A new method of ATP regeneration rate measurement using a pH meter

A new method was developed for measuring the ATP regeneration rate by creatine kinase from creatine phosphate and ADP. The ATP regeneration rate was calculated to be 0.20 mM x s(-1) at room temperature from the pH change of the regeneration mixture.

Quality control of postoperative acute pain service

To establish an effective method of continuous quality control of acute pain service, a retrospective study on incident reporting during postoperative analgesia period was conducted. Incidents were reported and analyzed in 1507 patients who received epidural postoperative analgesia, and the results of satisfaction of pain relief was compared with those of incident analysis. In this study, an incident was defined as any factor that might or had affected patient's safety during analgesia period. Our results showed that 1203 incidents were reported in 641 of 1507 patients, of which 122 incidents were critical. 78.3% of all incidents were detected by acute pain service stuff. The most common incidents included complications, insufficient analgesia and problems with delivery circuits. Human factors were involved in 28.9% of the incidents, most being associated with technical failure due to unskillfulness, poor communications between APS stuff and patients and lack of cooperation with surgeons and nurses. The general satisfaction rate of the patients was 90.8%. There was a very significant difference between the satisfaction of the patients who suffered from incidents and who did not (P < 0.001). It is concluded that incidents affect the satisfaction of the patients who received postoperative pain relief. Incident reporting is a more effective method for quality control of acute pain service.

Selective amplification by auto- and cross-catalysis in a replicating peptide system

Self-replication has been demonstrated in synthetic chemical systems based on oligonucleotides, peptides and complementary molecules without natural analogues. However, within a living cell virtually no molecule catalyses its own formation, and the search for chemical systems in which both auto- and cross-catalysis can occur has therefore attracted wide interest. One such system, consisting of two self-replicating peptides that catalyse each other's production, has been reported. Here we describe a four-component peptide system that is capable of auto- and cross-catalysis and allows for the selective amplification of one or more of the products by changing the reaction conditions. The ability of this system selectively to amplify one or more molecules in response to changes in environmental conditions such as pH or salt concentration supports the suggestions that self-replicating peptides may have played a role in the origin of life.

Solution structure of peptides from HIV-1 Vpr protein that cause membrane permeabilization and growth arrest

Vpr, one of the accessory gene products encoded by HIV-1, is a 96-residue protein with a number of functions, including targeting of the viral pre-integration complex to the nucleus and inducing growth arrest of dividing cells. We have characterized by 2D NMR the solution conformations of bioactive synthetic peptide fragments of Vpr encompassing a pair of H(F/S)RIG sequence motifs (residues 71-75 and 78-82 of HIV-1 Vpr) that cause cell membrane permeabilization and death in yeast and mammalian cells. Due to limited solubility of the peptides in water, their structures were studied in aqueous trifluoroethanol. Peptide Vpr59-86 (residues 59-86 of Vpr) formed an alpha-helix encompassing residues 60-77, with a kink in the vicinity of residue 62. The first of the repeated sequence motifs (HFRIG) participated in the well-defined alpha-helical domain whereas the second (HSRIG) lay outside the helical domain and formed a reverse turn followed by a less ordered region. On the other hand, peptides Vpr71-82 and Vpr71-96, in which the sequence motifs were located at the N-terminus, were largely unstructured under similar conditions, as judged by their C(alpha)H chemical shifts. Thus, the HFRIG and HSRIG motifs adopt alpha-helical and turn structures, respectively, when preceded by a helical structure, but are largely unstructured in isolation. The implications of these findings for interpretation of the structure-function relationships of synthetic peptides containing these motifs are discussed.

