Clinical Benefit of Therapeutic Drug Monitoring in Colorectal Cancer Patients Who Received Fluorouracil-Based Chemotherapy.

BACKGROUND The impact of therapeutic drug management (TDM) on reducing toxicity and improving efficacy in colorectal cancer (CRC) patients receiving fluorouracil-based chemotherapy is still unclear. MATERIAL AND METHODS A total of 207 patients (Study Group n=54, Historical Group n=153) with metastatic colorectal cancer were enrolled. All of them received 6 administrations of the 5-FU based regimens. Initial 5-FU dosing of all patients was calculated using body surface area (BSA). In the Study Group, individual exposure during each cycle was measured using a nanoparticle immunoassay, and the 5-FU blood concentration was calculated using the area under the curve (AUC). We adjusted the 5-FU infusion dose of the next cycle based on the AUC data of the previous cycle to achieve the target of 20-30 mg×h/L. RESULTS In the fourth cycle, patients in the target concentration range (AUC mean, 26.3 mg×h/L; Median, 28 mg×h/L; Range, 14-38 mg×h/L; CV, 22.4%) accounted for 46.8% of all patients, which were more than the ones in the first cycle (P<0.001). 5-FU TDM significantly reduced the toxicity of chemotherapy and improved its efficacy. The Study Group (30/289) showed a lower percentage of severe adverse events than that in the Historical Group (185/447) (P<0.001). The incidences of complete response and partial response in the Study Group were higher than those in the Historical Group (P=0.032). CONCLUSIONS TDM in colorectal cancer can reduce toxicity, improve efficacy and clinical outcome, and can be routinely used in 5-FU-based chemotherapy.

Analysis of lncRNA-mRNA networks after MEK1/2 inhibition based on WGCNA in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDA) responds poorly to treatment. Efforts have been exerted to prolong the survival time of PDA, but the 5-year survival rates remain disappointing. Understanding the molecular mechanisms of PDA development is significant. MEK/ERK pathway signaling has been proven to be important in PDA. lncRNA-mRNA networks have become a vital part of molecular mechanisms in the MEK/ERK pathway. Herein, weighted gene coexpression network analysis was used to investigate the coexpressed lncRNA-mRNA networks in the MEK/ERK pathway based on GSE45765. Differently expressed long noncoding RNA (lncRNA) and messenger RNA (mRNA) were found and 10 modules were identified based on coexpression profiles. Gene ontology and Kyoto Encyclopedia of Genes and Genomes were then performed to analyze the coexpressed lncRNA and mRNA in different modules. PDA cells and tissues were used to validate the analysis results. Finally, we found that NONHSAT185150.1 and B4GALT6 were negatively correlated with MEK1/2. By analyzing GSE45765, the genome-wide profiles of lncRNA-mRNA network after MEK1/2 was established, which might aid the development of drug-targeting MEK1/2 and the investigation of diagnostic markers.

Modulating NMDA receptors to treat MK-801-induced schizophrenic cognition deficit: effects of clozapine combining with PQQ treatment and possible mechanisms of action.

