Interaction Between Opioidergic and Dopaminergic Systems on Food Intake in Neonatal Layer Type Chicken

Central regulatory mechanisms for food intake regulation vary among animals. Evidence from animal studies suggests central opioids and dopamine have prominent role on appetite regulation but their interaction(s) have not been studied in layer-type chicken. Thus, in this study six experiments designed to investigate intracerebroventricular (ICV) administration of SCH23390 (D₁ like receptors antagonist), Sulpride (D₂ like receptors antagonist), DAMGO (μ-opioid receptors agonist), DPDPE (δ-opioid receptors agonist), U-50488H (κ-opioid receptors agonist) on feeding behavior in 3 h food deprived neonatal layer-type chickens. In experiment 1, chicks ICV injected with control solution, SCH23390 (2.5 nmol), DAMGO (125 pmol) and their combination (SCH23390 + DAMGO). In experiment 2: control solution, SCH23390 (2.5 nmol), DPDPE (δ-opioid receptors agonist, 40 pmol) and SCH23390 + DPDPE were applied to the birds. In experiment 3, injections were control solution, SCH23390 (2.5 nmol), U-50488H (30 nmol) and SCH23390 + U-50488H. In experiments 4–6 were similar to experiments 1–3 except Sulpride (2.5 nmol) applied instead of SCH23390. Then, cumulative food intake was recorded until 120 min after injection. According to the results, ICV injection of DAMGO (125 pmol) significantly decreased food intake but co-injection of DAMGO + SCH23390 diminished DAMGO-induced hypophagia (P < 0.05). Also, SCH23390 was not able to decrease the DPDPE- and U-50488H-induced hyperphagia (P > 0.05). Furthermore, Sulpride had no role on DAMGO, DPDPE and U-50488H-induced food intake (P > 0.05). These results suggest there is an interaction between opioidergic and dopaminergic systems via μ and D₁ receptors in appetite regulation in chicken.     

Comparison of covalent with reversible inhibitor binding sites of the gastric H,K-ATPase by site-directed mutagenesis

The gastric H,K-ATPase is covalently inhibited by substituted pyridyl-methylsulfinyl-benzimidazoles, such as omeprazole, that convert to thiophilic probes of luminally accessible cysteines in the acid space. The K(+) competitive inhibitor, SCH28080, prevented inhibition of acid transport by omeprazole. In stably expressing HEK293 cells, the benzimidazole-reactive cysteines, Cys-321 (transmembrane helix (TM) 3), Cys-813 and Cys-822 (TM5/6), and Cys-892 (TM7/8) were mutated to the amino acids found in the SCH28080-resistant Na,K-ATPase and kinetic parameters of H,K-ATPase activity analyzed. Mutations of Cys-822 and Cys-892 had insignificant effects on the K(i(app)), K(m(app)) or V(max), but mutations of Cys-813 to threonine and Cys-321 to alanine decreased the affinity for SCH28080. Mutation of Cys-321 to alanine produced mixed kinetics of inhibition, still with higher affinity for the cation-free form of phosphoenzyme. Since the phenylmethoxy ring of the imidazo-pyridine inhibitors binds to TM1/2, as shown by earlier photoaffinity studies, and the mutations in TM6 (Cys-813 --> Thr) as well as the end of TM3 (Cys-321 --> Ala) decrease the affinity for SCH28080, the TM1/2, TM3, and TM6 helices lie within approximately 16 A of each other based on the size of the active, extended conformation of SCH28080.     

