Association of non-HDL-C/apoB ratio with long-term mortality in the general population: A cohort study.

Background: In general, the identification of cholesterol-depleted lipid particles can be inferred from non-high-density lipoprotein cholesterol (non-HDL-C) concentration to apolipoprotein B (apoB) concentration ratio, which serves as a reliable indicator for assessing the risk of cardiovascular disease. However, the ability of non-HDL-C/apoB ratio to predict the risk of long-term mortality among the general population remains uncertain. The aim of this study is to explore the association of non-HDL-C/apoB ratio with long-term all-cause and cardiovascular mortality in adults of the United States. Methods: This retrospective cohort study was a further analysis of existing information from the National Health and Nutrition Examination Survey (NHANES). In the ultimate analysis, 12,697 participants from 2005 to 2014 were included. Kaplan-Meier (K-M) curves and the log-rank test were applied to visualize survival differences between groups. Multivariate Cox regression and restricted cubic spline (RCS) models were applied to evaluate the association of non-HDL-C/apoB ratio with all-cause and cardiovascular mortality. Subgroup analysis was conducted for the variables of age, sex, presence of coronary artery disease, diabetes and hypertriglyceridemia and usage of lipid-lowering drugs. Results: The average age of the cohort was 46.8 ± 18.6 years, with 6215 (48.9%) participants being male. During a median follow-up lasting 68.0 months, 891 (7.0%) deaths were documented and 156 (1.2%) patients died of cardiovascular disease. Individuals who experienced all-cause and cardiovascular deaths had a lower non-HDL-C/apoB ratio compared with those without events (1.45 ± 0.16 vs. 1.50 ± 0.17 and 1.43 ± 0.17 vs. 1.50 ± 0.17, both P values < 0.001). The results of adjusted Cox regression models revealed that non-HDL-C/apoB ratio exhibited independent significance as a risk factor for both long-term all-cause mortality [hazard ratio (HR) = 0.51, 95% confidence interval (CI): 0.33-0.80] and cardiovascular mortality (HR = 0.33, 95% CI: 0.12-0.90). Additionally, a significant sex interaction was discovered (P for interaction <0.05), indicating a robust association between non-HDL-C/apoB ratio and long-term mortality among females. The RCS curve showed that non-HDL-C/apoB ratio had a negative linear association with long-term all-cause and cardiovascular mortality (P for non-linearity was 0.098 and 0.314). Conclusions: The non-HDL-C/apoB ratio may serve as a potential biomarker for predicting long-term mortality among the general population, independent of traditional risk factors.

Elevated MIR100HG promotes colorectal cancer metastasis and is associated with poor prognosis.

mir-100-let-7a-2-mir-125b-1 cluster host gene (MIR100HG), which is located on chromosome 11q24.1, is a polycistronic microRNA host gene. MIR100HG overexpression in colorectal cancer (CRC) has been demonstrated to be associated with cetuximab resistance; however, the role of MIR100HG in CRC metastasis remains unclear. The present study aimed to investigate the impact of aberrant MIR100HG expression on metastasis and prognosis in patients with CRC. The results from reverse transcription-quantitative PCR demonstrated that MIR100HG expression was higher in CRC tissues compared with in corresponding normal mucosa tissues. In particular, MIR100HG expression was higher in advanced CRC compared with in early stage CRC. Furthermore, the results from Kaplan-Meier analysis followed by a log-rank test revealed that patients with CRC and high MIR100HG expression exhibited poorer disease-free survival and overall survival compared with patients with CRC and lower MIR100HG expression. Furthermore, results from in vitro Transwell assays and in vivo animal assays demonstrated that upregulated MIR100HG expression promoted CRC cell migration and invasion and the formation of liver metastatic colonies in mice. In conclusion, the present study demonstrated that MIR100HG overexpression may contribute to the progression of CRC and may predict a poorer prognosis in patients with CRC. MIR100HG may therefore be considered as a novel therapeutic target and a prognostic biomarker in patients with CRC.

Facile synthesis of Pt-decorated Ir black as a bifunctional oxygen catalyst for oxygen reduction and evolution reactions.

