过氧化氢氧化亚甲基蓝褪色催化动力学光度法测定镍

在pH 8.00的NH₃-NH₄Cl缓冲溶液中,在100 ℃加热条件下,痕量镍能催化过氧化氢氧化亚甲基蓝的褪色反应,建立了测定痕量镍的催化动力学光度方法。研究发现,非催化反应吸光度(A₀)和催化反应吸光度(A)在655 nm处的差值ΔA与镍的质量浓度在0.01～0.30 μg/mL范围内呈良好的线性关系,方法检出限为8.6×10^-3 μg/mL。该催化反应的表观速率常数为8.2×10^-4 s^-1,表观活化能为66.08 kJ/mol。方法用于延河水和自来水厂污水中痕量镍的测定,测定值与原子吸收光谱法一致,相对标准偏差(RSD,n=6)为1.2%～1.6%,加标回收率为99%~102%。     

Spectrophotometric determination of plasma thiocyanate by formation of an ion-pair with methylene blue

We describe a sensitive method for measuring thiocyanate in 500 microliters plasma samples. This technique, although slower than the standard method, improves sensitivity. It requires the extraction in chloroform of an ion-pair formed between thiocyanate ions and methylene blue in acidic medium. Within-day precision had a coefficient of variation of 2.5% and between-day precision a CV of 4.75%. The results were well-correlated (r = 0.997). For 30 non-smokers, the mean thiocyanate level was < 55 mumol/l, and for 30 smokers 90 mumol/l (SD = 20). The method was successfully applied to seven fire smoke victims treated with hydroxocobalamin.     

高碘酸钾氧化亚甲蓝动力学光度法测定痕量铁

在稀H2 SO4 介质中 ,以Fe 催化高碘酸钾 (KIO4 )氧化亚甲蓝 (MB)反应为基础 ,拟定了测定痕量铁的新方法。在90℃水浴中加热 2 0min ,于 664nm波长处 ,测定亚甲蓝的吸光度值 ,方法线性范围 0～ 4μg/L ,检出限为 0.10 μg/L。选择性和重复性好 ,操作简便。应用于测定蒸馏水、瓶装纯净水、自来水和瓶装矿泉水中的铁 ,加标回收率为 95.2 %～ 10 0.2 % ,相对标准偏差为 1.48%～ 3.1%。     

过氧化氢氧化亚甲基蓝褪色催化光度法测定铝合金中痕量镍

基于在pH 5.6的Na₃C₆H₅O₇-NaOH缓冲溶液中,痕量镍对H₂O₂氧化亚甲基蓝(MB)的褪色反应具有催化作用且褪色的程度与镍的含量成线性关系,建立了催化动力学光度法测定痕量镍的新方法。研究了影响催化褪色反应的因素,并测定了一些动力学参数。结果表明,非催化反应体系与催化反应体系的最大吸收波长均在664 nm处,方法的线性范围为0.02～1.4 μg/mL,线性回归方程为lg(A₀/A_t)=0.776 5 ρ(μg/mL)+0.157 1,相关系数r =0.998 6,检出限为0.011 8 μg/mL,反应的表观活化能为25.14 kJ/moL。方法用于铝合金标准样品中痕量镍的测定,结果与认定值基本一致,相对标准偏差(RSD)为2.9%和2.8%(n=5),回收率在98%～104%范围。     

亚甲蓝法直接快速测定环境样品中微量硫化物

提出了亚甲蓝法测定微量硫化物新的显色过程 ,研究了用普通分光光度法和全差示分光光度法测定微量硫化物的条件。采用普通光度法 ,标准曲线为A =1.2 8ρ +0 .0 0 2 ,r =0 .9995 ,表观摩尔吸收系数为 4 .0 6× 10 4 L/(mol·cm) ,线性范围为 0～ 0 .9mg/L ;采用全差示分光光度法 ,标准曲线为A =7.0 ρ +0 .0 0 4 ,r =0 .9996 ,表观摩尔吸收系数为 2 .2× 10 5L/(mol·cm) ,线性范围为0～ 0 .14mg/L。与原亚甲蓝法相比 ,灵敏度显著提高 ,显色反应迅速完成。两种方法的检测限均为1.0ng/ml;测定 10 0ng/mlS2 - ,相对标准偏差为 1.9% (n =10 )。实验了各种干扰离子对硫化物测定的影响 ,提出了消除干扰离子的方法。利用该方法测定环境样品中微量硫化物 ,结果令人满意。     

Methemoglobinemia induced by methylene blue pertubation during laparoscopy

Methylene blue is used to check tubal patency during laparoscopy. A case of methemoglobinemia which was induced by methylene blue is presented. Methemoglobinemia is usually treated with methylene blue; however, in patients with glucose-6-phosphate dehydrogenase deficiency, methylene blue can induce methemoglobinemia.     