Effects of Heavy Metal Cations and Other Sulfhydryl Reagents on Brain Dopamine D1 Receptors: Evidence for Involvement of a Thiol Group in the Conformation of the Active Site

To investigate aspects of the biochemical nature of membrane-bound dopamine D1 receptors, rat striatal homogenates were pretreated with heavy metal cations and some other chemical agents, and their effects on D1 receptors were subsequently determined using a standard [3H](R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1-N-3- benzazepine([3H]SCH 23390) binding assay. Incubation of striatal membranes with as little as 1 microM Hg2+, 10 microM Cu2+, and 10 microM Cd2+ completely prevented specific [3H]SCH 23390 binding. The effect of Cu2+, 1.5 microM, was noncompetitive in nature, whereas 3-5 microM Cu2+ afforded mixed-type inhibition. The inhibitory effect of Cu2+ was fully reversed by dithiothreitol (0.1-1 mM). Cu2+ (2 microM) did not affect the affinity of cis-flupenthixol or clozapine for remaining [3H]SCH 23390 sites. A second series of cations, Co2+ (30 microM), Ni2+ (30 microM), Mn2+ (1 mM), Ca2+ (25 mM), and Ba2+ (20 mM), inhibited specific [3H]SCH 23390 binding by 50% at the concentrations indicated. The thiol alkylating reagent N-ethylmaleimide (NEM) (0.2 mM) reduced specific binding by 70%. The effect of NEM was completely prevented by coincubation with a D1 receptor saturating concentration of SCH 23390 (20 nM) or dopamine (10 microM). The results indicated that the dopamine D1 receptor is a thiol protein and that a thiol group is essential for the ligand binding.     

Two antiviral compounds from the plant Stylogne cauliflora as inhibitors of HCV NS3 protease

The 70% aq methanolic extract of the Peruvian plant Stylogne cauliflora was found to contain two novel oligophenolic compounds SCH 644343 (1) and SCH 644342 (2), which were identified as inhibitors of HCV NS3 protease. The structure of 1 and 2 was established based on high-resolution NMR studies. Compound 1 inhibited HCV NS3 protease with an IC(50) of 0.3 microM, while compound 2 showed an IC(50) of 0.8 microM.     

Interaction of the D1 Receptor Antagonist Sch 23390 with the Central 5-HT System: Radioligang Binding Studies,Measurements of Biochemical Parameters and Effects on L-5-HTP Syndrome

Abstract

The interaction of SCH 23390 with dopamine (DA) and serotonin (5-HT) systems has been examined in vivo and in vitro. Like selective 5-HT₂ blockers, SCH 23390 inhibited in vivo [³H]spiperone binding in the rat frontal cortex (ID₅₀: 1.5 mg/kg) without interacting at D₂ sites. SCH 23390 was equipotent to cinanserin and methysergide. In vitro, SCH 23390 inhibited [³H]ketanserin binding to 5-HT₂ sites (IC₅₀ = 30 nM). Biochemical parameters linked to DA and 5-HT were not changed excepted in striatum where SCH 23390 increased HVA and DOPAC. In the L-5-HTP syndrome model, SCH 23390 clearly showed antagonism of 5-HT₂ receptors. SCH 23390 had weak affinity for 5-HT_1B (IC₅₀ = 0.5 μM), 5-HT_1A (IC₅₀ = 2.6 μM) and α;₁-adenergic receptors (IC₅₀ = 4.4 μM).     

Affinity chromatography of the D1 dopamine receptor from rat corpus striatum

The D1 dopamine receptor from rat corpus striatum has been purified 200-250-fold by using a newly developed biospecific affinity chromatography matrix based on a derivative of the D1 selective antagonist SCH 23390. This compound, (RS)-5-(4-aminophenyl)-8-chloro-2,3,4,5-tetrahydro-3-methyl-1H-3-benz azepin-7-o l (SCH 39111), possesses high affinity for the D1 receptor and, when immobilized on Sepharose 6B through an extended spacer arm, was able to adsorb digitonin-solubilized D1 receptors. The interaction between the solubilized receptor and the affinity matrix was biospecific. Adsorption of receptor activity could be blocked in a stereoselective fashion [SCH 23390 greater than SCH 23388; (+)-butaclamol greater than (-)-butaclamol]. The elution of [3H]SCH 23390 activity from the gel demonstrated similar stereoselectivity for antagonist ligands. Agonists eluted receptor activity with a rank order of potency consistent with that of a D1 receptor [apomorphine greater than dopamine greater than (-)-epinephrine much greater than LY 171555 greater than serotonin]. SCH 39111-Sepharose absorbed 75-85% of the soluble receptor activity, and after the gel was washed extensively, 35-55% of the absorbed receptor activity could be eluted with 100 microM (+)-butaclamol with specific activities ranging from 250 to 450 pmol/mg of protein. The affinity-purified receptor retains the ligand binding characteristics of a D1 dopamine receptor. This affinity chromatography procedure should prove valuable in the isolation and molecular characterization of the D1 dopamine receptor.     

