Packing-Shape Effects of Optical Properties in Amplified Spontaneous Emission through Dynamics of Orbit-Orbit Polarization Interaction in Hybrid Perovskite Quantum Dots Based on Self-Assembly

This paper reports packing-shape effects of amplified spontaneous emission (ASE) through orbital polarization dynamics between light-emitting excitons by stacking perovskite (MAPbBr₃) quantum dots (QDs sized between 10 nm and 14 nm) into rod-like and diamond-like aggregates. The rod-like packing shows a prolonged photoluminescence (PL) lifetime (184 ns) with 3 nm red-shifted peak (525 nm) as compared to the diamond-like packing (PL peak, 522 nm; lifetime, 19 ns). This indicates that the rod-like packing forms a stronger interaction between QDs with reduced surface-charged defects, leading to surface-to-inside property-tuning capability with an ASE. Interestingly, the ASE enabled by rod-like packing shows an orbit-orbit polarization interaction between light-emitting excitons, identified by linearly/circularly polarized pumping conditions. More importantly, the polarization dynamics is extended to the order of nanoseconds in the rod-like assembly, determined by the observation that within the ASE lifetime (2.54 ns) the rotating pumping beam polarization direction largely affects the coherent interaction between light-emitting excitons.

Circulating microRNAs Associated With Reversible Cerebral Vasoconstriction Syndrome

OBJECTIVE

The purpose of this study was to investigate the significance of circulating micro RNAs (miRNAs) in the pathogenesis of reversible cerebral vasoconstriction syndrome (RCVS).

METHODS

We prospectively recruited 3 independent cohorts of patients with RCVS and age-matched and sex-matched controls in a single medical center. Next-generation small RNA sequencing followed by quantitative polymerase chain reaction (PCR) was used to identify and validate differentially expressed miRNAs, which was cross-validated in migraine patients in ictal stage or interictal stage. Computational analysis was used to predict the target genes of miRNAs, followed by in vitro functional analysis.

RESULTS

We identified a panel of miRNAs including miR-130a-3p, miR-130b-3p, let-7a-5p, let-7b-5p, and let-7f-5p that well differentiated patients with RCVS from controls (area under the receiver operating characteristics curve [AUC] was 0.906, 0.890, and 0.867 in the 3 cohorts, respectively). The abundance of let-7a-5p, let-7b-5p, and let-7f-5p, but not miR-130a-3p nor miR-130b-3p, was significantly higher in patients with ictal migraine compared with that of controls and patients with interictal migraine. Target prediction and pathway enrichment analysis suggested that the transforming growth factor-β signaling pathway and endothelin-1 responsible for vasomotor control might link these miRNAs to RCVS pathogenesis, which was confirmed in vitro by transfecting miRNAs mimics or incubating the patients' cerebrospinal fluid (CSF) in 3 different vascular endothelial cells. Moreover, miR-130a-3p was associated with imaging-proven disruption of the blood-brain barrier (BBB) in patients with RCVS and its overexpression led to reduced transendothelial electrical resistance (ie, increased permeability) in in vitro human BBB model.

INTERPRETATION

We identified the circulating miRNA signatures associated with RCVS, which may be functionally linked to its headache, BBB integrity, and vasomotor function. ANN NEUROL 2021;89:459-473.

Multi-omics profiling reveals microRNA-mediated insulin signaling networks

Background

MicroRNAs (miRNAs) play a key role in mediating the action of insulin on cell growth and the development of diabetes. However, few studies have been conducted to provide a comprehensive overview of the miRNA-mediated signaling network in response to glucose in pancreatic beta cells. In our study, we established a computational framework integrating multi-omics profiles analyses, including RNA sequencing (RNA-seq) and small RNA sequencing (sRNA-seq) data analysis, inverse expression pattern analysis, public data integration, and miRNA targets prediction to illustrate the miRNA-mediated regulatory network at different glucose concentrations in INS-1 pancreatic beta cells (INS-1), which display important characteristics of the pancreatic beta cells.

