Transcription factor ZNF703 activates linc-UBC1 to stimulate the progression of glioma.

OBJECTIVE: To investigate the role of the transcription factor Zinc finger 703 (ZNF703) in influencing the progression of glioma by regulating linc-UBC1 level. MATERIALS AND METHODS: Linc-UBC1 level in glioma with different staging and tumor sizes was determined. The potential influences of linc-UBC1 on viability, cell cycle progression, and invasiveness of glioma cells were evaluated. Through RNA binding protein immunoprecipitation (RIP) assay and Dual-Luciferase reporter gene assay, the interaction between ZNF703 and linc-UBC1 was assessed. The rescue experiments were conducted to identify the role of ZNF703 in regulating cellular performances of glioma by interacting with linc-UBC1. RESULTS: Linc-UBC1 was highly expressed in glioma. Its level was higher in glioma with larger tumor size or advanced staging. The knockdown of linc-UBC1 reduced viability, arrested cell cycle in the G0/G1 phase, and attenuated invasiveness of U87 and LN229 cells. The presence of the binding sites was observed in the promoter regions of ZNF703 and linc-UBC1. The overexpression of ZNF703 could alleviate the inhibited proliferative and invasive potentials in U87 and LN229 cells with the linc-UBC1 knockdown. CONCLUSIONS: The transcription factor ZNF703 promotes the proliferative and invasive potentials in glioma cells by regulating the transcriptional activity of linc-UBC1.

[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.

[Comparison of aortic annular diameter defined by different measurement mordalities before transcatheter aortic valve implantation].

Objective: To compare aortic annular diameter measured by transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and multislice computed tomography (MSCT) in patients with severe aortic stenosis, and to evaluate the impact on selection of prosthetic valve type in transcatheter aortic valve implantation (TAVI). Methods: Clinical data of 138 patients with severe aortic stenosis referred for TAVI between January 2014 and June 2016 in our hospital were retrospectively analyzed.The difference of aortic annular diameter measured by TTE, TEE, and MSCT were compared.TTE was performed after TAVI to evaluate the accuracy of measurement before TAVI. Results: (1) Aortic annular diameter was (23.37±2.22) mm by TTE and (23.52±1.70) mm by TEE (P=0.12). Pearson correlation analysis showed that aortic annular diameter measured by TTE was correlated to that measured by TEE (r=0.87, P<0.05). (2)The long-axis diameter and the short-axis diameter measured by MSCT multiplanar reconstruction were significantly different ((27.86±2.87) mm vs. (21.91±2.53) mm, P<0.05). There was no significant difference between the mean of the long- and short-axis diameters and the diameter derived from cross-sectional area by MSCT ((24.92±2.38) mm vs. (24.84±2.25) mm, P=0.08). However, the diameter derived from the circumference ((25.35±2.34) mm) was significantly larger than the mean of the long- and short-axis diameters and the diameter derived from cross-sectional area by MSCT, and the difference were (0.43±0.62) mm and (0.51±0.62) mm respectively(both P<0.05). (3) Measurements of the aortic annulus diameter by MSCT including the mean of the long- and short-axis diameters, diameter derived from cross-sectional area, and diameter derived from the circumference were larger than the measurement by TTE and TTE (all P<0.05). (4) Implantation was successful in all patients.Moderate to severe paravalvular leakage was detected in 3 patients at 7 days post TAVI, and 1 patient developed severe prosthetic valve restenosis at 6 months post TAVI and received valve-in-valve implantation. Conclusions: In severe aortic stenosis patients referred for TAVI, the aortic annular diameter derived from TTE and TEE measurements are smaller than that from MSCT.In the absence of a gold standard, selection of prosthetic valve type in TAVI procedure should rely on comprehensive considerations, which is of importance to get good clinical results for severe aortic stenosis patients underwent TAVI.

[Association between SORCS1 rs1416406 and therapeutic effect of exenatide].

