Antioxidative effect of dietary flavonoid isoquercitrin on human ovarian granulosa cells HGL5 in vitro.

This study aimed to examine the effect of dietary flavonoid isoquercitrin on ovarian granulosa cells using the immortalized human cell line HGL5. Cell viability, survival, apoptosis, release of steroid hormones 17beta-estradiol and progesterone, and human transforming growth factor-beta2 (TGF-beta2) and TGF-beta2 receptor as well as intracellular reactive oxygen species (ROS) generation were investigated after isoquercitrin treatment at the concentration range of 5-100 microg.ml-1. It did not cause any significant change (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. No significant change was observed (p>0.05) in the proportion of live, dead and apoptotic cells as revealed by apoptotic assay using flow cytometry. Similarly, the release of 17beta-estradiol, progesterone, TGF-beta2 and its receptor were not affected significantly (p>0.05) by isoquercitrin as detected by ELISA, in comparison to control. Except for the highest concentration of 100 microg.ml-1, which led to oxidative stress, isoquercitrin exhibited antioxidative activity at lower concentration used in the study (5, 10, 25, and 50 microg.ml-1) by hampering the production of intracellular ROS, in comparison to control, as detected by chemiluminescence assay (p<0.05). Findings of the present study indicate an existence of the antioxidative pathway that involves inhibition of intracellular ROS generation by isoquercitrin in human ovarian granulosa cells.

Biocompatible glyconanomaterials based on HPMA-copolymer for specific targeting of galectin-3.

BACKGROUND: Galectin-3 (Gal-3) is a promising target in cancer therapy with a high therapeutic potential due to its abundant localization within the tumor tissue and its involvement in tumor development and proliferation. Potential clinical application of Gal-3-targeted inhibitors is often complicated by their insufficient selectivity or low biocompatibility. Nanomaterials based on N-(2-hydroxypropyl)methacrylamide (HPMA) nanocarrier are attractive for in vivo application due to their good water solubility and lack of toxicity and immunogenicity. Their conjugation with tailored carbohydrate ligands can yield specific glyconanomaterials applicable for targeting biomedicinally relevant lectins like Gal-3. RESULTS: In the present study we describe the synthesis and the structure-affinity relationship study of novel Gal-3-targeted glyconanomaterials, based on hydrophilic HPMA nanocarriers. HPMA nanocarriers decorated with varying amounts of Gal-3 specific epitope GalNAcß1,4GlcNAc (LacdiNAc) were analyzed in a competitive ELISA-type assay and their binding kinetics was described by surface plasmon resonance. We showed the impact of various linker types and epitope distribution on the binding affinity to Gal-3. The synthesis of specific functionalized LacdiNAc epitopes was accomplished under the catalysis by mutant ß-N-acetylhexosaminidases. The glycans were conjugated to statistic HPMA copolymer precursors through diverse linkers in a defined pattern and density using Cu(I)-catalyzed azide-alkyne cycloaddition. The resulting water-soluble and structurally flexible synthetic glyconanomaterials exhibited affinity to Gal-3 in low µM range. CONCLUSIONS: The results of this study reveal the relation between the linker structure, glycan distribution and the affinity of the glycopolymer nanomaterial to Gal-3. They pave the way to specific biomedicinal glyconanomaterials that target Gal-3 as a therapeutic goal in cancerogenesis and other disorders.

Spontaneously Hypertensive Rat Chromosome 2 with Mutant Connexin 50 Triggers Divergent Effects on Metabolic Syndrome Components.

Metabolic syndrome is a frequent condition with multifactorial aetiology. Previous studies indicated the presence of genetic determinants of metabolic syndrome components on rat chromosome 2 (RNO2) and syntenic regions of the human genome. Our aim was to further explore these findings using novel rat models. We derived the BN-Dca and BN-Lx.Dca congenic strains by introgression of a limited RNO2 region from a spontaneously hypertensive rat strain carrying a mutation in the Gja8 gene (SHR-Dca, dominant cataract) into the genomic background of Brown Norway strain and congenic strain BN-Lx, respectively. We compared morphometric, metabolic and cytokine profiles of adult male BN-Lx, BN-Dca and BN-Lx.Dca rats. We performed in silico comparison of the DNA sequences throughout RNO2 differential segments captured in the new congenic strains. Both BN-Dca and BN-Lx.Dca showed lower total triacylglycerols and cholesterol concentrations compared to BN-Lx. Fasting insulin in BN-Dca was higher than in BN-Lx.Dca and BN-Lx. Concentrations of several proinflammatory cytokines were elevated in the BN-Dca strain, including IL-1α, IL-1ß, IFN-γ and MCP-1. In silico analyses revealed over 740 DNA variants between BN-Lx and SHR genomes within the differential segment of the congenic strains. We derived new congenic models that prove that a limited genomic region of SHR-Dca RNO2 significantly affects lipid levels and insulin sensitivity in a divergent fashion.