Results

We applied our computational framework to the expression profiles of miRNA/mRNA of INS-1, at different glucose concentrations. A total of 1437 differentially expressed genes (DEGs) and 153 differentially expressed miRNAs (DEmiRs) were identified from multi-omics profiles. In particular, 121 DEmiRs putatively regulated a total of 237 DEGs involved in glucose metabolism, fatty acid oxidation, ion channels, exocytosis, homeostasis, and insulin gene regulation. Moreover, Argonaute 2 immunoprecipitation sequencing, qRT-PCR, and luciferase assay identified Crem, Fn1, and Stc1 are direct targets of miR-146b and elucidated that miR-146b acted as a potential regulator and promising target to understand the insulin signaling network.

Conclusions

In this study, the integration of experimentally verified data with system biology framework extracts the miRNA network for exploring potential insulin-associated miRNA and their target genes. The findings offer a potentially significant effect on the understanding of miRNA-mediated insulin signaling network in the development and progression of pancreatic diabetes.

Vaginal microbiome variances in sample groups categorized by clinical criteria of bacterial vaginosis

Background

One of the most common and recurrent vaginal infections is bacterial vaginosis (BV). The diagnosis is based on changes to the “normal” vaginal microbiome; however, the normal microbiome appears to differ according to reproductive status and ethnicity, and even among individuals within these groups. The Amsel criteria and Nugent score test are widely used for diagnosing BV; however, these tests are based on different criteria, and so may indicate distinct changes in the vaginal microbial community. Nevertheless, few studies have compared the results of these test against metagenomics analysis.

Methods

Vaginal flora samples from 77 participants were classified according to the Amsel criteria and Nugent score test. The microbiota composition was analyzed using 16S ribosome RNA gene amplicon sequencing. Bioinformatics analysis and multivariate statistical analysis were used to evaluate the microbial diversity and function.

Results

Only 3 % of the participants diagnosed BV negative using the Amsel criteria (A−) were BV-positive according to the Nugent score test (N+), while over half of the BV-positive patients using the Amsel criteria (A+) were BV-negative according to the Nugent score test (N−). Thirteen genera showed significant differences in distribution among BV status defined by BV tests (e.g., A − N−, A + N− and A + N+). Variations in the four most abundant taxa, Lactobacillus, Gardnerella, Prevotella, and Escherichia, were responsible for most of this dissimilarity. Furthermore, vaginal microbial diversity differed significantly among the three groups classified by the Nugent score test (N−, N+, and intermediate flora), but not between the Amsel criteria groups. Numerous predictive microbial functions, such as bacterial chemotaxis and bacterial invasion of epithelial cells, differed significantly among multiple BV test, but not between the A− and A+ groups.

Conclusions

Metagenomics analysis can greatly expand our current understanding of vaginal microbial diversity in health and disease. Metagenomics profiling may also provide more reliable diagnostic criteria for BV testing.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5284-7) contains supplementary material, which is available to authorized users.

Vacuum-Deposited Organometallic Halide Perovskite Light-Emitting Devices

In this work, a sequential vacuum deposition process of bright, highly crystalline, and smooth methylammonium lead bromide and phenethylammonium lead bromide perovskite thin films are investigated and the first vacuum-deposited organometallic halide perovskite light-emitting devices (PeLEDs) are demonstrated. Exceptionally low refractive indices and extinction coefficients in the emission wavelength range are obtained for these films, which contributed to a high light out-coupling efficiency of the PeLEDs. By utilizing these perovskite thin films as emission layers, the vacuum-deposited PeLEDs exhibit a very narrow saturated green electroluminescence at 531 nm, with a spectral full width at half-maximum bandwidth of 18.6 nm, a promising brightness of up to 6200 cd/m², a current efficiency of 1.3 cd/A, and an external quantum efficiency of 0.36%.