Modulation of platinum-induced toxicities and therapeutic index: mechanistic insights and first- and second-generation protecting agents

Platinum-type drugs have proven to be valuable in the treatment of a variety of solid tumors, beginning with the commercial approval of cisplatin 18 years ago. There are several clinically important toxicities commonly associated with the administration of these drugs. Despite the extensive use of cisplatin and carboplatin, the fundamental chemical transformations and mechanisms that underlie their antitumor and toxic effects have not been fully characterized. Several first-generation protective thiols have been clinically studied in an attempt to reduce the toxicity of platinum-type drugs; while some of these agents appear to protect against certain toxicities, nearly all platinum-protecting drugs have their own intrinsic toxicities, which can be additive to the toxicity of platinum-type drugs. Tumor protection by platinum-protecting drugs is an additional untoward effect that is associated with certain types of agents and must be addressed with care. Recent advances in theoretical and laboratory methods and the use of supercomputers have extended our understanding of the possible major mechanisms underlying platinum drug antitumor activity and toxicity; we present strong evidence that there are two classes of chemical species of platinum drug. One class appears to predominantly account for the antitumor activity, and the other class of chemical species produces many of the toxic effects of platinum drugs. We have discovered a new nontoxic, second-generation platinum-protecting agent, known as BNP7787, which appears to selectively inactivate and eliminate toxic platinum species. BNP7787 has recently entered phase I clinical testing in cancer patients.

NS398, a selective cyclooxygenase-2 inhibitor, induces apoptosis and down-regulates bcl-2 expression in LNCaP cells

Cyclooxygenase (COX)-2, an inducible enzyme that catalyzes the formation of prostaglandins and other eicosanoids from arachidonic acid, is constitutively expressed in LNCaP human prostate cancer cell line. To evaluate the potential role of COX-2 in prostate cancer, LNCaP cells were treated with NS398, a selective COX-2 inhibitor, and the effects on cell viability and apoptosis were determined. NS398 treatment induced apoptosis in LNCaP cells in a time- and dose-dependent fashion. Treatment with 100 microM NS398 caused a down-regulation in bcl-2 protein expression, followed by chromatin condensation, chromosomal DNA fragmentation, and changes in nuclear morphology detected by 4,6-diamidino-2-phenylindole staining, DNA fragmentation assay, and terminal deoxynucleotidyl transferase-mediated UTP-biotin nick end-labeling assay. In contrast, NS398 treatment had no effect on either cell viability or nuclear function and morphology in human fetal prostate fibroblasts. These results demonstrate that NS398 induces apoptosis in LNCaP cells but not in human fetal prostate fibroblasts, and that this induction is associated with a decreased level of bcl-2 protein.

[Effects of cadmium on 3H-leucine incorporation and cell growth of cultured myocardiocytes]

The effects of cadmium on 3H-leucine incorporation and cell growth of cultured cardiac myocytes were investigated by measuring the incorporation quantity of radioisotope labelled amino-acid and the cell volume on cultured myocardiocytes in neonatal Wistar rats. The results showed that 3H-leucine incorporation was decreased significantly in 1 x 10(-4) mmol/L CdCl2 for 24 h, and was gradually reduced with prolongation. The cell volume was decreased after exposed to Cd for 48 h. The volume was from (2053 +/- 189) microns 3 to (1847 +/- 176) microns 3. There was no significant difference in cell number between the treated group and the control group. These data indicated that cadmium can inhibit the synthesis of protein and the growth on cultured myocardiocytes.

Topotecan lactone selectively binds to double- and single-stranded DNA in the absence of topoisomerase I

We report the first experimental observation that a clinically important camptothecin [CPT; topotecan (TPT), a water-soluble CPT] binds directly and noncovalently to double-stranded DNA and single-stranded DNA structures in the absence of topoisomerase I, but only in the lactone form. We observed clear DNA sequence specificity of the TPT lactone binding to duplex DNA, which was comprised of alternating purine-pyrimidine sequences that contained dT. These structural studies of direct TPT lactone-DNA binding support several important considerations involving possible mechanism(s) of anticancer activity of CPT-type drugs containing a 20(S) lactone moiety.

A rapid method for determination of in vitro susceptibility to antibiotics with a bulk acoustic wave bacterial growth biosensor

A novel bulk acoustic wave (BAW) bacterial growth biosensor was developed to study in vitro susceptibility by continuous monitoring of disturbances of bacterial growth at low antibiotic concentrations, followed by the accurate and rapid estimation of growth kinetic parameters and minimum inhibitory concentrations (MICs). The susceptibilities of bacteria, e.g. Escherichia coli, Staphylococcus aureus, Proteus vulgaris, Pr. morganii and Pr. mirabilis, to various antibiotics, e.g. penicillin, streptomycin, gentamicin and cefotaxime, were investigated, respectively, and the MICs were rapidly determined with a higher reproducibility than the conventional broth micro-dilution technique (BMDT). The effects of cell constant of conductivity electrode, pH and temperature on bacterial growth and biosensor signals were discussed in detail. The proposed method offers an effective alternative to the conventional methods.

