Association of TLR2 and TLR4 non-missense single nucleotide polymorphisms with type 2 diabetes risk in a southern Chinese population: a case-control study.

Toll-like receptors (TLRs), the triggers of the innate and adaptive immune responses, are involved in the pathogenesis of type 2 diabetes mellitus (T2DM). Several studies have investigated the effects of genetic polymorphisms in TLR4 and TLR2, but they have yielded limited results. We investigated whether non-missense genetic polymorphisms in the regulatory regions of TLR4 and TLR2 were related to T2DM in a southern Chinese population. Single nucleotide polymorphisms (SNPs) in TLR4 (rs1927911, rs11536889, rs1927907, rs1927906, rs1927914, rs7873784, and rs2149356) and TLR2 (rs1898830, rs3804099, rs4696480, and rs3804100) were genotyped in 552 T2DM and 552 unrelated age- and gender-matched controls by SNaPShot Multiplex assay. Genotypes GG (OR = 0.09, 95%CI = 0.01- 0.83, P = 0.03) and CG (OR = 0.08, 95%CI = 0.01-0.74, P = 0.03) of the 3'-untranslated region (UTR) SNP rs7873784 in TLR4, and genotype AG (OR = 0.67, 95%CI = 0.46-0.97, P = 0.04) and allele G (OR = 0.88, 95%CI = 0.79-0.97, P = 0.01) of the intron SNP rs1898830 in TLR2 were identified as protective against the development of T2DM in southern Chinese people. In contrast, a meta-analysis of rs1927911 and rs1927914 showed no association. Haplotypes AGTT (OR = 0.34, 95%CI = 0.15-0.77, P = 0.01) and AATT (OR = 1.20, 95%CI = 1.01- 1.44, P = 0.05) in TLR2 were significantly associated with susceptibility to T2DM. Our results suggest that the effects of non-missense polymorphisms located in the regulatory regions of TLR4 and TLR2 should not be neglected in T2DM association analysis.

Reaction-frequencymetric method: a new analytical technique for determination of submicromolar concentration levels of vitamin C.

A new analytical technique for the assay of pharmaceutical substances at low concentration levels has been proposed and applied to the determination of vitamin C as an example of its application. It is based on the chemical reaction of vitamin C with iodine in a sodium citrate-hydrochloric acid medium, followed by measurement of the frequency change of a silver-plated piezoelectric quartz crystal. The frequency change is proportional to the vitamin C concentration from 2 x 10(-7) to 4 x 10(-6) M. The method was applied to the assay of vitamin C in pharmaceutical preparations.

Extraction-frequencymetric method. A new measurement technique for determination of micro amounts of chlorpheniramine.

A new measurement technique has been proposed and applied to the determination of chlorpheniramine as an example of its application. It is based on the extraction of free chlorpheniramine into carbon tetrachloride after neutralization with a basic agent, followed by measurement of the frequency change of the specially designed ring-coated piezoelectric sensor after evaporation of the extractant from the crystal surface. The frequency change is proportional to the chlorpheniramine amount in the range 0.025-1.2 microgram. The method has been applied to the determination of chlorpheniramine maleate in pharmaceutical preparations.

Bulk acoustic wave sensor for investigating hemorheological characteristics of plasma and its coagulation.

A method of using a bulk acoustic wave (BAW) device to study the hemorheological phenomena is proposed. By measuring the resonant resistance of a BAW device, the dependence of the plasma viscosity on its composition is investigated. It has been found that during the process of the plasma coagulation, the frequency response of a BAW device is dominated by the change in plasma viscoelasticity, and useful information such as the coagulation time and the viscoelasticity of coagulated plasma can be obtained from the curve of frequency response. Based on the BAW quartz detection system, effects of fibrinogen, thrombin and some drugs on the plasma coagulation are investigated. The results show that the BAW device based on the oscillator method possesses some advantages, such as high sensitivity, simplicity of use, cost effectiveness and small sample volume for clinical hemorheological study.

Potentiometric determination of penicillins with ion-selective electrodes.

Quaternary ammonium, phosphonium and arsonium membrane electrodes sensitive to benzylpenicillin, ampicillin and oxacillin have been investigated. The order of merit of electrode performance is cetyltrioctylammonium > cetyltrioctylphosphonium > cetyltrioctylarsonium. The electrodes are suggested for use in rapid determination of penicillin drugs by direct potentiometry.

Sulpha-drug sensitive membrane electrodes and their analytical applications.

Cetyltrioctylammonium sulphathiazole, sulphadoxine and sulphadimethoxine membrane electrodes are proposed for the potentiometric determination of sulpha-drugs. The construction and basic characteristics of the electrodes are discussed.

A trimethoprim-selective membrane electrode.

An electrode selective for trimethoprim is based on the ion-pair complex of trimethoprim with silicotungstate, and gives rapid response to change in trimethoprim concentration over the range 3 x 10(-5)-2 x 10(-2)M with a response slope of 51.0 +/- 1.5 mV/decade. No significant interferences are caused by sulpha-drugs. The electrode can be used for the potentiometric determination of trimethoprim.

