Korea. The mode diameter of these compounds of YS was around 4 µm, compared to 0.4～0.9 µm of AYS. Concentrations of SO₄ ^2? and NO₃ ^? were found to be highly correlated with that of Ca²⁺ in the coarse mode during the YS event, whereas they were well correlated with NH₄ ⁺ during the non-YS period.     

Enhanced seed production and metabolic alterations in Larix leptolepis by girdling

The demand for Japanese larch (Larix leptolepis) seeds has increased in Korea but their supply has been limited due to sporadic natural seed production. Among the various flower induction techniques, girdling woody stems has been recognized as a simple and efficient method to enhance seed production in a number of conifers. In this study, stem girdling was applied to 42-year-old Japanese larches, resulting in remarkable enhancement of seed cone production with no morphological changes in the seed characteristics. Metabolic alterations in needles of the girdled and the control trees were interrogated by using 23 individual metabolites including soluble sugars, polyamines and amino acids. In the girdled trees, the contents of both soluble sugars and polyamines were higher from June to July and then became similar to those in the control. The levels of amino acids were significantly increased only in August by girdling compared to the non-girdled trees. In control larch trees, the dominant amino acids were changed from Glu and Ala until July to Asp and Tyr in August. Interestingly, the concentrations of Asp-derived amino acids such as Lys, Met and Thr, were increased by girdling and they also showed significant correlations with the number of seed cones per trees, suggesting that the enhanced levels of three amino acids might positively influence on the development of seed cones in girdled larch trees. Although the role of Asp-derived amino acids on enhanced seed cone production remains unclear, the approach presented in this study might provide useful information in elucidating metabolic network modulation induced by girdling and will be further applied for enhanced seed cone production in Japanese larch trees.     

Source identification and assessment of heavy metal contamination in urban soils based on cluster analysis and multiple pollution indices

Purpose

To identify the sources and levels of contamination with anthropogenically derived heavy metals (HMs) for appropriate pollution control. We quantified anthropogenic influences with respect to HM pollution in soil, based on multiple pollution indices and cluster analysis derived from the results of an annual nationwide survey conducted in Korea.

Methods

Contamination levels of HMs in soils were quantitatively evaluated using multiple pollution indices: contamination factor (CF), geo-accumulation index (I_geo), Nemerow’s integrated pollution index (NIPI), and pollution load index (PLI). Hierarchical cluster analysis was conducted to elucidate the correlations between HMs and contamination sources. A total of 2214 HM concentration data including six contamination sources were used to evaluate the pollution state of anthropogenic effects of HMs.

Results

The CFs for Zn and Cu revealed a broad enrichment of these HMs in all pollution sources. Scrap recycling sites (SRS) had the highest likelihood of pollutant distribution in soil surfaces. NIPI and PLI varied with the extent of anthropogenic activities or land use, especially in SRS, waste disposal sites (WDS), transport maintenance sites (TMS), and industrial sites (INS), and anthropogenic sources were divided into three discrete clusters: INS-TMS-LDS (land development sites), SRS-WDS, and vicinities of industrial sites (VIS).

Conclusion

Our results confirmed that soil pollution indices combined with cluster analysis were useful to identify sources of anthropogenic HMs in urban soil, as well as to assess the levels of HM contamination.

     

Acute Toxicity and Sublethal Effects of Nitrite on Selected Hematological Parameters and Tissues in Dark-banded Rockfish, Sebastes inermis

Acute toxicity and sublethal effects of nitrite in dark‐banded rockfish, Sebastes inermis (83.3 ± 7.2 g), were studied under static conditions for a period of 96 h. The acute toxicity of nitrite evaluated for the 96‐h lethal concentration (LC₅₀) was 700 mg/L. The sublethal effects on selected hematological parameters of S. inermis, such as total erythrocyte count (TEC), hemoglobin, plasma glucose, and serum protein content, were measured after 0, 6, 12, 24, 48, 72, and 96 h of exposure to 0, 50, 100, 200, 400, and 700 mg/L of nitrite. Sublethal nitrite caused progressive reduction in the TEC, hemoglobin, and serum protein content in fish depending on the nitrite concentration and exposure period. The 96‐h exposure resulted in a 14–42% reduction in TEC and 25–33% reduction in hemoglobin content for 100–700 mg/L of nitrite compared to the control. A dose‐related reduction in plasma glucose (25.7–34.2%) was observed for concentrations of 200–700 mg/L of nitrite during 48 h of exposure, followed by an increase through 96 h. A significant reduction in serum protein (7.3–12.6%) was observed for 200–700 mg/L of nitrite after 96 h of exposure. Abnormal histological changes in skin, gill, liver, and kidney tissue were observed in fish exposed to 700 mg/L of nitrite after 96 h of exposure compared to the control. Although no mortality of S. inermis occurred at 500 mg/L of nitrite, all hematological parameters adversely responded to a nitrite dose of 200 mg/L for 96 h. These results showed that although acute toxicity concentration of nitrite in S. inermis is higher than 700 mg/L, sublethal concentrations of nitrite also negatively affect hematological parameters.     

Preparation of high molecular weight poly(methyl methacrylate) with high yield by room temperature suspension polymerization of methyl methacrylate

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25 °C by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P_n): 30,900–36,100) and of high yield (ultimate conversion of MMA into PMMA: 83–93 %) with diminishing heat generated during polymerization. The P_n and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.     

Effect of low dissolved oxygen on the oxygen consumption rate and rhythm of the mudskipper Scartelaos gigas (Pisces, Gobiidae)

The mudskipper Scartelaos gigas is expected to experience repeated severe hypoxia in its environment. Hence, we conducted experiments on the oxygen consumption rate (OCR) and OCR rhythm of S.?gigas at low graded dissolved oxygen (DO) levels, without access to atmospheric air, to estimate its tolerance to hypoxia. A dominant circadian OCR rhythm was observed at the control DO level of 6.96?C7.78?mg?O₂/l. This rhythm was unchanged until 2.06?mg?O₂/l, even though the amplitude of the peak was somewhat diminished at 2.06?C2.87?mg?O₂/l. The OCR rhythm amplitude was greatly diminished and the rhythm period was also greatly changed at 1.23?C2.05?mg?O₂/l. Nevertheless, the mean OCR (0.11?ml?O₂/g WW/h) at 1.23?C2.05?mg O₂/l was similar to that of control (0.12?ml O₂/g?WW/h). Thus, the weakness and period change of the OCR rhythm kept the metabolic rate level similar to control. These results suggest that S.?gigas does not have normal metabolic activity at 1.23?C2.05?mg O₂/l but barely manages to endure this DO level as a pre-emergency state. This species could be inhibited under a longer maintenance period at DO level of 1.23?C2.05?mg?O₂/l or still lower. It can be concluded that S.?gigas is quite tolerant to low DO environment and may have a specific strategy for such tolerance.