The relaxing effect of SCH 23390 in the molluscan smooth muscle

1. SCH 23390 (SCH, R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) produced the relaxation of ACh-induced contraction in the anterior byssus retractor muscle of Mytilus edulis (ABRM) in a dose-dependent manner between 10⁻⁹-10⁻⁶M.2. The dose-response curve of SCH was shifted in parallel to the right by ketanserin (KET) with pA₂ value of 5.14 ± 0.08 and by 1-(1-naphthyl)piperazine (NAP) with that of 5.06 ± 0.01, but not by cyproheptadine (CYP), mianserin (MIA), butaclamol (BUTA), ICS 205–930 (ICS) and MDL 72222 (MDL) at 3 × 10⁻⁵ M.3. α-Methyl-serotonin (α-Me-5-HT), a selective 5-HT₂ receptor agonist dose-dependently relaxed the ACh-induced contraction of ABRM. The dose-response curve of α-Me-5-HT was shifted in parallel to the right by KET with pA₂ value of 5.01 ± 0.02, but not by BUTA, CYP, MIA, ICS and MDL at 3 × 10⁻⁵ M.4. These findings suggest that 5-HT₂-like receptors exist in the ABRM, and that the relaxation induced by SCH is mediated through these receptors.     

Mutational analysis of the K+-competitive inhibitor site of gastric H,K-ATPase.

The gastric H,K-ATPase is inhibited selectively and K(+)-competitively from its luminal surface by protonated imidazo[1,2alpha]pyridines (e.g., SCH28080). Identification of the amino acids in the membrane domain that affect SCH28080 inhibition should provide a template for modeling a luminally directed vestibule in this enzyme, based on the crystal structure of the sr Ca-ATPase. Five conserved carboxylic residues, Glu343, Glu795, Glu820, Asp824, Glu936, and unique Lys791 in the H,K-ATPase were mutated, and the effects of mutations on the K(i) for SCH28080, V(max), and K(m,app)[NH(4)(+)] were measured. A kinetic analysis of the ATP hydrolysis data indicated that all of these residues significantly affect the interaction of NH(4)(+) ions with the protein but only three of them, Glu795, Glu936, and Lys791, greatly affected SCH28080 inhibition. A Glu795Asp mutation increased the K(i) from 64 +/- 11 to 700 +/- 110 nM. Since, however, the mutation Glu795Gln did not change the K(i) (86 +/- 31 nM), this site has a significant spatial effect on inhibitor kinetics. A Glu936Asp mutation resulted in noncompetitive kinetics while Gln substitution had no effect either on inhibitor affinity or on the nature of the kinetics, suggesting that the length of the Glu936 side chain is critical for the exclusive binding of the ion and SCH28080. Mutation of Lys791 to Ser, the residue present in the SCH28080-insensitive Na,K-ATPase, resulted in a 20-fold decrease in SCH28080 affinity, suggesting an important role of this residue in SCH28080 selectivity of the H,K-ATPase versus Na,K-ATPase. Mutations of Asp824, Glu343, and Glu820 increased the K(i) 2-3-fold, implying a relatively minor role for these residues in SCH28080 inhibition. It appears that the imidazopyridine moiety of SCH28080 in the protonated state interacts with residues near the negatively charged residues of the empty ion site from the luminal side (TM4, -5, -6, and -8) while the hydrophobic phenyl ring interacts with TM1 or TM2 (the latter conclusion based on previous data from photoaffinity labeling). The integrity of the SCH28080 binding site depends on the presence of Lys791, Glu936, and Glu795 in H,K-ATPase. A computer-generated model of this region illustrates the possible involvement of the residues previously shown to affect SCH28080 inhibition (Cys813, Ile816, Thr823, Met334, Val337) and may predict other residues that line the SCH28080 binding vestibule in the E(2) conformation of the pump.     

