Cisplatin augments FAS-mediated apoptosis through lipid rafts

Cisplatin is widely and effectively used for the treatment of various types of cancer. However, its biochemical mechanisms are still unelucidated. Previously, we reported that membrane sphingomyelin (SM) was important for FAS-mediated apoptosis through lipid raft function. In this study, we strikingly show that cisplatin combined with CH11 (anti-FAS antibody, IgM) was able to induce marked apoptosis in SM synthase-restored WR/Fas-SMS1 cells, but not in SM synthase-deficient WR/FAS-SM(-) cells. In addition, we demonstrated that membrane SM played an important role in cisplatin/CH11-induced apoptosis through the classical caspase-dependent pathway, mainly by enhancing the formation of FAS-associated signaling complexes.

Hedgehog signaling promotes the degradation of tumor suppressor Sufu through the ubiquitin-proteasome pathway

Sustained Sonic hedgehog (Shh) pathway activity is associated with tumorigenesis in a wide variety of tissues. Mutational inactivation of Shh receptor Patched (Ptch) and a downstream gene Suppressor of fused (Sufu), both of which are negative regulators of the pathway, increases susceptibility to cerebellum cancer in humans and mice. Sufu is a binding partner of Shh pathway transcription factor Gli. Recent data indicate that inactivation of Sufu, through either gene targeting in mice or RNAi-mediated silencing in cultured fibroblasts, is sufficient to turn on Shh target gene expression. Here, we report that Sufu is degraded rapidly in certain cancer cells and we show that Shh signaling promotes ubiquitination of Sufu, which leads to its destruction in the proteasomes. We identified an ubiquitin attachment site on K257 of Sufu, and showed that Sufu-K257R mutant is more potent as a transcription repressor and cell growth inhibitor because of increased stability. These results indicate that Shh signaling regulates Sufu activity by inducing its turnover via the ubiquitin-proteasome system.

Mechanism of neuroprotective effect induced by QingKaiLing as an adjuvant drug in rabbits with E. coli bacterial meningitis

OBJECTIVE

To explore the neuroprotective effects and underlying mechanism of QingKaiLing (QKL) as an adjuvant treatment for bacterial meningitis.

METHOD

E. coli bacterial meningitis rabbits were treated with antibiotics (ampicillin) alone or in combination with QKL. The number of leukocytes and the concentration of protein in the cerebrospinal fluid (CSF) of rabbits were determined at 0, 16, and 26 hours after treatment. Brain water, sodium, potassium, and calcium contents were determined at the 26-hour time point. The level of matrix metalloproteinase-9 in the brain was also determined by Western blot.

RESULT

The average number of leukocytes and the concentration of protein in CSF of the QKL adjuvant treatment group were reduced compared with the ampicillin alone group. Brain water, sodium, and calcium contents were reduced in the QKL adjuvant treatment group. The level of MMP-9 in brain tissue was also reduced in the QKL adjuvant treatment group.

CONCLUSION

QKL adjuvant treatment alleviates the aggravated inflammatory reaction and partially protects brain tissue from antibiotic-induced injury. The mechanism of this neuroprotective effect of QKL may be due to decreased levels of Ca2+ and MMP-9 in the brain.

The effect of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants

The influence of microstructure on the wear of cobalt-based alloys used in metal-on-metal hip implants was investigated in a boundary lubrication regime designed to represent the conditions that occurred some of the time in vivo. These cobalt-chromium-molybdenum alloys were either wrought, with a total carbon content of 0.05 or 0.23 wt %, cast with a solution-annealing procedure or simply as-cast but not solution annealed. Bars of these different alloy grades were subjected to various heat treatments to develop different microstructures. The wear was evaluated in a linear-tracking reciprocating pin-on-plate apparatus with a 25 per cent bovine serum lubricant. The wear was found to be strongly affected by the dissolved carbon content of the alloys and mostly independent of grain size or the carbide characteristics. The increased carbon in solid solution caused reductions in volumetric wear because carbon helped to stabilize a face-centred cubic crystal structure, thus limiting the amount of strain-induced transformation to a hexagonal close-packed crystal structure. Based on the observed surface twining in and around the contact zone and the potentially detrimental effect of the hexagonal close-packed phase, it was postulated that the wear of cobalt-based alloys in the present study was controlled by a deformation mechanism.

Novel multi-depth microfluidic chip for single cell analysis

A novel multi-depth microfluidic chip was fabricated on glass substrate by use of conventional lithography and three-step etching technology. The sampling channel on the microchip was 37 microm deep, while the separation channel was 12 microm deep. A 1mm long weir was constructed in the separation channel, 300 microm down the channel crossing. The channel at the weir section was 6 microm deep. By using the multi-depth microfluidic chip, human carcinoma cells, which easily aggregate, settle and adhere to the surface of the channel, can be driven from the sample reservoir to the sample waste reservoir by hydrostatic pressure generated by the difference of liquid level between sample and sample waste reservoirs. Single cell loading into the separation channel was achieved by applying a set of pinching potentials at the four reservoirs. The loaded cell was stopped by the weir and precisely positioned within the separation channel. The trapped cell was lysed by sodium dodecyl sulfate (SDS) containing buffer solution in 20s. This approach reduced the lysing time and improved the reproducibility of chip-based electrophoresis separations. Reduced glutathione (GSH) and reactive oxygen species (ROS) were used as model intracellular components in single human carcinoma cells, and the constituents were separated by chip-based electrophoresis and detected by laser-induced fluorescence (LIF). A throughput of 15 samples/h, a migration time precision of 3.1% RSD for ROS and 4.9% RSD for GSH were obtained for 10 consecutively injected cells.