Bulk acoustic wave bacterial growth sensor applied to analysis of antimicrobial properties of tea

A bulk acoustic wave (BAW) bacterial growth sensor has been proposed for study of inhibitory effects of tea by continuous monitoring of disturbances in Proteus growth in the aqueous extracts of various teas, e.g. green tea, Fuzhuan brick tea, Oolong tea, Kudin tea, and black tea. The kinetic parameters, e.g. asymptote (A), maximum specific growth rate (microm), lag time (lambda), and generation time (g), accurately estimated by using the growth response model, have been first used to characterize antimicrobial properties of tea. All of the parameters were changed via the inhibitory effects by tea. Green tea gives the weakest inhibitory action while others show stronger inhibitory actions. These inhibitory effects have also been examined by using the pour plate count technique. Both of the results show that, in addition to the antimicrobial properties of tea polyphenols and catechins, etc., the inhibitory effects may be attributed to the metabolites produced during the fermentation processing of these teas except green tea. The conventional disk diffusion test has been used to determine the minimum inhibitory concentration (MIC) against P. rettgeri. The MICs of green tea, Fuzhuan brick tea, Oolong tea, and black tea were found to be 1113, 818.0, 681.2, and 510.4 microg/mL, respectively. The BAW bacterial growth sensor has shown to have advantages over other techniques, including the disk diffusion test, photometry, and the impedance method.

Mutation of a gene encoding a protein with extracellular matrix motifs in Usher syndrome type IIa

Usher syndrome type IIa (OMIM 276901), an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa, maps to the long arm of human chromosome 1q41 between markers AFM268ZD1 and AFM144XF2. Three biologically important mutations in Usher syndrome type IIa patients were identified in a gene (USH2A) isolated from this critical region. The USH2A gene encodes a protein with a predicted size of 171.5 kilodaltons that has laminin epidermal growth factor and fibronectin type III motifs; these motifs are most commonly observed in proteins comprising components of the basal lamina and extracellular matrixes and in cell adhesion molecules.

[Pressure control system for the hermetically sealed cabin of the recoverable satellite]

There are many precision instruments and equipment for scientific researches and experiments in the hermetically sealed cabin of satellite. Appropriate pressure must be controlled in the cabin in order to ensure the instruments and equipment from the adverse space environment. This paper describes a pressure control system for the hermetically sealed cabin in the recoverable scientific detect and experimental satellite. The cabin pressure is regulated automatically into the specific levels by venting or supplying the air from or to the cabin during launch, on orbit and before reentry of the satellite. The system has low mass, low power consumption and high reliability. It was used successfully in the recoverable satellite first in September 1987 and had been used many times since then. It is the first active pressure control system for the hermetically sealed cabin of the satellite in China.

Improved Estimation of Protein Rotational Correlation Times from 15N Relaxation Measurements

In the study of protein backbone dynamics by 15N relaxation measurements, an initial estimation of the isotropic global correlation time, taum, is usually obtained from the average T1/T2 ratio of nuclear spins that do not exhibit slow internal motion and with T2 values not significantly shortened by chemical or conformational exchange processes. Different methods have been used for identification of the rates of internal motion. However, the number of nuclear spins included in the taum estimation is often larger than the number that ultimately can be fitted to a single-order parameter, S2, implying that some nuclear spins involved in the initial taum estimation actually have an effective internal correlation time, taue, not as fast as assumed. As a consequence, taum is underestimated, since internal motion reduces the T1/T2 ratio. This situation becomes more obvious if the molecule has a large taum value because the reduction in T1/T2 ratio arising from internal motion is more significant than for molecules with smaller taum and the same degree of internal motion. This Communication describes a more reliable method for identifying nuclear spins which should be excluded from the taum estimation because of insufficiently rapid internal motion. This results in an improved taum value, giving a much better agreement between the number of nuclear spins fitted successfully to a single-order parameter, S2, and those used in the taum estimation. Copyright 1998 Academic Press.