DDX3 Represses Stemness by Epigenetically Modulating Tumor-suppressive miRNAs in Hepatocellular Carcinoma

Studies indicate that the presence of cancer stem cells (CSCs) is responsible for poor prognosis of hepatocellular carcinoma (HCC) patients. In this study, the functional role of DDX3 in regulation of hepatic CSCs was investigated. Our results demonstrated that reduced DDX3 expression was not only inversely associated with tumor grade, but also predicted poor prognosis of HCC patients. Knockdown of DDX3 in HCC cell line HepG2 induced stemness gene signature followed by occurrence of self-renewal, chemoreisistance, EMT, migration as well as CSC expansion, and most importantly, DDX3 knockdown promotes tumorigenesis. Moreover, we found positive correlations between DDX3 level and expressions of tumor-suppressive miR-200b, miR-200c, miR-122 and miR-145, but not miR-10b and miR-519a, implying their involvement in DDX3 knockdown-induced CSC phenotypes. In addition, DDX3 reduction promoted up-regulation of DNA methyltransferase 3A (DNMT3A), while neither DNMT3B nor DNMT1 expression was affected. Enriched DNMT3A binding along with hypermethylation on promoters of these tumor-suppressive miRNAs reflected their transcriptional repressions in DDX3-knockdown cells. Furthermore, individual restoration of these tumor-suppressive miRNAs represses DDX3 knockdown-induced CSC phenotypes. In conclusion, our study suggested that DDX3 prevents generation of CSCs through epigenetically regulating a subset of tumor-suppressive miRNAs expressions, which strengthens tumor suppressor role of DDX3 in HCC.

Bacterial communities in semen from men of infertile couples: metagenomic sequencing reveals relationships of seminal microbiota to semen quality

Some previous studies have identified bacteria in semen as being a potential factor in male infertility. However, only few types of bacteria were taken into consideration while using PCR-based or culturing methods. Here we present an analysis approach using next-generation sequencing technology and bioinformatics analysis to investigate the associations between bacterial communities and semen quality. Ninety-six semen samples collected were examined for bacterial communities, measuring seven clinical criteria for semen quality (semen volume, sperm concentration, motility, Kruger's strict morphology, antisperm antibody (IgA), Atypical, and leukocytes). Computer-assisted semen analysis (CASA) was also performed. Results showed that the most abundant genera among all samples were Lactobacillus (19.9%), Pseudomonas (9.85%), Prevotella (8.51%) and Gardnerella (4.21%). The proportion of Lactobacillus and Gardnerella was significantly higher in the normal samples, while that of Prevotella was significantly higher in the low quality samples. Unsupervised clustering analysis demonstrated that the seminal bacterial communities were clustered into three main groups: Lactobacillus, Pseudomonas, and Prevotella predominant group. Remarkably, most normal samples (80.6%) were clustered in Lactobacillus predominant group. The analysis results showed seminal bacteria community types were highly associated with semen health. Lactobacillus might not only be a potential probiotic for semen quality maintenance, but also might be helpful in countering the negative influence of Prevotella and Pseudomonas. In this study, we investigated whole seminal bacterial communities and provided the most comprehensive analysis of the association between bacterial community and semen quality. The study significantly contributes to the current understanding of the etiology of male fertility.

Fabrication and characterization of back-side illuminated InGaN/GaN solar cells with periodic via-holes etching and Bragg mirror processes

In this study, the design and fabrication schemes of back-side illuminated InGaN/GaN solar cells with periodic via-holes etching and Bragg mirror processes are presented. Compared to typical front-side illuminated solar cells, the improvements of open-circuit voltage (V(oc)) from 1.88 to 1.94 V and short-circuit current density (J(sc)) from 0.84 to 1.02 mA/cm(2) are observed. Most significantly, the back-side illuminated InGaN/GaN solar cells exhibit an extremely high fill factor up to 85.5%, leading to a conversion efficiency of 1.69% from 0.66% of typical front-side illuminated solar cells under air mass 1.5 global illuminations. Moreover, the effects of bottom Bragg mirrors on the photovoltaic characteristics of back-side illuminated solar cells are studied by an advanced simulation program. The results show that the J(sc) could further be improved with a factor of 10% from the original back-side illuminated solar cell by the structure optimization of bottom Bragg mirrors.