BACKGROUND: Clozapine has remarkable efficacy on both negative and cognitive symptoms of schizophrenia due to its slight activation of NMDA receptor. In fact, much evidence to the contrary. NMDAR is a complex containing specific binding sites, which are regulated to improve negative symptoms and cognitive deficits associated with individuals affected by schizophrenia. PQQ is a powerful neuroprotectant that specifically binds with NMDA receptors in the brain to produce beneficial physiological and cognitive outcomes. The aim of this study was to enhance NMDAR function and improve cognitive ability in schizophrenia by PQQ combined with clozapine. METHODS: Rats were divided into four groups (n = 5) including control (saline), model (MK-801, 0.5 mg·kg- 1·d- 1), atypical antipsychotic (MK-801 (0.5 mg·kg- 1·d- 1) + Clozapine (1.0 mg·kg- 1·d- 1), and co-agonist NMDA receptor (MK-801 (0.5 mg·kg- 1·d- 1) + Clozapine (0.5 mg·kg- 1·d- 1) + PQQ (1.0 µg·kg- 1·d- 1) group. Each group of rats was injected subcutaneously every day for 6 weeks. Behavior test, including stereotyped behavior, locomotor hyperactivity, learning and memory, was performed. The Western blot assay was performed to analyze the expression of GSK-3ß, Akt, NMDAR1, and MGLUR in rat hippocampus. RESULTS: Results indicated that clozapine and PQQ combination therapy can improve MK801-induced schizophrenia behavior including stereotyped behavior, locomotor hyperactivity and cognitive impairment. Furthermore, we found that modulating NMDA receptors could ameliorate the memory impairments in Mk-801 induced schizophrenia rats by reducing the expression of NMDAR1 and MGLUR3, decreasing hippocampal tau hyperphosphorylation and inhibiting apoptosis through Akt /GSK-3ß signaling pathway. CONCLUSIONS: These findings suggest that combination therapy for enhancing NMDA receptors may be able to rescue cognition deficit in schizophrenia. More studies are needed to better elucidate these mechanisms.

The effect of the earliest COVID-19 outbreak on survival in uninfected advanced NSCLC patients receiving chemotherapy in Jiangsu Province, China: A retrospective cohort study.

Coronavirus disease 2019 (COVID-19) is still rampant and uncontrolled across the globe. China's strict epidemic prevention measures have had an impact on the treatment in patients with non-small cell lung cancer (NSCLC). The aim of this study is to explore the impact of the COVID-19 outbreak on the uninfected NSCLC patients. The chemotherapeutic efficacy and survival of 89 uninfected advanced NSCLC patients were retrospectively analyzed. The endpoints were overall survival (OS), progression-free survival (PFS), and response rate. Forty and forty-nine patients with advanced NSCLC received chemotherapy during the COVID-19 outbreak and nonoutbreak periods, respectively. Mean delay time was 12.8 months for COVID-19 outbreak stage versus 5.68 months for nonoutbreak stage (P = .003). There was no significant difference in the rates of chemotherapy delay and discontinuation between the 2 groups (P = .055 and .239). Significant difference was not detected in median OS (15.8 months) for COVID-19 outbreak stage versus 16.0 months for nonoutbreak stage (adjusted hazard ratio, 1.058; 95% confidence interval, 0.593-1.888; P = .849); Median PFS was 7.9 months for COVID-19 outbreak stage versus 10.3 months for nonoutbreak stage (adjusted hazard ratio, 0.878; 95% confidence interval 0.513-1.503; P = .634). There was also no statistical difference in the disease control rate between the 2 groups (P = .137). The earliest COVID-19 outbreak had no significant impact on the PFS and OS in uninfected advanced NSCLC patients receiving chemotherapy. However, the mean delay time of receiving chemotherapy was prolonged during the COVID-19 outbreak.

Supplementation of PQQ from pregnancy prevents MK-801-induced schizophrenia-like behaviors in mice.

RATIONALE: At present, the research on the prevention of schizophrenia is still in its infancy. Pyrroloquinoline quinone (PQQ) has potential to treat psychological and neurological diseases including schizophrenia. However, the preventive effect of PQQ on schizophrenia remains unclear. OBJECTIVES: In this study, we aimed to examine the preventive effect of supplementation of dietary PQQ from pregnancy or after birth on dizocilpine (MK-801)-induced schizophrenia-like behaviors in mice. RESULTS: Supplementation of dietary PQQ from pregnancy could effectively prevent MK-801-induced weight gain decrease, hyperlocomotion, stereotypical behavior, ataxia, exploratory activity decrease, social interaction disorder, memory deficit, and depression in mice. Supplementation of dietary PQQ after birth could effectively prevent MK-801-induced weight gain decrease, stereotypical behavior, ataxia, and memory deficit in mice. Female mice responded to a greater degree than males in preventing MK-801-induced weight gain decrease in both forms of PQQ supplementation. For mice that began PQQ supplementation after birth, females performed better than males in preventing MK-801-induced ataxia, memory deficit, and depression. For mice that began PQQ supplementation from pregnancy, males performed better than females in preventing MK-801-induced memory deficit. In vitro experiments indicated that PQQ supplementation in the earlier stage of life contributed to the growth of neurons and the development of neurites. CONCLUSIONS: Our current study suggested that PQQ supplementation from pregnancy or postpartum could prevent some schizophrenia-like behaviors induced by MK-801 in mice. Our work supported the potential usage of dietary supplement of PQQ in preventing or alleviating symptoms associated with schizophrenia.