[Spectral determination of the contents of elements in bean and bean-product]

Determination of the contents of elements in Bean and Bean product using Z-8000 atomic absorption spectrometry is described. This results obtained indicate that high amounts of Mn, Fe and Mg are embodied in Bean and Bean-products. The Beans are good food for longevity and intelligence development.

Endothiopeptide inhibitors of HIV-1 protease

Endothiopeptide inhibitors of HIV-1 protease were synthesized by chemical and enzymatic methods to individually replace each backbone amide bond in 1 with a thioamide-linkage. Interestingly, agent 7, which contains a thioamide-linkage between the P2' and P3' positions of 1, was the most potent, competitive inhibitor of HIV-1 protease with a Ki of 3.4 microM.

[One year observation of craniomandibular structure changes of skeletal Class II patients in early permanent dentition]

OBJECTIVE

To study the craniomandibular growth of skeletal class II patients in early permanent dentition so that demonstrate malocclusion development and decide orthodontic treatment opportunity.

METHODS

Forty skeletal class II patients in early permanent dentition were selected at random and observed for one year. The lateral cephalometric X-ray films were taken before and after observation for every patient, then Downs analysis and doublet test were made.

RESULTS

Female patients' jaws relation didn't change in early permanent dentition, but upper incisors were more protrusive than before, and lower incisors inclined lingualy. Male patients' mandible grew upward and forward, but the absolute value of small change.

CONCLUSION

It is necessary to treat skeletal class II deformities early.

Conformational and topological requirements of cell-permeable peptide function

Cell-permeable peptide import recently was developed to deliver synthetic peptides into living cells for studying intracellular protein functions. This import process is mediated by an N-terminal carrier sequence which is the hydrophobic region of a signal peptide. In this study, the conformational consequence of the interaction of cell-permeable peptides with different mimetic membrane environments was investigated by circular dichroism analysis. We showed that cell-permeable peptides adopted alpha-helical structures in sodium dodecyl sulfate (SDS) micelles or aqueous trifluoroethanol (TFE). The potency of these peptides in forming helical structures is higher in an amphiphilic environment (SDS) than in a hydrophobic environment (TFE), suggesting that some hydrophilic molecules associated with the cell membrane may be involved in peptide import. We also studied topological requirements of cell-permeable peptide function. We demonstrated that peptides containing the carrier sequence in their C-termini can also be imported into cells efficiently. This important discovery can avoid repetitious synthesis of the membrane-translocating sequence for peptides with different functional cargoes and is potentially useful for developing a cell-permeable peptide library. Finally, we showed that, when a retro version of the carrier sequence was used, the peptide lost its translocating ability despite retaining a high content of alpha-helical structure in mimetic membrane environments. This suggests that the propensity of peptides to adopt a helical conformation is required but not sufficient for cellular import and that other structural factors such as the side-chain topology of the carrier sequence are also important. Our studies together contribute to the more rational design of useful cell-permeable peptides.

[Spectral study of podophyllotoxin and its derivatives]

In this paper, we have studied all kinds of static absorption spectra and transient absorption spectra of podophyllotoxin and its derivatives. We have located the site of absorption spectra and their forming mechanism with spectrofluorometry, Ultraviolet, pulse radiolysis and laser photolysis, and suggested the connection of their structrue with their anti-tumour and toxicity.

[Spectral studies of vitamin K3 in aqueous solution by pulse radiolysis and laser photolysis]

The absorption spectra of VK3 in aqueous solution were studied by pulse radiolysis and laser photolysis technique, and the formation mechanism of intermediates of transient species was suggested, which gave the examples for studying the mechanism of blood-clotting of VK3 and provided the theoretic evidence for further understanding the reasons of VK3 as a radiosensitizer.

