Room Temperature Light Research Articles

钝顶节旋藻SOD活性测定条件及稳定性的研究<br>Research of Determination Conditions and Enzyme Stability of Arthrospira SOD

采用邻苯三酚自氧化法研究了鄂尔多斯高原碱湖钝顶节旋藻SOD活性的测定条件以及酶的稳定性，为进一步从钝顶节旋藻中提取、纯化SOD酶制剂提供可参考的基础数据。结果显示，SOD在紫外光区320 nm处有最大吸收值；在Tris-HCl缓冲溶液中最适pH值为8.2，最适温度为25℃。该酶的pH值稳定性范围为6~10；在不同温度下保温20 min时，高于40℃时酶活性开始下降，保温60 min时，高于35℃时酶活性开始下降；室温下存放2 d后活性开始下降，7 d时活性基本丧失；室温下避光保存9 d时SOD活性完全丧失。 To obtain the basic data of extracting and purifying the SOD enzyme preparation from Arthrospira, the determination conditions and enzyme stability of Arthrospira SOD in alkaline lake in Erdos plateau were studied by the method of pyrogallol auto-oxidation. The results showed that SOD met its ultimate absorption at 320 nm in UV area. The optimum pH in Tris-HCl buffer was 8.2 and its optimum temperature is 25˚C. This enzyme remained stable in the range of pH = 6 - 10. Its activity began to fall over 40˚C when the enzyme was preserved at different temperature for 20 min, and to fall over 35˚C for 60 min. Enzyme activity began to decline after 2 days and almost nothing at the seventh day at room temperature in light. Its activity lost absolutely at the ninth day when the enzyme was stored at room temperature without light.

钝顶节旋藻SOD活性测定条件及稳定性的研究

采用邻苯三酚自氧化法研究了鄂尔多斯高原碱湖钝顶节旋藻SOD活性的测定条件以及酶的稳定性，为进一步从钝顶节旋藻中提取、纯化SOD酶制剂提供可参考的基础数据。结果显示，SOD在紫外光区320 nm处有最大吸收值；在Tris-HCl缓冲溶液中最适pH值为8.2，最适温度为25℃。该酶的pH值稳定性范围为6~10；在不同温度下保温20 min时，高于40℃时酶活性开始下降，保温60 min时，高于35℃时酶活性开始下降；室温下存放2 d后活性开始下降，7 d时活性基本丧失；室温下避光保存9 d时SOD活性完全丧失。 To obtain the basic data of extracting and purifying the SOD enzyme preparation from Arthrospira, the determination conditions and enzyme stability of Arthrospira SOD in alkaline lake in Erdos plateau were studied by the method of pyrogallol auto-oxidation. The results showed that SOD met its ultimate absorption at 320 nm in UV area. The optimum pH in Tris-HCl buffer was 8.2 and its optimum temperature is 25˚C. This enzyme remained stable in the range of pH = 6 - 10. Its activity began to fall over 40˚C when the enzyme was preserved at different temperature for 20 min, and to fall over 35˚C for 60 min. Enzyme activity began to decline after 2 days and almost nothing at the seventh day at room temperature in light. Its activity lost absolutely at the ninth day when the enzyme was stored at room temperature without light.

Receptor retinoid‐binding protein (IRBP) binds cone outer segments differentially in light and dark

Abstract Purpose Vision requires the continuous exchanges of visual cycle retinoids through the interphotoreceptor matrix (IPM). IRBP, which is synthesized by the rods and cones, is the major soluble protein component of the IPM. In the matrix, IRBP protects and targets retinoids trafficking between the photoreceptors, RPE and Muller cells. Methods Organ culture of isolated Xenopus retina was used to characterize the cellular binding of recombinant full‐length IRBP protein free of fusion tags. Xenopus was selected for these studies because of their large photoreceptors which are easily detached in both light and dark‐adapted states. xIRBP was covalently bound to the fluorescent dye Alexa‐647 at 1:1 molar ratio. Labeling had no effect on the retinoid ligand‐binding properties of the protein. Xenopus retinas were detached and incubated with xIRBP‐647 for 1 hour at room temperature in light and dark. The distribution of xIRBP‐647 was studied by confocal microscopy in retinal flat whole mounts and cryosections. Results In light, xIRBP‐647 bound to cone outer segments with lighter labeling of the rod outer segments. Retinas incubated with the xIRBP‐647 in the presence of a 50 fold excess of unlabeled protein showed reduced cone and rod outer segment labeling. In dark, outer segment binding was not appreciated. Positive staining near the level of the external‐limiting membrane was noted in dark but not light. Conclusion The binding of xIRBP‐647 to cells of the isolated retina was different in light versus dark. Our data suggests that the direct interaction of IRBP with the outer segments and Muller cells plays an important role in retinoid trafficking in the the visual cycle.

