A ratiometric fluorescent sensing of proanthocyanidins by MnO2 nanosheets simultaneously tuning the photoluminescence of Au/AgNCs and thiamine

By simultaneously regulating the photoluminescence of alloy Au/Ag nanoclusters (NCs) and thiamine (VB1) through MnO₂ nanosheets (MnO₂ NS), a novel ratiometric fluorescent probe (RF-probe) was established for sensitively and selectively monitoring proanthocyanidins (PAs). The introduction of Ag (I) ions could enhance significantly the quantum yields (QYs, 11.1%) of AuNCs based on the synthetic method of UVI (UV irradiation) combined with MWH (microwave heating). MnO₂ NS could quench the fluorescence (FL) of Au/AgNCs mainly coming from Förster resonance energy transfer (FRET), while it could act as a nanozyme catalyst for directly catalyzing the oxidation of VB1 to produce highly fluorescent oxVB1. In the presence of PAs, MnO₂ was reduced to Mn²⁺, which caused that its quenching capacity and oxidase-like activity were vanished, thus the FL of oxVB1 and Au/AgNCs was reduced and recovered. The concentration of PAs could be monitored by the RF-probe with a linear range of 0.27-22.4 μmol L^-1 and corresponding limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 75.9 and 250.5 nmol L^-1. Furthermore, the RF-probe was successfully used for the determination of PAs in mineral water, PAs additive and PAs capsule with satisfactory results compared to the standard HPLC method.

[Analysis on correlation between single nucleotide polymorphisms of vitamin D receptor gene with susceptibility to allergic rhinitis]

Objective: To investigate the relationship between single nucleotide polymorphism(SNP) of vitamin D receptor(VDR) gene with susceptibility to allergic rhinitis(AR). Method: Two hundred and ten AR patients were selected as AR group, and 180 healthy volunteers from the same period were selected as control group. Fasting venous blood was collected from all subjects and blood DNA was extracted. Polymorphisms at ApaⅠ(rs7975232) and FokⅠ(rs2228570) loci of VDR gene were detected by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP), and the relationships between different genotypes with susceptibility to AR were comparatively analyzed. The Hardy-Weinberg's law of genetic balance verifies whether the two genotype frequencies were representative; Logistic multiple regression analysis was used to analyze the related factors affecting susceptibility of AR. Result: There were SNPs at rs7975232 locus of VDR gene, which were wild homozygote CC type, mutant heterozygote AC, and mutant homozygote AA. SNPs existed at rs2228570 locus, which were wild homozygote GG, mutant heterozygote GA, and mutant homozygote AA. The distributions of genotypes at rs7975232 and rs2228570 locus of VDR gene conformed to Hardy-Weinberg law. There was a significant difference in the distribution of rs7975232 genotype(P<0.05), and the frequency of C allele in the study group was significantly higher than that in the control group(P<0.05). There was no significant difference in genotype distribution of rs2228570 locus (P>0.05). Logistic analysis showed that CC genotype of ApaⅠwas a risk factor for AR susceptibility. Conclusion: The polymorphism of ApaⅠ(rs7975232) locus of VDR gene is correlated with AR susceptibility. CC genotype may be a susceptible factor for AR patients, but there is no significant correlation between FokⅠ polymorphism and AR. .

[Analysis on treatment of eight extremely severe burn patients in August 2nd Kunshan factory aluminum dust explosion accident]