The design and preliminary evaluation of a home electrocardiography and blood pressure monitoring network

A home electrocardiography (ECG) and blood pressure (BP) monitoring network was established in Beijing. The network consisted of three parts: (1) the home ECG and BP monitoring devices; (2) the monitoring centre at the hospital; and (3) the data communication network, for which we chose the public telephone network. The system was tested in our university hospital for two months with 30 patients and six normal volunteers. A preliminary evaluation by the users indicated that the system was acceptable in terms of its efficiency and effectiveness. This paper describes the system design, the preliminary testing procedure, and results.

[Exploration of processing principles for fructus Psoralea]

This paper deals with the exploration of processing principles for Fructus Psoralea using GC method with the content of active constituents--psoralen and isopsoralen as the criteria. The result showed that both temperature and enzyme would enhance the content of psoralen and isopsoralen, and the latter was stronger in action than the former.

[Application of mean EMG to the evaluation of human workload during manual operation]

To evaluate human workload during manual operation, 9 subjects participated in the attitude maintaining experiment with simulated earth scenery as the display and a stick as the controller. Mean-rectified EMG was chosen as the index. Surface EMG was recorded in a couple of agonist and antagonist. Kinematics equation was simulated on a analog computer, and three difficulty of work were controlled by changing the amplifier's coefficients. 486 Computer was used to record the quantity of subject's operation and the data of Mean EMG from amplifier. Relevant software was compiled. The results showed that there was a linear relationship between mean-rectified EMG and difficulty of work. The effects of training on workload were also discussed. Mean EMG can be used as an index for evaluating human workload.

[The study on three-dimensional laser scanning of dental model and computer aided set-up]

A new laser scanning and measurement method was introduced for dental model three-dimensional form. A laser diode was used as scanning light source, two CCDs (they were fixed specially) received the diffused light reflected from the dental model. The dental model rotating-moved back and forth, and horizontal moved from one side to another along horizontal axis simultaneously. Whole dental model can be scanned in 3 minutes, general precision was up to 0.03 mm. The computer can display distinctly three-dimensional images of dental model in different directions and give three-dimensional coordinate data, distance, angle, and remove teeth and make set-up after scanning. With advantages of high precision, fast speed and excellent object, the new method can be of an important applied value in orthodontic clinic.

An alternative to phosphotyrosine-containing motifs for binding to an SH2 domain

Shc is an important signalling protein whose overexpression leads to cell transformation in NIH 3T3 fibroblasts. Although the formation of Shc/Grb2 complexes involving Shc tyrosine residue 317 is necessary to induce this transformation, the Shc proteins in these Shc-overexpressing cells are not substantially tyrosine-phosphorylated. This observation led to our hypothesis that the non-phosphorylated Tyr317-containing region of Shc might have specific affinity for the Grb2 protein. We show here that cell-permeable peptides encompassing the Shc Tyr317 region, 312FDD-PSYVNVQNL323, can bind to the SH2 domain of Grb2 regardless of the state of tyrosine phosphorylation. When delivered into cells, both phosphorylated and non-phosphorylated Shc peptides inhibit growth factor-induced Shc/Grb2 protein-protein interaction. The non-phosphorylated Shc peptides with single point mutations at Asp313, Asp314, or Tyr317 are inactive, suggesting that these residues play an important role in Grb2 protein recognition. Our findings represent the first paradigm of the specific interaction between an unphosphorylated tyrosine-containing region and an SH2 domain and have important implications for understanding the mechanism of cell transformation by Shc overexpression.

[Fluorescence and FT-IR spectroscopic studies on the mixed solid complexes of europium and terbium phthalate]

In this investigation, the fluorescence and FT-IR spectroscopic studies on synthesized Eu-Tb phthalate complexes and mixed solid complexes of europium and terbium phthalates were perfomed. The experimental results of the emission spectra excited by 365nm UV-light showed that the emission peak positions of Eu ( III ) [or Tb ( III )] wer shifted slightly due to the interaction between Tb ( III )and Eu ( III ) ions. However, the fluorescence intensities of one rare eath ion Eu ( III ) [or Tb (III )] were strongly influenced by the other. FT-IR spectra indicated that the coordination structures of carboxyl groups, both in mechanically mixed and synthesized solid complexes, were also changed. These results suggested that there are interactions between Eu ( III ) and Tb ( III ) ions in their mixed complexes.