Connexin 50 mutation lowers blood pressure in spontaneously hypertensive rat.

We assessed the effect of the previously uncovered gap junction protein alpha 8 (Gja8) mutation present in spontaneously hypertensive rat - dominant cataract (SHR-Dca) strain on blood pressure, metabolic profile, and heart and renal transcriptomes. Adult, standard chow-fed male rats of SHR and SHR-Dca strains were used. We found a significant, consistent 10-15 mmHg decrease in both systolic and diastolic blood pressures in SHR-Dca compared with SHR (P<0.01 and P<0.05, respectively; repeated measures analysis of variance (ANOVA)). With immunohistochemistry, we were able to localize Gja8 in heart, kidney, aorta, liver, and lungs, mostly in endothelium; with no differences in expression between strains. SHR-Dca rats showed decreased body weight, high-density lipoprotein cholesterol concentrations and basal insulin sensitivity in muscle. There were 21 transcripts common to the sets of 303 transcripts in kidney and 487 in heart showing >1.2-fold difference in expression between SHR and SHR-Dca. Tumor necrosis factor was the most significant upstream regulator and glial cell-derived neurotrophic factor family ligand-receptor interactions was the common enriched and downregulated canonical pathway both in heart and kidney of SHR-Dca. The connexin 50 mutation L7Q lowers blood pressure in the SHR-Dca strain, decreases high-density lipoprotein cholesterol, and leads to substantial transcriptome changes in heart and kidney.

Sugared biomaterial binding lectins: achievements and perspectives.

Lectins, a distinct group of glycan-binding proteins, play a prominent role in the immune system ranging from pathogen recognition and tuning of inflammation to cell adhesion or cellular signalling. The possibilities of their detailed study expanded along with the rapid development of biomaterials in the last decade. The immense knowledge of all aspects of glycan-lectin interactions both in vitro and in vivo may be efficiently used in bioimaging, targeted drug delivery, diagnostic and analytic biological methods. Practically applicable examples comprise photoluminescence and optical biosensors, ingenious three-dimensional carbohydrate microarrays for high-throughput screening, matrices for magnetic resonance imaging, targeted hyperthermal treatment of cancer tissues, selective inhibitors of bacterial toxins and pathogen-recognising lectin receptors, and many others. This review aims to present an up-to-date systematic overview of glycan-decorated biomaterials promising for interactions with lectins, especially those applicable in biology, biotechnology or medicine. The lectins of interest include galectin-1, -3 and -7 participating in tumour progression, bacterial lectins from Pseudomonas aeruginosa (PA-IL), E. coli (Fim-H) and Clostridium botulinum (HA33) or DC-SIGN, receptors of macrophages and dendritic cells. The spectrum of lectin-binding biomaterials covered herein ranges from glycosylated organic structures, calixarene and fullerene cores over glycopeptides and glycoproteins, functionalised carbohydrate scaffolds of cyclodextrin or chitin to self-assembling glycopolymer clusters, gels, micelles and liposomes. Glyconanoparticles, glycan arrays, and other biomaterials with a solid core are described in detail, including inorganic matrices like hydroxyapatite or stainless steel for bioimplants.

Silymarin component 2,3-dehydrosilybin attenuates cardiomyocyte damage following hypoxia/reoxygenation by limiting oxidative stress.