Laser conization guided by endocervical staining with methylene blue

The authors report their experience of the use of a vital stain--methylene blue--as a surgical guide in laser cervical conization for CIN2-CIN3/CIS. During the period 1 October 1991-31 December 1992 a total of 40 laser cervical conizations were performed under local anesthesia using a CO2 laser connected to a microhandpiece and colposcope in patients with exo-endocervical lesions which were histologically positive for CIN2-CIN3/CIS. In 33/40 patients an aqueous solution of 1% methylene blue was introduced preoperatively in the endocervix using a cotton-wool bud with consequent impregnation of the pseudoglandular crypts: laser biopsy was performed along the guidelines of the stain itself. This enabled the direction of resection to be varied: in 3 patients due to an anomalous and eccentric direction of cervical canal; in 10 patients to remove glandular structures surrounding or underneath lesions; in 8 patients following pseudoglandular section to carry out deep vaporization (3 patients) or correct cutting edges (5 patients). The apex and edges of the cone were always intact. Fourteen patients completed a 12-month follow-up and a further 6 were followed up for 9 months; only 1/14 patients (with AIDS) showed recidivation after 1 year. In the authors' experience the use of a vital stain as a guide during laser cervical cone biopsy is an easily used method which ensures the greatest possible respect for healthy cervical structures, also in order to preserve fertility in young patients.     

Photoinactivation of amelanotic and melanotic melanoma cells sensitized by axially substituted Si-naphthalocyanines

The incidence of risk factors for atherosclerosis was investigated in a group of 846 patients under 65 years of age, hospitalized with acute myocardial infarction (AIM) in coronary hospital units in 21 districts of the Czech Republic in 1996. The group of patients comprises 649 men and 197 women. The incidence of risk factors in patients was compared with the incidence of risk factors in the population of the Czech Republic: the mean values of the investigated indicators are in patients with AIM higher in both sexes (total serum cholesterol, triacylglycerols, BMI, WHR). As to anamnestic data, in the majority low or irregular physical activity predominates, a high percentage of patients reported that they "do not restrict" or "rather do not restrict" their total food intake nor the intake of animal fats. Among the patients 52.6% males and 42.1% females were smokers. The results indicate that patients with AIM have a higher incidence of risk factors for atherosclerosis, a higher percentage of patients have cumulated risks and a higher percentage of patients has a higher risk score than the general population. The incidence of AIM is markedly higher in subjects with lower education.     

Early detection of melanoma metastases with radioiodinated methylene blue

Melanin synthesised in melanoma cells presents a unique target to which the treatment can be selectively addressed, provided the pigment is recognised by a suitable drug. Methylene blue (MTB) possesses a high affinity for melanin and, therefore, accumulates preferentially in melanoma cells. Since not directly toxic to the tumour, MTB serves as a carrier for radioisotopes and, once taken up by melanoma cells, acts as a selectively localised source of radiation. Hence, radioderivatives of the compound can be used for both diagnosis and therapy of disseminated melanoma. Eleven patients with confirmed metastatic melanoma and one with a recent local recurrence were studied using radioiodinated (iodine-123 or iodine-131) MTB and a gamma camera. Biopsies of cutaneous lesions were taken to determine directly the compound uptake in tumours. This first clinical investigation concerning the diagnostic potential of radioiodinated MTB in patients with disseminated melanoma confirmed the existence of approximately 80% of internal lesions previously identified by routine methods and, additionally, enabled detection of unknown secondaries in 6 of 12 patients studied. There were no false-positive gamma camera images regardless of whether 123I or 131I was used. 131I proved to be more suitable than 123I for detecting melanoma metastases with radioiodinated MTB. Hazy images of the lesions treated with external beam radiation and/or some drugs suggest that initial radio- and chemotherapy might affect MTB uptake in melanoma metastases and reduce the clarity of the scintigrams obtained from a gamma camera. However, small, untreated internal lesions that cannot be visualised easily with the standard diagnostic methods are revealed with 131I-MTB regardless of their localisation. It is concluded that use of radioiodinated MTB in conjunction with gamma camera or positron emission tomographic imaging might prove to be a useful and accessible tool for the detection of early melanoma dissemination.     

