Organic vapor sensors based on SAW resonator and organic films

The majority of investigations of SAW devices used as chemical sensors are based on delay line oscillators. However, SAW resonator oscillator offers some advantages over the SAW delay line oscillator for its higher stability. In the incipient stage of fabricating gas sensors based upon SAW resonator, taking detection of organic vapor as an example, the analysis method that combines the SAW theory with organic film technology has been adopted to give an intensive insight into the responses of two-port SAW resonator coated with LB-film and cast-film after exposure to organic vapors.

Identification of amino acid residues required for a specific interaction between Src-tyrosine kinase and proline-rich region of phosphatidylinositol-3' kinase

The binding of ligand to B-cell antigen receptors (BCR) leads to the activation of receptor-associated Src-family kinases and phosphatidylinositol-3' kinase (PI-3 kinase). Although it has been demonstrated that SH3 domains of several Src-family kinases interact with PI-3 kinase by binding to a proline-rich region of PI-3 kinase in vitro, there is no direct evidence to support their interaction in vivo. Thus, we utilized the yeast two-hybrid assay to reconstitute this protein-protein interaction. This genetic screen clearly indicates that the interaction between SH3 domain of Fyn and the proline-rich region (residues: 80-104) of PI-3 kinase is highly specific. Mutational analysis revealed that amino acid residues Asp92, Tyr93, Arg96 and Thr97 of the SH3 domain of Fyn are essential for interacting with the proline-rich peptide of PI-3 kinase.

Assessing the requirements for nucleotide excision repair proteins of Saccharomyces cerevisiae in an in vitro system

Nucleotide excision repair (NER) is the primary mechanism by which both Saccharomyces cerevisiae and human cells remove the DNA lesions caused by ultraviolet light and other mutagens. This complex process involves the coordinated actions of more than 20 polypeptides. To facilitate biochemical studies of NER in yeast, we have established a simple protocol for preparing whole cell extracts which perform NER in vitro. As expected, this assay of in vitro repair was dependent on the products of RAD genes such as RAD14, RAD4, and RAD2. Interestingly, it was also dependent upon proteins encoded by the RAD7, RAD16, and RAD23 genes whose precise roles in NER are uncertain, but not the RAD26 gene whose product is believed to participate in coupling NER to transcription. Replication protein A (RPA/Rpa), known to be required for NER in human cell extracts, was also shown by antibody inhibition and immunodepletion experiments to be required for NER in our yeast cell extracts. Moreover, yeast cells with temperature-sensitive mutations in the RFA2 gene, which encodes the 34-kDa subunit of Rpa, had increased sensitivity to UV and yielded extracts defective in NER in vitro. These data indicate that Rpa is an essential component of the NER machinery in S. cerevisiae as it is in mammalian cells.

Synchrony in binary-oscillator networks with local couplings

Since synchronous oscillations in the visual cortex may be responsible for some features of visual scene, many works have been done to study the dynamics of oscillatory neural networks. Most of the oscillator network models rely on a global connection to reach synchronization. Here we propose a class of neural network models based on a simplified binary-oscillator, and find that the neurons of networks with local couplings will be in global synchrony under some criteria.

Prediction of the secondary structure content of globular proteins based on structural classes

The prediction of the secondary structure content (alpha-helix and beta-strand content) of a globular protein may play an important complementary role in the prediction of the protein's structure. We propose a new prediction algorithm based on Chou's database [Chou (1995), Proteins Struct. Funct. Genet. 21, 319]. The new algorithm is an improved multiple linear regression method, taking the nonlinear and coupling terms of the frequencies of different amino acids into account. The prediction is also based on the structural classes of proteins. A resubstitution examination for the algorithm shows that the average errors are 0.040 and 0.033 for the prediction of alpha-helix content and beta-strand content, respectively. The examination of cross-validation, the jackknife analysis, shows that the average errors are 0.051 and 0.044 for the prediction of alpha-helix content and beta-strand content, respectively. Both examinations indicate the self-consistency and the extrapolative effectiveness of the new algorithm. Compared with the other methods available currently, our method has the merits of simplicity and convenience for use, as well as a high prediction accuracy. By incorporating the prediction of the structural classes, the only input of our method is the amino acid composition of the protein to be predicted.