Reduced efficiency droop in blue InGaN light-emitting diodes by thin AlGaN barriers

The phenomenon of efficiency droop in blue InGaN light-emitting diodes (LEDs) is studied numerically. Simulation results indicate that the severe Auger recombination is one critical mechanism corresponding to the degraded efficiency under high current injection. To solve this issue, LED structure with thin AlGaN barriers and without the use of an AlGaN EBL is proposed. The purpose of the strain-compensation AlGaN barriers is to mitigate the strain accumulation in a multiquantum well (MQW) active region in this thin-barrier structure. With the proposed LED structure, the hole injection and transportation of the MQW active region are largely improved. The carriers can thus distribute/disperse much more uniformly in QWs, and the Auger recombination is suppressed accordingly. The internal quantum efficiency and the efficiency droop are therefore efficiently improved.

Investigation of InGaN green light-emitting diodes with chirped multiple quantum well structures

The effect of using chirped multiple quantum-well (MQW) structures in InGaN green light-emitting diodes (LEDs) is numerically investigated. An active structure, which is with both thick QWs with low indium composition on the p-side and thin QWs with high indium composition next to the n-region, is presented in this study. The thickness and indium composition in each single QW is specifically tuned to emit the same green emission spectrum. Comparing with conventional active structure design of green LEDs, which is using uniform MQWs, the output power is increased by 27% at 20 mA, and by 15% at 100 mA current injections. This improvement is mainly attributed to the enhanced efficiency of carrier injection into QWs and the improved capability of carrier transport.

Highly efficient CdS-quantum-dot-sensitized GaAs solar cells

We demonstrate a hybrid design of traditional GaAs-based solar cell combined with colloidal CdS quantum dots. With anti-reflective feature at long wavelength and down-conversion at UV regime, the CdS quantum dot effectively enhance the overall power conversion efficiency by as high as 18.9% compared to traditional GaAs-based device. A more detailed study showed an increase of surface photoconductivity due to UV presence, and the fill factor of the solar cell can be improved accordingly.

Numerical study of passive Q switching of a Tm:YAG laser with a Ho:YLF solid-state saturable absorber

In a previous work [Appl. Phys. Lett. 65, 3060 (1994)] we experimentally demonstrated that passive Q switching of a 2,017-nm, flashlamp-pumped Tm,Cr:YAG laser with a Ho:YLF saturable absorber could be obtained with an internal focusing lens. We numerically investigate the optical performance of the Ho:YLF Q-switched Tm:YAG laser system by solving the coupled rate equations. The simulation results indicate that the results obtained numerically are in good agreement with those obtained experimentally. With typical laser configuration, a Q-switched laser pulse of 35 mJ in 30 ns is obtained.

Evaluation of magnetic alginate beads as a solid support for positive selection of CD34+ cells

Paramagnetic alginate beads with a 10-100 microns size range have been developed. These beads, when activated with chloroacetic anhydride and covalently coupled to avidin (30 micrograms/mg beads), were able to bind biotinylated goat anti-mouse (B-GAM) antibody (Ab). The beads with immobilized antibody were then used as a model system for the capture and non-enzymatic release of CD34+ (KG1a) cells. A maximum of 82% KG1a (average = 65 +/- 16.1%) cell capture, and 57% (average = 51 +/- 5.9%) cell release has been attained using this model system. Optimization of the system in terms of further bead size reduction, and in terms of developing a system to recover released cells with high purity, will make an excellent system for cell capture and nonenzymatic release.