Detection and analysis of the growth characteristics of Proteus vulgaris with a bulk acoustic wave ammonia sensor

A bulk acoustic wave ammonia sensor to monitor the growth of Proteus vulgaris is described. The corresponding bacterial growth response equation was derived based on the basic growth characteristics of P. vulgaris, and was verified experimentally. The application of the equation to the estimation of kinetic parameters (such as the asymtote, the maximum specific growth rate and the lag time) was accomplished successfully. The generation time is 33.3 min at 37 degrees C. The influence of temperature on bacterial growth was also investigated and the activation energy of P. vulgaris growth was estimated. Furthermore, the initial bacterial concentrations were determined based on the linear relationship between the inflection time, ti, and the logarithm of the initial bacterial concentration in the range 10(2)-10(7) (cells ml-1). The results were in good agreement with those from the pour plate count method and the precision was better than that of the frequency detection time method.

An investigation of the fluidity of concentration polarisation layers in crossflow membrane filtration of an oil-water emulsion using chemical shift selective flow imaging

A chemical shift selective NMR flow imaging sequence using stimulated echoes for data acquisition is presented. The sequence was tested using a 20% (vol/vol) oil-water emulsion formed from a soluble cutting oil, which was passed through a simple flow phantom to yield two-dimensional velocity distribution maps of the oil droplets and of the water separately. It was then used to investigate the fluidity of concentration polarisation layers formed from the oil droplets during crossflow membrane filtration of a 5% (vol/vol) emulsion of the same cutting oil. A simple membrane filtration module was used for this purpose, with the feedstock emulsion fed into the lumen of a single tubular membrane at a trans-membrane pressure difference P approximately 70 kPa and crossflow Reynolds number, Re, in the range 100-1000. The results confirm a net axial flow rate < 7.5 microns/s (half digital resolution in the velocity dimension) for the oil polarisation layer. Under these conditions, the upper limit for oil flow tangential to the membrane in the polarised layer is less than 15% of the convective flow of oil towards the membrane.

Controlling epidermal growth factor (EGF)-stimulated Ras activation in intact cells by a cell-permeable peptide mimicking phosphorylated EGF receptor

Epidermal growth factor (EGF)-stimulated Ras activation involves specific interactions between the EGF receptor (EGFR), the adaptor proteins Grb2 and Shc, and the nucleotide exchange factor Sos-1. Study and control of these protein-protein interactions in vivo can be greatly promoted by introducing intracellular reagents that mimic EGFR functions. Here, we showed that a synthetic phosphopeptide encompassing the autophosphorylation site 1068 of EGFR formed a complex with endogenous Grb2 after this peptide was delivered into intact cells by a cell-permeable peptide import technique. Consequently, this intracellular peptide inhibited EGF-induced EGFR/Grb2 associations but not EGFR/Shc or Shc/Grb2 associations. Peptide-mediated disruption of the EGF/Grb2/Sos-1 cascade led to reduced Ras activation and mitogen-activated protein kinase activation. These results indicate that the binding of Grb2 to the phosphorylated Tyr-1068 of EGFR is crucial to the EGF-induced Ras/mitogen-activated protein kinase signaling pathway. The application of cell-permeable peptides to this study demonstrates a useful biochemical tool to probe and control various intracellular processes involved in signal transduction and gene transcription.

[Pearl and mother-of-pearl powder in health-care]

Based on pharmacological studies in files, mice and rats, the powder of sea pearl (Pteria martensii), mother-of-pearl and freshwater pearl has been proved to have tonic, anti-aging and anti-radiative actions. The effect of the sea pearl and mother-of-pearl powder is higher than that of freshwater pearl powder.

[Comparison of ancient and modern processing methods for fructus Psoraleae]

The contents of 3 active compounds psoralen, isopsoralen and poisonous bakuchiol in 5 differently processed samples of Fructus Psoraleae were analysed by GC. The results indicate that the content of psoralen and isoporalen in the sample processed by the method of "Leigong's theory of processing" are 3-4 times that in the salt-fried sample, while the content of poisonous bakuchiol shows a tendency to decrease.