Pt-Decorated Ir black (Pt@Ir) nanoparticles with two varying Pt mass fractions (Pt4@Ir96 and Pt16@Ir84) were generated by a facile method in water with the aid of Ir black. The Pt@Ir nanoparticles were investigated as a bifunctional oxygen catalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in acidic medium. Benefiting from the good dispersion of ultrafine Pt nanodots on the Ir black surface and the synergistic effect between the Pt and underlying Ir atoms, Pt@Ir nanoparticles have exhibited outstanding ORR activity and comparable OER performance in comparison with commercial Ir black. In particular, Pt16@Ir84 shows an ORR mass activity of 2.6 times that of commercial Pt black and exhibits much better bifunctional performances than a mixture of Pt black and Ir black with a Ir/Pt mass ratio of 50/50 (Pt50Ir50). Our work highlights the effectiveness of decorating Ir black with Pt nanodots to fabricate bifunctional oxygen catalysts.

Suppression of miR-21-3p enhances TRAIL-mediated apoptosis in liver cancer stem cells by suppressing the PI3K/Akt/Bad cascade via regulating PTEN.

BACKGROUND: TNF-related apoptosis-inducing ligand (TRAIL) functions as a selective apoptosis-inducing ligand in cancer cells with normal cells remaining unaffected; however, resistance limits its anticancer properties. Cancer stem cells (CSCs) are involved in the treatment of resistant cancer cases including liver cancer (LC). The aim of this study was to look into the approaches for increasing the sensitivity of liver cancer stem cells (LCSCs) toward TRAIL. METHODOLOGY: PLC, HepG2 and Huh7 LC cell lines were used in this study. Quantitative reverse transcription PCR (qRT-PCR) analysis was done for evaluating the expression of miR-21-3b. Fluorescent-activated cell-sorting equipment was used for separation and identification of LCSCs and non-LCSCs. The cells were transfected with RNA along with miR-21-3p mimics, anti- miR-21-3p, miR-NC and the phosphatase and tensin homologue (PTEN) siRNA. MTT assay for cell viability, Luciferase assay for luciferase activity, Western blots for the expression of proteins and flow cytometry for the measurement of ROS and apoptosis, respectively, were carried out. Tumor xenografts nude mice were used for tumor growth in vivo. RESULTS: We found that miR-21-3p was overexpressed in LCSCs compared to non-LCSCs and that the suppression of miR-21-3p along with anti-miR-21-3p enhanced the sensitivity of LCSCs to TRAIL-mediated apoptosis. We further found that miR-21-3p regulated the expression of PTEN in Huh7-LCSCs directly and that the suppression of miR-21-3p enhanced the levels of PTEN. The study confirmed that inhibition of the PI3K/Akt/Bad signaling pathway was involved in enhancing TRAIL-mediated apoptosis of LC cells. CONCLUSION: The study suggested that overexpression of miR-21-3p suppresses the sensitivity to TRAIL in LCSCs. This study concludes that the suppression of miR-21-3p is a potential approach for enhancing the sensitivity of LC cells toward TRAIL by PI3K/Akt/Bad cascade via the miR-21-3p/PTEN axis.

[Risk analysis of the canceration of colorectal large polyps].