CO2 control of breathing: parameter estimation and stability evaluation

A method is developed to evaluate system stability for the CO2 control of breathing in individuals by using data from the dynamics of CO2 rebreathing and elimination. The theoretical basis of the method is a physiological model of the CO2 respiratory control system and an explicit stability index (SI). The SI is algebraically related to the model parameters: system volume (Vs), cardiac output (Q), circulatory transit time (ts), and controller gain (G). A sequential optimization scheme is shown to yield estimates of the model parameters by comparing the alveolar ventilation and PCO2 of the model output with corresponding experimental data. Model simulation of CO2 rebreathing and elimination with different parameter values demonstrate that all parameters except ts have significant effect on the outputs. Least-squares estimation of the parameters using model-generated data with added noise showed good precision for all parameters (except ts). This analysis is performed with parameter values chosen to produce overdamped and underdamped responses that would occur in normal and abnormal respiratory control systems, respectively. It is anticipated that SI values of the (overdamped) normal and (underdamped) abnormal systems differ by much more than the variation produced by imprecision of the parameter estimates. For this circumstance, the method is expected to be sensitive enough to distinguish normal from abnormal CO2 respiratory control of individual subjects.

New application of silane coupling agents for covalently binding antibodies to glass and cellulose solid supports

Bifunctional silane reagents (3-iodopropyl)trimethoxysilane (1), (gamma-glycidoxypropyl)trimethoxysilane (2), and [1-(trimethoxysilyl)-2-(m- (or p-)chloromethyl)phenyl]ethane (3) were used to covalently link goat anti-mouse (GAM) antibodies (Ab) to glass microbeads and cuprammonium rayon hollow-fiber dialyzers. An average of 0.79 and 0.83 microgram of GAM Ab/cm2 was immobilized on the hollow-fiber dialyzers and the glass beads, respectively. The antibodies immobilized on glass microbeads or on hollow-fiber dialyzers were then used to selectively deplete CD34+ cells or CD4+ peripheral blood mononuclear cells (PBMC), respectively. Glass microbeads depleted 80% CD34+ cells with good selectivity, and the hollow-fiber dialyzers depleted an average of 81% CD4+ PBMC.

Activating hydroxyl groups of polymeric carriers using 4-fluorobenzenesulfonyl chloride

4-Fluorobenzenesulfonyl chloride (fosyl chloride), due to the strong electron-withdrawing property of its fluoride atom, is found to be an excellent activating agent for the covalent attachment of biologicals to a variety of solid supports (e.g. functionalized polystyrene microspheres, Sepharose beads, or cellulose rods and hollow fibers). This reagent reacts rapidly with primary or secondary hydroxyl groups, at ambient temperature and pressure, to form 4-fluorobenzenesulfonate leaving groups. The activated solid support can be used immediately or preserved for several months without loss of activity by freeze-drying or by storage at 4 degrees C in aqueous solution at pH 5. Enzymes, antibodies, avidin, and other biologicals can be covalently attached to the activated solid phase with excellent retention of biological function. Potential therapeutic applications of the fosyl chloride chemistry for bioselective separation of human lymphocyte subsets from whole blood and tumor cells from bone marrow are presented.

Interaction of permanently uncharged dopamine analogs with the D-2 dopaminergic receptor