Effect of microstructure on the dry sliding friction behavior of CoCrMo alloys used in metal-on-metal hip implants

The microstructure and its effect on the friction behavior of a medical grade wrought cobalt-chromium-molybdenum (CoCrMo) alloy for surgical implants were studied in this work. In particular, the effects of compression and carbon (C) content on the above characteristics were analyzed. Increasing amounts of deformation resulted in a decrease in the number of annealing twins in the microstructures. In addition, there was an increase in the volume fraction of the hexagonal closed-packed (HCP) phase due to a strain-induced transformation (SIT) from the metastable face-centered cubic (FCC) phase. The high C (HC) alloy had a lower volume fraction of this SIT phase. Friction studies conducted on these alloys revealed a higher coefficient of friction for the HC alloy and no significant effect of SIT on the friction characteristics.

Nanofluidic channels fabrication and manipulation of DNA molecules

Nanofluidic channel arrays, which have a width of about 40 nm, depth of 60 nm and length of 50 mum, were created using a focused-ion-beam milling instrument on a silicon nitride film swiftly and exactly, as is necessary. Stained -DNA molecules were put inside these sub-100 nm conduits by capillary force and they were stretched and transferred along these conduits, which were dealt with activating reagent Brij aqueous solution in advance. The movements of DNA molecules in these channels were discussed. These nano-structure channels may be useful in the study and analysis of the statics as well as the dynamics of single biomolecules.

Frustrated nesting behaviour: relation to extra-cuticular shell calcium and bone strength in White Leghorn hens

1. The inability of hens to express normal nesting behaviour in battery cages results in frustration, manifesting itself as stereotyped pacing. Frustration can cause hens to retain their eggs beyond the expected time of lay, resulting in an extra-cuticular layer of calcium on eggshells. 2. This study investigated whether frustrated nesting behaviour caused extra-cuticular calcification of eggshells and whether this loss of non-structural calcium to eggshells may have subsequently contributed to weak bones in spent hens. 3. One hundred and twenty hens were assigned to one of three treatments: NB (hens given nest boxes in their cages), NN (no nest box) and R (access to nest box periodically restricted). 4. NB hens spent the least amount of time pacing in the hour before oviposition. NN and R hens spent similar amounts of time pacing. 5. Contrary to expectation, eggshells from hens under different treatments yielded the same amount of extra-cuticular calcium. Similarly tibia strength did not significantly differ among treatments.

[Changes of glutamate and GABA in cerebrospinal fluid of patients with pneumonia complicated with central nervous system damage]

Glutamate(Glu), gamma-aminobutyric acid(GABA), and malondialdehyde(MDA) in cerebrospinal fluid (CSF) were measured in 18 children with pneumonia complicated with central nervous system(CNS) damage, 14 children with pneumonia without CNS damage, and 7 children with hypocalcemic tetany. The concentration of Glu and MDA and the ratio of Glu/GABA in CSF of pneumonia without CNS damage were significantly higher than the others. The ratio of Glu/GABA in CSF of the children with pneumonia with consciousness obstacle after convulsion was higher than that without consciousness obstacle after convulsion. These results suggest that Glu and free radicals may play a critical role in the CNS damage caused by pneumonia, however GABA may reduce the CNS damage caused by pneumonia.

[Protective effect of c-fos antisense oligonucleotides on brain damage induced by glutamate]

OBJECTIVE

To investigate the relation between glutamate neurotoxicity and c-fos gene expression.

METHODS

c-fos antisense oligonucleotides (AS ODN) was injected into the right lateral ventricles of 9 SD rats to block the c-fos gene expression in brain tissue. c-fos sense oligonucleotides (S ODN) was used a control. The numbers and morphology of neurons in both cerebral cortex and hippocampal CA1 were detected by MIAS-300 image analysing instrument. c-fos gene expression in brain was observed by immunohistochemical method. The content of water and electrolytes in the brain tissue and Ca(2+) in the synapse were measured.

RESULTS

The c-fos AS ODN blocked the c-fos gene expression and reduced the content of both water and sodium in brain tissue and Ca(2+) in symptosome, thus alleviating the morphological damage in neuron. S ODN did not have such effect.

CONCLUSION

c-fos gene expression plays an important role in mediating the effect of glutamate neurotoxicity. Blocking the c-fos gene expression could antagonize glutamate neurotoxicity.

The spinocerebellar ataxia type 1 protein, ataxin-1, has RNA-binding activity that is inversely affected by the length of its polyglutamine tract

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurodegenerative disease caused by the expansion of a polyglutamine tract within the SCA1 product, ataxin-1. Previously, using transgenic mice, it was demonstrated that in order for a mutant allele of ataxin-1 to cause disease it must be transported to the nucleus of the neuron. Using an in vitro RNA-binding assay, we demonstrate that ataxin-1 does bind RNA and that this binding diminishes as the length of its polyglutamine tract increases. These observations suggest that ataxin-1 plays a role in RNA metabolism and that the expansion of the polyglutamine tract may alter this function.