Objective: To summarize the measures and experience of treatment in mass extremely severe burn patients. Methods: The clinical data and treatment of 8 extremely severe burn patients in August 2 Kunshan factory aluminum dust explosion accident who were admitted in the 100th Hospital of PLA on August 2nd, 2014, were retrospectively analyzed. There were 4 males and 4 females, aging 22-45 (34±7) years, with total burn area of 55%-98% [(89±15)%] total body surface area (TBSA) and full-thickness burn area of 45%-97% [(80±21)%] TBSA. All the 8 patients were accompanied with severe shock, inhalation injury, and blast injury. According to the requirements of former PLA General Logistics Department and Nanjing Military Command, a treatment team was set up including a special medical unit and a special care unit, with Chai Jiake from the First Affiliated Hospital of PLA General Hospital as the team leader, Zheng Qingyi from the 175th Hospital of PLA (the Affiliated Dongnan Hospital of Xiamen University) as the deputy leader, the 100th Hospital of PLA as the treatment base, and burn care, respiratory, nephrology, nursing specialists from the First Affiliated Hospital of PLA General Hospital, and the burn care experts and nursing staff from the 180th Hospital of PLA, 118th Hospital of PLA, 98th Hospital of PLA, and 175th Hospital of PLA, and nurses from the 85th Hospital of PLA, 455th Hospital of PLA, 101th Hospital of PLA, 113th Hospital of PLA as team members. Treatment strategies were adopted as unified coordination by the superior, unified responsibility of team leader, division of labor and cooperation between team members, and multidisciplinary cooperation led by department of burns. With exception of one patient who received deep vein catheterization before admission, the other 7 patients were treated with deep vein catheterization 0.5 to 3.0 hours after admission to correct hypovolemic shock as soon as possible. Eight patients received tracheotomy, and 7 patients were treated with mechanical ventilation by ventilator in protective ventilation strategy with low tide volume and low volume pressure to assist breathing. Fiberoptic bronchoscopy was done one to three times for all the 8 patients to confirm airway injuries and healing status. Escharectomy and Meek dermatoplasty in the extremities of all the 8 patients were performed 3 to 6 days after injury for the first time. Escharectomy, microskin grafting, and covering of large pieces of allogeneic skin on the trunks of 4 patients were performed 11 to 16 days after injury for the second time. The broad-spectrum antibiotics were uniformly used at first time of anti-infective therapy, and then the antibiotics species were adjusted in time. The balance of internal environment was maintained and the visceral functions were protected. One special care unit was on responsibility of only one patient. Psychological intervention was performed on admission. The rehabilitative treatment was started at early stage and in company with the whole treatment. Results: Acute renal injury occurred in 5 patients within 36 hours after injury and their renal function was restored to normal 4 days after injury due to active adjustment of fluid resuscitation program. No pulmonary complications, such as severe pulmonary infection and ventilator-associated pneumonia, occurred in the survived patients. One of the 8 patients died, and the other 7 patients were cured successfully. The wounds were basically healed in 2 patients in 26 or 27 days by 2 or 3 times of operation, and in 5 patients by 4 or 5 times of operation. The basic wound healing time was 26-64 (48±15) days for all the 7 patients. Conclusions: Treatment strategies of unified coordination by the superior, unified responsibility of team leader, division of labor and cooperation between team members, and multidisciplinary cooperation led by department of burns are the bases to successful treatment. Correcting shock as soon as possible is the prerequisite and closing wound as soon as possible is the key to successful treatment. Comprehensive treatment measures, such as maintaining and regulating the function of viscera, improving the body immunity, and preventing and treating the complications, are the important components to successful treatment. It is emphasized that in the treatment of mass extremely severe burn patients, specialist burn treatment should always be in the dominant position, and other related disciplines may play a part in auxiliary function.

The Association Between Obstructive Sleep Apnea and Nonarteritic Anterior Ischemic Optic Neuropathy: A Systematic Review and Meta-Analysis

PURPOSE

Nonarteritic anterior ischemic optic neuropathy (NAION) is a multifactorial disease, and recently epidemiologic studies have investigated the association between obstructive sleep apnea (OSA) and NAION. A systematic review of the association of OSA and NAION has not been performed. Therefore, the current meta-analysis was performed to assess such potential association between OSA and risk of NAION.

METHODS

A systematic search of PubMed and EMBASE databases was performed for published studies evaluating the association between OSA and NAION. The summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for categorical risk estimates. Sensitivity analyses and subgroup analyses were also performed to assess the robustness of pooled outcomes.

RESULTS

A total of four prospective cohort studies and one case-control study met our inclusion criteria. The pooled OR of developing NAION in the subjects with OSA was 6.18 (95% CI, 2.00-19.11) versus non-OSA controls. Sensitivity analyses showed that no matter one study excluded, the pooled OR did not change significantly, which indicated that the evidence was robust. In subgroup analyses, a significant association was seen in studies matched systemic risk factors (OR, 5.00; 95% CI, 2.22-11.25), but not in those non-matched. The magnitude and direction of effects were also affected by methodological variability, including study design, and diagnosis of OSA.