The purpose of this study was to determine if structural analogs of dopamine in which the side chain nitrogen has been replaced by a permanently uncharged monomethylsulfide, monomethylselenide or sulfoxide group are capable of binding to the striatal D-2 dopamine receptor and acting as agonists at this receptor. All the permanently uncharged dopamine analogs were found to bind to the D-2 dopamine receptor as evidenced by their abilities to inhibit significantly [3H]spiperone binding to striatal homogenates. However, the inhibition of [3H]spiperone binding by the uncharged dopamine analogs was incomplete and was almost abolished by the addition of NaCl (125 mM) to the incubation medium or by the addition of dopamine or quinpirole at a concentration that that saturates the high-affinity state of the D-2 dopamine receptor. These effects of NaCl, dopamine and quinpirole suggest that the uncharged dopamine analogs bind primarily to the high-affinity state of the D-2 dopamine receptor. Whether the uncharged monomethylsulfide and sulfoxide analogs could function as dopamine agonists at the striatal D-2 dopamine receptor was assessed by determining the abilities of these compounds to inhibit the K+-evoked release of [3H]acetylcholine from striatal slices. Both the monomethylsulfide and sulfoxide analogs inhibited the K+-evoked release of [3H]acetylcholine, but this inhibitory effect does not appear to be due to the activation of the D-2 dopamine receptor since it was not reversed by the selective D-2 dopamine antagonist, sulpiride. Additionally, the uncharged monomethylsulfide and sulfoxide dopamine analogs were found to antagonize the ability of apomorphine to inhibit the K+-evoked release of [3H]acetylcholine, but this antagonistic effect does not appear to be due to the reversible blockade of the D-2 dopamine receptor since it was not reduced by increasing the concentration of apomorphine. Therefore, while the permanently uncharged analogs of dopamine appear to bind to the high-affinity state of the D-2 dopamine receptor, they are not dopamine agonists or antagonists at the striatal D-2 dopamine receptor involved in regulating the release of acetylcholine. These results suggest that a positive charge may be a requirement for the activation of the striatal D-2 dopamine receptor.

Synergistic inhibition of growth of breast and colon human cancer cell lines by site-selective cyclic AMP analogues

Our past studies on the mechanism of cyclic AMP (cAMP)-mediated control of tumor growth, using the experimental rat mammary tumor models as well as human breast cancer cell lines, indicated that the action of cAMP is mediated by the RII cAMP receptor protein, the regulatory subunit of cAMP-dependent protein kinase type II (Y. S. Cho-Chung, J. Cyclic Nucleotide Res., 6: 163, 1980). We now shown that the site-selective cAMP analogues, which are manyfold more active in binding to the cAMP receptor protein than previously studied analogues, demonstrate a potent growth inhibition of seven breast and three colon human cancer cell lines. The cAMP receptor protein has two different cAMP binding sites, and cAMP analogues that selectively bind to either one of the two binding sites are known as either site 1 selective (C-8 analogues) or site 2 selective (C-6 analogues). Nineteen site-selective analogues, C-6 and C-8 monosubstituted and C-6,-8 disubstituted, were tested for their growth regulatory effect. The majority of these analogues demonstrated an appreciable growth inhibition, with no sign of toxicity in all 10 cancer lines at micromolar concentrations. The three most potent inhibitors were 8-Cl-, N6-benzyl-, and N6-phenyl-8-thio-p-chlorophenyl-cAMP, demonstrating 50% growth inhibition at 5-25 microM concentrations (IC50). Furthermore, N6-analogues, in combination with halogen or thio derivatives of C-8 analogues, demonstrated synergistic enhancement of growth inhibition. The growth inhibition paralleled a change in cell morphology, an augmentation of the RII cAMP receptor protein, and a reduction in p21 ras protein. The growth inhibition by 8-Cl-cAMP was not due to its metabolite, 8-Cl-adenosine, since: (a) the growth inhibition by 8-Cl-cAMP was released upon cessation of treatment, whereas that by 8-Cl-adenosine was not released; (b) 8-Cl-cAMP treatment did not affect cell cycle progression, whereas 8-Cl-adenosine brought about G1 synchronization; (c) 8-Cl-cAMP treatment caused reduction of p21 ras protein, whereas 8-Cl-adenosine did not affect p21 levels; and (d) 8-Cl-adenosine was not detected in either cell extracts or medium from the cells treated with 8-Cl-cAMP for 48-72 h. Site-selective cAMP analogues thus provide a new physiological means to control the growth of breast and colon human cancer cells.