Purification and characterization of an oxygen-sensitive, reversible 3,4-dihydroxybenzoate decarboxylase from Clostridium hydroxybenzoicum

A 3,4-dihydroxybenzoate decarboxylase (EC 4.1.1.63) from Clostridium hydroxybenzoicum JW/Z-1T was purified and partially characterized. The estimated molecular mass of the enzyme was 270 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave a single band of 57 kDa, suggesting that the enzyme consists of five identical subunits. The temperature and pH optima were 50 degrees C and pH 7.0, respectively. The Arrhenius energy for decarboxylation of 3,4-dihydroxybenzoate was 32.5 kJ . mol(-1) for the temperature range from 22 to 50 degrees C. The Km and kcat for 3,4-dihydroxybenzoate were 0.6 mM and 5.4 x 10(3) min(-1), respectively, at pH 7.0 and 25 degrees C. The enzyme optimally catalyzed the reverse reaction, that is, the carboxylation of catechol to 3,4-dihydroxybenzoate, at pH 7.0. The enzyme did not decarboxylate 2-hydroxybenzoate, 3-hydroxybenzoate, 4-hydroxybenzoate, 2,3-dihydroxybenzoate, 2,4-dihydroxybenzoate, 2,5-dihydroxybenzoate, 2,3,4-trihydroxybenzoate, 3,4,5-trihydroxybenzoate, 3-F-4-hydroxybenzoate, or vanillate. The decarboxylase activity was inhibited by 25 and 20%, respectively, by 2,3,4- and 3,4,5-trihydroxybenzoate. Thiamine PPi and pyridoxal 5'-phosphate did not stimulate and hydroxylamine and sodium borohydride did not inhibit the enzyme activity, indicating that the 3,4-dihydroxybenzoate decarboxylase is not a thiamine PPi-, pyridoxal 5'-phosphate-, or pyruvoyl-dependent enzyme.

The use of alprostadil sterile powder in a home self-injection study of Asian men with erectile dysfunction

This study evaluated the individual optimal dose of alprostadil in the office setting that could be used as the basis for effective home self-injection therapy. The study included 150 Asian men with erectile dysfunction (ED). The mean age of study participants was 48.3 years (range, 21 to 74 years), and the mean duration of ED was 3.6 years. The most common cause of ED was venogenic (24%), psychogenic (21%), arteriogenic (13%), neurogenic (0.7%), or a combination of these (41%). An optimal response was seen in 72% of patients (n = 108) in the office and 96% of patients (n = 100) at home. The mean +/- SD office dose of alprostadil was 19.4 +/- 12.8 micrograms versus 18.0 +/- 12.2 micrograms at home. More than half of the patients (57% in an office setting and 53% at home) achieved an optimal response at a dose between 5 and 15 micrograms. By the 20-micrograms dose, 82% of patients had achieved an optimal dose at home compared with 70% of patients in the office. An optimal response was seen at the same dose in the office and home in 75% of patients; the dose at home decreased from the office dose for 16% of the patients and increased for 9%. There were 24 patients who experienced adverse events: penile pain after injection (18 patients), cold sweating (2 patients), pediculosis (1 patient), broken leg (1 patient), ankle pain (1 patient), and prolonged erection (1 patient). One patient discontinued the study because of penile pain. Alprostadil sterile powder offered safe and effective treatment of ED for home self-injection therapy. Once an optimal dose response had been established in the physician's office, further home adjustments were needed in 25% of patients. Penile pain, usually mild, was the most common, possibly related adverse effect reported.