CONCLUSIONS

The findings from this meta-analysis supported the robust evidence that OSA was a strong independent risk factor of NAION. Relative to non-OSA controls, the subjects with OSA were found to have a more than sixfold risk of NAION. In future, more well-designed studies are needed to confirm these findings.

Using comparative genomics to develop a molecular diagnostic for the identification of an emerging pest Drosophila suzukii

Drosophila suzukii (Spotted Wing Drosophila) has recently become a serious invasive pest of fruit crops in the USA, Canada, and Europe, leading to substantial economic losses. D. suzukii is a direct pest, ovipositing directly into ripe or ripening fruits; in contrast, other Drosophilids utilize decaying or blemished fruits and are nuisance pests at worst. Immature stages of D. suzukii are difficult to differentiate from other Drosophilids, posing problems for research and for meeting quarantine restrictions designed to prevent the spread of this pest in fruit exports. Here we used a combined phylogenetic and bioinformatic approach to discover genetic markers suitable for a species diagnostic protocol of this agricultural pest. We describe a molecular diagnostic for rapid identification of single D. suzukii larva using multiplex polymerase chain reaction. Our molecular diagnostic was validated using nine different species of Drosophila for specificity and 19 populations of D. suzukii from different geographical regions to ensure utility within species.

Interaction between water-soluble rhodium complex RhCl(CO)(TPPTS)₂ and surfactants probed by spectroscopic methods

The interactions of rhodium complex RhCl(CO)(TPPTS)(2) [TPPTS=P(m-C(6)H(4)SO(3)Na)(3)] with cationic, nonionic, and anionic surfactants have been investigated by UV-vis, fluorescence and (1)H NMR measurements. The presence of four different species of RhCl(CO)(TPPTS)(2) in cationic cetyltrimethylammonium (CTAB) solution has been demonstrated: free rhodium complex, rhodium complex bound to CTAB monomer, rhodium complex bound to CTAB premicelles, rhodium complex bound to CTAB micelles. The spectroscopy data show that RhCl(CO)(TPPTS)(2) can adsorb on the interface of cationic CTAB micelles by strong electrostatic attraction, weakly bind to the nonionic polyoxyethylene (20) sorbitan monolaurate (Tween 20) micelles by hydrophobic interaction, and does not interact with anion sodium dodecyl sulfate (SDS) micelles due to the strong electrostatic repulsion.

The mechanism of lipid raft mediating chemoresistance of cervical cancer

OBJECTIVE

To investigate the mechanism of lipid raft mediating chemotherapy resistance in cervical cancer.

METHODS

This experiment was carried out in the Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China from June 2010 to February 2011. Hela cells were divided into 6 groups: control group (Ctrl), cisplatin group (Cis), lipid raft interference agent group (MCD), NADPH oxidase inhibitor group (Apo), lipid raft interference agent combined with cisplatin group (MCD+Cis), and NADPH oxidase inhibitor combined with cisplatin group (Apo+Cis). After the cervical cancer cells were treated with a correspondent agent for 24 hours, the number of surviving cells were measured utilizing cell counting kits-8 (CCK-8), and the hypoxia inducible factor-1alpha (HIF-1alpha) levels were detected by Western blotting. Reactive oxygen species (ROS) levels were measured indirectly by detection of dichlorodihydrofluorescein fluorescence activity.

RESULTS

The cell growth of MCD slowed down (survival cells was 62% compared with the Ctrl group), with the Apo group showing a similar effect (65% in the control group), and 49% for the Cis group, MCD+Cis was 21%, and Apo+Cis was 23%. While the level of HIF-1alpha protein and ROS of the MCD group, Apo group, Cis group, MCD+Cis group and Apo+Cis group were decreased significantly compared to the control group. The level of HIF-1alpha of MCD group decreased by 69.9%, Apo group by 60.2%, Cis group was 55.5%, MCD+Cis group by 21.1% and Apo+Cis group by 25.4%, while the level of ROS also decreased in the MCD group by 38.6%, Apo group by 35.3%, Cis group by 24%, MCD+Cis group by 12.3% and Apo+Cis group by 12.8%.

CONCLUSION

Lipid raft may up-regulate ROS level and HIF-1alpha expression through activating NADPH oxidase, and thus promote chemotherapy resistance in cervical cancer.