OBJECTIVE: To analyze the risk factors of carcinogenesis of large colorectal polyps (diameter ≥ 10 mm) found by colonoscopy. METHODS: Clinicopathological and follow-up data of 418 consecutive patients who were diagnosed as colorectal polyps with diameter≥10 mm by colonoscopy at two endoscopy centers of the Affiliated Wuxi Second People's Hospital, Nanjing Medical University (n=207) and Zhongshan Hospital, Fudan University (n=211) from January 2015 to December 2016 were retrospectively collected. High-grade intraepithelial neoplasia and cancer were defined as malignancy in this study. Chi square test was used for univariate analysis, and logistic regression was used for multivariate analysis (in patients with multiple polyps, if the pathological findings were all low grade intraepithelial neoplasia, one polyp with the largest diameter was selected to enter the model; in patients with high grade intraepithelial neoplasia, one polyp of high grade intraepithelial neoplasia with the largest diameter was selected to enter the model). Associated risk factors of malignancy were analyzed. RESULTS: Among the 418 patients, 278(66.5%) were male and 140(33.5%) were female, with mean age of (58.7±10.2) (range 15-87) years old. Of 398 patients undergoing endoscopic treatment with resected 456 polyps, 142 cases with 150 polyps were malignant, including 134 polyps of high-grade intraepithelial neoplasia and 16 polyps of intra-mucosal cancer. The other 20 patients showed negative elevation signs after endoscopic submucosal injection and were transferred to surgery, of whom 20 polyps were resected. Histological examination of these 20 polyps indicated invasive cancer. Univariate analysis showed that age ≥ 50 years [40.5% (150/370) vs. 25.0% (12/48), χ² =4.323, P=0.041], multiple polyps [77.5%(31/40) vs. 34.7%(131/378), χ² =12.900, P=0.001], polyp locating at rectum [59.0%(36/61) vs. 32.3%(134/415), χ² =22.736, P=0.000], polyp diameter ≥31 mm [74.1%(20/27) vs. 33.4%(150/449), χ² =36.493, P=0.000] and tubular villous adenoma [67.4%(120/178) vs. 16.8%(50/298), χ² =71.810, P=0.000] were associated with malignancy. Multivariate analysis showed that age ≥ 50 years(OR=2.473, 95%CI:1.209-5.058, P=0.013), multiple polyps (OR=2.472, 95%CI: 1.300-4.702, P=0.006), polyp locating at rectum (OR=1.253, 95%CI: 1.091-1.439, P=0.001) and the polyp diameter ≥31 mm (OR=1.500, 95%CI:1.196-1.881, P=0.000) were independent risk factors for malignancy of large colorectal polyps. The mean follow-up time was (9.6±4.2) months. During the follow-up period, 86 patients (20.5%) who received endoscopic resection developed recurrent adenoma which all were successfully removed by colonoscopic polypectomy. Two patients(0.5%) developed colon cancer 6 months after endoscopic resection and both underwent radical surgery and chemotherapy. Their previous pathology from endoscopic resection was tubular villous adenoma and high grade intraepithelial neoplasia. All the patients were alive during the follow-up period. CONCLUSIONS: Age ≥50 years old, multiple polyps, polyps locating at rectum and polyps with diameter ≥ 31 mm are the risk factors of malignancy. Emphasized examination should be recommended for those with the above mentioned risk factors to avoid missed diagnosis and misdiagnosis. The choice of endoscopic treatment must be reasonable for curative resection.

The role of regulatory B cells in digestive system diseases.

INTRODUCTION: The past decade has provided striking insights into a newly identified subset of B cells known as regulatory B cells (Bregs). In addition to producing antibody, Bregs also regulate diseases via cytokine production and antigen presentation. This subset of B cells has protective and potentially therapeutic effects. However, the particularity of Bregs has caused some difficulties in conducting research on their roles. Notably, human B10 cells, which are Bregs that produce interleukin 10, share phenotypic characteristics with other previously defined B cell subsets, and currently, there is no known surface phenotype that is unique to B10 cells. METHODS: An online search was performed in the PubMed and Web of Science databases for articles published providing evidences on the role of regulatory B cells in digestive system diseases. RESULTS AND CONCLUSIONS: Abundant evidence has demonstrated that Bregs play a regulatory role in inflammatory, autoimmune, and tumor diseases, and regulatory B cells play different roles in different diseases, but future work needs to determine the mechanisms by which Bregs are activated and how these cells affect their target cells.

A promoter polymorphism in the hMLH1 gene (-93G/A) associated with sporadic colorectal cancer.