Ischemic postconditioning and remote conditioning are potentially useful tools for protecting ischemic myocardium. This study tested the hypothesis that 2,3-dehydrosilybin (DHS), a flavonolignan component of Silybum marianum, could attenuate cardiomyocyte damage following hypoxia/reoxygenation by decreasing the generation of reactive oxygen species (ROS). After 5-6 days of cell culture in normoxic conditions the rat neonatal cardiomyocytes were divided into four groups. Control group (9 h at normoxic conditions), hypoxia/reoxygenation group (3 h at 1 % O2, 94 % N2and 5 % CO2followed by 10 min of 10 micromol·l⁻¹DHS and 6 h of reoxygenation in normoxia) and postconditioning group (3 h of hypoxia, three cycles of 5 min reoxygenation and 5 min hypoxia followed by 6 h of normoxia). Cell viability assessed by propidium iodide staining was decreased after DHS treatment consistent with increased levels of lactatedehydrogenase (LDH) after reoxygenation. LDH leakage was significantly reduced when cardiomyocytes in the H/Re group were exposed to DHS. DHS treatment reduced H2O2production and also decreased the generation of ROS in the H/Re group as evidenced by a fluorescence indicator. DHS treatment reduces reoxygenation-induced injury in cardiomyocytes by attenuation of ROS generation, H2O2and protein carbonyls levels. In addition, we found that both the postconditioning protocol and the DHS treatment are associated with restored ratio of phosphorylated/total protein kinase C epsilon, relative to the H/Re group. In conclusion, our data support the protective role of DHS in hypoxia/reperfusion injury and indicate that DHS may act as a postconditioning mimic.

Chemistry of silybin.

Silybin, a secondary metabolite isolated from the seeds of the blessed milk thistle (Silybum marianum) was discovered as the first member of a new family of natural compounds called flavonolignans in 1959. Over the years it has received the research attention of many organic chemists. This research has resulted in a number of semisynthetic derivatives prepared in an effort to modulate and better target the biological activities of silybin or to improve its physical properties, such as its solubility. A fundamental breakthrough in silybin chemistry was the determination of the absolute configurations of silybin A and silybin B, and the development of methods for their separation. This review covers articles dealing with silybin chemistry and also summarizes all the derivatives prepared.

Recent progress in the genetics of spontaneously hypertensive rats.

The spontaneously hypertensive rat (SHR) is the most widely used animal model of essential hypertension and accompanying metabolic disturbances. Recent advances in sequencing of genomes of BN-Lx and SHR progenitors of the BXH/HXB recombinant inbred (RI) strains as well as accumulation of multiple data sets of intermediary phenotypes in the RI strains, including mRNA and microRNA abundance, quantitative metabolomics, proteomics, methylomics or histone modifications, will make it possible to systematically search for genetic variants involved in regulation of gene expression and in the etiology of complex pathophysiological traits. New advances in manipulation of the rat genome, including efficient transgenesis and gene targeting, will enable in vivo functional analyses of selected candidate genes to identify QTL at the molecular level or to provide insight into mechanisms whereby targeted genes affect pathophysiological traits in the SHR.

CD36-deficient congenic strains show improved glucose tolerance and distinct shifts in metabolic and transcriptomic profiles.

Deficiency of fatty acid translocase Cd36 has been shown to have a major role in the pathogenesis of metabolic syndrome in the spontaneously hypertensive rat (SHR). We have tested the hypothesis that the effects of Cd36 mutation on the features of metabolic syndrome are contextually dependent on genomic background. We have derived two new congenic strains by introgression of limited chromosome 4 regions of SHR origin, both including the defective Cd36 gene, into the genetic background of a highly inbred model of insulin resistance and dyslipidemia, polydactylous (PD) rat strain. We subjected standard diet-fed adult males of PD and the congenic PD.SHR4 strains to metabolic, morphometric and transcriptomic profiling. We observed significantly improved glucose tolerance and lower fasting insulin levels in PD.SHR4 congenics than in PD. One of the PD.SHR4 strains showed lower triglyceride concentrations across major lipoprotein fractions combined with higher levels of low-density lipoprotein cholesterol compared with the PD progenitor. The hepatic transcriptome assessment revealed a network of genes differentially expressed between PD and PD.SHR4 with significant enrichment by members of the circadian rhythmicity pathway (Arntl (Bmal1), Clock, Nfil3, Per2 and Per3). In summary, the introduction of the chromosome 4 region of SHR origin including defective Cd36 into the PD genetic background resulted in disconnected shifts of metabolic profile along with distinct changes in hepatic transcriptome. The synthesis of the current results with those obtained in other Cd36-deficient strains indicates that the eventual metabolic effect of a deleterious mutation such as that of SHR-derived Cd36 is not absolute, but rather a function of complex interactions between environmental and genomic background, upon which it operates.

Genetic regulation of catecholamine synthesis, storage and secretion in the spontaneously hypertensive rat.