Kinetic assay of antitrypsin in human serum by a surface acoustic wave (SAW)-impedance sensor

Antitrypsin in human serum was determined by using both the SAW-impedance sensor system and spectrophotometry, indicating that the mean value for women was significantly higher than the mean value for men; the value for acute pancreasis patients is about 2-folds of the normal values, and there is no significant difference between the acute pancreasis patients and the pancreatic cancer patients.

Reaction of hydroxyl radical with phenylpropanoid glycosides from Pedicularis species: a pulse radiolysis study

Using pulse radiolysis technique, the reaction between hydroxyl radical and 7 phenylpropanoid glycosides: echinacoside, verbascoside, leucosceptoside A, martynoside, pediculariosides A, M and N which were isolated from Pedicularis were examined. The rate constants of these reactions were determined by transient absorption spectra. All 7 phenylpropanoid glycosides react with hydroxyl radical at high rate constants within (0.97-1.91) x 10(10)L.mol-1.s-1, suggesting that they are effective hydroxyl radical scavengers. The results demonstrate that the numbers of phenolic hydroxyl groups of phenylpropanoid glycosides are directly related to their scavenging activities. The scavenging activities are likely related to o-dihydroxy group of phenylpropanoid glycosides as well.

Repair of dGMP hydroxyl radical adducts by verbascoside via electron transfer: a pulse radiolysis study

The repair activity of verbascoside (VER), isolated from Pedicularis spicata, towards the oxidizing hydroxyl radical adduct of dGMP and its reaction mechanism were studied using pulse radiolysis. Upon pulse radiolysis of nitrous oxide saturated aqueous solution of 2'-deoxyguanosine-5'-monophosphate (dGMP) and VER, it was found that the transient absorption spectrum of the hydroxyl adduct of dGMP decays with the formation of that of the phenoxyl radical of VER, several tens of microseconds after the electron pulse. From the formation kinetics of the phenoxyl radical of VER, the rate constant of the repair reaction was determined to be 1.12 x 10(9) dm(3) mol(-1) s(-1).

Similar conformations of hairpins with TTT and TTTT sequences: NMR and molecular modeling evidence for T.T base pairs in the TTTT hairpin

The conformations of the d[G(1)C(2)G(3)C(4)-T(a)T(b)T(c)T(d)-G(5)C(6)G(7)C(8)] (T4) and d[G(1)C(2)G(3)C(4)-T(a)T(b)T(c)-G(5)C(6)G(7)C(8)] (T3) DNA hairpins have been studied. The 1H and 31P signals of the two hairpins have been nearly completely assigned by means of two-dimensional NMR spectroscopy in D2O (NOESY (two-dimensional nuclear Overhauser effect and exchange spectroscopy) at mixing times of 5, 50, 100, 300 and 500 ms, double-quantum-filtered correlation spectroscopy (DQF-COSY) and 1H-31P reverse chemical shift correlation (RCSC), and one-dimensional NOE spectra in 90% H2O. Conformational analysis using distance geometry (DG), molecular mechanics (MM) and molecular dynamics (MD) gave model conformations, which were evaluated by comparison of experimental and simulated 2D NOESY spectra. For the T4 sequence in T4, both NMR data and modeling indicated a T(a).T(d) wobble base pair. Although two types of T(a).T(d) base pairs are possible, the one with T(a)NH-T(d)O4 and T(a)O2-T(d)NH H-bonds was calculated to be more stable. Because the T(a).T(d) base pair of T4 extends the stem, there are only two residues (T(b) and T(c) in the loop. Although there are three residues in the T3 loop, the T(c) base projects into the solvent. The resulting conformational models have very similar loop folding patterns (FP): the bases of the two adjacent residues that begin the loop [T(b)T(c) of T4 and T(a)T(b) or T3] have a minor groove/major groove orientation with the first residue each having a trans alpha torsion angle; and the phosphodiester group that links the residues at the 3' end of the loop and the 5' top of the stem [T(c)pT(d) of T4 and T(c)pG(5) of T3] has a gauche+, gauche+ zeta,alpha conformation with a trans gamma angle for the second residue in both. These or similar features appear to be present in most of the few other hairpins studied previously by conformational methods. Thus, we believe that the conformations of the loops in T3 and T4 hairpins have greater similarities than previously recognized.