Colorectal cancer (CRC) is a worldwide problem for public health. mutL homolog 1 (MLH1) is a key component of the mismatch repair system, and the MLH1-93G/A polymorphism (rs1800734) is predicted to affect MLH1 protein expression, suggesting that the polymorphism may be associated with the cancer risk; however, the results concerning this have been inconsistent. In order to investigate the possible correlation between human (h)MLH1-93G/A polymorphism and the development and progression of sporadic CRC (SCRC) in China, the genotypes of hMLH1-93G/A were detected by the TaqMan MGB probe method in 312 SCRC patients and 300 healthy controls, and immunohistochemical staining was also performed to measure the expression of hMLH1 in cases with different alleles among the SCRC patients and normal controls. It was observed that the A/A genotype and A allele significantly increased the risk of developing Duke's stage C+D CRC and lymphatic metastasis. hMLH1 expression of the A allele was lower than that of the G allele in CRC. By contrast, there was no statistically significant difference in hMLH1 expression for the A allele and the G allele in the normal controls. These results suggested that hMLH1-93G/A polymorphism may not be associated with the overall risk of CRC, but that the hMLH1-93A/A genotype and A allele are associated with the progression of CRC.

[Clinical value of the narrow-band imaging combined with endoscopic submucosal dissection for gastric high grade intraepithelial neoplasia].

OBJECTIVE: To determine the feasibility, safety and short-time efficacy of narrow-band imaging (NBI) combined with endoscopic submucosal dissection (ESD) for treating gastric high grade intraepithelial neoplasia (HGIN). METHODS: Clinical data of 78 patients with gastric HGIN diagnosed by gastroscope and pathology undergoing NBI combined with ESD at Wuxi No.2 People's Hospital and Zhongshan Hospital of Fudan University from January 2014 to December 2015 were retrospectively analyzed. Their clinicopathological and follow-up data were analyzed. RESULTS: There were 47 males and 31 females aged from 38 to 85 years old. Preoperative NBI showed that lesions of all the 78(100%) patients had clear resection margin, and 91%(71/78) lesions had abundant vessels in the central depression area. One case was converted to open abdominal operation due to intra-operational perforation, 77(98.7%) gastric HGIN lesions were successfully dissected under ESD, including 74 cases(94.9%) of en bloc dissection, and other 3 cases with severe adhesion of submucosa whose lesion wound after ESD was treated with argon plasma coagulation(APC). The mean maximum diameter of the lesion size was (1.2±0.8) cm. The average operation time was(48±21) minutes. Delayed hemorrhage occurred in 5 cases(6.4%) who were also treated successfully by endoscopic hemostasis. Postoperational pathology revealed en bloc dissection rate was 91.0%(71/78), positive rate of resection margin was 3.8%(3/78), and healing dissection rate was 89.7%(70/78). Thirty-two lesions (41.0%) remained the diagnosis as HGIN, 6 lesions(7.7%) were diagnosed as low grade intraepithelial neoplasia, and 40 lesions (51.3%) were diagnosed as adenocarcinoma. Fifty-seven cases were followed up for 12 months, 21 cases were followed up for 6 months, and there was no recurrence in those 3 patients with positive margin. Two cases (2.6%) relapsed and were diagnosed as adenocarcinoma by repeat pathology examination. CONCLUSION: NBI combined with ESD for diagnosis and treatment of gastric HGIN is safe and effective, and can achieve en bloc complete resection of the lesions with a low complication rate.

Role of high-mobility group box 1 protein in inflammatory bowel disease.

High-mobility group box 1 (HMGB1) protein is a nuclear non-histone DNA-binding protein. It is released into the extracellular milieu and mediates inflammatory responses, which contribute to the pathogenesis of numerous inflammatory diseases, including inflammatory bowel disease (IBD). An online search was performed in PubMed and Web of Science databases for articles providing evidence on the role of HMGB1 in IBD. HMGB1 plays an important role in IBD pathogenesis. Application of HMGB1 antagonists reduced inflammatory reactions and ameliorated colitis in rodent models, which may provide new insights into the diagnosis and treatment of IBD.

Optimization of physicochemical properties and safety profile of novel bacterial topoisomerase type II inhibitors (NBTIs) with activity against Pseudomonas aeruginosa.