Differential transcriptional regulation of the apoAI gene by retinoic acid receptor homo- and heterodimers in yeast

Several members of the nuclear receptor superfamily including RXR (retinoid X receptor) bind to a specific retinoic acid response element (site A) of the apoAI promoter. However, transcriptional activation of the apoAI gene by different homo- and heterodimeric forms of RXR or RAR (retinoic acid receptors) cannot be evaluated in mammalian cells, which contain endogenous RXR or RAR. In order to circumvent this limitation, we assessed the DNA-binding activities and transcriptional activation of different homo- and heterodimers of these receptors in yeast. Electrophoretic mobility shift assays (EMSA) demonstrated that yeast expressed RARalpha does not bind to site A of the apoAl promoter, whereas binding of RARbeta to site A is ligand-dependent. Both RARalpha and RARbeta form heterodimers with RXRalpha and bind to site A with high affinity. These DNA-binding studies correlate with the transcriptional data, which indicated that RARbeta but not RARalpha activates transcription from site A in response equally well to 9-cis and all-trans retinoic acids. 9-cis RA is a more potent ligand than all-trans RA to activate transcription via RXR/RAR heterodimers. We conclude that this yeast expression system is a useful tool to elucidate the 'transactivation code' for apoAl site A via specific combinations of different homo and heterodimeric versions of RXR and RAR.

[In vitro transformation of human embryonic nasopharyngeal epithelial cells with Epstein-Barr virus]

EBV from B95-8 cells were used to infect directly the human embryonic nasopharyngeal epithelial (HENE) cells in vitro.

RESULTS

Primary HENE cells treated with EBV did not have a significantly increased colony-forming rate in soft agarose, while cells that were treated with EBV in combination with tumor promotor 12-O-tetradecanoylphorbol-13 acetate (TPA) showed a marked increase in colonyforming rate from 0-5 cells to 20-40 colonies per 10,000 cells. (2) HENE cells treated with inactivated (56 degrees C for 30 minutes) virus, in spite of adding TPA at the same time, did not significantly increase agarose colony forming rate; (3) HENE cells treated with TPA after EBV exposure for a week had significantly increased colony forming rate in soft agarose, while the cells exposed to EBV after using TPA treatment did not. In addition, EBV BNLF1 (LMP) fragment in HENE cells treated with EBV or EBV+TPA was detected by polymerase chain reaction using specific oligonucleotide primer. Only HENE cells treated with EBV+TPA presented positive band in aragose gel electrophoresis. The results suggest that transformation of EBV on HENE cells depends on infectious virus and an intact viral genome. TPA not only can promote the transformation, but also promote EBV's entering HENE cells.

[Anti-metastasis gene nm23 expression in buccal cancer studied by immunohistochemistry stain]

The nm23 gene has been proposed as a candidate metastasis-suppressor gene. In this study we used immunohistochemistry stain for polyclone antibody nm23 in 62 cases of buccal carcinoma. The results showed that both the epithelium of mucosa and the duct epithelium of minor salivary gland nearby the tumor were strong positive. The stains on tumor cells were various. 31.0% (9/29) of the cases with lymph-node metastasis were positive while 57.6% (19/33) of those with no lymph-node metastasis positive (P = 0.044). Histologically, 59.4% (19/32) of the cases were positive in Grade I, while 37.5% (6/16) positive in Grade II and 21.4% (3/14) in Grade III (P = 0.048). The positive rate increased with the patients survival time from less than 3 years to 3-5 years and more than 5 years correspondingly, but there was no statistical significance (P = 0.126). The results suggested that the expression of nm23 might be one of the factors influencing the lymph-node metastasis and prognosis of buccal cancer.

L-arginine ameliorates cerebral blood flow and metabolism and decreases infarct volume in rats with cerebral ischemia

Effects of L-arginine, 300 mg/kg, i.p., on the regional cerebral blood flow (rCBF), brain metabolism, and infarct volume were examined in spontaneously hypertensive rats subjected to occlusion of both left middle cerebral artery and left common carotid artery. Rats treated with L-arginine had higher rCBF, determined by hydrogen clearance method, in the ischemic core (7 +/- 1 ml/100 g/min, mean +/- S.E.M.) and penumbral regions (16 +/- 2) than did rats treated with saline (5 +/- 0 and 7 +/- 1, respectively). Simultaneously, L-arginine attenuated metabolic derangement in the ischemic tissue at 60 min, i.e. well maintained adenosine triphosphate (ATP) in ischemic region (1.29 +/- 0.07 mmol/kg in L-arginine group vs. 1.05 +/- 0.06 in saline group), and also close to normal levels in ATP (2.61 +/- 0.02 mmol/kg vs. 2.45 +/- 0.05), glucose (2.29 +/- 0.12 mmol/kg vs. 1.80 +/- 0.17) and lactate (1.63 +/- 0.10 mmol/kg vs. 2.24 +/- 0.21) in periischemic region. In another experiment, the effects of L-arginine on rCBF in the subcortical regions and on infarct volume were evaluated. L-arginine, compared with saline, increased rCBF by 8 ml/100 g/min in the ischemic side and reduced infarct volume by 29% at 24 h of ischemia. These findings support that L-arginine may be potentially useful for the treatment of acute cerebral ischemia.