Toll-like receptor 4 signaling promotes the immunosuppressive cytokine production of human cervical cancer

OBJECTIVES

To investigate the expression of TLR-4 (toll-like receptor) on human cervical cancer and find the biological function of the TLR-4 signal system.

METHODS

The immunohistochemistry method was performed to study the protein expression and distribution of TLR-4. The viability of HeLa cells was determined by cell viability assay. Cell proliferation was detected by FCM, ELISA and Western blot were used to observe the gene and protein expression of IL-6 and TGF-beta1 in Hela cell lines.

RESULTS

TLR-4 was over-expressed in cervix cancer, and its activation by LPS promotes proliferation and anti-apoptosis in Hela cells in vitro. Moreover the cell line proliferation increased in a dose- and time-dependent manner. The production of IL-6 and TGF-beta1 were promoted through the activation of the NF-kappaB signaling pathway.

Enantiomer separation of mandelates and their analogs on cyclodextrin derivative chiral stationary phases by capillary GC

Enantiomer separation of mandelates and their analogs, which are important intermediates in asymmetric synthetic and pharmaceutical chemistry, was investigated by capillary gas chromatography using different cyclodextrin derivative chiral stationary phases (CD CSPs). The used cyclodextrin derivatives included permethylated beta-CD (PMBCD), permethylated gamma-CD, heptakis(2,6-di-O-butyl-3-O-butyryl)-beta-CD, heptakis(2,6-di-O-pentyl-3-O-acetyl)-beta-CD and heptakis(2,6-di-O-nonyl-3-O-trifluoroacetyl)-beta-CD (DNTBCD), respectively. Among all the CSPs used, PMBCD and DNTBCD exhibited the broadest and best enantioselectivity for all the racemates investigated. Some thermodynamic parameters were evaluated and an enthalpy-entropy compensation effect was observed in enantiomer separation processes of mandelates and their analogs. Based on thermodynamic data and molecular mechanics calculations, the chiral recognition mechanism of mandelate derivatives on CD CSPs is discussed.

Predictors of pain control in patients undergoing flexible bronchoscopy

The purpose of this study was to assess the extent to which patients undergoing flexible bronchoscopy (FOB) experience pain and to identify patient factors and process of care factors that are associated with pain. We conducted a prospective cohort study on 481 patients undergoing FOB. Overall control of pain during FOB was the primary outcome. The mean age of the patients was 48 yr, 50% were male, and 32% required supplemental oxygen prior to FOB. Pain control was excellent in 36% of patients, but 10% considered it to be fair or poor. Patient factors associated with excellent pain control were excellent health (versus poor health, OR = 6.25 [95% CI, 2.28-16.67]), more education (college education versus high school education, OR = 1.72 [95% CI, 1.05-2.86]), and not having asthma (OR = 2.86 [95% CI, 1.09-7.14]). Process of care factors associated with excellent pain control were not being bothered by scope insertion (versus bothered, OR = 3.65 [95% CI, 1.99-6.98]), no memory of FOB (versus some memory, OR = 2.33 [95% CI, 1.24-4.44]), and higher ratings of information about the procedure (per 1-point increase on a 12-point scale, OR = 1.57 [95% CI, 1.41-1.78]). This is the first large-scale, prospective study to evaluate patient and process of care factors that influence pain control during FOB. It demonstrated that there are patient characteristics and process of care factors that need to be considered when evaluating pain during bronchoscopy. Improved preparation of patients with lower education, inferior health status, and asthma may lead to decreased pain during FOB. Bronchoscopists may be able to reduce pain during FOB by identifying methods to decrease pain on scope insertion, by improving the information provided to patients, and by achieving greater levels of amnesia during FOB.