Interaction of permanently charged analogs of dopamine with the D-2 dopaminergic receptor

Dopamine can exist in both charged and uncharged forms at physiological pH. At present it is unclear which of these forms is responsible for dopaminergic agonist activity. The purpose of this study was to determine whether permanently charged structural analogs of dopamine containing either a nitrogen, sulfur, or selenium atom in the side chain can bind to and activate the D-2 dopamine receptor. Binding to and activation of the D-2 dopamine receptor were measured by determining the abilities of the permanently charged dopamine analogs to inhibit [3H]spiperone binding to striatal homogenates and to inhibit K+-stimulated [3H]acetylcholine release from striatal slices respectively. The quaternary ammonium, dimethylsulfonium and dimethylselenonium analogs of dopamine were all found to inhibit [3H]spiperone binding to the same extent and in a manner qualitatively similar to the parent amines, dopamine and dimethyldopamine. Thus, [3H]spiperone inhibition curves for dopamine, dimethyldopamine and the permanently charged dopamine analogs were generally shallow and fit best to a two-site binding model as indicated by computer-assisted analyses. The addition of 125 mM NaCl to the incubation medium resulted in a significant decrease in the proportion of high affinity binding sites for both the permanently charged analogs and the parent amines. Similarly, the permanently charged dopamine analogs were found to maximally inhibit the K+-stimulated release of [3H]acetylcholine to the same extent as dopamine and dimethyldopamine. However, the permanently charged analogs were less potent in inhibiting both [3H]spiperone binding and K+-stimulated [3H]acetylcholine release than dopamine and dimethyldopamine. These results show that dopamine analogs possessing a permanent positive charge in the side chain can bind to and activate the D-2 dopamine receptor. The lower potencies of the permanently charged analogs in binding to and activation of the D-2 dopamine receptor suggest that, while the ability of a compound to exist in an uncharged form is not a requirement, both charged and uncharged forms of the agonist molecule appear to play a role in D-2 dopamine agonist activity.

Charged analogues of chlorpromazine as dopamine antagonists

Chlorpromazine (1, CPZ) is a potent dopamine antagonist that has been used widely as an antipsychotic agent. Since dopaminergic antagonists, like dopaminergic agonists, exist in solution as the charged and uncharged molecular species, it is not clear which form of the amine is most important for interaction with the dopamine receptor. Previous work from our laboratory has indicated that a variety of permanently charged species could replace the amine/ammonium moiety of dopamine and retain dopamine agonist activity. This paper describes the synthesis and dopamine antagonist activity of both the trimethylammonium iodide and the dimethylsulfonium iodide analogues of chlorpromazine. The permanently uncharged methyl sulfide analogue was also synthesized; however, due to its lack of aqueous solubility, its pharmacological activity could not be evaluated. Binding of both the dimethylsulfonium iodide and the trimethylammonium iodide analogues to D-2 dopamine receptors of rat striatal tissue was observed. The observed relative order of binding was CPZ greater than CPZ sulfonium analogue greater than CPZ ammonium analogue. These compounds had a similar order of activity in antagonizing the apomorphine-induced inhibition of potassium-induced release of [3H]acetylcholine from mouse striatal slices.

Effect of permanently charged and uncharged dopaminergic agonists on the potassium-induced release of [3H]acetylcholine from striatal slices