Understanding catecholamine metabolism is crucial for elucidating the pathogenesis of hereditary hypertension. Here we integrated transcriptional and biochemical profiling with physiologic quantitative trait locus (eQTL and pQTL) mapping in adrenal glands of the HXB/BXH recombinant inbred (RI) strains, derived from the spontaneously hypertensive rat (SHR) and normotensive Brown Norway (BN.Lx). We found simultaneous down-regulation of five heritable transcripts in the catecholaminergic pathway in young (6 weeks) SHRs. We identified cis-acting eQTLs for Dbh, Pnmt (catecholamine biosynthesis) and Vamp1 (catecholamine secretion); enzymatic activities of Dbh and Pnmt paralleled transcripts, with pQTLs for activities mirroring eQTLs. We also detected trans-regulated expression of Vmat1 and Chga (both involved in catecholamine storage), with co-localization of these trans-eQTLs to the Pnmt locus. Pnmt re-sequencing revealed promoter polymorphisms that result in decreased response of the transfected SHR promoter to glucocorticoid, compared with BN.Lx. Of physiological pertinence, Dbh activity negatively correlated with systolic blood pressure in RI strains, whereas Pnmt activity was negatively correlated with heart rate. The finding of such cis- and trans-QTLs at an age before the onset of frank hypertension suggests that these heritable changes in biosynthetic enzyme expression represent primary genetic mechanisms for regulation of catecholamine action and blood pressure control in this widely studied model of hypertension.

Induction, purification and characterization of alpha-N-acetylgalactosaminidase from Aspergillus Niger.

A set of filamentous fungi (42 strains) was screened for alpha-N-acetylgalactosaminidase activity, and a series of inducers and different cultivation conditions were tested. Enzyme production by the best producer Aspergillus niger CCIM K2 was optimized and scaled up. alpha-N-Acetylgalactosaminidase was purified to apparent homogeneity by cation exchange chromatography, gel filtration, and chromatofocusing, and basic biochemical data of the enzyme were determined: The native molecular weight was estimated by gel filtration to be approximately 440 kDa, the molecular weight of the subunit was determined to be 76 kDa and the pI = 4.8. The K (M) was 0.73 mmol/l for o-nitrophenyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside (o-NP-alpha-GalNAc), and optimum enzyme activity was achieved at pH 1.8 and 55 degrees C. This alpha-N-acetylgalactosaminidase is a retaining-type glycosidase, and it was N-deglycosylated without any loss of activity.

Region of rat chromosome 8 determines complex nutrigenetic interactions under conditions of sucrose and cholesterol diets.

We have previously established a congenic strain SHR-Lx that carries a differential segment of rat chromosome 8 introgressed from a model of metabolic syndrome--the polydactylous rat strain--on the genomic background of spontaneously hypertensive rat (SHR). We compared the glucose tolerance and lipid profile of adult SHR and SHR-Lx males under conditions of standard diet and diets enriched in sucrose and cholesterol, respectively. While there was no evident difference between the SHR and SHR-Lx on standard diet, the one-week sucrose administration revealed the congenic strain sensitivity to carbohydrate-induced dyslipidemia conferred by the differential segment with only mild derangement of glucose tolerance. On the other hand, the high-cholesterol diet administration for three-weeks resulted in a contrasting pattern as the congenic strain displayed significantly lower concentrations of free fatty acids and improved glucose tolerance compared to SHR. After one-month washout period, the SHR-Lx showed higher insulin, triglyceride and cholesterol concentrations together with diminished insulin sensitivity of visceral adipose tissue. In summary, we have identified a genomic region syntenic to human chromosome 11q23, which determines complex nutrigenetic interactions under conditions of sucrose- and cholesterol-enriched diets.

The in vitro biological activity of Lepidium meyenii extracts.

The biological activity of methanolic and aqueous extracts from dehydrated hypocotyls of Lepidium meyenii (Brassicaceae, vernacular name "maca"), was studied on rat hepatocytes and human breast cancer MCF-7 cells. The extracts did not exhibit cytotoxicity in hepatocyte primary cultures up to 10 mg/ml as measured by the MTT viability test, and lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) leakage. Moreover, after 72 h, extracts inhibited LDH and AST leakage from the hepatocytes. When hepatocytes were intoxicated by t-butyl hydroperoxide, neither extract prevented oxidative damage. Both extracts showed weak antioxidant activity in the DPPH radical scavenging test with IC(50) values of 3.46 +/- 0.16 and 0.71 +/- 0.10 mg/ml, for aqueous and methanolic extracts, respectively. Thus, the observed effect on spontaneous enzyme leakage is probably mediated through mechanisms other than antioxidant activity. Both methanolic and aqueous extracts have shown estrogenic activity comparable with that of silymarin in MCF-7 cell line. Maca estrogenicity was exhibited in the range from 100 to 200 mug of extract per ml. The findings in the present study show that maca does not display in vitro hepatotoxicity. In contrast, a slight cytoprotective effect, probably not mediated by antioxidant capacity, was noted. Maca extracts exhibited estrogenic activity comparably to the effect of silymarin in MCF-7 cells.