Mechanism-based inactivation of porcine kidney diamine oxidase by 1,4-diamino-2-butene

Cis- and trans-1,4-diamino-2-butene are substrates and potent inactivators of porcine kidney diamine oxidase. Evidence from absorption and NMR spectra indicates that both are oxidized to pyrrole. Both substrates are irreversible mechanism-based inactivators of the enzyme, although the trans isomer is more potent and results in complete inactivation in a reaction which follows pseudo-first-order kinetics with an apparent Ki of 0.34 mM and a second-order inactivation constant of 500 M-1 s-1. Under the same conditions, 46% of the activity remains when the enzyme is reacted with cis-1,4-diamino-2-butene. Trans-4-amino-2-butenal, the product of oxidation of the trans diamine, has been synthesized and shown to undergo cyclization to pyrrole in a concentration-dependent manner, approaching second-order at low concentrations. Trans-4-amino-2-butenal is itself a potent irreversible inhibitor with IC50 of 2.5 microM. We propose that the irreversible inactivation by both cis- and trans-1,4-diamino-2-butene involves attack by a protein-based nucleophilic residue on the unsaturated aminoenal products of the enzymatic reactions, resulting in a covalent adduct. Cyclization of the cis-aminoenal to pyrrole is much more rapid than in the trans case, thus it is less available for inhibitory reaction with the protein.

[Use of perfluorodecalin in giant retinal tear retinal detachment surgery]

Perfluorodecalin is used for the treatment of 11 eyes with giant retinal tear retinal detachment surgery. Perfluorocarbon liquids can be used as an operative hydrodynamic tool during vitreous surgery. The high specific gravity of perfluorocarbon liquids allows an easy unfolding of the inverted flap and flattening of the retina, displacing the subretinal fluid and stabilizing the retina for membrane peeling. Endophotocoagulation may be performed under optimal visual condition. The success rate was 81.8% (9/11). The retina failed to reattach in patients with advanced proliferative vitreoretinopathy. The surgical techniques were discussed.

Precise localization of aphidicolin-induced breakpoints on the short arm of human chromosome 3

The common fragile site at 3p14.2 (FRA3B) has been described as the most active fragile site in the human genome. This locus may predispose chromosome 3 to specific losses due to deletions and translocations that have been associated with several malignancies, including hereditary renal cell carcinoma. We have previously described induction of breakage around FRA3B using aphidicolin in a somatic cell hybrid whose only human component was a single intact chromosome 3. That work led to the isolation of hybrids with breakpoints in the 3p13-p21.1 region with loss of all sequences distal to their respective breakpoints. In this report we describe the further characterization of the breakpoints in many of these cell lines using newly available molecular markers. We also report the identification of YAC clones that span the breakpoints present in many of these hybrids.

Cyanide inhibition of porcine kidney diamine oxidase and bovine plasma amine oxidase: evidence for multiple interaction sites

The interactions of cyanide and phenylhydrazine with porcine kidney diamine oxidase (PKDAO) and bovine plasma amine oxidase (BPAO) (EC 1.4.3.6) have been investigated. Cyanide displays mixed noncompetitive inhibition against amine substrates and also against O2. EPR spectroscopy shows that cyanide binds to an equatorial site on Cu(II) and can be displaced by chloride, which is not an inhibitor, without recovery of activity, indicating that Cu(II)-bound cyanide is not inhibitory. 14CN-. studies have shown that one cyanide in PKDAO and two in BPAO are covalently and irreversibly bound per enzyme dimer at an unknown site, even under conditions where cyanide is not bound to Cu(II). These cyanides have no effect on activity or on binding of phenylhydrazine to the enzymes. Cyanide also binds reversibly to the organic cofactor in both enzymes, presumably as a cyanohydrin, leading to the observed mixed noncompetitive inhibition against substrate. In both enzymes, two phenylhydrazines react per enzyme dimer. The kinetics of phenylhydrazine titration are affected by cyanide, which indicates that phenylhydrazine and cyanide react at the same carbonyl group in the enzymes. The results suggest that inhibition of amine oxidases by cyanide is through a carbonyl reagent and a Cu(I) ligand rather than through a Cu(II) ligand.

