Wntless regulates dentin apposition and root elongation in the mandibular molar.

Wnt signaling plays an essential role in the dental epithelium and mesenchyme during tooth morphogenesis. However, it remains unclear if Wnt ligands, produced from dental mesenchyme, are necessary for odontoblast differentiation and dentin formation. Here, we show that odontoblast-specific disruption of Wntless (Wls), a chaperon protein that regulates Wnt sorting and secretion, leads to severe defects in dentin formation and root elongation. Dentin thickness decreased remarkably and pulp chambers enlarged in the mandibular molars of OC-Cre;Wls(CO/CO) mice. Although the initial odontoblast differentiation was normal in the mutant crown, odontoblasts became cuboidal and dentin thickness was reduced. In immunohistochemistry, Wnt10a, ß-catenin, type I collagen, and dentin sialoprotein were significantly down-regulated in the odontoblasts of mutant crown. In addition, roots were short and root canals were widened. Cell proliferation was reduced in the developing root apex of mutant molars. Furthermore, Wnt10a and Axin2 expression was remarkably decreased in the odontoblasts of mutant roots. Deletion of the Wls gene in odontoblasts appears to reduce canonical Wnt activity, leading to inhibition of odontoblast maturation and root elongation.

Removal of road deposited sediments by sweeping and its contribution to highway runoff quality in Korea.

Highway runoff is known to be an important non-point source (NPS), increasing the load of pollutants in receiving water. For reducing NPS pollutants in runoff, removal of road deposited sediment (RDS) by sweeping is considered effective. However, the contribution of sweeping to the improvement of runoff quality has not been clearly and quantitatively demonstrated so far. In this study, a field test was carried out on a section of operating highway in Korea to investigate the effectiveness of sweeping on improving the quality of highway runoff. Results showed that the average reduction in the load of RDS by sweeping was 61.10% with a standard deviation of 1.74%. RDS removal efficiency decreased when the sweeping speed increased from 4-8 to 20 km h(-1), the load decreased from 12.5 to 1.25 g m(-2) and particle size decreased from sand to silt/clay size ranges. Runoff was induced by applying a 15 mm h(-1) artificial rainfall to both swept and non-swept sections. Analysis of runoff quality showed that the event mean concentrations of total suspended solid, biological oxygen demand, chemical oxygen demand, nutrients and most of the heavy metals were reduced by 31-87% after sweeping. In addition, field tests for RDS build-up indicated a sweeping frequency of once every four or five days to prevent re-suspension of RDS. The results of this study suggest that sweeping can be the best management practice for effectively reducing RDS on highways and improving the quality of highway runoff.

ß-catenin is required in odontoblasts for tooth root formation.

The tooth root is an important part of the tooth that works together with the surrounding periodontium to maintain the tooth in the alveolar socket. The root develops after crown morphogenesis. While the molecular and cellular mechanisms of early tooth development and crown morphogenesis have been extensively studied, little is known about the molecular mechanisms controlling tooth root formation. Here, we show that ß-catenin is strongly expressed in odontoblast-lineage cells and is required for root formation. Tissue-specific inactivation of ß-catenin in developing odontoblasts produced molars lacking roots and aberrantly thin incisors. At the beginning of root formation in the mutant molars, the cervical loop epithelium extended apically to form Hertwig's epithelial root sheath (HERS), but root odontoblast differentiation was disrupted and followed by the loss of some HERS inner layer cells. However, the outer layer of the HERS extended without the root, and the mutant molars finally erupted. The periodontal tissues extensively invaded the dental pulp. These results indicate that there is a cell-autonomous requirement for Wnt/ß-catenin signaling in the dental mesenchyme for root formation.

Transformation of dissolved organic matter by oxidative polymerization with horseradish peroxidase.

Dissolved organic matter (DOM) has significant influence on the transport and fate of contaminants in multiple phases and it has potential hazard by acting as a precursor of disinfection by-products in water supply. The changes in DOM characteristics, especially by oxidative polymerization might result in different behaviour in the interaction with many contaminants. The aim of this work was to verify the catalytic effects of peroxidase on oxidative polymerization of humic and fulvic substances by examination of the structural characteristics. Transformation of humic acid (HA) and fulvic acid (FA) by oxidative polymerization catalyzed by horseradish peroxidase and hydrogen peroxide were investigated. Size exclusion chromatography, excitation-emission matrices spectra (EEMs), synchronous fluorescence spectra, and infrared spectroscopy was used to evaluate the structural transformation of HA and FA. Molecular weight of HA and FA was continuously changed and their weight-average molecular weight (MWw) reached maximum after 8 h. The MWw of HA and FA were proportionally increased with a dosage of horseradish peroxidase and hydrogen peroxide, indicating that HA and FA was transformed into larger and complex molecules. Spectroscopic results indicated that HA and FA structure contains strong polycyclic aromatic structures with more aromatic rings and a higher degree of conjugation.

