Rapid detection of Escherichia coliform with a bulk acoustic wave sensor based on the gelation of Tachypleus amebocyte lysate

A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscosity and density of the mixture increased, and as a result, the resonance frequency decreased correspondingly after TAL was mixed with the heated E. coli solution that contained endotoxin. Results showed that the frequency shift was linearly related to the logarithm of E. coli concentration in the range of 2.7x10(4)-2.7x10(8) cells/ml. The correlation coefficient was 0.996. This BAW-TAL method was compared with the standard pour plate counts (PPC) method. The proposed method was much more rapid and simpler for detection of E. coli than the traditional methods.     

Discrimination between endotoxin and (1----3)-beta-D-glucan using turbidimetric kinetic assay with Limulus amebocyte lysate

A procedure for the Limulus amebocyte lysate (LAL) test discriminating between endotoxin and (1----3)-beta-D-glucan based on the turbidimetric kinetic method was proposed. Endotoxin and (1----3)-beta-D-glucan, which are elicitors of the activation of LAL, showed different reaction courses with this lysate. To analyze the difference in the reactions, two parameters, the maximum differential coefficient of the reaction (Dmax) and the reaction time required to obtain Dmax (Tp) were defined. The logarithmic plottings of Tp versus Dmax (Tp-Dmax plot) discriminated between endotoxin and (1----3)-beta-D-glucan. Endotoxin was measured with a standard curve plotting logarithmic endotoxin concentration versus Dmax (ET-Dmax plot). The endotoxin calculated from Dmax was less influenced by (1----3)-beta-D-glucan than that calculated from the usual gelation time. A small amount of endotoxin in a sample could be concealed by the addition of polymyxin B, which inhibited the activation of LAL by endotoxin. (1----3)-beta-D-glucan was measured without being affected by the presence of a small amount of endotoxin using LAL with polymyxin B. The following procedure is proposed as a LAL test to discriminate between endotoxin and (1----3)-beta-D-glucan. (1) Identify the main substance (endotoxin or (1----3)-beta-D-glucan) triggering the activation of LAL using the Tp-Dmax plot. (2) Use the appropriate method to measure the main substance: the ET-Dmax plot for endotoxin or the LAL with polymyxin B for (1----3)-beta-D-glucan.     

Specific assay for endotoxin using immobilized histidine, Limulus amoebocyte lysate and a chromogenic substrate.

The Limulus amoebocyte lysate (LAL) test is inhibited or enhanced by many substances. In order to overcome this problem, a specific endotoxin assay method using a membrane filter unit, a chromogenic LAL reagent, and immobilized histidine (which is a specific adsorbent for endotoxins) was developed. Endotoxins are quantitatively adsorbed on immobilized histidine. The adsorbed endotoxins are separated from LAL-inhibiting or -enhancing substances by the membrane filter unit, and their activities are directly assayed with the LAL reagent in a filter cup without any inhibition or enhancement. The reproducibility and the accuracy of this method are high. This new endotoxin assay method using immobilized histidine can be used for the determination of endotoxins in a solution containing LAL-inhibiting or -enhancing substances such as amino acids and antibiotics, as an alternative to the more common gel-clot technique.     

New method for preparing 5(6)-(1-adamantyl)-benzimidazole

I. Dzhavakhishvili Tbilisi State University, Tbilisi 380028. Georgia State Zootechnical and Veterinary Educational and Research Institute, Tbilisi 38017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, p. 843, June, 1994. Original article submitted June 7, 1994.     

A simple method for preparing racemic dolichols from the polyprenols of pine needles (Pinus silvestris)

A simple method for preparing racemic mammalian dolichols by a three-stage transformation of a native mixture of plant polyprenols has been developed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1009–1011, May, 1999.     

A method for preparing N-alkylated kanosamines from diacetone d-glucose

The aminoglycoside (AG) antibiotics have seen a resurgence in their clinical use given the increase in multi drug resistant bacterial infections. Campaigns to generate novel analogs show promise that structural modification can lead to compounds with improved pharmacological properties. The results described herein include a new method to synthesize mono-, di-, and mixed N-alkylated kanosamine sugars and their elaboration into novel glycosides that inhibit bacterial protein synthesis in vitro.     

Empirical method for preparing a plutonium predominance-region diagram

An empirical method for preparing a plutonium predominance-region diagram is illustrated by an example. The method estimates the boundaries of the forbidden, unique, and ambiguous regions as defined by the equilibrium fraction of hexavalent plutonium and the plutonium oxidation number.     

5,10,15,20-中位-四(4-氨基苯基)卟吩合成方法的改进

在还原剂维生素C存在下,将4-氨基苯甲醛与吡咯在丙酸中缩合得到5,10,15,20-中位-四(4-氨基苯基)卟吩,操作简单,产率高于文献方法。     

One-pot method of preparing novel macrocyclic(thio arylene) oligomers

A series of macrocyclic(thio arylene) oligomers were synthesized under high dilution conditions by reacting diphenyl ether, diphenyl, diphenyl disulfide or diphenyl methane with dichloro disulfide in the presence of trace amount of iron powder by a one-step method. The composition of these macrocyclic oligomers was analyzed by MALDI-TOF technology, and the experimental results showed that the cyclics were a mixture with repeating units separated by one to seven sulfur atoms. These macrocyclics can undergo ring-opening polymerization to form linear polymers under mild conditions. The glass transition temperatures of produced polymers varied with the sulfur content.     

