Sonic hedgehog inhibition induces mouse embryonic stem cells to differentiate toward definitive endoderm.

In the experimental group (shh inhibited group), there were significant decreases in the expression of Oct4, Nanog, Shh, GATA4, Brachyury and Goosecoid, while increases were observed for TAT and Pdx1. The expression of Sox17 did not differ between two control and experimental groups. In experimental group, the amount of GSC positive cells was somehow lower but it seems that there was no difference for Sox17. Shh inhibition induces ESCs to differentiate toward definitive endoderm by committing mesendodermal lineages.

[Development of quick method for the qualitative and semi-quantitive determination of lead in water]

A simple sensitive and low cost method is developed as a semi-quantitative screening method for field detection of lead in water, which based on the reaction of lead with 1.5-diphenylthiocarbazone. The test is carried out in a test bottle has a cap contains the dry reagent, while the bottle contains the solvent and activator chemical compounds. To perform the test the sample is added to the bottle, the cap is pressured and the bottle is shaken for one minute which permits the formation of lead- dithizonate causing visually detectable color change. The concentration of lead is determined by comparing the resulting color to the prepared provided color chart. Some samples are tested with this method, and with the graphite furnace atomic absorption spectrometry method. The comparison of results showed that this test has satisfactory sensitivity and it is suitable for the field detection of lead in water as a semi-quantitative test

Spectrophotometric determination of trace amounts of lead in Benghazi-city coast as its dithizone complex using solvent extraction

A simple and sensitive extraction-spectrophotometric method for the determination of lead is described. The complex formed between lead and Dithizone is extracted with chloroform at pH 9.5, and shows maximum absorbance at 520nm with a molar absorptivity of 1.8 x 10[5] L mol[-1] cm[1]. It obeys Beer's law over the range 0.16-1ppm. Various experimental parameters were studied for establishing the optimum conditions for the determination of lead. The method had been applied to the determination of lead in marine environmental samples. A step-by-step approach has been taken, through sampling, laboratory cleanliness, pre-treatment, extraction, instrumental measurement and, finally, the now much emphasised areas of method validation, analytical quality control and proper reporting of results

Experimental Micro Encapsulation of Pancreatic Islets with Air-driven Droplet Generator and Alginate / 대한이식학회지

PURPOSE: Transplantation of microencapsulated islets is proposed as an ideal therapy for the treatment of type 1 diabetes mellitus without immunosuppression. This is based on the principle that foreign cells are protected from the host immune system by an artificial membrane. The aim of this study is to establish an ideal condition of microencapsulation by using an air-driven droplet generator and alginate in vitro. METHODS: Islets were prepared from Sprague Dawley rat and semi SPF-micro pig. Alginate concentrations were changed from 1.5% to 3.0%, and inflow rate of alginate was varied from 10 mL/hr to 40 mL/hr. CO2 flow rate was regulated from 2.0 L/min to 4.0 L/min. Viability was checked by dithizone and FDA/PI staining. Secretory function was tested with glucose challenge and insulin stimulation index was investigated. RESULTS: The optimal conditions for islet encapsulation were revealed with alginate inflow rate of 10 mL/hr, CO2 flow rate of 2.0 L/min in concentration of 2% alginate. In concentration of 2.5% alginate, alginate inflow rate of 20 mL/hr, CO2 flow rate 3.0 L/min was ideal, and alginate inflow rate of 40 mL/hr, CO2 flow rate of 4.0 L/min showed good conditions of microcapsules in concentration of 3% alginate. Viability of encapsulated islets was higher than 90% in both rat and porcine. In terms of insulin secretion, encapsulated islets secreted insulin in response to glucose in static culture medium. However there was no normal response to low and high glucose challenge with stimulation index of less than 2.0. CONCLUSION: Microencapsulation of islets in rat and pig was successful with air-driven droplet generator and alginate in vitro. Further studies about biocompatibility and glucose control in vivo should be followed to be a useful tool for treatment of diabetes mellitus patients in clinical setting.

Residual Mercury in Soy-Bean Sprouts by Steps of Cooking / 예방의학회지

This study was carried out in order to estimate the residual amount of mercury in soy-bean sprouts in each steps of cooking. Samples were taken at markets and also cultured at home without applying the mercury containing pesticides as control. Mercury was determined by dithizone method. It was disclosed that soy-bean sprouts purchased at markets contained 1.32+/-0.274 ppm, 13 times as high as the maximal allowable concentration of mercury in food recommended by Ministry of Health and Social Affairs. Mercury contents, however, dropped off steadily by steps of cooking: rinsed with distilled water and boiled in distilled water showing concentrations of 0.11+/-0.025 ppm in boiled sprouts and 0.03+/-0.022 ppm in sprout-soup. These values were not statistically different from those in control samples, and not exceeded the maximal allowabled levels of mercury in food. It can be concluded that the use of mercury containing pesticides in the cultivation of soy-bean sprouts is not so serious problem as it has been suspected in respect of food contamination, but careful attention must be paid to indiscriminate use of mercury containing pesticides as they may contaminate air, water and soil and secondarily bring harm to human health through food chains.