Kinetic studies of reductive dechlorination of chlorophenols with Ni/Fe bimetallic particles.

The catalytic dechlorination of five chlorophenols, by Ni/Fe bimetal was investigated through batch experiments. The results showed that the destruction of chlorophenols by hydrodechlorination over Ni / Fe was very effective and followed the pseudo-first-order kinetics under aqueous conditions. The order of reaction rate was 2-chlorophenol > 4-chlorophenol > 2,4-dichlorophenol > 2,4,6-trichlorophenol > 2,6-dichlorophenol (2,6-DCP). The dechlorination rate of chlorophenol increased linearly with increasing nickel coating on iron. In general, increasing the degree of chlorine substitution on the phenol ring decreased the rate of dechlorination except for 2,6-DCP. Chlorophenols were dechlorinated to phenol via both stepwise as the major pathway and concerted mechanisms with minor contribution. The relative contribution of each reaction pathway is discussed through a model fitting.

Determination of first flush criteria using dynamic EMCs (event mean concentrations) on highway stormwater runoff.

Recently the Ministry of Environment in Korea has developed the total maximum daily load program in accordance with the target pollutant and its concentration goal on four major large rivers. Since the program is largely related to regional development, nonpoint source control is both important and topical. Of the various nonpoint sources, highways are stormwater intensive land uses since they are impervious and have high pollutant mass emissions from vehicular activity. The event mean concentration (EMC) is useful in estimating the loadings to receiving water bodies. However, the EMC does not provide information on the time varying changes in pollutant concentration or mass emissions, which are often important for best management practice development, or understanding shock loads. Therefore, in this study a new concept, the dynamic EMC determination method, will be introduced to clearly verify the relationship between EMC and the first flush effect. Three monitoring sites in Daejeon metropolitan city areas were equipped with an automatic rainfall gauge and a flow meter for accumulating the data such as rainfall and runoff flow. The dynamic EMC method was applied to more than 17 events, and the improved first flush criteria were determined on the ranges of storm duration and accumulated rainfall.

Modification of coagulation and Fenton oxidation processes for cost-effective leachate treatment.

Physicochemical processes have been used to remove nonbiodegradable organic compounds in leachate generated from sanitary landfills. In this study, a coagulation process combined with Fenton oxidation was evaluated for the removal of refractory organics in leachate. Recycling of sludge generated from Fenton oxidation to a coagulation process was attempted to reduce operation cost and to improve organic removal rate. The addition mode of Fenton reagent was also modified to obtain a better organic removal rate and more cost-effective operation. With Fenton sludge recycling, 9% higher COD removal was obtained, and the sludge to be disposed could be reduced up to 50%. Also, the coagulant could be reduced by 50%. For Fenton oxidation process, stepwise addition of reagents gave a 5% higher COD removal, and a 25% reduction in chemical consumption.

[Clinical efficiency of combined chemotherapy of patients with progressive forms of pulmonary tuberculosis]. / Klinichna efektyvnist' kompleksnoï khimioterapiï khvorykh z prohresuiuchymy formamy tuberkul'ozu lehen'.

Presented in the report are results of treatment of 217 patients with progressive forms of pulmonary tuberculosis. Results of treatment were found out to be dependent on the duration of progression of tuberculosis and degree of immunodepression, the ratio of exudative to caseous changes in the lungs. With more than 4-month duration of progression intensive chemotherapy is of no effect. Cure is only possible in those patients with freshly detected processes, with the duration of progression not exceeding 4 months, immunodepression not too profound.

Blood gas and electrolyte changes after tourniquet application in total knee replacement surgery.

The tourniquet is widely used in upper and lower extremity surgery in orthopedic practice. However, safe working guidelines for the application of the tourniquet are not clearly defined. The use of a tourniquet is an important step in performing total knee arthroplasty, and it seems plausible that mechanical damage is directly related to the height and the duration of the pressure of the tourniquet applied. Even the tourniquet pressure which is widely accepted in clinical practice, if it is applied for several hours, would permanently damage not only tissues directly under the tourniquet but also the muscles and the nerves distal to the tourniquet. The resultant ischemia to limb produces local changes including hypoxemia, acidosis and hyperkalemia. Relatively little is known about the systemic effects of tourniquet release when the patient is undergoing total knee replacement surgery under a general anesthesia. Therefore, we studied the systemic effects. The results were as follows: 1) Approximately five minutes after the tourniquet was released there was a statistically significant increase in mean heart rate.: 2) Serum potassium levels tended to increase significantly until five minutes while the serum sodium level rose significantly only one minute, and the lactate level rose significantly for only two minutes after tourniquet released; 3) PaCO2 increased for five minutes after tourniquet release and remained elevated for 30 minutes; 4) PaO2 did not change significantly two minutes after tourniquet release; 5) The mean pH dropped to 7.34 and remained low for over five minutes.