Reduction and uptake of methylene blue from rat air spaces

The use of methylene blue (MB) to estimate dilution of epithelial lining fluid, which occurs during bronchoalveolar lavage (BAL), is complicated by loss of this redox dye from the air spaces. The rate of MB uptake from the air spaces of isolated rat lungs and the effects of oxidation and reduction on this process were investigated in this study. Movement of MB from the air spaces to perfusate was compared with the corresponding transport of 125I-labeled albumin, [14C]-dextran, 99mTc-labeled diethylenetriaminepentaacetate, [3H]-sucrose, and 3H2O. By the end of 2 min, MB concentrations in the BAL had fallen by 58 +/- 4% (SE; n = 11) and 3H2O by 78 +/- 2% (n = 13), whereas concentrations of the other indicators decreased by approximately 6%. All but 10% of the 3H2O lost from the air spaces was found in the perfusate, whereas 19% of the lost MB was not recovered in the perfusate, suggesting retention of MB in the pulmonary tissues. Absorption of MB from the air spaces was slowed by 20% when the lungs were left unperfused, and absorption was accelerated threefold by reduction of MB to leukomethylene blue with Na2S2O4. In contrast, MB losses from the air space were slowed by the oxidizing agent K3Fe(CN)6 and by addition of superoxide dismutase or ascorbic oxidase. It is therefore possible that ascorbic acid and O2- entering the air spaces reduce MB to the uncharged leuko form. Lowering the pH of the BAL fluid to 3.5 also slowed MB reabsorption. This suggests that acid aspiration may stimulate release of oxidants into the air spaces.     

Photochemotherapy of experimental colonic tumours with intra-tumorally applied methylene blue

INTRODUCTION: Phototoxicity of intra-tumoral injected methylene blue (MB+) was studied in 48 experimental colonic tumours in comparison with photosan-3, Zn-phthalocyanine and tetrasulphanated ClAl-phthalocyanine. METHODS: In mice. xenotransplanted subcutaneous tumours about 1 cm in diameter were treated photodynamically twice, with different sensitisers. The irradiation was performed at the sensitiser-specific wavelength, and a density of 100 mW/cm2 and a dose of 100 J/cm2. RESULTS: Light alone without sensitiser did not induce any effect in mice tumours. Surprisingly, Al-phthalocyanine could only be used for intratumoral injections because of toxic effects after intravenous applications in nude mice. Using MB+ (1%), 75% of the tumours were destroyed by a single photodynamic treatment (PDT). In addition, toxicity of MB+ was most intense when compared with Zn-phthalocyanine and photosan-3. However, after the second PDT, there was no statistically significant difference among these sensitisers. Dark toxicity of MB+ (1%) could be well demonstrated by sufficient sensitiser incorporation without irradiation, which led to a stationary tumour volume up to 3 weeks after injection. CONCLUSION: Intra-tumoral MB+ PDT is a potential treatment for inducing necrosis in vivo. With regard to tumour tissue, the selectivity of MB+ is high and depends on a precise local injection of the dye.     

The measurement of bioreductive capacity of tumor cells using methylene blue

PURPOSE: Methylene blue (MB) can be used as an intracellular electron acceptor. The purpose of this study was to demonstrate the usefulness of MB for the determination of total bioreductive capacity of cell suspensions. METHODS AND MATERIALS: We measured oxygen consumption by Clark electrode and pentose cycle activity by release of 14CO2 from 1-14C-glucose. RESULTS: Methylene blue catalyzes the reaction of intracellular reductants NADPH, NADH, and reduced glutathione (GSH) with oxygen, causing the production of hydrogen peroxide. The reaction rate correlates with the negative charge of molecule (NADPH(-4) > NADH(-2) > GSH(-1)), suggesting that reaction with positively charged oxidized MB is the limiting step of the reaction. In a cellular system MB causes the electron flow from cellular endogenous substrates to oxygen. It is activated by the disruption of the NADP+/NADPH ratio due to several processes. These are direct oxidation of NADPH and GSH, the GSH peroxidase catalyzed reaction of GSH with H2O2, followed by NADPH oxidation by oxidized glutathione (GSSG). This results in increased cellular oxygen consumption and stimulation of the oxidative limb of pentose cycle (PC) in the presence of MB. The cellular effect of MB differs from other electron accepting drugs. Diamide and tert-butylhydroperoxide act as direct oxidants, while MB is an electron carrier to oxygen. Accordingly, MB shows the highest effect on PC activation and oxygen consumption. CONCLUSIONS: Our results indicate that MB may be used for the determination of the total bioreductive capacity of the cells, measured by oxygen consumption and PC activation.     