A 14-gene region of rat chromosome 8 in SHR-derived polydactylous congenic substrain affects muscle-specific insulin resistance, dyslipidaemia and visceral adiposity.

The SHR and the PD/Cub are two established rodent models of human metabolic syndrome. Introgression of a ca 30 cM region of rat chromosome 8 from PD/Cub onto the genetic background of SHR was previously shown to influence several of the metabolic syndrome-related traits along with causing the PLS in the SHR-Lx congenic strain. In the process of identification of the causative alleles, we have produced several congenic sublines. The differential segment of SHR-Lx PD5 congenic substrain [SHR.PD(D8Rat42-D8Arb23)/Cub] spans approximately 1.4 Mb encompassing only 14 genes. When comparing the metabolic, morphometric and gene expression profiles of the SHR-Lx PD5 vs. SHR, the polydactyly and several distinct metabolic features observed in the original SHR-Lx congenic were still manifested, suggesting that the responsible genes were "trapped" within the relatively short differential segment of PD/Cub origin in SHR-Lx PD5. Particularly, the SHR-Lx PD5 displayed substantial reduction of insulin sensitivity confined to skeletal muscle. Among the candidate genes, the promyelocytic leukaemia zinc-finger Plzf (Zbtb16) transcription repressor is most likely responsible for the Lx mutation resulting in PLS and could also be involved in the alteration of metabolic pathways. The sequence analysis of the Plzf gene revealed a SNP leading to a threonine to serine substitution in SHR at aminoacid position 208 (T208S). In summary, we have isolated a 1.4 Mb genomic region syntenic to human chromosome 11q23, which, apart from causing polydactyly-luxate syndrome (PLS), affects total body weight, adiposity, lipid profile, insulin sensitivity of skeletal muscle and related gene expression as shown in the SHR-Lx PD5 congenic substrain.

N-glycosylated catalytic unit meets O-glycosylated propeptide: complex protein architecture in a fungal hexosaminidase.

beta-N-Acetylhexosaminidase from a filamentous fungus Aspergillus oryzae is a secreted enzyme known to be an important component of the binary chitinolytic system. Cloning of the hexA gene and sequencing of the enzyme revealed its unique preproprotein structure. While the enzyme's zincin-like and catalytic domain had significant similarities with members of the glycohydrolase 20 family, the propeptide was unique for the fungal enzyme. Detailed pulse-chase and inhibition studies revealed that propeptide was processed during the biosynthesis of the enzyme. Moreover, the presence of propeptide was necessary for enzyme activation, dimerization and secretion. The catalytic unit was N-glycosylated, and the propeptide was O-glycosylated, both in their C-terminal parts. Deglycosylation experiments revealed that the N-glycosylation increased the stability and solubility of the enzyme. In contrast, O-glycosylated propeptide was necessary to attain the full enzymic activity.

Molecular analysis of the sex hormone-binding globulin gene in the rat hypodactylous mutation (Hd).

Sex hormone-binding globulin or ABP/SHBG is an extracellular androgen and oestrogen carrier. In the rat, ABP/SHBG is secreted by Sertoli cells of the testis and is thought to regulate androgen bioavailability in the male reproductive tract. During ontogenesis, ABP/SHBG is expressed in many mesoderm-derived tissues, including interdigital mesenchyme of the developing autopodium. Shbg is thus a candidate for Hd, comprising autopodium (hand and foot) reduction and male sterility resulting from spermatogenesis impairment. Moreover, linkage mapping of Hd revealed that an intragenic marker for Shbg, D10Wox12, was non-recombinant with Hd. Sequencing of the entire coding sequence of Shbg failed to identify any variation in hypodactylous animals, distinct from two control strains. However, RT-PCR analysis revealed a significantly higher level of the Shbg transcript in hypodactylous rats compared to SHR controls. Whether Shbg expression is upregulated due to a cis-acting mutation in regulatory elements of the Shbg gene or it is a secondary result of spermatogenesis failure remains to be determined.

Genetic analysis of "metabolic syndrome" in the spontaneously hypertensive rat.