[Determining the distribution of Mutans Streptococci in human dental plaque by monoclonal antibody against SA I/II and SPAa of Mutans Streptococci]

OBJECTIVE

To explore the possibility of detecting the distribution of Mutans Streptococci in human dental plaque by Monoclonal antibody (WC2E10c, WC3A6d) against SA I/II and SPAa of Mutans Streptococci, which was prepared in our lab.

METHODS

60 subjects were divided into the experimental group and the control group. The distributions of Mutans Streptococci (serotype c and d) in dental plaques were detected in 60 subjects by the clonal blot technique. Positive colonies were examined by bacterial morphology, serology, biochemistry and SDS-PAGE.

RESULTS

Bacterial colony was significantly different between the experimental group and the control group with eye observation. Colonies of the experimental group were deep brown and easily differentiated, but colonies of control group were white. Brown colonies were proved to be Mutans Streptococci (serotype c and d) by using assay of bacterial morphology, serology, biochemistry and SDS-PAGE, but white colonies were not.

CONCLUSION

McAbs (WC2E10c, WC3A6d) were shown high specificity in Mutans Streptococci (Serotype c and d) of human dental plaques.

Identification and genetic mapping of four novel genes that regulate leaf development in Arabidopsis

Molecular and genetic characterizations of mutants have led to a better understanding of many developmental processes in the model system Arabidopsis thaliana. However, the leaf development that is specific to plants has been little studied. With the aim of contributing to the genetic dissection of leaf development, we have performed a large-scare screening for mutants with abnormal leaves. Among a great number of leaf mutants we have generated by T-DNA and transposon tagging and ethyl-methae sulfonate (EMS) mutagenesis, four independent mutant lines have been identified and studied genetically. Phenotypes of these mutant lines represent the defects of four novel nuclear genes designated LL1 (LOTUS LEAF 1), LL2 (LOTUS LEAF 2), URO (UPRIGHT ROSETTE). and EIL (ENVIRONMENT CONDITION INDUCED LESION). The phenotypic analysis indicates that these genes play important roles during leaf development. For the further genetic analysis of these genes and the map-based cloning of LL1 and LL2, we have mapped these genes to chromosome regions with an efficient and rapid mapping method.

[Experimental study of protective effect of qingkailing on glutamate induced neurotoxic damage of brain]

OBJECTIVE

To observe the effect of Qingkailing (QKL) on glutamate induced damage of brain, in order to seek for effective drugs for antagonizing neurotoxicity of glutamate.

METHODS

Number and morphology metrology of neuron in cerebral cortex and hippocampus were detected by using MIAS-300 image analysing instrument, electron microscope and immunohistochemical methods.

RESULTS

QKL could allevate the glutamate induced accumulation of water and sodium in the brain tissue, relief the damage of cerebral cells and reduce the percentage of c-fos positive cell in brain.

CONCLUSION

QKL could protect brain damage induced by glutamate, which might be related to inhibition of QKL on glutamate caused enhancement of c-fos gene expression.

Fluorescence detection of proteins in sodium dodecyl sulfate-polyacrylamide gels using environmentally benign, nonfixative, saline solution

SYPRO Tangerine stain is an environmentally benign alternative to conventional protein stains that does not require solvents such as methanol or acetic acid for effective protein visualization. Instead, proteins can be stained in a wide range of buffers, including phosphate-buffered saline or simply 150 mM NaCl using an easy, one-step procedure that does not require destaining. Stained proteins can be excited by ultraviolet light of about 300 nm or with visible light of about 490 nm. The fluorescence emission maximum of the dye is approximately 640 nm. Noncovalent binding of SYPRO Tangerine dye is mediated by sodium dodecyl sulfate (SDS) and to a lesser extent by hydrophobic amino acid residues in proteins. This is in stark contrast to acidic silver nitrate staining, which interacts predominantly with lysine residues or Coomassie Blue R, which in turn interacts primarily with arginine and lysine residues. The sensitivity of SYPRO Tangerine stain is similar to that of the SYPRO Red and SYPRO Orange stains - about 4-10 ng per protein band. This detection sensitivity is comparable to colloidal Coomassie blue staining and rapid silver staining procedures. Since proteins stained with SYPRO Tangerine dye are not fixed, they can easily be eluted from gels or utilized in zymographic assays, provided that SDS does not inactivate the protein of interest. This is demonstrated with in-gel detection of rabbit liver esterase activity using alpha-naphthyl acetate and Fast Blue BB dye as well as Escherichia coli beta-glucuronidase activity using ELF-97 beta-D-glucuronide. The dye is also suitable for staining proteins in gels prior to their transfer to membranes by electroblotting. Gentle staining conditions are expected to improve protein recovery after electroelution and to reduce the potential for artifactual protein modifications such as the alkylation of lysine and esterification of glutamate residues, which complicate interpretation of peptide fragment profiles generated by mass spectrometry.

[Separation and selection of salivary adhesion receptors of Streptococcus mutans to tooth surface]

OBJECTIVE

To select and purify salivary receptors of Streptococcus mutans from experimental salivary acquired pellicle.