Objective: To study the relationship between SORCS1 gene rs1416406 and efficiency of exenatide. Methods: Between August 2010 and August 2012, a hundred and one newly diagnosed patients with type 2 diabetes mellitus (T2DM) were from CONFIDENCE study covering 25 university-affiliated hospitals in 13 provinces of China. All patients received exenatide treatment for 48 weeks. Hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), body mass index (BMI), oral glucose tolerance test (OGTT) glucose and insulin levels were measured before and after therapy. ß-cell function was assessed by fasting proinsulin/insulin (PI/I), disposition index (DI) and acute insulin response (AIR). SORCS1 gene rs1416406 was genotyped by improved multiple ligase detection reaction. The relationship between rs1416406 and the glucose-lowering effect as well as ß-cell function improvement of exenatide was analyzed by multiple linear regression. Results: There were statistically significant differences of HbA1c, FPG, 2 h plasma glucose (2 h PG), ß-cell function (PI/I, DI and AIR) and changes of PI/I in three genotypes (GG, GA, AA) of rs1416406 between baseline and 48-week therapy of exenatide (all P<0.05). No statistically significant difference was found in changes of HbA1c, FPG, 2 h PG, DI, AIR except for PI/I, after stratifying by genotypes of rs1416406. Multiple linear regression analysis showed rs1416406 was significantly associated with the PI/I change (P<0.05) after adjustment of age, sex, baseline BMI, HbA1c and PI/I. Conclusion: SORCS1 gene rs1416406 was associated with the PI/I improvement induced by exenatide. Patients carrying GG genotype had greater reduction in PI/I after exenatide treatment as compared with those carrying allele A. The results suggests that the newly diagnosed T2DM patients with GG genotype might obtain more benefit from the early treatment of exenatide .

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.

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.

Comparison between transareola singlesite endoscopic thyroidectomy and minimally invasive video-assisted thyroidectomy.

OBJECTIVES: To compare surgical outcomes between transareola single-site endoscopic thyroidectomy (TASSET) and minimally invasive video-assisted thyroidectomy (MIVAT). METHODS: Patients with thyroid nodules were randomized to TASSET (n = 24) or MIVAT (n = 24). Surgical outcomes and patient-rated cosmetic results, based on numerical (0 [worst], 10 [best]) and verbal (1 [poor], 4 [excellent]) response scales, were compared. RESULTS: There were no significant differences between groups for age, sex, indication for operation, estimated blood loss, postoperative pain and length of postoperative stay. TASSET was associated with a significantly longer mean ± SD operative time than MIVAT (156.84 ± 41.42 vs. 66.38 ± 17.58 min), and significantly improved cosmetic results according to the numerical (9.63 ± 0.60 vs 7.90 ± 1.38) and verbal response (3.8 ± 0.5 vs 3.1 ± 0.7) scales. Postoperative complaints were comparable between the two approaches, although MIVAT involved a shorter operation time. CONCLUSIONS: Patients treated with TASSET had superior cosmetic results compared with those treated with MIVAT.

Negative Goos-Hänchen shift on a concave dielectric interface.

We study the Goos-Hänchen shift (GHS) on a curved surface through numerical simulation by the boundary element method. A negative GHS is first discovered on a concave dielectric interface below the critical angle, accompanied by a large positive GHS on the convexity. The simulation shows that the GHS on a planar interface is the composition of the GHS from a concave and the corresponding convex interface. This work will enrich the study of the GHS for different curved surfaces, which will have potential applications in micro-optics and near-field optics.

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.

PIP: The association of hemoglobin in the second gestational month with preterm birth and low birth weight (LBW), as well as the impact on this relationship of using hemoglobin values collected at times other than the second month, were investigated in a prospective observational study of 829 pregnant women from Shanghai, China, in 1991-92. Rates of LBW and preterm birth were related to early pregnancy hemoglobin concentrations in a U-shaped manner. The relative risks for preterm birth by g/l of hemoglobin were 2.52 (95% confidence interval (CI), 0.95-6.64) for 130 g/l and above, 1.11 (95% CI, 0.41-2.99) for 120-129 g/l, 1.64 (95% CI, 0.77-3.47) for 100-109 g/l, 2.63 (95% CI, 1.17-5.90) for 90-99 g/l, and 3.73 (95% CI, 1.36-10.23) for 60-89 g/l. Use of hemoglobin values in the 5th or 8th month of pregnancy attenuated the association with preterm birth. When the lowest pregnancy hemoglobin values were used, the association of anemia with both outcomes was obscured and the risk of preterm birth at high hemoglobin values increased markedly.

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.

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.

(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.