Type II bacterial topoisomerases are well validated targets for antimicrobial chemotherapy. Novel bacterial type II topoisomerase inhibitors (NBTIs) of these targets are of interest for the development of new antibacterial agents that are not impacted by target-mediated cross-resistance with fluoroquinolones. We now disclose the optimization of a class of NBTIs towards Gram-negative pathogens, especially against drug-resistant Pseudomonas aeruginosa. Physicochemical properties (pKa and logD) were optimized for activity against P. aeruginosa and for reduced inhibition of the hERG channel. The optimized analogs 9g and 9i displayed potent antibacterial activity against P. aeruginosa, and a significantly improved hERG profile over previously reported analogs. Compound 9g showed an improved QT profile in in vivo models and lower clearance in rat over earlier compounds. The compounds show promise for the development of new antimicrobial agents against drug-resistant Pseudomonas aeruginosa.

Bortezomib-induced apoptosis in cultured pancreatic cancer cells is associated with ceramide production.

PURPOSE: The proteasome inhibitor bortezomib (PS-341) has displayed significant efficiency against pancreatic cancer cells. However, the underlying mechanisms are not fully understood. Here, we tested if ceramide production was involved in the bortezomib's effect. METHODS: Two transformed pancreatic cancer cell lines (PANC-1 and Mia) and the primary pancreatic cancer cells were used. Cell death was analyzed by MTT viability assay and trypan blue staining. Cell apoptosis was analyzed by Histone DNA-ELISA assay and Annexin V FACS. Western blots were used to test signal protein changes. The cellular ceramide level after bortezomib treatment was also determined. RESULTS: In cultured pancreatic cancer cells, bortezomib increased cellular ceramide production to promote cell apoptosis. The ceramide de novo synthase inhibitor fumonisin B1 (F-B1) suppressed bortezomib-induced ceramide production and apoptosis, while exogenously added C6-ceramide facilitated bortezomib-induced pancreatic cancer cell death. Meanwhile, 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), the inhibitor of glucosylceramide synthetase as well as the sphingosine kinase 1 inhibitors (SKI-II and SKI-IV), facilitated bortezomib-induced ceramide production and subsequent cell apoptosis. Further, bortezomib-induced pro-apoptotic c-Jun N-terminal kinase (JNK) activation was also associated with ceramide production. JNK activation by bortezomib was suppressed by F-B1, but was enhanced by SKI-II and PDMP in pancreatic cancer cells. Finally, C6-ceramide, SKI-II, and PDMP dramatically enhanced bortezomib-induced cytotoxicity in primary cultured pancreatic cancer cells. CONCLUSIONS: We found that bortezomib-induced apoptosis was associated with ceramide production in primary and transformed pancreatic cancer cells.

Building clinical data groups for electronic medical record in China.

This article aims at building clinical data groups for Electronic Medical Records (EMR) in China. These data groups can be reused as basic information units in building the medical sheets of Electronic Medical Record Systems (EMRS) and serve as part of its implementation guideline. The results were based on medical sheets, the forms that are used in hospitals, which were collected from hospitals. To categorize the information in these sheets into data groups, we adopted the Health Level 7 Clinical Document Architecture Release 2 Model (HL7 CDA R2 Model). The regulations and legal documents concerning health informatics and related standards in China were implemented. A set of 75 data groups with 452 data elements was created. These data elements were atomic items that comprised the data groups. Medical sheet items contained clinical records information and could be described by standard data elements that exist in current health document protocols. These data groups match different units of the CDA model. Twelve data groups with 87 standardized data elements described EMR headers, and 63 data groups with 405 standardized data elements constituted the body. The later 63 data groups in fact formed the sections of the model. The data groups had two levels. Those at the first level contained both the second level data groups and the standardized data elements. The data groups were basically reusable information units that served as guidelines for building EMRS and that were used to rebuild a medical sheet and serve as templates for the clinical records. As a pilot study of health information standards in China, the development of EMR data groups combined international standards with Chinese national regulations and standards, and this was the most critical part of the research. The original medical sheets from hospitals contain first hand medical information, and some of their items reveal the data types characteristic of the Chinese socialist national health system. It is possible and critical to localize and stabilize the adopted international health standards through abstracting and categorizing those items for future sharing and for the implementation of EMRS in China.