Thiol-based inhibitors of mammalian collagenase. Substituted amide and peptide derivatives of the leucine analogue, 2-[(R,S)-mercaptomethyl]-4-methylpentanoic acid

To define the inhibitory requirements of mammalian collagenase, several N-substituted amide and peptide derivatives of the mercaptomethyl analogue of leucine, 2-[(R,S)mercaptomethyl]-4-methylpentanoic acid (H psi[SCH2]-DL-leucine), were synthesized and tested as inhibitors of pig synovial collagenase with soluble type I collagen as substrate. H psi[SCH2]-DL-leucine (IC50 = 320 microM) was about 10 times more potent than the beta-mercaptomethyl compound, N-acetylcysteine. The amide of H psi[SCH2]-DL-leucine was six times more potent than the parent thiol acid. Aliphatic N-substituted amides were less potent than the unsubstituted amide, whereas the N-benzyl amide was slightly more potent. Dipeptides, particularly those with an aromatic group at P2', were up to 20-fold more potent, while tripeptides with an aromatic L-amino acid at P2' and Ala-NH2 at P3' were up to 2200 times more potent than H psi[SCH2]-DL-leucine. The resolved diastereomers of H psi[SCH2]-DL-Leu-Phe-Ala-NH2 inhibited by 50% at 0.3 and 0.04 microM, respectively. The most potent inhibitor synthesized, an isomer of H psi[SCH2]-DL-Leu-L-3-(2'-naphthyl)alanyl-Ala-NH2, exhibited an IC50 of 0.014 microM, a value about 300 times less than similar thiol-based analogues of the P'-cleavage sequence of type I collagen, H psi[SCH2]-DL-Leu-Ala-Gly-Gln-. These structure-function studies establish within the present series of compounds that the most effective inhibitors of mammalian collagenase are not closely related to the P2'-P3' elements of the cleavage site of the natural substrate but rather have an aromatic group at the P2' position and Ala-NH2 at the P3' position.     

Enhancement of γ-Aminobutyric Acid Binding by Quazepam, a Benzodiazepine Derivative with Preferential Affinity for Type I Benzodiazepine Receptors

We evaluated the effect of the two N-trifluoroethyl benzodiazepines, quazepam and its 2-oxo metabolite SCH 15725, which possess preferential affinity for type I benzodiazepine recognition sites, on the binding of [3H] gamma-aminobutyric acid ([3H]GABA) to rat brain membrane preparations. The study also included compounds such as diazepam and N-desalkyl-2-oxoquazepam (SCH 17514), which have equal affinity for the type I and type II receptor subtypes. Binding of [3H]GABA was studied in frozen-thawed and repeatedly washed cortical membranes incubated in 20 mM KH2PO4 plus 50 mM KCl, pH 7.4, at 4 degrees C in the absence and presence of quazepam or its metabolites. Addition of 10(-6) M quazepam increased by 30% specific [3H]GABA binding; as revealed by Scatchard plot analysis, the effect was due to an increase in the total number of GABA receptors. The effect of quazepam was concentration dependent, and it was shared by its active metabolite SCH 15725. The potency of quazepam and SCH 15725 in enhancing [3H]GABA binding was similar to that of diazepam, whereas CL 218872 and SCH 17514 were less active. Moreover, the [3H]GABA binding-enhancing effect of quazepam was mediated by an occupancy of benzodiazepine receptors, because it was specifically antagonized by 5 X 10(-6) M Ro15-1788.     

