The characterization of PCDDs, PCDFs and coplanar PCBs during the past 50 years in Gwangyang Bay, South Korea.

The PCDD/DFs and coplanar PCBs (co-PCBs) in sediment samples from Gwangyang Bay in South Korea was investigated. The total concentration of dioxins and their toxic equivalent quantity (TEQ; calculated with the WHO 2005 Toxic Equivalency Factors) value in the surface sediment of the outer site (261 pg g(-1) TOC, 4.4 pg-TEQ g(-1)) were 3-fold higher than the inner site (90 pg g(-1) TOC, 1.1 pg-TEQ g(-1)) in the Bay. The dioxin in the sediment samples was found to come from a mixture of the impurities of pentachlorophenol (PCP), chloronitrofen (CNP) and combustion based on the result of hierarchical cluster analysis (HCA). These dioxin sources have been influenced by the characterization associated with this region which was both an agricultural-centered and industrial-centered area. According to principal component analysis (PCA) related to the Kow values for the congener-specific composition of co-PCBs in the sediment core, the Kanechlor (KC)-500 and the atmospheric deposition were identified as the possible sources. The maximum burden in the sediment core was 1.3 kg for 1967-1974 and the total burdens of PCDD/DFs and co-PCBs in the sediment core were estimated to be 6.6 kg during the past 50 years. The cumulative burdens of dioxin are still increasing in Gwangyang Bay.

Physiological comparison of the longitudinal and circular muscles of the pregnant rat uterus.

A comparative investigation of the longitudinal and circular muscles in the pregnant rat uterus (10-15 days) was made by means of electrical and mechanical recordings. The response of the circular muscle strip was characterized in the following respects: application of stretch caused acceleration of spontaneous activity that was greater in extent than in the longitudinal muscle strip; tetanic contraction was not produced by repetitive stimuli in the range of 0.1-5 Hz; slow potential was dominant in the circular muscle cells. The longitudinal contraction of the uterine segment occurred in synchronization with the change in the intraluminal pressure. Either the longitudinal stretch or the increase in the intraluminal volume caused the acceleration of synchronized activity. Stimulation of the longitudinal muscle caused membrane response in the circular muscle cells and vice versa, suggesting electrical interference between longitudinal and circular muscle cells.

Adenovirus isolation from spleen lymphocytes of apparently healthy pigs.

A polyethylene glycol treatment was given to fuse KSEK6 cells, an established cell line derived from porcine embryo kidney, with the lymphocytes, separated from spleens of 35 apparently healthy slaughtered pigs. Eight cytopathic virus strains were isolated from the lymphocytes of these pigs. Two virus strains were isolated by inoculating the spleen tissue homogenates to KSEK6 monolayer cultures. All of viruses were identified as porcine adenoviruses according to their physicochemical, serological and immunological properties. One of these virus strains was serologically proved to be independent from six serotypes of porcine adenoviruses ever known. The electrophoretic property of viral DNA of this strain was indicated to be different from those of other reference porcine adenoviruses. This means the presence of a 7th serotype in porcine adenoviruses.

Influences of sodium and calcium on the recovery process from potassium contracture in the guinea-pig taenia coli.

1. In the guinea-pig taenia coli, influences of Na and Ca ions on the recovery process from the K contracture were investigated. In the absence of Na ion (sucrose-Krebs solution), the K contracture did not recover when the external K (143 mM) was returned to the normal concentration (5.9 mM), although the membrane was repolarized to normal resting potential.2. After reducing the external K concentration to normal, the addition of Na rapidly terminated the contracture. About 5 mM-Na was enough to produce the relaxation, but the rate of relaxation was slower the lower the Na concentration.3. Lithium could substitute for Na in the relaxation, but Tris-hydroxymethyl aminomethane could not. The possibility of a chloride contribution was excluded.4. Ouabain (2 x 10(-6) g/ml.) and K removal reduced the rate of relaxation by Na ion only slightly. Lowering the temperature also had a small effect, having a Q(10) of about 1.4. Therefore, the Na-K pump may not be involved in this process, but a physical process seems responsible.5. The contracture in K-Krebs solution and in sucrose-Krebs solution was dependent on the external Ca concentration suggesting a high Ca permeability of the membrane. When sucrose was isosmotically replaced with Mn, Mg, La or Ca ions the relaxation was produced with a relatively fast speed in the absence of external Na ions.6. These results may be explained by assuming that external Na ions are involved in decreasing the Ca permeability of the membrane and in reducing the intracellular Ca concentration by Na-Ca exchange, energy for which is supplied by Na influx. In the relaxation by polyvalent cations, suppression of the Ca permeability is probably the main factor.

The effects of glucose concentration on early embryogenesis using the whole embryo culture system on rats.

In order to investigate the effect of hyperglycemia on fetal teratogenesis, rat embryo culture was performed according to the method of New et al. The effect of hyperglycemia was then studied at glucose concentrations of 300, 600, 900 and 1,200 mg/dl in the medium. The embryos from the high glucose medium (600 mg/dl) had significantly shorter CRLs and fewer somites. Major anomalies characterized by neural lesions and minor anomalies characterized by extraneural lesions increased as the glucose concentration increased. However, fetal growth was promoted with statistical significance in the medium with 300 mg/dl of glucose, where the incidence of malformations remained unchanged as compared to the control group. The findings indicate that the glucose is one of the substantial compounds which influences embryo growth, development and abnormalities, but glucose alone appears to have no major effect on early embryogenesis in diabetic pregnancy.