Sensitive enzymatic assay for erythrocyte creatine with production of methylene blue

We developed a new, highly sensitive enzymatic method for quantifying creatine in erythrocytes, which comprises creatine amidinohydrolase, sarcosine oxidase, and peroxidase. In the present method, an N-methylcarbamoyl derivative of methylene blue, 10-N-methylcarbamoyl-3,7-bis(dimethylamino)phenothiazine (MCDP), was used as a sensitive chromogenic compound. Potassium ferrocyanide was used to prevent nonspecific oxidation of MCDP. The enzymatic method exhibited good analytical performance: precision, within-run CVs <1.0% and between-day CVs <2.0%; average analytical recovery, 99.3% +/- 1.8%; detection limit, 1.0 micromol/L in hemolysate; and linearity, at least up to 500 micromol/L as creatine concentration in hemolysate. Excellent agreement was observed between the present method (y) and HPLC (x), y = 1.029x - 0.002 micromol/g hemoglobin, r = 0.9998, S(y/x) = 0.053 micromol/g hemoglobin (n = 110). No significant interference was produced by various compounds, including guanidino compounds, amino acids, and reducing materials. The reference intervals (mean +/- 2 SD) for erythrocyte creatine obtained from 60 males and 60 females were (in micromol/g hemoglobin) 1.18 +/- 0.52 (0.66-1.70) for males and 1.35 +/- 0.49 (0.86-1.84) for females. Using this method, we documented changes in erythrocyte creatine in patients with various hemolytic conditions, including hemolytic anemia, liver cirrhosis, renal insufficiency, and chronic renal failure treated with hemodialysis with or without the administration of erythropoietin. We conclude that the use of MCDP allows sensitive measurement of erythrocyte creatine and that MCDP with potassium ferrocyanide can improve the sensitivity of assays that use peroxidase for detection of H2O2.     

混合微乳液对紫外分光光度法测定锑的协同增敏作用

研究了在乳化剂OP和CTMAB等组成的混合微乳液介质中 ,锑 与溴邻苯三酚红形成红色络合物的紫外吸收光谱。结果表明 ,于OP ,CTMAB及正丁醇、正庚烷组成的混合微乳液存在下 ,显色体系的灵敏度显著提高 ,从而建立了混合微乳液协同增敏溴邻苯三酚红紫外光度法测锑的光度体系。在选定测定条件下 ,2 5mL溶液中Sb 质量在 1 0～ 60 μg范围内符合比尔定律 ,表观摩尔吸收系数ε30 8=5 1× 10 4 ,与混合表面活性剂存在下的表观摩尔吸收系数ε30 8=3. 5× 10 4 相比 ,灵敏度     

Mechanisms of methylene blue stimulation of the hexose monophosphate shunt in erythrocytes

The response of the hexose monophosphate shunt in erythrocytes was studied with the ionization chamber-electrometer apparatus to measure continuously 14CO2 derived from 14C-labeled substrates. The effect of methylene blue at high (0.1 mM) and low (1 muM) concentrations was evaluated under different gas mixtures; air, carbon monoxide, and 6% carbon monoxide in air. The latter gas mixture results in nearly 100% carboxyhemoglobin but provides a physiologic partial pressure of oxygen. The extent to which pentose is recycled through the shunt in response to methylene blue stimulation was examined with radioactive glucose substrates labeled on the first, second, and third carbon positions. Generation of hydrogen peroxide after stimulation of erythrocytes with methylene blue was evaluated by the catalase-aminotriazole trapping technique, [14C]formate oxidation, and oxidation of reduced glutatione. Stimulation of the shunt with 1 muM methylene blue was markedly impaired in the absence of oxyhemoglobin, but stimulation with 0.1 mM methylene blue was only slightly impaired under the carbon monoxide-air mixture. The higher concentration of methylene blue produced evidence of hydrogen peroxide generation of all three techniques. Despite the evidence for the involvement of oxygen, oxyhemoglobin, and hydrogen peroxide in the response to methylene blue, cells containing methemoglobin induced by sodium nitrite or from a patient with congenital methemoglobinemia responded normally to methylene blue in the absence of oxygen. These experiments indicate that the reactions induced by methylene blue in erythrocytes are more complex than generally thought and that high concentrations are associated with production of peroxide.     

Inhibitory effect of light on growth-supporting properties of eosin methylene blue agar

Exposure of eosin methylene blue agar to visible light can alter the ability of that medium to support microbial growth. Proteus species were most sensitive to the photodynamic action.     

三乙醇胺-磷钼蓝光度法快速测定钢中磷

针对用NaF-SnCl₂作还原剂的磷钼蓝光度法测定钢铁中磷的显色不稳定,进一步研究了该法的显色条件,并在显色体系中加入三乙醇胺作为显色反应稳定剂。结果表明,三乙醇胺对该体系具有良好的稳定作用,显色液在室温下放置5 min后,能使磷钼蓝的吸光度值稳定50 min以上。当磷的含量在0.00～1.00 μg/mL 范围内时,吸光度与浓度呈良好的线性关系。实验方法用于钢中磷含量的测定时,结果稳定,相对误差小于5%,RSD在1.5%～3.2%之间,加标回收率在98.7%～103.2%之间,表观摩尔吸光系数ε_{max,700 nm}=3.18×10⁴ L· mol^-1· cm^-1。方法容易掌握,适用于钢中磷含量的快速和准确测定。