Functional antagonism of D-1 and D-2 dopaminergic mechanisms affecting striatal acetylcholine release

Rat striatal slices prelabelled with [3H]choline were superfused with dopamine D-1 and D-2 agonists and antagonists, separately and in combination, during measurement of [3H]acetylcholine (ACh) release. SKF38393 (D-1 agonist), 10(-7)-10(-4) M, and SCH23390 (D-1 antagonist), 10(-7)-10(-5) M, produced a dose-dependent increase in [3H]ACh release when given separately. The increased [3H]ACh release induced by either drug could not be attenuated by sufficient L-sulpiride to block D-2 receptors. Yet both SKF38393, 10(-6)-10(-5) M, and SCH23390, 10(-6)-10(-5) M, were able to partially or fully overcome the [3H]ACh release-depressant effect of cosuperfused LY171555 (D-2 agonist), 10(-6) M. This suggests that a functional antagonism regarding striatal ACh release exists between D-1 and D-2 dopaminergic receptor-mediated mechanisms, but that D-1 modulation of local ACh release does not occur at the level of the recognition site of the striatal D-2 receptor. Finally, although attenuation of the increased release of striatal [3H]ACh induced by 10(-5) M SCH23390 by SKF38393 was seen, it is possible that such functional antagonism is not mediated by exclusively D-1 dopaminergic means.     

Requirements for membrane attack complex formation and anaphylatoxins binding to collagen-activated platelets

Background

The activation of complement during platelet activation is incompletely understood. Objectives: We sought to explore the formation of C5b-9 and anaphylatoxins binding to collagen-activated platelets.

Methods

C5b-9, anaphylatoxins C3a, C4a and C5a, and anaphylatoxin receptors C3aR1 and C5aR were measured by flow cytometry and/or confocal microscopy. Platelet microparticles were quantified by flow cytometry, and their C5b-9 content was determined by western blot analyses. In all experiments, sodium citrate was used for blood anticoagulation.

Results

C5b-9 rapidly formed on the platelet surface following activation with collagen, TRAP, ADP or A23187, but was surprisingly restricted to a subset of platelets (1 to 15%) independently of P-selectin or phosphatidylserine exposure. Following collagen activation, C5b-9-positive platelets in thrombi were found associated with collagen fibres. C5b-9 formation was obliterated by Mg²⁺-EGTA and significantly reduced by the thrombin inhibitor hirudin (−37%, p<0.05), but was unaffected by chondroitinase, compstatin, {"type":"entrez-protein","attrs":{"text":"SCH79797","term_id":"1052762130","term_text":"SCH79797"}}SCH79797 (PAR-1 inhibitor), or in the PRP of a MBL-deficient donor. Compstatin and Mg²⁺-EGTA, but not hirudin, {"type":"entrez-protein","attrs":{"text":"SCH79797","term_id":"1052762130","term_text":"SCH79797"}}SCH79797 or chondroitinase, inhibited the formation of collagen-induced microparticles (−71% and −44%, respectively, p<0.04). These microparticles contained greater amounts of C5b-9 compared with the other agonists. Platelet activation by collagen or convulxin resulted in the strong binding of anaphylatoxins and the exposure of receptors C3aR1 and C5aR (CD88) on their surface.

Conclusions

C5b-9 formation on collagen-activated platelets is i) partially controlled by thrombin, ii) restricted to a subset of platelets, and iii) can occur without P-selectin expression or phosphatidylserine exposure. Activated platelets bind anaphylatoxins on their surface and express C3a and C5a receptors, which may contribute to the localization of inflammatory processes during thrombosis.     

In Vivo Partial Inactivation of Dopamine D1 Receptors Induces Hypersensitivity of Cortical Dopamine-Sensitive Adenylate Cyclase: Permissive Role of α1-Adrenergic Receptors