METHODS

Experimental salivary acquired pellicle (SAP) was performed by coating hydroxyapatite (HA) with whole saliva. Then SAP was washed from HA by 1 mol/L NaCl and 0.5 mol/L phosphate buffer sequentially. The proteins were further separated by chromatography of Sephadex G75 and DEAE-Sephadex A25. Receptors of Streptococcus mutans were selected by bacterial adhesion test and competitive inhibition adhesion test. Identification was performed by PAGE, SDS-PAGE, IP-PAGE and detection of amylase activity and inmunodifusion test.

RESULTS

IgA degraded fragments, a protein of 13 kD and amylases were the receptors of S. mutans. The first two only promote the adhesion but the amylases can both promote and inhibit S. mutans adhesion.

CONCLUSION

The adhesion of S. mutans to tooth surface is a result of interaction between adhesins of S. mutans and multiple salivary receptors.

Constitutive activation of the delta opioid receptor by mutations in transmembrane domains III and VII

We have investigated whether transmembrane amino acid residues Asp128 (domain III), Tyr129 (domain III) [corrected], and Tyr308 (domain VII) in the mouse delta opioid receptor play a role in receptor activation. To do so, we have used a [35S]GTPgammaS (where GTPgammaS is guanosine 5'-3-O-(thio)triphosphate) binding assay to quantify the activation of recombinant receptors transiently expressed in COS cells and compared functional responses of D128N, D128A, Y129F, Y129A, and Y308F point-mutated receptors to that of the wild-type receptor. In the absence of ligand, [35S]GTPgammaS binding was increased for every mutant receptor under study (1.6-2.6-fold), suggesting that all mutations are able to enhance constitutive activity at the receptor. In support of this finding, the inverse agonist N,N-diallyl-Tyr-Aib-Aib-Phe-Leu (where Aib represents alpha-aminobutyric acid) efficiently reduced basal [35S]GTPgammaS binding in the mutated receptor preparations. The potent agonist BW373U86 stimulated [35S]GTPgammaS binding above basal levels with similar (D128N, Y129F, and Y129A) or markedly increased (Y308F) efficacy compared with wild-type receptor. BW373U86 potency was maintained or increased. In conclusion, our results demonstrate that the mutations under study increase functional activity of the receptor. Three-dimensional modeling suggests that Asp128 (III) and Tyr308 (VII) interact with each other and that Tyr129 (III) undergoes H bonding with His278 (VI). Thus, Asp128, Tyr129, and Tyr308 may be involved in a network of interhelical bonds, which contributes to maintain the delta receptor under an inactive conformation. We suggest that the mutations weaken helix-helix interactions and generate a receptor state that favors the active conformation and/or interacts with heterotrimeric G proteins more effectively.

[A study on biological properties of fimbriae of Actinomyces viscosus. II. Chemical characteristics of fimbriae of A. viscosus]

OBJECTIVE

To investigate the chemical characteristics of two purified fimbriae.

METHODS

The specific antibodies against type I and type II fimbriae of A. viscosus were prepared and the purity of the two purified fimbriae had been identified by the specific antibodies. Then, chemical analysis and amino acid analysis of the two purified fimbriae were done.

RESULTS

The two purified fimbriae were mainly composed of proteins and small amount of carbohydrate. The two types of fimbriae contained large amounts of aspartic acid, glutamic acid, alanine, lysine and glycine, and high percentage of nonpolar amino acid was analysed while basic amino acids were present in a very small amounts.

CONCLUSION

These results may help to understand the relationship between the chemical characteristics of two types of fimbriae and their biological activity.

[A study on biological properties of fimbriae of A. viscosus. III. Adherence activity of fimbriae of A. viscosus]

OBJECTIVE

To investigate the adherence activity of two types of fimbriae of A. viscosus on tooth surface or with S. sanguis 34.

METHODS

The inhibited adherence tests, coaggregation tests and the inhibited coaggregation tests were done.

RESULTS

1. The purified type I and type II fimbriae inhibited the adherence of A. viscosus to salivary-treated hydroxyapatite (SHA) and the two specific IgG to type I and type II fimbriae blocked the adsorption of strain T14V, strain 5519 and strain 5951 to SHA; 2. Only type II fimbria indirectly mediated the visible agglutination of S. sanguis 34 and only IgG to type II fimbriae inhibited coaggregation of strain T14V and strain 5915 with S. sanguis 34.

CONCLUSION

Type I and type II fimbriae have adherence ability, and only type II fimbria has the agglutination activity. Additionally, the methods which were used to prepare fimbriae don't damage the biological activity of fimbriae.

Characterization of SYBR Gold nucleic acid gel stain: a dye optimized for use with 300-nm ultraviolet transilluminators

The highest sensitivity nucleic acid gel stains developed to date are optimally excited using short-wavelength ultraviolet or visible light. This is a disadvantage for laboratories equipped only with 306- or 312-nm UV transilluminators. We have developed a new unsymmetrical cyanine dye that overcomes this problem. This new dye, SYBR Gold nucleic acid gel stain, has two fluorescence excitation maxima when bound to DNA, one centered at approximately 300 nm and one at approximately 495 nm. We found that when used with 300-nm transillumination and Polaroid black-and-white photography, SYBR Gold stain is more sensitive than ethidium bromide, SYBR Green I stain, and SYBR Green II stain for detecting double-stranded DNA, single-stranded DNA, and RNA. SYBR Gold stain's superior sensitivity is due to the high fluorescence quantum yield of the dye-nucleic acid complexes ( approximately 0.7), the dye's large fluorescence enhancement upon binding to nucleic acids ( approximately 1000-fold), and its capacity to more fully penetrate gels than do the SYBR Green gel stains. We found that SYBR Gold stain is as sensitive as silver staining for detecting DNA-with a single-step staining procedure. Finally, we found that staining nucleic acids with SYBR Gold stain does not interfere with subsequent molecular biology protocols.