Generation of a liver targeting fusion interferon and its bioactivity analysis in vitro.

The objective of this study was to generate a liver targeting fusion interferon, galactosyl-human serum albumin-interferon alpha2b (G-HSA-IFN) and to evaluate its bioactivity in vitro on HepG2.2.15 cells which express hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg). The cell proliferation was determined by Sulpho Rhodamine B (SRB) staining method and flow cytometry (FCM) assay. Hochest33342 and Propidium Iodide (PI) double staining and Western blot analysis of Bcl-2/Bax were also performed to evaluate cell lethality and apoptosis. The concentrations of HBsAg and HBeAg secreted in culture supernatant were detected using Enzyme-Linked Immunosorbent Assay (ELISA). The results demonstrated that G-HSA-IFN could inhibit the proliferation of HepG2.2.15 cells and the cell cycle was arrested at G0/G1 phase. Western blotting results showed that the expression of Bcl-2 was inhibited in a dose-dependent manner while the expression of Bax was enhanced. The expression of HBsAg was inhibited by G-HSA-IFN in a dose-dependent manner, while no significant inhibiting effect on the expression of HBeAg was observed. Conclusively, G-HSA-IFN could not only significantly inhibit the HBsAg expression and the proliferation of HepG2.2.15 cells, but also induce the apoptosis of the target cells, rendering it a promising drug candidate for hepatitis B.

LINC00839/miR-144-3p/WTAP (WT1 Associated protein) axis is involved in regulating hepatocellular carcinoma progression.

The present work aimed to explore LINC00839 expression level and its function in hepatocellular carcinoma (HCC), and identify the downstream molecular mechanisms. qRT-PCR (Real-Time Quantitative Reverse Transcription PCR) and western blot were employed to detect mRNA and protein levels. Functional investigations were performed by flow cytometric-based apoptosis assay, CCK8 (Cell Counting Kit-8) assay, clone formation assay, Transwell migration and invasion assay. Functional interactions between LINC00839 and miR-144-3p or miR-144-3p and WTAP were validated by dual luciferase reporter assay. siRNA (small interfering RNA) was used for LINC00839 silencing, and microRNA mimic or inhibitor were employed to modulate miR-144-3p activity. LINC00839 was upregulated in HCC cells and tissues. Silencing LINC00839 suppressed the proliferation, invasion, migration of HCC cells and induced apoptosis. Additionally, LINC00839 served as a sponge to negatively impact on miR-144-3p activity, which contributed to the high expression of WTAP (WT1 Associated Protein) and the malignant phenotype of HCC cells. Our study revealed an oncogenic role of LINC00839 in HCC, and identified miR-144-3p/WTAP axis as downstream effectors mediating the oncogenic function of LINC00839. LINC00839 might serve as a potential therapeutic target and prognostic marker for HCC.

Efficacy of gecko polysaccharide on suppressed immune response induced by cyclophosphamide in mice.