As shown by autoradiography, peripheral injections of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) induced a dose-dependent decrease of [3H]SCH 23390 and [3H]prazosin high-affinity binding sites in the rat prefrontal cortex. EEDQ showed similar efficacy in inactivating cortical and striatal dopamine (DA) D1 receptors, whereas prazosin-sensitive alpha 1-adrenergic receptors were more sensitive to the action of the alkylating agent, as for all doses of EEDQ tested (from 0.8 to 3 mg/kg, i.p.), the decrease in cortical [3H]SCH 23390 binding was less pronounced than that of [3H]prazosin. The effects of EEDQ on [3H]SCH 23390 binding and DA-sensitive adenylate cyclase activity were then simultaneously compared in individual rats. In the striatum, whatever the dose of EEDQ used, the decrease of DA-sensitive adenylate cyclase activity was always lower than that of D1 binding sites, suggesting the occurrence of a large proportion of spare D1 receptors. In the prefrontal cortex, a significant increase in DA-sensitive adenylate cyclase activity was observed in rats treated with a low dose of EEDQ (0.8 mg/kg), this effect being associated with a slight reduction in [3H]SCH 23390 binding sites (-20%). Parallel decreases in the enzyme activity and D1 binding sites were observed with higher doses. The EEDQ-induced supersensitivity of DA-sensitive adenylate cyclase did not occur in rats in which the decrease in [3H]prazosin binding sites was higher than 35%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of chronic antidepressant treatment on dopamine-related [3H]SCH 23390 and [3H]Spiperone binding in the rat striatum

1. The effects of chronic administration of antidepressants on dopamine-related [3H]SCH 23390 and [3H]spiperone binding to rat striatal membranes were assessed. 2. The monoamine oxidase inhibitors phenelzine (5 or 10 mg kg-1/day) and tranylcypromine (1 mg kg-1/day) and the tricyclic desipramine (10 mg kg-1/day) were administered for 28 days by constant subcutaneous infusion using Alzet (2ML4) osmotic minipumps. 3. These treatments did not alter Kd estimates for either [3H]SCH 23390 or [3H]spiperone binding sites. The monoamine oxidase inhibitors induced a decrease in the Bmax values for both [3H]SCH 23990 and [3H]spiperone binding sites. Desipramine induced a decrease in the Bmax value for [3H]SCH 23390 binding but had no effect on the Bmax value for [3H]spiperone binding.     

Application of LCSA to used cooking oil waste management

Purpose

Used cooking oil (UCO) is a domestic waste generated as the result of cooking and frying food with vegetable oil. The purpose of this study is to compare the sustainability of three domestic UCO collection systems: through schools (SCH), door-to-door (DTD), and through urban collection centres (UCC), to determine which systems should be promoted for the collection of UCO in cities in Mediterranean countries.

Methods

The present paper uses the recent life cycle sustainability assessment (LCSA) methodology. LCSA is the combination of life cycle assessment (LCA), life cycle costing, and social life cycle assessment (S-LCA).

Results and discussion

Of the three UCO collection systems compared, the results show that UCC presents the best values for sustainability assessment, followed by DTD and finally SCH system, although there are no substantial differences between DTD and SCH. UCC has the best environmental and economic performance but not for social component. DTD and SCH present suitable values for social performance but not for the environmental and economic components.

Conclusions

The environmental component improves when the collection points are near to citizens’ homes. Depending on the vehicle used in the collection process, the management costs and efficiency can improve. UCO collection systems that carry out different kind of waste (such as UCC) are more sustainable than those that collect only one type of waste. Regarding the methodology used in this paper, the sustainability assessment proposed is suitable for use in decision making to analyse processes, products or services, even so in social assessment an approach is needed to quantify the indicators. Defining units for sustainability quantification is a difficult task because not all social indicators are quantifiable and comparable; some need to be adapted, raising the subjectivity of the analysis. Research into S-LCA and LCSA is recent; more research is needed in order to improve the methodology.     