Understanding peptic ulcer disease pharmacotherapeutics

The implication that Helicobacter pylori is responsible for peptic ulcer disease (PUD) has revolutionized the pharmacotherapeutic management of PUD. There has been a shift from long-term therapy with antacids and histamine2 (H2) antagonists to short-term therapy with triple antimicrobials with or without an antisecretory agent or a double antimicrobial therapy with an antisecretory agent. A case of PUD in a 53-year-old woman and its management with double antimicrobial agents and an antisecretory agent is discussed. Research evidence suggests that a treatment regimen aimed at eradicating H. pylori without diagnostic testing enhances the ability to effectively manage suspected cases of PUD before complications arise and referrals to specialists are necessary. Discouraging the use of over-the-counter H2 antagonists, ruling out long-term use of nonsteroidal anti-inflammatory drugs before selecting the treatment regimen, and considering expected treatment compliance are important aspects of PUD management that emerged from this case.

Comparison of SYBR Green I nucleic acid gel stain mutagenicity and ethidium bromide mutagenicity in the Salmonella/mammalian microsome reverse mutation assay (Ames test)

SYBR Green I nucleic acid gel stain is an unsymmetrical cyanine dye developed for sensitive detection of nucleic acids in electrophoretic gels. Its mechanism of nucleic acid binding is not known, whereas the most commonly used nucleic acid gel stain, ethidium bromide, is a well-characterized intercalator. We compared the mutagenicity of SYBR Green I stain with that of ethidium bromide in Salmonella/mammalian microsome reverse mutation assays (Ames tests). As expected [J. McCann, E. Choi, E. Yamasaki, B.N. Ames, Proc. Natl. Acad. Sci. USA, 72 (1975) 5135-5139], ethidium bromide showed high revertant frequencies in several frameshift indicator strains (averaging 68-fold higher than vehicle controls in TA98, 80-fold higher in TA1538, 15-fold higher in TA1537, and 4.4-fold higher in TA97a), only in the presence of rat liver extracts (S9). Small increases in revertant frequencies were observed for ethidium bromide in the base-substitution indicator strain TA102 both in the presence and absence of S9 (averaging 2.0- and 1.8-fold higher than vehicle controls, respectively) and in base-substitution indicator strain TA100 in the presence of S9 (averaging 1.6-fold higher than vehicle controls). A small mutagenic effect was detected for SYBR Green I stain in frameshift indicator strain TA98 (averaging 2. 2-fold higher than vehicle controls) only in the absence of S9 and in base-substitution indicator strain TA102, both in the presence and absence of S9 (averaging 2.2- and 2.7-fold higher than vehicle controls, respectively). Thus, SYBR Green I stain is a weak mutagen and appears to be much less mutagenic than ethidium bromide. These results suggest that SYBR Green I stain may not intercalate, and if it does, that its presence does not give rise to point mutations at a high frequency.

[A study on the biological properties of fimbriae of Actinomyces viscosus. I. The preparation and determination of fimbriae of A. viscosus]

OBJECTIVE

To build up the methods to prepare and determine the fimbriae of A. viscosus.

METHODS

Type 1 and 2 fimbriae were prepared from A. viscosus 5519 and 5951 respectively. Fimbriae were isolated from bacteria cells by mechanical shaking, obtained by collecting the supernatant after centrifugation, and purified by ammonium sulfate precipitations and gel filtration.

RESULTS

Electron microscope showed that fimbriae existed in the preparations. The immunological reaction between the fimbriae preparations and specific antibodies against fimbriae attested that they were type 1 or type 2 fimbriae.

CONCLUSION

The present study become a foundation for further study on the biological properties of fimbriae of A. viscosus.

[Comparison of demineralization of different organic acid to enamel]

The rates of demineralization of 5 organic acids (mathanoic acid, formic acid, propionic acid, Lactic acid, acetic acid, mixed acid) to the bovine enamel were tested and analysed with the self-made calcium ionselective microelectrodes(Ca(2+)-ISME) basing on a neutral carriers of ETH1001. The results showed; 1. The difference between the rates of demineralization of formic acid and lactic acid, formic acid and propionic acid, formic acid and acetic acid, acetic acid and mixed acid, acetic acid and lactic acid, propionic acid and mixed acid, propionic acid and lactic acid, lactic acid and mixed acid were of great significance (P < 0.01); 2. The rates of demineralization of acetic and mixed acid decreased with time, due to saturation of the solution during demineralization; 3. Ca(2+)-ISME was of the advantages of simplicity, rapidity, sensitivity and accuracy. The results suggest that the cariogenic potential is related to different acid products of different cariogenic bacteria, and the degree of mineral saturation within solution affects the rate of demineralization.

[Living related liver transplantation: a case report]

OBJECTIVE

To study a case of living related liver transplantation.