The development of clinical document standards for semantic interoperability in china.

OBJECTIVES: This study is aimed at developing a set of data groups (DGs) to be employed as reusable building blocks for the construction of the eight most common clinical documents used in China's general hospitals in order to achieve their structural and semantic standardization. METHODS: The Diagnostics knowledge framework, the related approaches taken from the Health Level Seven (HL7), the Integrating the Healthcare Enterprise (IHE), and the Healthcare Information Technology Standards Panel (HITSP) and 1,487 original clinical records were considered together to form the DG architecture and data sets. The internal structure, content, and semantics of each DG were then defined by mapping each DG data set to a corresponding Clinical Document Architecture data element and matching each DG data set to the metadata in the Chinese National Health Data Dictionary. By using the DGs as reusable building blocks, standardized structures and semantics regarding the clinical documents for semantic interoperability were able to be constructed. RESULTS: Altogether, 5 header DGs, 48 section DGs, and 17 entry DGs were developed. Several issues regarding the DGs, including their internal structure, identifiers, data set names, definitions, length and format, data types, and value sets, were further defined. Standardized structures and semantics regarding the eight clinical documents were structured by the DGs. CONCLUSIONS: This approach of constructing clinical document standards using DGs is a feasible standard-driven solution useful in preparing documents possessing semantic interoperability among the disparate information systems in China. These standards need to be validated and refined through further study.

Harmonization of health data at national level: a pilot study in China.

OBJECTIVE: For the purpose of establishing electronic health record (EHR), business-oriented health data distributed in different systems should be integrated to focus on individuals. This study is aimed at collecting health data items that are now nationally available in various health information systems, and harmonizing them by modeling and defining the data elements. METHODS: This study followed a bottom-up strategy in data standard development. Health data items were identified and collected by referring to national health service regulations, consulting domain experts and performing field investigations. Data items were classified and modeled based on recognized domain knowledge, information standards and specifications developed by standard development organizations (SDOs) of other countries. Data elements were extracted from data items and defined according to ISO/IEC 11179 -Metadata registries (MDR) and confirmed needs. RESULTS: 1588 data items were collected from 33 recording forms that have been used nationally in health services, and were classified with a conceptual data model that was composed of 7 super classes (healthcare clients, healthcare providers, birth registry, health event/act, healthcare process, death, and others) and 15 classes (person's identification, person's socio-demographic characteristics, address, communication, provider-organization, provider-individual, birth, health event/act, observation, procedure, drug and material administration, recommendation, evaluation, expenditure, death, others). By normalizing the concepts and representations of data items, data elements were derived and defined as the attributes of classes in the data model. Data items were specified as instances of corresponding data elements. CONCLUSIONS: A large number of health data have been collected nationwide but person's life-long health record is incomplete and inconsistent now. To integrate such massive quantity of health data from various sources, a conceptual data model was established to organize data items, avoiding conflicts and duplications in between. For data consistency, data elements should be extracted from the data items and defined as attributes of classes in the data model by choosing essential metadata attributes. Treating data items as instances of well defined data elements might make data in different contexts manageable and agreeable. To be semantically unambiguous, further study should be performed to deal with the standardization of detailed medical information, and perfect the approach of data harmonization.

Portable laser speckle perfusion imaging system based on digital signal processor.

The ability to monitor blood flow in vivo is of major importance in clinical diagnosis and in basic researches of life science. As a noninvasive full-field technique without the need of scanning, laser speckle contrast imaging (LSCI) is widely used to study blood flow with high spatial and temporal resolution. Current LSCI systems are based on personal computers for image processing with large size, which potentially limit the widespread clinical utility. The need for portable laser speckle contrast imaging system that does not compromise processing efficiency is crucial in clinical diagnosis. However, the processing of laser speckle contrast images is time-consuming due to the heavy calculation for enormous high-resolution image data. To address this problem, a portable laser speckle perfusion imaging system based on digital signal processor (DSP) and the algorithm which is suitable for DSP is described. With highly integrated DSP and the algorithm, we have markedly reduced the size and weight of the system as well as its energy consumption while preserving the high processing speed. In vivo experiments demonstrate that our portable laser speckle perfusion imaging system can obtain blood flow images at 25 frames per second with the resolution of 640 × 480 pixels. The portable and lightweight features make it capable of being adapted to a wide variety of application areas such as research laboratory, operating room, ambulance, and even disaster site.