In the current review, we summarize results of genetic analyses of "metabolic syndrome" in the spontaneously hypertensive rat (SHR). These results include (1) linkage analyses in the HXB/BXH recombinant inbred (RI) strains derived from SHR and Brown Norway (BN-Lx) strains which revealed quantitative trait loci (QTL) for hemodynamic and metabolic traits on several chromosomes, (2) genetic isolation of these putative QTL within differential chromosome segments of SHR.BN congenic strains, (3) detailed mapping of these QTL within limited chromosome segments of SHR.BN congenic sublines, (4) sequencing of selected positional candidate genes which revealed important mutations in the Cd36 and Srebp1 SHR genes, (5) functional tests of these candidate genes in SHR transgenic lines, and (6) integrated gene expression profiling and linkage mapping in RI strains which will be used to identify co-regulated genes and to determine co-segregation of transcriptional profiles with physiological and pathophysiological phenotypes.

Isotretinoin and fenofibrate induce adiposity with distinct effect on metabolic profile in a rat model of the insulin resistance syndrome.

OBJECTIVE: To investigate the effect of transcription-modulating drugs, fenofibrate and isotretinoin, on metabolic profile, insulin sensitivity of adipose and muscle tissues and gene expression in a genetic model of insulin resistance syndrome, polydactylous rat strain (PD/Cub). DESIGN: Administration of fenofibrate (100 mg/kg/day), isotretinoin (30 mg/kg/day) or vehicle to adult male PD/Cub rats fed standard laboratory chow for 15 days. MEASUREMENTS: Parameters of lipid and carbohydrate metabolism-oral glucose tolerance test, serum concentrations of insulin, triglycerides (TG), free fatty acids (FFA), glycerol, total cholesterol (CH); morphometric variables, in vitro insulin sensitivity of adipose and muscle tissues, catecholamine-stimulated lipolysis and the expression of ApoC-III and Hnf-4 genes in liver. RESULTS: Both experimental groups displayed an increase in adiposity with contrasting effects on TG (lowered by fenofibrate and increased by isotretinoin) and gene expression (no change in fibrate-treated rats and increased expression of ApoC-III and Hnf-4 in isotretinoin-treated group). Fenofibrate-treated rats also showed decreased concentrations of FFA and CH with concomitant decrease of catecholamine-induced lipolysis in adipocytes, but also hyperinsulinemia and the highest insulin/glucose ratio. Isotretinoin increased glycerol concentrations and decreased the insulin sensitivity of peripheral tissues. CONCLUSION: The PD/Cub rat showed a distinct pharmacogenetic reaction to fenofibrate and isotretinoin administration. Several lines of evidence now implicate specific variant(s) of ApoC-III and/or ApoA-V alleles as responsible for the dyslipidemia observed in this genetic model. The PD/Cub strain may also serve as a pharmacogenetic model for dissection of the retinoid-induced hypertriglyceridemia.

Pergolide, terguride and N,N'-spacer-linked oligomers of both interact with 5-HT2A receptors of rat tail artery.

Pergolide, terguride and N,N'-spacer-linked oligomers of both have been tested for their ability to interact with 5 hydroxytryptamine(HT)2A receptors of rat tail artery. Pergolide was a potent partial agonist (pEC50 7.5, Emax 55 %) and antagonized 5-HT-induced contractions (pKp 7.2). Pergolide dimer 3 with a p-xylene spacer between the indole nitrogens (N-1) displayed somewhat lower agonist potency than pergolide (pEC50 7.0, Emax 55 %, pKp 6.6). The contractile responses to pergolide and dimer 3 were antagonized by the 5-HT2A receptor antagonist ketanserin (pA2 9.4, 9.1). In contrast to pergolide dimer 3, pergolide dimers 5 and 9 with an alkyl and an aralkyl spacer between the piperidine nitrogens (N-6) lacked agonism and displayed low affinity at 5-HT2A receptors (pA2 < 5.5). Terguride behaved as an insurmountable antagonist of 5-HT (pA2 8.4). Oligomers of terguride showed 5 to 50-fold lower affinity. It is concluded that pergolide and terguride show a high affinity for 5-HT2A receptors, but dimerization (oligomerization) of both drugs fails to increase affinity.

The CD36 protein functions as an immunogenic domain of the RT8 alloantigen.

Completely concordant distributions of Cd36 and Rt8 deletion/null and wild-type alleles among inbred and congenic strains, together with Western blot analysis of RT8/CD36 proteins, indicated that the CD36 protein functions as an immunogenic domain of the RT8 alloantigen.