Determination of ammonium in Kjeldahl digests by gas-diffusion flow-injection analysis with a bulk acoustic wave-impedance sensor.

A novel flow-injection analysis (FIA) system has been developed for the rapid and direct determination of ammonium in Kjeldahl digests. The method is based on diffusion of ammonia across a PTFE gas-permeable membrane from an alkaline (NaOH/EDTA) stream into a stream of diluted boric acid. The trapped ammonium in the acceptor is determined on line by a bulk acoustic wave (BAW)-impedance sensor and the signal is proportional to the ammonium concentration present in the digests. The proposed system exhibits a favorable frequency response to 5.0 x 10(-6)-4.0 x 10(-3) mol l(-1) ammonium with a detection limit of 1.0 x 10(-6) mol l(-1), and the precision was better than 1% (RSD) for 0.025-1.0 mM ammonium at a through-put of 45-50 samples h(-1). Results obtained for nitrogen determination in amino acids and for proteins determination in blood products are in good agreement with those obtained by the conventional distillation/titration method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rates and potential interferents on the FIA signals were discussed in detail.

Determination of sulpha-drugs with a piezoelectric sensor.

A piezoelectric sensor is used for the determination of sulpha-drugs, as pure substances and in their dosage forms, by an indirect micro method based on reaction of the sulpha-drug with bromine and reduction of the resultant N-bromoderivative with iodide to form iodine, which after extraction is monitored with a piezoelectric quartz sensor. The response of the sensor is linear from 2 x 10(-5) to 4 x 10(-4)M sulpha-drug.

Electropolymerized m-phenylenediamine as a means to immobilize active protein on thickness-shear-mode quartz crystal.

Electropolymerized m-phenylenediamine was used as an active coating for immobilizing urease and lectin on a gold-plated thickness-shear-mode (TSM) crystal. To enhance effectiveness of immobilization. a bilayer polymer film composed of polyaniline and poly-m-phenylenediamine was proposed. Compared with single poly-m-phenylenediamine film, the bilayer polymer film gave better results in terms of immobilizing capacity, stability and reproductivity. On this bilayer-film-coated TSM quartz crystal, the amount of immobilized lectin was estimated about 1.8 mug/cm(2). Detection of purified human erythrocytes is demonstrated as an example of potential application of this lectin-modified TSM biosensor in clinic.

Ion chromatographic determination of calcium and magnesium cations in human saliva and urine with a piezoelectric detector.

In this present paper, simultaneous determination of Ca(2+) and Mg(2+) cations in saliva, urine was achieved using an ion chromatography method, in which a piezoelectric quartz crystal (PQC) sensor was used as a detector, and a solution containing tartaric acid (4 mmol 1(-1)) and ethylenediamine (2 mmol 1(-1)) as a mobile phase. Good linearities were obtained over the ranges of 0.8-500 mg 1(-1) Ca(2+) and 1.0-500 mg 1(-1) Mg(2+). The detection limits were 0.4 mg 1(-1) for Ca and 0.2 mg 1(-1) for Mg, respectively.

Determination of dipyridamole by modified extraction-gravimetry with a surface acoustic wave resonator sensor.

A simple and sensitive extraction-gravimetric method for the determination of dipyridamole is presented. The method is based on the extraction of free dipyridamole with chloroform, after neutralization with a basic agent, followed by measurement of the frequency shift response of the specially designed surface acoustic wave resonator sensor after evaporation of the extractant from the surface of the resonator. The frequency shift response was proportional to the amount of dipyridamole in the range 0.065-1.12 micrograms. Experimental parameters and the effect of interfering substances on the assay of dipyridamole were also examined in this study. The method was applied to the determination of dipyridamole in tablets.

Flow-injection determination of total ammonia and total carbon dioxide in blood based on gas-diffusion separation and with a bulk acoustic wave impedance sensor.

A novel flow-injection (FIA) system, for the rapid and direct determination of both total ammonia (T[NH3]) and total carbon dioxide (T[CO2]) in clinical blood samples, has been developed. Samples were injected into a carrier stream of H2O, then emerged with a reagent stream, where the analyte was converted into a gaseous species and diffused across a PTFE gas-permeable membrane into an acceptor stream. The trapped NH3/CO2 in the acceptor was determined on line by a bulk acoustic wave (BAW) impedance sensor. At a through-put of 20 and 65 h(-1), the proposed system exhibited a linear frequency response up to 200 micromol l(-1) ammonium and 20 mmol l(-1) bicarbonate with a detection limit of 1.0 and 10 micromol l(-1), respectively. Results obtained for T(NH3) in serum and T(CO2) in plasma were in agreement with those obtained by the conventional glutamate dehydrogenase (GDH) method and gas-sensing electrode method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rate and potential interferents on the FIA signals were also discussed.

Simultaneous determination of nitrate and nitrite in saliva and foodstuffs by non-suppressed ion chromatography with bulk acoustic wave detector.