Rapid and sensitive method for measuring the plasma concentration of doxorubicin and its metabolites

Doxorubicin is an anti-cancer drug with a wide therapeutic range. However, it and its metabolites cause severe side effects, limiting its clinical use. Therefore, measuring the plasma concentration of doxorubicin and its metabolites is important to study the dosing regimen of doxorubicin. We developed a rapid and sensitive method by ultra-high-performance liquid chromatography with fluorescent detection for measuring the plasma concentration of doxorubicin and its metabolites in small volumes (around 10?μL), enabling repeated measurements from the same mouse. The sensitivity of 7-deoxydoxorubicinolone, a major metabolite of doxorubicin, increased about 5 times than those ever reported using conventional HPLC, and the run time was within 3?min. The area under the curve (AUC0-24?h) of doxorubicin was 5.9?μg h/mL similar to the value of 4.16?μg?h/mL obtained previously using a conventional HPLC method. This method would provide information that could be used to refine the therapeutic approach to doxorubicin use.     

Novel method for preparing 4-haloquinoline N-oxide hydrohalides from 4-nitroquinoline N-oxide

A simple method has been developed for preparation of 4-haloquinoline N-oxide hydrohalides involving passage of the gaseous hydrohalide at room temperature through a solution of 4-nitroquinoline N-oxide in chloroform.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 516–518, April, 1996.     

Rapid and sensitive lateral flow immunoassay method for determining alpha fetoprotein in serum using europium (III) chelate microparticles-based lateral flow test strips

Alpha-fetoprotein (AFP), a primary marker for many diseases including various cancers, is important in clinical tumor diagnosis and antenatal screening. Most immunoassays provide high sensitivity and accuracy for determining AFP, but they are expensive, often complex, time-consuming procedures. A simple and rapid point-of-care system that integrates Eu (III) chelate microparticles with lateral flow immunoassay (LFIA) has been developed to determine AFP in serum with an assay time of 15 min. The approach is based on a sandwich immunoassay performed on lateral flow test strips. A fluorescence strip reader was used to measure the fluorescence peak heights of the test line (H_T) and the control line (H_C); the H_T/H_C ratio was used for quantitation. The Eu (III) chelate microparticles-based LFIA assay exhibited a wide linear range (1.0–1000 IU mL⁻¹) for AFP with a low limit of detection (0.1 IU mL⁻¹) based on 5ul of serum. Satisfactory specificity and accuracy were demonstrated and the intra- and inter-assay coefficients of variation (CV) for AFP were both <10%. Furthermore, in the analysis of human serum samples, excellent correlation (n = 284, r = 0.9860, p < 0.0001) was obtained between the proposed method and a commercially available CLIA kit. Results indicated that the Eu (III) chelate microparticles-based LFIA system provided a rapid, sensitive and reliable method for determining AFP in serum, indicating that it would be suitable for development in point-of-care testing.     

A sensitive and selective spectrophotometric method for the determination of chromium (III)

Microchimica Acta - Chromium (III) forms a golden yellow colour with tropolone on heating on a boiling water-bath, and is extractable into chloroform. The complex absorbs maximum at 400 nm. The...     

New sensitive method for quantitative determination of proteins by zone immunoelectrophoresis (ZI)

Conclusion This method is more rapid than radial immunodiffusion (a few hours compared with a few days), is much more sensitive and has a much lower detection limit. Proteins in concentrations as low as 0.05 g/ml can be determined. ZI also has some major advantages over rocket immunoelectrophoresis: 1.Simpler equipment and working procedures — no sample wells and no electrode wicks. 2. Less consumption of antibodies, agarose and buffer substances per sample; 3.The total time needed to obtain a final result is shorter than that of conventional rocket immunoelectrophoresis; 4. Much lower detection limit (about 1/20 to 1/100); 5. Simpler evaluation because of much larger concentration range with a linear calibration curve which means less rerunning of samples and no area measurements or calculations. The small need of antibodies (about 0.3 l of antiserum per sample) with ZI is not only economically attractive (especially for expensive highly specific antibodies) but it may also be of the utmost importance when the total available amount is limited.Summarizing, zone immunoelectrophoresis appears very promising and advantageous for quantitative determination of proteins and some other antigens.

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Neues empfindliches Verfahren zur quantitativen Bestimmung von Proteinen durch Zonen-Immunoelektrophorese

     

A sensitive fluorescence anisotropy method for detection of lead (II) ion by a G-quadruplex-inducible DNA aptamer

Sensitive and selective detection of Pb²⁺ is of great importance to both human health and environmental protection. Here we propose a novel fluorescence anisotropy (FA) approach for sensing Pb²⁺ in homogeneous solution by a G-rich thrombin binding aptamer (TBA). The TBA labeled with 6-carboxytetramethylrhodamine (TMR) at the seventh thymine nucleotide was used as a fluorescent probe for signaling Pb²⁺. It was found that the aptamer probe had a high FA in the absence of Pb²⁺. This is because the rotation of TMR is restricted by intramolecular interaction with the adjacent guanine bases, which results in photoinduced electron transfer (PET). When the aptamer probe binds to Pb²⁺ to form G-quadruplex, the intramolecular interaction should be eliminated, resulting in faster rotation of the fluorophore TMR in solution. Therefore, FA of aptamer probe is expected to decrease significantly upon binding to Pb²⁺. Indeed, we observed a decrease in FA of aptamer probe upon Pb²⁺ binding. Circular dichroism, fluorescence spectra, and fluorescence lifetime measurement were used to verify the reliability and reasonability of the sensing mechanism. By monitoring the FA change of the aptamer probe, we were able to real-time detect binding between the TBA probe and Pb²⁺. Moreover, the aptamer probe was exploited as a recognition element for quantification of Pb²⁺ in homogeneous solution. The change in FA showed a linear response to Pb²⁺ from 10 nM to 2.0 μM, with 1.0 nM limit of detection. In addition, this sensing system exhibited good selectivity for Pb²⁺ over other metal ions. The method is simple, quick and inherits the advantages of aptamer and FA.