METHOD

The patient was a 10-year-old girl who suffered from congenital diffuse intrahepatic cholangiectasis, recurrent cholangitis and hepatocirrhosis. The donor was the patient's father aged 40. The left lateral lobe of donor's liver was cut and grafted to the patient. Intensive care and treatment as well as follow-up were given after operation.

RESULT

For the donor, the operation lasted 400 min, with 410 ml bleeding and 300 g liver removed. The recovery was satisfactory. For the recipient, the operation lasted 652 min, with 1665 ml bleeding, 80 min non-liver stage, 0 min graft hot ischemic stage, and 137 min cold ischemic stage. Immunosuppressive therapy was given using cyclosporin A, azathioprine and adrenocortical hormones. There was an acute rejection 11 days after operation, which was controlled using hormone impulsive therapy. The patient has been surviving 7 months with normal liver function.

CONCLUSION

The living related liver transplantation is feasible under modern surgical conditions. It is demonstrated that perfect postoperative management is the key for the successful liver transplantation.

[Study on the adhesion of an endemic strain of Streptococcus mutans serotype C to acquired pellicle. II. Isolation and extraction of adhesins of an endemic strain of Streptococcus mutans serotype C]

Surface proteins of S. mutans WD9463 A(c) were separated by DEAE-Sephadex A25 Chromatography and Sepharose C1-6B Chromatography. The adhesins were distinguished by bacterial adhesin inhibition experiment and were identified by PAGE, SDS-PAGE, IEP-PAGE, immunol diffusion test, GTF activity test and annalization of the sorts of amino acid. The results showed P1, two proteins with molecular weight of 117 kD and 127 kD and two proteins with GTF activity could inhibit the adhesion effectively. On the other hand, another kind of GTF could improve the adhesion of the strain. These indicated that S. mutans may be many kinds of adhesins.

[Study on the adhesion of an endemic strain of Streptococcus mutans serotype C to acquired pellicle. I. A comparison of the methods to extract adhesins from Streptococcus mutans]

The adhesins of S. mutans serotype c endemic strain WD9463A were extracted from culture superant by cold ethol precipitation, or were extracted from cell surface by 0.5 mol/L phosphate buffer, 6 mol/L urea or 2% SDS solution. The composition and adhesive activities of the extracts were compared by SDS-PAGE and bacterial adhesion inhibition experiments. The results showed that the protein composition of the four extracts were similar, and all extracts inhibited the adhesion of the endemic strain dramatically. It indicates that four methods can be used to extract adhesins of S. mutans, but extracting adhesins from culture superant is better than the others.

[Determination of salidroside in eight Rhodiola species by TLC-UV spectrometry]

Quantitative determination of the salidroside in eight Rhodiola species by TLC-UV spectrometry is reported. The salidroside was separated on a silica GF254 TLC plate using CHCl3-CH3OH-H2O(26:14:3) as developing solvent and determined at wavelength 223.8 nm. The results show that this method in simple and convenient.

[The immune response in rats immunized systemically by the surface protein antigen P1 from streptococcus mutans conjugated with procholeragenoid]

This study was carried out to observe the antibody responses in rats after they were immunized with the surface protein P1 of streptococcus mutans when a special adjuvant was used. Antigen P1 was conjugated covalently with procholeragenoid (PCG), and then Sprague Dawley rats were immunized with P1 or the conjugated antigen P1-PCG subcutaneously or intragastrically. Anti-P1 antibody level was assayed at different time points by ELISA. The results showed that the levels of anti-P1 SIgA antibody in saliva rose when P1-PCG was given subcutaneously or intragastrically; the antibody level following the subcutaneous injection was higher and lasted longer, compared with that following the intragastric administretion. The level of anti-P1 IgG antibody in serum only rose when the rats were immunized subcutaneously. These results implied that mucosal immune response or humoral immune response could be induced subcutaneously when PCG was used as an adjuvant.

Fatigue fracture of a forged cobalt-chromium-molybdenum femoral component inserted with cement. A report of ten cases

Ten patients who had had a total hip replacement with a forged cobalt-chromium-molybdenum femoral prosthesis (Precoat or Precoat Plus) inserted with cement were seen with a fatigue fracture of the stem an average of fifty months (range, nineteen to seventy-four months) postoperatively. The average age of the patients was sixty-one years (range, forty-three to seventy-three years), and the average weight was ninety-six kilograms (range, seventy to 130 kilograms). Eight patients had had a primary total hip replacement, and two had had a revision; all of the acetabular components had been inserted without cement. Radiographs that had been made before the fracture were available for four of the eight hips that had had a primary replacement; all four had radiographic evidence of debonding of the cement mantle from the proximal end of the stem. This probably caused exaggerated cantilever bending stresses on the proximal aspect of the stem as the distal end of the stem was well fixed. The radiographs of both hips that had had a revision demonstrated a non-union of the greater trochanter, which had resulted in separation at the cement-bone interface at the proximal portion of the femur before the fracture. Scanning electron micrographs of five of the ten fractured prostheses demonstrated a fatigue fracture that began near the anterolateral corner of the prosthesis, through characters that had been etched on the implant with a laser. Metallurgical analysis indicated subsurface voids or inclusions, or both, immediately under the region that had been etched. This finding is consistent with thermal changes to the microstructure of the alloy that probably caused a focal reduction in the material strength. A high proportion (seven) of the ten stems had a poor cement mantle. Also, of the seven small stems that were used, six had been implanted in patients who weighed more than eighty kilograms, so there was relative undersizing of the prostheses. Early debonding of the proximal end of a Precoat femoral prosthesis from the cement mantle may occur as a result of a thin cement mantle, leading to loosening and possibly to early fatigue fracture of the stem if the distal portion of the stem remains solidly fixed in the distal portion of the cement column. On the basis of our experience, we recommend that patients who have radiographic evidence of a debonded Precoat femoral component should be informed of the risk of fatigue fracture of the stem and be followed closely even though there may be no symptoms of loosening of the femoral component.