In the present paper, nitrate and nitrite in foodstuffs and saliva were simultaneously determined using a non-suppressed ion chromatography (IC) method with a bulk acoustic wave sensor (BAW) as detector, and 1.5 mmol/L potassium hydrogenphthalate (KHP) as mobile phase. The IC-BAW method is simple, rapid and accurate. The determination limits for nitrite and nitrate are 0.20 and 0.30 mg/L, respectively. The IC-BAW is comparable and agrees with the conventional spectrophotometric method for nitrite and nitrate determination.

Application of a series piezoelectric sensor as a detector in ion chromatography.

The application of a series piezoelectric sensor as a detector for ion chromatography (IC) is investigated. The device is used with sensitive response between the series piezoelectric quartz crystal oscillation frequency and specific conductivity of liquids for ion chromatographic detection. Two platinum wires are used as conductivity electrodes and inserted oppositely in the detection cell. The dead-volume of the detection is 15 microL, the noise is less than or equal to 1 Hz, the baseline drift is 5 Hz/h, and the detection limits of F- and Na+ are 5 and 25 ng, respectively. The effects of temperature, background conductivity, cell constant of the conductivity electrode, and dead volume on the sensitivity of the detector are discussed. The detector temperature should equal that of the column. An optimum sensitivity is obtained when the cell constant is approximately 3.5 cm. The optimum range of the background conductivity of the mobile phase is 150 to 1200 microseconds. When the solution conductivity is greater than 3000 microseconds, the detector does not work satisfactorily. The proposed IC cerebrospinal fluid detection method is applied to the determination of vitamin C in apple and Zn2+, Ca2+, Mg2+, and Cu2+ in human cerebrospinal fluid.

[Use of extraction-frequency metric method for the determination of microquantities of ephedrine and its application in pharmaceutical analysis].

A new extraction--frequency metric method has been proposed for the determination of ephedrine, which can not be determined by the conventional extraction--weighing method due to its volatility. The method is based on extraction of the free alkaloid followed by measuring the frequency shift of a specially constructed ring--coated piezoelectric crystal at room temperature. The frequency shift is in linear relationship with the content of ephedrine hydrochloride over a range 0.05-1.2 micrograms with a correlation coefficient of 0.999 and a detection limit of 0.02 micrograms. Methods for the assay of ephedrine hydrochloride tablet and nasal solution have been proposed.

[Determination of micro-amount of dipyrone with a piezoelectric detector].

A new method for the determination of dipyrone (analgin) using a piezoelectric quartz crystal as detector has been proposed. An iodine-potassium iodide solution is added to the sample and the frequency shift of the crystal immersed in the sample solution with respect to the blank is directly proportional to the concentration of dipyrone over a range from 2 x 10(-7) to 3 x 10(-6) mol/L at pH 3.5-6.5 according to the equation C (mol/L) = 6.85 x 10(-9) delta F (Hz). No significant interferences were caused by commonly met inorganic substances, amino acids and a number of other organic substances. The method has been suggested for determining dipyrone at ppm level and in micro-samples of mg or microliters level.

[Determination of microgram-amount pentoxyverine citrate using a piezoelectric detector and neutralization-extraction technique].

A new method for the rapid determination of microgram and submicrogram amounts of pentoxyverine citrate has been suggested using a ring-coated piezoelectric quartz crystal in combination with the neutralization extraction technique. The detection limit is 0.02 microgram. Frequency shift is directly proportional to the pentoxyverine citrate concentration in the range of 0.05-1.6 micrograms, with a correlation coefficient of 0.999 and a coefficient of variation of 2.3%. The new method suggests a number of advantages over the classical neutralization-extraction method.

[Characteristics of ion selective electrodes with hetero-poly anion sites].

Drug ion-selective electrodes made with hetero-poly anion as exchange site exhibit better performances than the respective electrodes of conventional tetraphenylboron type, yielding low detection limits and fast responses. Functions of propantheline, berberine, dibazol, thiamine, streptomycin, moroxydine, tetracycline, oxytetracycline, doxycycline, erythromycin, carbetapentane, benzydamine, tetramisole and trifluoperazine electrodes are reported. The electrodes can be used in potentiometric determinations of the respective drugs in aqueous solutions, urine and mixture of water and organic solvents.

[Simultaneous determination of vitamin B1 and vitamin C in aqueous solution with piezoelectric crystal quartz sensors].

According to the response properties of piezoelectric crystal quartz sensors to the solution conductivity the frequency shift response was derived to show a linear dependence on the concentrations of vitamin B1 (VB1) and vitamin C (VC). This was experimentally verified and a calibration model for simultaneous determinations of the two vitamins was established. The usefulness of the technique was evaluated by quantitation of mixtures of unknown composition using common multiple linear regression (MLR) and partial least squares (PLS). The average relative standard deviations for six samples were 4.46% for VB1 and 6.63% for VC with MLR; and 1.97% for VB1 and 2.74% for VC with PLS, respectively.