The T-superfamily of conotoxins

We report the discovery and initial characterization of the T-superfamily of conotoxins. Eight different T-superfamily peptides from five Conus species were identified; they share a consensus signal sequence, and a conserved arrangement of cysteine residues (- -CC- -CC-). T-superfamily peptides were found expressed in venom ducts of all major feeding types of Conus; the results suggest that the T-superfamily will be a large and diverse group of peptides, widely distributed in the 500 different Conus species. These peptides are likely to be functionally diverse; although the peptides are small (11-17 amino acids), their sequences are strikingly divergent, with different peptides of the superfamily exhibiting varying extents of post-translational modification. Of the three peptides tested for in vivo biological activity, only one was active on mice but all three had effects on fish. The peptides that have been extensively characterized are as follows: p5a, GCCPKQMRCCTL*; tx5a, gammaCCgammaDGW(+)CCT( section sign)AAO; and au5a, FCCPFIRYCCW (where gamma = gamma-carboxyglutamate, W(+) = bromotryptophan, O = hydroxyproline, T( section sign) = glycosylated threonine, and * = COOH-terminal amidation). We also demonstrate that the precursor of tx5a contains a functional gamma-carboxylation recognition signal in the -1 to -20 propeptide region, consistent with the presence of gamma-carboxyglutamate residues in this peptide.

Relation of hemoglobin measured at different times in pregnancy to preterm birth and low birth weight in Shanghai, China

This paper addresses two questions: 1) What is the relation of hemoglobin in the second gestational month to preterm birth and low birth weight? 2) How does the relation differ when hemoglobin in the fifth or eighth month or the lowest pregnancy hemoglobin are examined in place of first trimester values? These relations were examined prospectively in 829 women from Shanghai, China in 1991-1992. The population was nearly homogeneous by race, parity, antenatal care, and smoking. Rates of birth outcomes were compared between hemoglobin categories based on 10 g/liter groupings, with 110-119 g/liter as the reference group. Rates of low birth weight and preterm birth (but not small-for-gestational age) were related to early pregnancy hemoglobin concentration in a U-shaped manner. The relative risks (95% confidence intervals) for preterm birth in women by g/liter of hemoglobin were 2.52 (0.95-6.64) for > or = 130 g/liter, 1.11 (0.41-2.99) for 120-129 g/liter, 1.64 (0.77-3.47) for 100-109 g/liter, 2.63 (1.17-5.90) for 90-99 g/liter, and 3.73 (1.36-10.23) for 60-89 g/liter. Use of hemoglobin values in the fifth or eighth month attenuated the association with preterm birth. When lowest pregnancy hemoglobin values were used, the association of anemia with both outcomes was obscured, and risk of preterm birth at high hemoglobin values increased dramatically.

Molecular features associated with polyamine modulation of NMDA receptors

The effect of 1,3-diamines on basal and spermine-stimulated [3H]MK-801 binding was investigated. Systematic variations in the molecular parameters revealed that, in general, lipophilic 1,3-diamines inhibited and hydrophilic 1,3-diamines enhanced [3H]MK-801 binding in the nominal absence of glutamate and glycine. Furthermore, 1,3-diamines which were highly monoprotonated at physiologic pH were more effective in modulating basal binding (at 100 microM 1,3-diamine) than analogues which were mostly diprotonated or unprotonated. Finally, the internuclear distance between the amino nitrogens and the extent of modulation of basal [3H]MK-801 binding were correlated. Similar, but more modest, effects were seen for spermine-enhanced [3H]MK-801 binding. These results are consistent with the existence of two polyamine binding sites associated with the NMDA receptor complex. One of the sites appears to preferentially recognize lipophilic substances while the other favors hydrophilic materials. Both sites appear to recognize polyamines with at least one charged (protonated) amino group and one uncharged amino group. The distance between amino groups is a determining factor as well.

Conantokin-G precursor and its role in gamma-carboxylation by a vitamin K-dependent carboxylase from a Conus snail

Conantokin-G isolated from the marine snail Conus geographus is a 17-amino acid gamma-carboxyglutamate (Gla)-containing peptide that inhibits the N-methyl-D-aspartate receptor. We describe the cloning and sequence of conantokin-G cDNA and the possible role of the propeptide sequence. The cDNA encodes a 100amino acid peptide. The N-terminal 80 amino acids constitute the prepro-sequence, and the mature peptide is derived from the remaining C-terminal residues after proteolysis, C-terminal amidation, and a unique post-translational modification, gamma-carboxylation of glutamate residues to Gla. Mature conantokin-G peptide containing Glu residues (E.Con-G) in place of Gla is a poor substrate for the vitamin K-dependent gamma-glutamyl carboxylase (apparent Km = 3.4 mM). Using peptides corresponding to different segments of the propeptide we investigated a potential role for the propeptide sequences in gamma-carboxylation. Propeptide segment -20 to -1 covalently linked to E.Con-G or the synthetic pentapeptide FLEEL increased their apparent affinities 2 orders of magnitude. These substrates are not efficiently carboxylated by the bovine microsomal gamma-glutamyl carboxylase, suggesting differences in specificities between the Conus and the mammalian enzyme. However, the role of propeptide in enhancing the efficiency of carboxylation is maintained.