A novel 3-step enantioselective synthesis of pyrenylalanine with subsequent incorporation into opioid, CCK, and melanotropin ligands.

Pyrene possesses unique spectroscopic properties such as a high quantum yield, a long half-life in the excited state, and the ability to form excimers when in proximity to each other in the excited state. These properties allow pyrenylalanine, which is a pyrene moiety incorporated into an amino acid, to be used as a fluorescent probe in peptides and proteins. The common route for the synthesis of pyrenylalanine involves 5 steps, with subsequent separation of the two isomers by recrystallization. This paper reports a novel 3-step asymmetric synthesis of pyrenylalanine with high enantioselectivity, good yields, and facile isomer purification. After synthesis, pyrenylalanine was incorporated into a series of opioid, CCK, and melanotropin peptide ligands in order to study the effects of aromaticity, lipophilicity, and steric properties on their potency and efficacy at their corresponding biological receptors. The change in binding and efficacy of the labeled ligands as compared to the unlabeled ligands demonstrates the possible role of lipophilicity/aromaticity in the binding and signal transduction of the ligand-receptor interaction.

(2S,3R) beta-methyl-2',6'-dimethyltyrosine-L-tetrahydroisoquinoline-3-carboxylic acid [(2S,3R)TMT-L-Tic-OH] is a potent, selective delta-opioid receptor antagonist in mouse brain.

The constrained opioid peptide (2S,3R)beta-methyl-2',6'-dimethyltyrosine-L-tetrahydroisoquinoline-3-carboxylic acid [(2S,3R)TMT-L-Tic-OH] exhibits high affinity and selectivity for the delta-opioid receptors (). In the present study, we examined the pharmacological properties of (2S,3R)TMT-L-Tic-OH in mouse brain. A 5'-O-(3-[(35)S]thiotriphosphate) ([(35)S]GTP gamma S) binding assay was used to determine the effect of (2S,3R)TMT-L-Tic-OH on G protein activity in vitro, in mouse brain membranes. delta- (SNC80; (+)-4-[(alpha R)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxy-benzyl]-N,N-diethyl-benzamide) or mu- (DAMGO; [D-Ala(2), Me-Phe(4),Gly(ol)(5)]enkephalin) selective opioid full agonists stimulated [(35)S]GTP gamma S binding in mouse brain membranes 150 +/- 4.5% and 152 +/- 5.7% over the basal level, respectively. (2S,3R)TMT-L-Tic-OH did not influence basal [(35)S]GTP gamma S binding in mouse brain membranes but dose dependently shifted the dose-response curve of SNC80 to the right, with a K(e) value of 3.6 +/- 0.7 nM. In contrast, (2S,3R)TMT-L-Tic-OH had no effect on the dose-response curve of the mu-selective opioid agonist, DAMGO. Warm water (55 degrees C) tail-flick and radiant heat paw-withdrawal tests were used to determine the in vivo nociceptive properties of (2S,3R)TMT-L-Tic-OH in the mouse. Intracerebroventricular injection of (2S,3R)TMT-L-Tic-OH had no significant effect on withdrawal latencies in either nociceptive tests. (2S,3R)TMT-L-Tic-OH (30 nmol/mouse) attenuated deltorphin II- but not DAMGO-mediated antinociception (40 +/- 13 and 100% of maximal possible effect, respectively) when administered intracerebroventricularly 10 min before the agonist. Taken together these results suggest that (2S,3R)TMT-L-Tic-OH is a potent highly selective neutral delta-opioid antagonist in mouse brain.