Stability and viscosity of a flavored omeprazole oral suspension for pediatric use

The stability and viscosity of preparations of a commercially available, flavored, immediate-release powder for oral suspension (omeprazole-sodium bicarbonate) during refrigerator and room temperature storage were investigated. Omeprazole-sodium bicarbonate 20-mg packets were suspended to initial omeprazole concentrations of 0.6 and 2 mg/mL, and omeprazole-sodium bicarbonate 40-mg packets were suspended to initial omeprazole concentrations of 1.2, 2, 3, and 4 mg/mL. Suspensions were stored at 4 degrees C in darkness (refrigerated) or 22-25 degrees C (room temperature) in light for one week. A third set of suspensions was stored refrigerated for one month. Omeprazole's stability was quantified after 0, 6, 12, 24, 48, and 168 hours in one-week samples and after 0, 7, 14, 21, and 28 days in one-month samples using high-pressure liquid chromatography. Viscosities of refrigerated suspensions were measured after 0, 1, and 7 days. Refrigerated suspensions retained >98% and >96% of their initial omeprazole concentrations after one week and one month, respectively. Stability of room temperature suspensions was concentration dependent. After one week, the 0.6- and 1.2-mg/mL suspensions retained 87.2% and 93.1% of their respective initial omeprazole concentrations, whereas the 2-, 3-, and 4-mg/mL suspensions retained >97% of their initial omeprazole concentrations. Suspension viscosities varied 10-fold over the concentrations studied, but all were within the viscosity ranges of other commercially available oral suspensions. Prolonged refrigeration did not increase the suspensions' viscosities. Omeprazole-sodium bicarbonate suspensions of 0.6-4 mg/mL omeprazole were stored at 4 degrees C in darkness for up to 28 days. The viscosities of refrigerated suspensions did not increase over 7 days. Except for the 0.6 mg/mL preparations, suspensions stored at room temperature in the light retained >90% of their initial omeprazole content after 7 days, despite turning yellow.

Efficacy of Chlorine Dioxide as a Gas and in Solution in the Inactivation of Two Trichothecene Mycotoxins

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated. In the first experiment, verrucarin A (1, 5, or 10 microg) and roridin A (5 or 10 microg) were each inoculated onto square-inch sections of glass, paper, and cloth and exposed to 1000 ppm of ClO2 for either 24 or 72 h at room temperature. In the second experiment, verrucarin A and roridin A (1 or 2 ppm in water) were treated with 200, 500, or 1000 ppm ClO2 for up to 116 h at room temperature in light and dark conditions (N = 9 per treatment for test and control). A yeast assay using Kluyveromyces marxianuswas used to quantify the toxicity of verrucarin A and roridin A. Additionally, high-performance liquid chromatography was performed on selected samples. Results for the first experiment showed that ClO2 treatment had no detectable effect on either toxin. For the second experiment, both toxins were completely inactivated at all tested concentrations in as little as 2 h after treatment with 1000 ppm ClO2. For verrucarin A, an effect was seen at the 500 ppm level, but this effect was not as strong as that observed at the 1000 ppm level. Roridin A toxicity was decreased after treatment with 200 and 500 ppm ClO2, but this was not significant until the 24-h exposure time was reached. These data show that ClO2 (in solution) can be effective for detoxification of roridin A or verrucarin A at selected concentrations and exposure times.

Phytophthora cinnamomi

<i>Phytophthora cinnamomi</i>

Development and validation of a high-performance liquid chromatographic assay using solid-phase extraction for the novel antitumor agent pancratistatin in human plasma

The stability of the experimental anti-tumour agent pancratistatin in human plasma has been investigated. A solid-phase extraction technique and an HPLC assay with external standards have been developed and validated. Extraction was performed using C 18 cartridges and HPLC, analysis was performed on a 15 cm Hypersil BDS column using isocratic elution with 13% acetonitrile and aqueous solution of 1% (w/v) acetic acid. The lower limit of quantification for pancratistatin in 5% DMF–95% water was found to be 0.58 ng/ml (±10.58%) and 2.3 ng/ml (±9.2%) following extraction from human plasma. Mean recovery of 89.4% (±4.73%) was obtained over the concentration range 0.0023–9.45 μg/ml for a five day validation study. Pancratistatin was stable at room temperature in light or dark for at least 15 days, in the refrigerator at 4°C for at least 16 days and in the freezer at −20°C or −80°C for at least 28 days. Under all conditions monitored, % recovery of pancratistatin from human plasma was greater than 95% and no evidence of degradation had occurred. There also was no loss of pancratistatin after three cycles of freezing and thawing.

Stability of folic acid in 25% dextrose, 3.5% amino acids, and multivitamin solution.

The chemical stability of folic acid in 25% dextrose, 3.5% amino acids, and multivitamin solution was investigated. Solutions of 0.25, 0.5, 0.75, and 1.0 mg/liter of folic acid admixed in the study solution were prepared. Solutions were stored in light-room temperature, light-refrigeration, dark-room temperature, or dark-refrigeration. Samples were drawn to determine folic acid concentration and again at 4, 8, 12, 18, 24, 36, and 48 hr after admixture. Folic acid concentration was determined by competitive binding radioassay, and results are expressed as percent of initial folic acid concentration. Folic acid was stable for 48 hr with each tested concentration and stability was found to be independent of temperature or light storage effects. Folic acid admixed in the study solution is chemically stable for up to 48 hr after initial admixture under normal total parenteral nutrition storage conditions.