Measurement conditions for cadmium in urine by flame atomic absorption spectrophotometry / 예방의학회지

The optimum conditions for measuring cadmium content of less than 0.2ppm by flame atomic absorption spectrophotometry were investigated. The cadmium in urine was extracted by APDC-MIBK for the analysis by atomic absorption spectrophotometry after ashing them by a wet method. 1. Optimum conditions by APDC-MIBK and DDTC-MIBK extractions. The acidic aqueous solution was prepared with appropriate amount of 0.1N nitric acid, 5ml of 25% (W/V) sodium potasstum tartarate, 10ml of saturated ammonium sulfate, and 2ml of 2% APDC(or 1 ml of 5% DDTC) chelating agent. The total volume of solution was adjusted to 55ml and pH to 2~10 (or 7~10). The aqueous solution was extracted with 10ml MIBK. Concentration of Triton X-100 did not effect the absorbance for APDC-MIBK extraction of cadmium, but absorbance decreased as the concentration increased for DDTC-MIBK extraction. The sensitivity and detection limits for the cadmium determination from APDC-MIBK extraction were 0.0038ppm and 0.0102, 0.0022ppm and 0.0116 for DDTC-MIBK, and 0.0132ppm and 0.0034 for 0.1N nitric acid. APDC-MIBK and DDTC-MIBK extractions were 3 times higher than 0.1N nitric acid for the sensitivity. 2. Excretion of cadmium in 24-hour urine by APDC-MIBK extraction. Determination of cadmium in urine by atomic absorption spectrophotometry of A.A. (Cd=2 mA) mode and B.C. (Cd=4 mA) mode and B.C. (Cd=4mA, D2=20mA) mode showed some difference (p0.05, 93.48+/-11.78%, 94.83+/-22.00%). Excretion of cadmium in 24-hour urine collection from normal person and variance analysis within measurement variation was not significant (p>0.05), but between inter-individual was significant (0.05). Determination of cadmium content by two different methods of flame atomic absorption spectrophotometry and dithizone colorimetry showed that the results from the two methods can be described by a regression line with a good correlation (y=1.0153x-0.2927, x=Cd by D.C., y=Cd by A.A.S., r=0.8651*, p<0.01).

Mercury Contents in Normal Blood of Koreans / 예방의학회지

Normal range of mercury contents in blood and its relationship with urinary mercury excretion were studies with 68 healthy male adults living in Seoul city, who had no obvious evidence of either occupational exposure to mercury or therapeutic use of mercurial agents. Mercury analysis was made by means of dithizone colorimetric method with coefficient of variation of 10.9% in an average ranging from 5.1% to 18.0%. 1. Mercury contents in normal human blood were both normally and log-normally distributed, and better fitted to the latter. 2. Geometric mean and standard deviation of the mercury contents were 24.0%(log(-1) 1.38)+/-1.66 microgram/100 ml (log(-1) 0.22 microgram/100 ml) ranging from 7.2 to 79.7 microgram/100 ml with 95% confidence interval. 3. Mercury contents in normal human blood differed from person to person (p0.05). 4. Mercury in the blood was contained much higher in erythrocytes than I!in plasma (p<0.01), showing the geometric means of 21.0+/-1.25 microgram/100 ml in red blood cells and 14.3+/-1.62 microgram/100 ml in plasma, respectively. 5. Mercury contents in normal human blood had a relationship of power function with mercury excretion in urine corrected with a gram of creatinine excretion per liter of urine (p<0.10).

Some Statistical Considerations for the Estimation of Urinary Mercury Excretion in Normal Individuals / 예방의학회지

Purpose of this study is to find out proper means of estimating the urinary mercury excretion the normal individuals. Whole void volume was collected every 2 hours beginning from 6 o'clock in the morning until 6 o'clock next morning. Mercury excretion in each urine specimen was measured by NIOSH recommended dithizone colorimetric method (Method No. : P & CAM 145). Urinary concentration of mercury was adjusted by two means : specific gravity of 1.024 and a gram of creatinine excretion per liter of urine comparing the data with the unadjusted ones. Mercury excretion in 24-hour urine specimen was calculated by adding the amounts measured with the hourly collected specimens of each individual. Statistical analysis of the urinary mercury excretion revealed the following results : 1. Frequency distribution curve of mercury excreted in urine of hourly specimens was best fitted to power function expressed in the form of y=ax(b), Adjustment of the urinary mercury concentration by creatinine excretion was shown to be superior (y=1674x(-1.52)), r(2)=0.95) over nonadjustment(y=2702x(-1.57)), r(2)=0.92) and adjustment by specific gravity of 1.024(y=4535x(-1.66), r(2)=0.93). 2. Both log-transformed mercury excretion in hourly voided specimens and mercury excretion itself in 24 hour specimens showed the normal distributions. 3. The frequency distribution of mercury adjusting the urinary concentration of mercury by creatinine excretion was best fitted to a theoretical normal distribution with the sample means and excretion was best fitted to a theoretical normal distribution with the sample means and standard deviation than those unadjusted or adjusted with specific gravity of 1,024. 4. Average urinary mercury excretions in 24-hour urine specimen in an individual were as follows : a) Unadjusted urinary mercury excretions. mean and standard deviation :18.6+/-13.68 microgramHg/liter. median : 16.0 microgramHg/liter. range : 0.0-55.10 microgramHg/liter. b) Adjusted with specific gravity. mean : 20.7+/-11.76 microgramHg/liter x 0.024/(S.G.-1.000). median : 20.7 microgramHg/liter x 0.024/(S.G.-1.000). range : 0.0-52.9 microgramHg/liter x 0.024/(S.G.-1.000). c) Adjuested with creatinine excretion. mean and standard deviation : 10.5+/-6.98 microgramHg/g creatinine/liter. median : 9.4 microgramHg/g creatinine/liter. range : 0.0-26.7 microgramHg/g creatinine/liter. 5. No statistically significant differences were found between means calculated from 24-hour urine specimens and those from hourly specimens transformed into logarithmic values. (P<0.05).

simplified method for the determination of lead in blood

An accurate rapid micro method for the determination of lead in whole blood is presented. The method consists of precipitation of blood proteins with trichloroacetic acid solution, formation of a cyanide, extraction with dithizone, and subsequent spectrophotometric comparison of the colour complex formed. One hundred experiments clearly demonstrated that almost complete recovery can be obtained if proper concentrations of dithizone solution are used