Involvement of D1 dopamine receptors in the cognitive effects of angiotensin IV and des-Phe6 angiotensin IV

An important role for angiotensin IV (Ang IV) in the processes of learning and memory has now been well established. We have previously found that intracerebroventricular (ICV) administration of Ang IV as well as des-Phe6-Ang IV enhances learning of conditioned avoidance responses (CARs), facilitates recall of a passive avoidance (PA) task, and improves object recognition (OR) in rats. Since the dopaminergic system is crucial for the cognitive processes, in this study our aim was to determine the dopaminergic D1 mediation of these effects using SCH 23390 as a selective D1 receptor antagonist. Male Wistar rats (180-200 g), pretreated with SCH 23390 (R-[+]-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) 0.05 mg/kg intraperitoneally (IP), were given Ang IV or des-Phe6-Ang IV (1 nmol ICV) 1 h later and then tested in the above cognitive paradigms, as well as in the open field and an elevated 'plus' maze to control for the unspecific, respectively, motor and emotional, effects of our treatments. Both, Ang IV and des-Phe6-Ang IV effectively enhanced learning of CARs (P < 0.05), recall of PA (P < 0.001), and improved OR (P < 0.001). Pretreatment with SCH 23390 abolished the cognitive effects of both peptides. SCH 23390, Ang IV, and des-Phe6-Ang IV, given at the same doses and routes as in the cognitive tests, did not significantly influence crossings, rearings and bar approaches in the open field, nor the parameters measured in the elevated 'plus' maze, thus making a major contribution of the unspecific effects of our treatments to the results of the memory tests improbable. In conclusion, these results indicate that the functional dopaminergic D1 receptors are necessary for the Ang IV and des-Phe6-Ang IV cognitive effects to occur.     

Evidence for a dopamine receptor subtype sensitive to combination of D1 with D2 antagonist in measurement of G-protein activity using rat striatal membranes

In rat striatal membranes, various kinds of dopamine receptor agonists stimulated low-Km GTPase activity in a concentration-dependent manner. This stimulation by bromocriptine, pergolide and apomorphine was partially inhibited by sulpiride (SUL), a D2-selective antagonist, markedly inhibited by combination of SUL with SCH 23390 (SCH), a D1-selective antagonist, and not modified by SCH alone. The stimulation by BAM-1110 was resistant to SUL or SCH alone but abolished by combination of SUL with SCH. These findings suggest the presence of another subtype of a dopamine receptor in a functional in vitro bioassay system in rat striata.     

Effects of Subclinical Hypothyroidism on Maternal and Perinatal Outcomes during Pregnancy: A Single-Center Cohort Study of a Chinese Population

Objective

Adverse maternal outcomes and perinatal complications are closely associated with overt maternal hypothyroidism, but whether these complications occur in women with subclinical hypothyroidism (SCH) during pregnancy remains controversial. The aim of this study was to evaluate the effects of SCH on maternal and perinatal outcomes during pregnancy.

Methods

A prospective study of data from 8012 pregnant women (371 women with SCH, 7641 euthyroid women) was performed. Maternal serum samples were collected in different trimesters to examine thyroid hormone concentrations. SCH was defined as a thyroid stimulating hormone concentration exceeding the trimester-specific reference value with a normal free thyroxine concentration. The occurrence of maternal outcomes, including gestational hypertension (GH), gestational diabetes mellitus, placenta previa, placental abruption, prelabor rupture of membranes (PROM), and premature delivery; and perinatal outcomes, including intrauterine growth restriction (IUGR), fetal distress, low birth weight (LBW; live birth weight ≤2500 g), stillbirth, and malformation, was recorded. Logistic regression with adjustment for confounding demographic and medical factors was used to determine the risks of adverse outcomes in patients with SCH.

Results

Compared with euthyroid status, SCH was associated with higher rates of GH (1.819% vs. 3.504%, P = 0.020; χ ² = 7.345; odds ratio (OR), 2.243; 95% confidence interval (CI), 1.251–4.024), PROM (4.973% vs. 8.625%, P = 0.002; χ ² = 72.102; adjusted OR, 6.014; 95% CI, 3.975–9.099), IUGR (1.008% vs. 2.965%, <0.001; χ ² = 13.272; adjusted OR, 3.336; 95% CI, 1.745–6.377), and LBW (1.885% vs. 4.582%, P<0.001; χ ² = 13.558; adjusted OR, 2.919; 95% CI, 1.650–5.163).