(2S,4R)-4-methylglutamic acid (SYM 2081): a selective, high-affinity ligand for kainate receptors

Glutamic acid activates ionotropic glutamate receptors that mediate excitatory transmission in the central nervous system. The introduction of a methyl group at position 4 of glutamic acid imparts selectivity for kainate receptors, relative to other (N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) ionotropic glutamate receptors. Among the stereoisomers of 4-methylglutamic acid, the potency of the (2S,4R)-isomer (SYM 2081) to inhibit [3H]kainic acid binding to both wild-type (rat forebrain) and recombinant (GluR6) kainate receptors (IC50 values of approximately 32 and 19 nM, respectively) was comparable to that of kainic acid (IC50 values of approximately 13 and 28 nM, respectively). SYM 2081 was approximately 800- and 200-fold less potent as an inhibitor of radioligand binding to wild-type (rat forebrain) alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate receptors, respectively. Preexposure of human embryonic kidney 293 cells stably expressing GluR6 receptors to low concentrations of SYM 2081 (30-300 nM) resulted in a reversible blockade of the rapidly desensitizing currents produced by kainate application. At higher concentrations, SYM 2081 (EC50 of approximately 1 microM) elicited kainate-like, rapidly desensitizing, inward currents. Pretreatment of recombinant GluR6 receptors with concanavalin A both abolished the effect of SYM 2081 to block kainate-induced currents and revealed nondesensitizing currents induced by SYM 2081 alone. The latter observations provide strong support for the hypothesis that SYM 2081 blocks kainate-induced currents through a process of agonist-induced desensitization. SYM 2081 also activated alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor currents in primary cultures of cerebral cortex and, consistent with data obtained by radioligand binding, was approximately 5-fold less potent than kainate (EC50 values of 325 and 70 microM, respectively) in this measure. SYM 2081 is a high-affinity, selective, kainate agonist that may prove useful both as a probe to examine the physiological functions of kainate receptors and as the prototype of a novel class of therapeutic agents.

Cytotoxic effects of kainate ligands on HEK cell lines expressing recombinant kainate receptors

Exposure of neurons either for prolonged periods of time or to high concentrations of excitatory amino acids (EAA), such as glutamate, results in neuronal death. Kainate also causes cell toxicity through the glutamate receptors. However, it is unclear whether the kainate receptor itself mediates any of the toxic responses. In the present study, HEK cells expressing the GluR6 +/- KA2 receptor subunit(s) were studied for their susceptibility to toxicity through the kainate receptor by kainate ligands. The natural ligand, glutamate, did not result in toxicity to the recombinant cell lines over that observed with the untransfected HEK cells, whereas kainate produced a 2-3-fold increase in LDH in both the HEK/GluR6 (ANOVA, P = 0.0001) and HEK/GluR6 + KA2 (ANOVA, P = 0.0002) cell lines following treatment with various dosages, but did not affect the HEK cells. Similar 2-3-fold increases in LDH activity were detected in both recombinant cell lines following treatment with 100 nM of SYM2081 ((2S,4R)-4-methylglutamic acid), a dose at which agonistic activity is elicited. The rank order potencies for eliciting toxicity are consistent with the previously reported EC50 values (SYM2081 > kainate > > > glutamate). Surprisingly, the kainate antagonist, NBQX, was the most toxic of the compounds tested although it had an affinity for the kainate receptor similar to glutamate. Treatment with as little as 10 nM elicited a dramatic increase in toxicity (6-10-fold) in the recombinant cell lines. At 1 microM, NBQX was significantly more toxic (Fisher PLSD, P < 0.05) than any of the other compounds tested. Thus, it appears that cell toxicity can be mediated via kainate receptor through two independent mechanisms: activation and blockage of the kainate receptor.