The effects of chemical analogs of dopamine, which are permanently charged or which lack a net positive charge, on the potassium-evoked release of [3H]acetylcholine from mouse striatal slices were studied in order to determine whether a positive charge on the dopamine agonist molecule is required to activate dopaminergic receptors. The striatal slices were first preincubated with [3H]choline, transferred to a superfusion chamber, and then superfused in physiological medium. [3H]Acetylcholine release was evoked by exposure of the slices to a high potassium medium and potential dopamine agonist drugs were added to the medium 10 min before superfusing with high potassium. A permanently charged quaternary ammonium analog and dimethylselenonium analog of dopamine inhibited the potassium-evoked release of [3H]acetylcholine, and this inhibition was antagonized by sulpiride, a dopamine receptor antagonist. However, this inhibition was not antagonized by reserpine and alpha-methyl-p-tyrosine, which was shown to completely antagonize the inhibitory effect of amphetamine, an indirectly acting amine. This suggests that the charged dopamine analogs are acting directly on dopaminergic receptors. In contrast to the permanently charged dopamine analogs, analogs of dopamine with no net positive charge produced no inhibition of the potassium-evoked [3H]acetylcholine release. These in vitro observations are in agreement with a behavioral model in which a permanently uncharged monomethylsulfide analog of dopamine was ineffective in eliciting circling behavior after its unilateral injection into the striatum of rats in which dopamine neurons were previously lesioned by the injection of 6-hydroxydopamine into the medial forebrain bundle. In contrast, under these same conditions, the intrastriatal injection of the charged quaternary ammonium or dimethylsulfonium analog of dopamine elicited intense contralateral circling. These results suggest that the charged form of a dopamine agonist molecule is required to bind to and activate the dopamine receptor regulating [3H]acetylcholine release and circling behavior.

Dopamine agonists: effects of charged and uncharged analogues of dopamine

Dopamine, at physiological pH, may exist as either an uncharged amine or a charged ammonium species. In order to gain insight as to which species is better suited for interaction with the dopamine receptor, we have synthesized dopamine analogues in which the nitrogen atom is replaced with a neutral methyl sulfide, a neutral methyl selenide, a charged dimethylsulfonium iodide, and a charged dimethylselenonium iodide. These analogues were tested for their ability to inhibit the K+-stimulated release of [3H]acetylcholine from striatal slices. At 30 microM concentration, the charged sulfonium and selenonium salts possessed significant agonist activity while the corresponding neutral species were inactive, suggesting that a charged species is optimal for dopamine agonist activity. In addition, the methyl sulfide was converted into the corresponding sulfoxide and sulfone; however, neither of these oxidation products possessed significant activity as dopaminergic agonists.

Assessment of a potential dopaminergic prodrug moiety in several ring systems

The ortho hydroxy/methyl, hydroxy/hydroxymethyl, hydroxy/formyl, and hydroxy/carboxy substitution patterns, some of which confer dopaminergic agonist effects upon 2-aminotetralin ring systems, have been incorporated into beta-phenethylamine, 2-aminoindan, and trans-octahydrobenzo[f]quinoline rings. Certain of the 2-aminoindan derivatives displayed pharmacologic properties consistent with their being dopaminergic agonists. The beta-phenethylamine derivative did not show any significant dopamine-like activity. The 7-hydroxy-8-methyloctahydrobenzo[f]quinoline derivative 4a was a moderately potent, short-acting DA2 receptor antagonist. All of the carboxylic acid derivatives were inert. Of the ortho hydroxy/methyl derivatives, only the 5-hydroxy-6-methyl-2-aminotetralin derivative displayed pharmacological properties consistent with its being a dopaminergic prodrug. It is concluded that 5-hydroxy-6-methyl-2-(di-n-propylamino)tetralin (1a) is structurally unique for a dopaminergic drug.

Dopaminergic agonists: comparative actions of amine and sulfonium analogues of dopamine

We have investigated the possibility that structural modifications of the sulfonium analogue of dopamine (4) would produce the same pattern of biological activity as structural modifications of dopamine. A series of methyl- tetralinyl -, and naphthalenylsulfonium analogues 5-7 were prepared and tested for their ability to inhibit the potassium-evoked release of [3H]acetylcholine from striatal slices. All compounds were tested under normal conditions and after depletion of dopamine stores with reserpine and alpha-methyl-p-tyrosine. The amine and sulfonium analogues 2-6 all showed direct agonist activity. The sulfonium analogue 7 produced, predominantly, indirect activity. In contrast to the amine analogues, chemical modifications of the sulfonium compounds produced little change in their dopamine agonist activity.