The effect of heat treatment on the fatigue strength of microknurled Ti-6Al-4V

Microknurling, a high pressure surface indentation technique, was devised as an alternative to traditional heat-bonded porous coatings found on many orthopedic implants designed for fixation by tissue ingrowth. Heat-bonded porous coating can cause at the surface of an implant stress concentrations that reduce fatigue strength. However, microknurling may reduce stress intensification without eliminating it. Thus the purpose of this work was to explore surface thermal/mechanical processing of Ti-6Al-4V to improve the fatigue strength of microknurled specimens via the production of a Ti-6Al-4V dual microstructure. The latter consists of a surface layer of equiaxed grains known to be effective against crack initiation and a bulk microstructure of lamellar grains that possesses optimum fatigue crack propagation resistance. Rotating-bending fatigue tests showed that such a microstructure had some benefits, but this was offset by the reduction in compressive strains imparted to the surface by the heat treatments needed to obtain this microstructure.

Reaction of a platinum(IV) complex with native Cd,Zn-metallothionein in vitro

The first observation of a redox process following a substitution reaction between a platinum(IV) complex K2PtCl6 with rabbit liver native Cd,Zn-MT is presented. The reaction features and products are studied by UV-visible and circular dichroism spectroscopy, chromatography, and X-ray photoelectron spectroscopic measurements. It is a significant complicated reaction comprising redox and substitution reactions. The reaction generates monomeric and dimeric products, and higher oligomers precipitate with intra- or intra- and intermolecular CyS-SCy linkages. Pt(IV) is reduced to Pt(II), which then binds to the monomeric and dimeric products, and may also bind to higher oligomers. The beta-cluster is more reactive than the alpha-cluster, and reacts first with K2PtCl6. Cd5Pt2 and Cd4Pt4 were found when native Cd,Zn-MT reacted with 2 and 4 molar equivalents of Pt(IV) for 2 h in which four Cd ions were located in the alpha-cluster. The amounts of Cd and Pt ions decreased in both monomeric and dimeric products when the reaction was prolonged and intramolecular CyS-SCy linkages increased. Besides the oligomers which precipitated, only dimeric products were formed when the reaction molar ratio of Pt(IV) to MT was more than 10:1. Cd3Pt6 and Cd1Pt8 were obtained when the reaction occurred for 2 and 72 h, respectively. The structure of the clusters may exist when native Cd, Zn-MT reacts with substoichiometric quantities of K2PtCl6 (< 0.5 K2PtCl6 per MT thiolate) for a short time (2 h), but may be partly disrupted with stoichiometric or excess quantities of K2PtCl6 (> or = 0.5 K2PtCl6 per MT thiolate) for a long time. The disruption of the cluster structures results in an increase of the nonbridge thiolate and an increase of the binding sites to Pt ions. The mechanism of the antitumor activity and developing drug resistance of Pt(IV) complex drugs is discussed.

Interaction of sodium chloroplatinate and iproplatin with metallothionein in vivo

The abilities of platinum(IV) complexes to induce the biosynthesis of metallothionein (MT) were investigated in rabbits given injections s.c. of sodium chloroplatinate (Na2PtCl6) and iproplatin (cis-dichloro-bis-isopropylamine-trans-dihydroxylplatinum IV). It is revealed for the first time that both complexes can induce MT synthesis in the liver and the kidney, but the induction ability was weaker compared to Zn2+ compounds. The induced MT was purified and identified. The hepatic MT resulting from Na2PtCl6 injection only contained Zn, whereas the hepatic MT from iproplatin injection and the renal MT from injection of both complexes contained 4-5 Zn and 1-2 Pt per mole of protein, and the renal MT also contained 1-2 Cu per mole of protein. The oxidation state of platinum in the MT is +2 as determined by X-ray photoelectron spectroscopic measurements. Pretreatment with Zn(NO3)2 elevated the levels of MT, but the binding of Pt to MT was significantly less compared to that without Zn(NO3)2 pretreatment. The data obtained from the amino acid composition analysis were consistent with the theoretical values. Upon these bases, the role of MT in relation to its involvement in the metabolism of Pt(IV) complexes and the mechanism of drug resistance to the Pt(IV) complexes as antitumor agents are discussed.

[The study of actinomyces viscosus adhere to teeth. III. The identification of mutants of A. viscosus and preparation of rabbit IgG against type 1 and type 2 fimbriae]

The authors prepared rabbit antisera against 5519 and 5951. The IgGs against type 1, type 2 fimbriae were purified from the antisera using sera absorbed with the other strain and IgG purification method. It was identified by SDS-PAGE and ELISA. This result suggested the purified proteins were the IgG against type 1 and type 2 fimbriae.