Synthetic analogues of conantokin-G: NMDA antagonists acting through a novel polyamine-coupled site

Conantokin-G (con-G) is a 17-amino-acid polypeptide that acts as an N-methyl-D-aspartate (NMDA) antagonist. This action has been attributed to a specific but noncompetitive inhibition of the positive modulatory effects of polyamines at NMDA receptors. Con-G possesses several unusual structural features, including five gamma-carboxyglutamate (Gla) residues and a high degree of helicity in aqueous media. Previous structure-activity studies indicated that one or more Gla residues are necessary for NMDA antagonist activity. Con-G analogues were synthesized with alanine (Ala), serine (Ser), and phosphoserine substituted for Gla to assess the contribution of individual Gla residues to biological activity and secondary structure. Replacement of Gla in positions 3 and 4 resulted in polypeptides with markedly reduced and no NMDA antagonist actions, respectively. In contrast, Gla residues in positions 7, 10, and 14 are not required for NMDA antagonist actions because the potencies of con-G analogues containing Ser7, Ser10, Ala14, and Ser14 to inhibit spermine-stimulated [3H]MK-801 binding are similar to the parent peptide. Moreover, the Ala7 derivative of con-G was about fourfold more potent than the parent peptide both as an inhibitor of spermine-stimulated increases in [3H]MK-801 binding (IC50 of approximately 45 nM) and in reducing NMDA-stimulated increases in cyclic GMP levels (IC50 of approximately 77 nM) in cerebellar granule cell cultures. Although con-G and its analogues assumed mixtures of 3(10) and alpha-helices, no clearcut relationship was evinced between the NMDA antagonist properties of these peptides and the degree of helicity they assumed in aqueous solutions. Together with the inability of con-G to affect 5,7-dichloro[3H]kynurenic acid, [3H]CGP-39653, and [3H]ifenprodil binding, these data are consistent with the hypothesis that this polypeptide acts at a unique, polyamine-associated site on NMDA receptors.

Synthesis of N,N'-substituted piperazine and homopiperazine derivatives with polyamine-like actions at N-methyl-D-aspartate receptors

A series of N,N'-substituted piperazine and homopiperazine derivatives have been synthesized with the objective of producing compounds that interact with polyamine modulatory sites on N-methyl-D-aspartate (NMDA) receptors. These novel compounds exhibited polyamine-like actions, enhancing [3H]MK-801 binding to NMDA receptors in rat forebrain membranes. The potencies of N,N'-bis(2-aminoacetyl)homopiperazine (15), N,N'-bis(N-methyl-4-aminobutyl)-piperazine (7), and N,N'-bis(3-aminopropyl)homopiperazine (11) (EC50 18.0, 21.3, and 24.4 microM, respectively) to enhance [3H]MK-801 binding were comparable to that of spermine (EC50 5.2 microM). However, the efficacies of 15, 7, and 11 in this measure were lower (by approximately 40%, 32%, and 24%, respectively) than spermine, which may be indicative of partial agonist actions. Like spermine, the ability of these piperazine and homopiperazine derivatives to enhance [3H]MK-801 binding could be inhibited by both a competitive polyamine antagonist (arcaine) and a specific, noncompetitive polyamine antagonist (conantokin-G). However, unlike endogenous polyamines, high concentrations (up to 1 mM) of these novel polyamine-like compounds did not inhibit [3H]MK-801 binding. N,N'-Aminoalkylated and aminoacylated piperazine and homopiperazine derivatives may prove useful for studying polyamine recognition sites associated with NMDA receptors.

Chronic NMDA receptor stimulation: therapeutic implications of its effect on adenosine A1 receptors