An oligodeoxyribonucleotide N3'--> P5' phosphoramidate duplex forms an A-type helix in solution

The solution conformations of the dinucleotide d(TT) and the modified duplex d(CGCGAATTCGCG)2 with N3'--> P5' phosphoramidate internucleoside linkages have been studied using circular dichroism (CD) and NMR spectroscopy. The CD spectra indicate that the duplex conformation is similar to that of isosequential phosphodiester RNA, a A-type helix, and is different from that of DNA, a B-type helix, NMR studies of model dimers d(TpT) and N3'--> P5' phosphoramidate d(TnpT) show that the sugar ring conformation changes from predominantly C2'-endo to C3'-endo when the 3'-phosphoester is replaced by a phosphoramidate group. Two-dimensional NMR (NOESY, DQF-COSY and TOCSY spectra) studies of the duplex provide additional details about the A-type duplex conformation of the oligonucleotide phosphoramidate and confirm that all furanose rings of 3'-aminonucleotides adopt predominantly N-type sugar puckering.

A new urea sensor based on combining the surface acoustic wave device with urease extracted from green soya bean and its application--determination of urea in human urine

The urea sensor was prepared by combining a surface acoustic wave (SAW) device, in which a SAW resonator operating at 61 MHz and a pair of parallel electrodes were used in series, with urease extracted from green soya bean. The Michaelis constant and maximum reaction rate of the urease were estimated as 2.14 mM and 27.18 kHz min-1, respectively, at pH 7.0 and 25.0 degrees C. Influences of pH, temperature and effectors on the response properties of the SAW urea sensor were investigated. Recovery of the sensor ranged from 95 to 105% and the detection limit of urea was 1.0 micrograms ml-1 (1.7 x 10(-5) M). The proposed sensor has been successfully applied to the rapid determination of urea in human urine samples. The results are consistent with the reported values and also support the clinical diagnosis.

Behaviour of surface acoustic wave interdigitated array electrode sensor in non-aqueous solution and determination of blood plasma recalcification time

A novel SAW-IDA sensor system was constructed for the first time by connecting the IDA electrodes in series with a SAW resonator. The frequency characteristics of the SAW-IDA sensor in non-aqueous solution were investigated. The effects of the parallel capacitance and cell constant were studied, and were calculated with the circuit network theory. These calculations provide guiding rules for design of the SAW-IDA sensor system. The SAW-IDA sensor was applied to determination of recalcification time and activated partial thromboplastin time of blood plasma. The sensor offers a new and effective way of studying clinical and laboratory haemostasis.

1D and 2D 1H NMR studies on bisantrene complexes with short DNA oligomers

The binding of bisantrene to four DNA tetramers, d(CGCG)2, d(GCGC)2, d(CATG)2, and d(GTAC)2, was investigated by 1D and 2D NMR spectroscopy. Bisantrene is a well known anticancer drug and has been used clinically for years. DNA is believed to be one of its cellular targets. Results from both 1D and 2D 1H NMR are in agreement with an intercalation binding mode of bisantrene with the four DNA tetramers in this study. The results further indicate that a threading intercalation binding mode, in which one bisantrene side chain is in the minor groove and the other in the major groove of DNA, is preferred. The NMR results also suggest that bisantrene prefers binding at pyrimidine-(3',5')-purine intercalation sequences rather than at purine-(3',5')-pyrimidine sequences. The intramolecular and intermolecular NOE contacts of bisantrene-DNA tetramer complexes indicate that a C2'-endo uniform sugar pucker, rather than a mixed sugar conformation, is preferred by the intercalation site of both the 5'-(TA)-3' and the 5'-(CG)-3' binding steps.

[Determination of bakuchiol in the fruit of Psoralea corylifolia L]

A GC method for the determination of bakuchiol of described. GC conditions for analysing are as follows: stationary phase: SE-30: injector temperature: 250 degrees C: column temperature: 200 degrees C and detector: FID. The linear range of this method is 0.24-2.4 micrograms and the average recovery is 98.82%, with a relative standard deviation of 1.58%. This method has been successfully used to determine the content of bakuchiol in the samples on the market in 11 different areas, the contents being 1%-7%.