[The study of actinomyces viscosus adhere to teeth. IV. The study of salivary protein receptors of A. viscosus]

In order to determine the receptors of A. viscosus for adhesion, 7 kinds of main purified proteins from pellicle formed by whole saliva were tested. The result indicated that: 1. APRP, statherin, PRPG and SIgA were the receptors of standard and fresh isolated A. viscosus; 2. APRP and stather promoted the adherence of 5519 (1+2-) to HA, and SIgA promoted the adherence 5951 (1-2+) to HA; PRPG was the common receptor of the two fimbriae. It suggested that there were receptors not only type 1 fimbriae but also type 2 in pellicle. Two types of fimbriae were involved in the adherence of A. viscosus to pellicle. The difference existed in the receptor of adherence and the activity site of the same receptor.

Engineering issues and wear performance of metal on metal hip implants

A major concern in total hip arthroplasty is the generation of polyethylene wear particles at the articulating surfaces and resulting macrophage mediated periimplant osteolysis. There is renewed interest in metal on metal bearings as a solution to this problem in view of their potential for greatly improved wear performance. Using a commercially available hip simulator, the wear performance of metal on metal femoral head and acetabular cup combinations was evaluated and various parameters affecting metal on metal implant wear were identified. Nine implants custom manufactured from 2 medical grades of CoCrMo alloy (ASTM F1537-95 and F75-92) were tested within bovine serum as the lubricant to 3 million cycles (equivalent to approximately 3 years of service in vivo). The progressive wear of the components was determined by gravimetric methods at approximately every 300,000 cycles. The wear rates were characterized by an initial period of accelerated wear after which a lower steady state wear rate was observed for subsequent cycles. The presence of calcium phosphate films on the component surfaces, the microstructure of the lower carbon, wrought alloy, and increased effective radii (decreased diametral clearances) were identified as factors that may be favorable to improved wear performance. The extent of the effect on wear of each parameter, however, cannot be discerned at this point and necessitates a study in which parametric changes are more tightly controlled. The present study suggests that the use of metal on metal articulating surfaces may mitigate the problem of osteolysis by offering improved wear performance.

Reaction of metallothionein with ethylenediamine-N,N,N',N'-tetraacetic acid

The reactions of various rabbit MTs (Cd7Th, Zn7Th, Hg7Th, Bi7Th, Pb7Th) with EDTA were studied at different pH and EDTA concentrations, and were determined to be pseudo-first-order reactions. The reactions were all divided into two steps: one faster and EDTA-dependent, and the other EDTA-independent. The mechanism is also described in detail. Based on obtained results, the varied induction behaviors of MT formation for those metals are discussed.

[The electron microscopic observation of the effect of monoclonal antibody on the form and structure of mutans streptococci OMZ176]

The effect of monoclonal antibody on the form and structure of Mutans Streptococci OMZ176 was studied. The result showed that a great number of Mutans Streptococci OMZ176 was agglutianated after treating with monoclonal antibody prepared by a cell wall protein antigen (molecular weight 220 kd) of Mutans Streptococci OMZ176. Bacterial cells were swollen obviously. The gap between cell wall and cytoplasmic was widened. The electronic density of cell plasm was greatly decreased.

Dyes providing increased sensitivity in flow-cytometric dye-efflux assays for multidrug resistance

In an effort to improve detection of P-glycoprotein-mediated multidrug resistance (mdr), several dyes were compared to rhodamine 123 (R123) in efflux assays. Two dyes (SY-38 and SY-3150) were found that provided better sensitivity. These dyes were effluxed by a cell line known to be mdr-positive (P388/R84) but not by an mdr-negative cell line (P388). Efflux was blocked by both verapamil and cyclosporine A. Efflux from KG1a cells was less than from P388/R84, just as has been seen with R123 and daunomycin. In further experiments, a model system was used to demonstrate two-color immunofluorescence plus efflux measurements. This was done using a sequential staining method. A procedure was devised that, at least for this model system, allowed single-step staining with both dye and antibody. The sensitivity of the efflux measurement was slightly compromised by using this one-step staining method.

A method of stimulating an immune response with a hapten immobilized on a nitrocellulose membrane

Hapten refers to a chemical compound of small molar mass (typically less than 1000 daltons) that can bind with an antibody, but cannot initiate an immune response by itself unless it is conjugated to a protein carrier of larger molar mass. A novel method to prepare a hapten to generate anti-hapten immunity without covalent conjugation to a carrier was developed. Coating both water-soluble and -insoluble haptens onto a nitrocellulose membrane effectively presented haptens to the system and caused the generation of specific anti-hapten B lymphocytes and antibodies by immunization both in vitro and in vivo. This method has a potential to substitute for conventional hapten carrier conjugation to generate anti-hapten immunity.

[Pathological study of enamel caries produced by oral bacteria in vitro]

The authors used the bacterial culture method to study early enamel caries-like lesions in vitro. Pathologic changes in the lesions were observed under polarized light microscope and scanning electron microscope. The results showed that this method could simulate the destructive procedures in carious development. The destructive way and pathologic changes of the caries-like lesions were very similar to those of natural caries. Under microscope, the ultrastructures of the relatively intact layer of the enamel surfaces were already changed. The prisms in the enamel surfaces were destroyed, and dissolved to form small pores. The pores could be an important path of the carious development.