It is known that stimulation of adenosine A1 receptors has a modulatory effect on the excitability of postsynaptic NMDA receptors. Conversely, acute stimulation of NMDA receptors results in release of adenosine via calcium-independent mechanisms. These findings indicate a close functional relationship between these receptors. It is, therefore, possible that chronic, low level stimulation of the NMDA receptor may have a negative impact on these modulatory processes. To investigate this possibility, we have subjected C57BL mice either to an acute injection of a N6-cyclopentyladenosine (CPA, 0.01 mg/kg) or deoxycoformycin (1 mg/kg) followed by a convulsant dose of N-methyl-D-aspartate (NMDA) (60 mg/kg) or to chronic, low level (20 mg/kg i.p. daily) exposure to NMDA for 8 weeks. One day after the last injection of NMDA, animals were injected either with a convulsant dose of NMDA alone, or with either CPA at 0.001 or 0.01 mg/kg, or with 1 mg/kg deoxycoformycin followed 15 min later by 60 mg/kg NMDA. Neither CPA nor deoxycoformycin were protective when NMDA was given acutely at 60 mg/kg. Chronic treatment with NMDA alone or chronic administration of NMDA followed by 0.001 mg/kg CPA had no significant effect on mortality following a convulsant dose of NMDA. However, when the chronic regimen of NMDA was followed by either 0.01 mg/kg CPA or 1 mg/kg deoxycoformycin, mortality was reduced to 10% (CPA), or eliminated completely (deoxycoformycin). Moreover, combination of chronic NMDA treatment with either CPA (both doses) or deoxycoformycin produced a significant improvement in other measures, i.e., seizure onset, intensity of neurological impairment, and extension of time to death.(ABSTRACT TRUNCATED AT 250 WORDS)

Sar1-p-benzoylphenylalanine-angiotensin, a new photoaffinity probe for selective labeling of the type 2 angiotensin receptor

Previous photoaffinity labeling of angiotensin II (Ang) receptors with azidophenylalanine containing Ang analogs produced high yield labeling of a 60 kDa protein on bovine adrenocortical membranes. This preparation is mostly enriched in the type 1 Ang receptor (AT1) and AT1 selective ligands (L158,809) totally prevented labeling, therefore confirming the AT1 nature of the labeled protein. Our attempt to photolabel the type 2 Ang receptor (AT2) of human myometrium with [Sar1,D-Phe(N3)8]Ang was unsuccessful, revealing a high degree of photolabeling selectivity. An Ang analog, [Sar1,Bpa8]Ang (or BpaAng) was prepared containing the photosensitive amino acid p-benzoylphenylalanine (Bpa). This compound was a specific but non-competitive Ang antagonist on rabbit aorta with a pA2 of 8.5. It displayed good binding affinities for bovine adrenocortical membranes (Kd = 6.5 nM), a predominantly AT1 preparation, and for human myometrium membranes (Kd = 0.39 nM), a predominantly AT2 preparation. Photolabeling experiments with iodinated BpaAng showed that AT1 was not covalently labeled whereas AT2 was covalently labeled with high yield. Labeling specificity was verified with the AT2-selective ligand PD123319 and with the AT1-selective antagonist L158,809. Our results indicate that 125I-BpaAng is exclusively labeling AT2 sites. This compound should be a useful tool for further biochemical characterization of the AT2 binding site.

Mutations leading to constitutive expression from the TOL plasmid meta-cleavage pathway operon are located at the C-terminal end of the positive regulator protein XylS

The XylS protein is the positive activator of the TOL plasmid meta-cleavage pathway operon for the metabolism of alkylbenzoates in Pseudomonas putida. The regulator stimulates transcription from the TOL meta pathway operon promoter (Pm) when activated by benzoate effectors or in the absence of effectors when overproduced. xylS mutant alleles that encode regulators which constitutively mediate expression from Pm were isolated and characterized. The mutant proteins all exhibit single amino acid substitutions adjacent to putative alpha-helix-turn-alpha-helix domains at their C-terminal ends. The XylS mutant proteins can still be partially activated by the usual and unusual benzoate effectors for the wild-type regulator and when activated stimulate higher levels of transcription from Pm.

Compositional analysis of the three main gangliosides from adult human myometrium by a rapid capillary gas chromatographic method

A new capillary GC method is described for the compositional analysis of the three main gangliosides isolated from adult human myometrium. The sample was subjected to methanolysis, acetylation and trimethylsilylation which allows all the constituents to be analyzed simultaneously. The predominant ganglioside was found to be GD3, with GM3 and GT1b the next most abundant.

Direct determination of vanillylmandelic acid in human urine by reversed-phase HPLC

A reversed-phase HPLC method for the determination of epinephrine, norepinephrine, dopamine, and vanillylmandelic acid (VMA) has been developed. The concentration of VMA in the urine of hypertensive patients was measured by direct injection after centrifugation. The method is useful for the diagnosis of pheochromocytoma.