Conclusions

The results of this study indicate that pregnant women with SCH had increased risks of GH and PROM, and their fetuses and infants had increased risks of IUGR and LBW. Thus, routine maternal thyroid function testing is necessary to improve maternal and perinatal outcomes.     

Subclinical Hypothyroidism Is Associated with Increased Risk for Cancer Mortality in Adult Taiwanese—A 10 Years Population-Based Cohort

Background

The association between subclinical hypothyroidism (SCH) and cancer mortality is seldom discussed.

Methods

A total of 115,746 participants without thyroid disease history, aged 20 and above, were recruited from four nationwide health screening centers in Taiwan from 1998 to 1999. SCH was defined as a serum thyroid-stimulating hormone (TSH) level of 5.0–19.96 mIU/L with normal total thyroxine concentrations. Euthyroidism was defined as a serum TSH level of 0.47–4.9 mIU/L. Cox proportional hazards regression analyses were used to estimate the relative risks (RRs) of death from cancer for adults with SCH during a 10-year follow-up period.

Results

Among 115,746 adults, 1,841 had SCH (1.6%) and 113,905 (98.4%) had euthyroidism. There were 1,532 cancer deaths during the 1,034,082 person-years follow-up period. Adjusted for age, gender, body mass index, diabetes, hypertension, dyslipidemia, smoking, alcohol drinking, betel nut chewing, physical activity, income, and education level, the RRs (95% confidence interval) of cancer deaths among subjects with SCH versus euthyroid subjects were 1.51 (1.06 to 2.15). Cancer site analysis revealed a significant increased risk of bone, skin and breast cancer among SCH subjects (RR 2.79, (1.01, 7.70)). The risks of total cancer deaths were more prominent in the aged (RR 1.71, (1.02 to 2.87)), in females (RR 1.69 (1.08 to 2.65)), and in heavy smokers (RR 2.24, (1.19 to 4.21)).

Conclusions

Subjects with SCH had a significantly increased risk for cancer mortality among adult Taiwanese. This is the first report to demonstrate the association between SCH and cancer mortality.     

A hybrid between Na+,K+-ATPase and H+,K+-ATPase is sensitive to palytoxin, ouabain, and SCH 28080

Na(+),K(+)-ATPase is inhibited by cardiac glycosides such as ouabain, and palytoxin, which do not inhibit gastric H(+),K(+)-ATPase. Gastric H(+),K(+)-ATPase is inhibited by SCH28080, which has no effect on Na(+),K(+)-ATPase. The goal of the current study was to identify amino acid sequences of the gastric proton-potassium pump that are involved in recognition of the pump-specific inhibitor SCH 28080. A chimeric polypeptide consisting of the rat sodium pump alpha3 subunit with the peptide Gln(905)-Val(930) of the gastric proton pump alpha subunit substituted in place of the original Asn(886)-Ala(911) sequence was expressed together with the gastric beta subunit in the yeast Saccharomyces cerevisiae. Yeast cells that express this subunit combination are sensitive to palytoxin, which interacts specifically with the sodium pump, and lose intracellular K(+) ions. The palytoxin-induced K(+) efflux is inhibited by the sodium pump-specific inhibitor ouabain and also by the gastric proton pump-specific inhibitor SCH 28080. The IC(50) for SCH 28080 inhibition of palytoxin-induced K(+) efflux is 14.3 +/- 2.4 microm, which is similar to the K(i) for SCH 28080 inhibition of ATP hydrolysis by the gastric H(+),K(+)-ATPase. In contrast, palytoxin-induced K(+) efflux from cells expressing either the native alpha3 and beta1 subunits of the sodium pump or the alpha3 subunit of the sodium pump together with the beta subunit of the gastric proton pump is inhibited by ouabain but not by SCH 28080. The acquisition of SCH 28080 sensitivity by the chimera indicates that the Gln(905)-Val(930) peptide of the gastric proton pump is likely to be involved in the interactions of the gastric proton-potassium pump with SCH 28080.