RPA involvement in the damage-recognition and incision steps of nucleotide excision repair

Human replication protein (RPA) functions in DNA replication, homologous recombination and nucleotide excision repair. This multisubunit single-stranded DNA-binding protein may be required to make unique protein-protein contacts because heterologous single-stranded binding proteins cannot substitute for RPA in these diverse DNA transactions. We report here that, by using affinity chromatography and immunoprecipitation, we found that human RPA bound specifically and directly to two excision repair proteins, the xeroderma pigmentosum damage-recognition protein XPA (refs 8, 9) and the endonuclease XPG (refs 10-13). Although it had been suggested that RPA might function before the DNA synthesis repair stage, our finding that a complex of RPA and XPA showed a striking cooperativity in binding to DNA lesions indicates that RPA may function at the very earliest stage of excision repair. In addition, by binding XPG, RPA may target this endonuclease to damaged DNA.

Changes of gastric acid secretion and somatostatin after Roux-en-Y cholangiojejunostomy

The authors studied the changes of gastric acid secretion and determined the levels of somatostatin (SS) and gastrin (Gn) in blood, gastric juice and pyloric antrum in 28 patients Roux-en-Y with cholangiojejunostomy (CJR-Y). Gastric acid hypersecretion was identified, and the level of SS was found dropped while the content of Gn increased in these specimens. It was considered that the reduction of SS synthesis and secretion might have a key effect on the mechanism of secondary gastric acid hypersecretion in patients after CJR-Y.

Purification and characterization of an oxygen-sensitive reversible 4-hydroxybenzoate decarboxylase from Clostridium hydroxybenzoicum

A 4-hydroxybenzoate decarboxylase from the anaerobe Clostridium hydroxybenzoicum strain JW/Z-1T was purified and partially characterized. It had an apparent molecular mass of 350 kDa and consisted of six identical subunits of 57 kDa each. The temperature optimum for the decarboxylation was approximately 50 degrees C, the optimum pH 5.6-6.2. The pI of the enzyme was 5.1. The activation energy for decarboxylation of 4-hydroxybenzoate was 65 kJ.mol-1 (20-37 degrees C). The enzyme also catalyzed decarboxylation of 3,4-dihydroxybenzoate. The apparent Km and kcat values obtained for 4-hydroxybenzoate were 0.40 mM and 3.3 x 10(3) min-1, and for 3,4-dihydroxybenzoate 1.2 mM and 1.1 x 10(3) min-1, respectively, at pH 6.0 and 25 degrees C. The enzyme activity was not influenced by the addition of biotin or avidin to either the crude cell extracts or the purified enzyme. The p-hydroxyl group of hydroxybenzoate appears to be essential for binding by the enzyme. The N-terminal amino acid sequence shows some similarity to the uroporphyrinogen decarboxylases from Synechococcus and Saccharomyces. The enzyme catalyzed the reverse reactions, that is, the carboxylation of phenol to 4-hydroxybenzoate and of catechol to 3,4-dihydroxybenzoate. The carboxylation did not require ATP.

The structure of the human sterol carrier protein X/sterol carrier protein 2 gene (SCP2)

Sterol carrier protein X (SCPx) is a 58-kDa protein that is localized to peroxisomes. The amino acid sequence of the protein suggests that SCPx may function as a thiolase. The gene encoding SCPx also codes for a 15.3-kDa protein called sterol carrier protein 2 (SCP2). Here we report the structure of this gene (SCP2), which spans approximately 80 kb and consists of 16 exons and 15 introns. Multiple transcription start sites were identified. The 5' flanking region has characteristics of other peroxisomal protein promoters, which include the absence of a TATA box and a G+C-enriched region containing several reverse GC boxes.