OBJECTIVE: To evaluate the efficacy of gecko polysaccharide on the cyclophosphamide-induced suppressed immune response in mice. METHODS: Polysaccharides were extracted from fresh gecko for the first time using an orthogonal method and protein was removed using Sevag reagent (chloroform:N-butanol, 5:1, v/v). The gecko polysaccharide (GPCE) content was determined by the phenol-concentrated sulfuric acid method. An immunocompromised mouse model was established by intraperitoneally injecting cyclophosphamide at 100 mg/kg into 48 mice. The effects of GPCE on immune regulation in mice were assessed by a thymus-spleen index, serum hemolysin levels, and the proliferation of splenic lymphocytes. Spleen cell CD4+, CD8+, and the CD4+/CD8+ ratio were evaluated by flow cytometry and the tumor necrosis factor-α (TNF-α) levels were measured by ELISA. RESULTS: The optimal extraction process for gecko polysaccharide included a 1:20 ratio of material to liquid (v/v), an extraction temperature of 60 ℃ and a time of 2 h. The polysaccharide content of the extract was 65.74%. GPCE was analyzed by HPLC and primarily contained glucose and small amounts of mannose, rha, and gal. Compared with the model, the thymus index, the spleen index were indices for GPCE increased with dose, whereas the high and medium groups exhibited significant differences (P < 0.05, P < 0.01). Higher doses of GPCE increased serum TNF-α levels and there was a significant difference between the medium and high GPCE doses and the model (P < 0.05, P < 0.01); The number of CD4+ cells and the CD4+/CD8+ ratio in the gecko polysaccharide group were increased (P < 0.05) and there was no statistical difference in the number of CD8+ cells in the gecko polysaccharide group (P > 0.05); The high GPCE dose significantly increased the level of serum hemolysin (P < 0.01). CONCLUSIONS: Gecko polysaccharide significantly improved the suppressed immune response induced by cyclophosphamide in mice and promoted the secretion of tumor necrosis factor. The mechanism of gecko polysaccharide as an antitumor agent warrants further study.

5-(4-Methyl-phen-yl)-2,3-diphenyl-5,6-dihydro-imidazo[1,2-c]quinazoline.

In the title compound, C(29)H(23)N(3), the pyrimidine ring adopts an envelope conformation. The dihedral angle between the phenyl rings attached to the pyrimidine-ring double bond is 62.09 (7)°. In the crystal, mol-ecules are linked by N-H⋯N hydrogen bonds, forming extended chains in the c-axis direction.

2-(4-Methyl-phen-yl)-2H-indazole.

The title compound, C(14)H(12)N(2), was synthesized by the reaction of 4-methyl-N-(2-nitro-benz-yl)aniline with tin(II) chloride dihydrate in ethanol at 313 K. The indazole ring system is almost planar with a dihedral angle of 1.58 (10)° between the rings, whereas the plane of the attached p-tolyl substituent shows a dihedral angle of 46.26 (5)° with respect to the indazole core.

Neurotoxicity and apoptosis induced by pyrroloquinoline quinone and its ester derivative on primary cortical neurons.

Pyrroloquinoline quinone (PQQ) and its esterified derivative, PQQ ester (PQQE), have potential to treat or diagnose neurological and psychological disorders. However, their neurotoxicity remains unclear. To provide reference data for the brain targeting drug delivery techniques, the cytotoxic effects of PQQ and PQQE were examined in primary mouse cortical neurons. The results indicated that both PQQ and PQQE decreased neuron viability, reduced intracellular ATP level and disrupted the mitochondrial membrane potential in a concentration- and time-dependent manner, while PQQ was less potent than PQQE. PQQ and PQQE induced apoptosis involving increase of Bax, decrease of Bcl-2, release of mitochondrial cytochrome C into the cytosol, activation of caspase-3 and cleavage of PARP. A single mouse intracephalic injection of PQQ or PQQE showed similar results. Based on these findings, high-concentration PQQ or PQQE treatment could induce a wide range of neurotoxicity and apoptosis. The lowest observed adverse effect levels (LOAELs) of PQQ and PQQE were 10 µM and 2 µM respectively and the no observed adverse effect levels (NOAELs) were 5 µM and 1 µM respectively in mice cortical neurons.

The effect of TKI therapy and chemotherapy treatment delivery sequence on total progression-free survival in patients with advanced EGFR-mutated NSCLC.

The present study aimed to evaluate the total progression-free survival (PFS) time of the 1st-line chemotherapy (CHT)/2nd-line tyrosine kinase inhibitor (TKI) and 1st-line TKI/2nd-line CHT therapeutic regimens. Data from patients with non-small-cell lung cancer (NSCLC) harboring sensitizing epidermal growth factor receptor (EGFR) mutations, who had received both TKI and platinum CHT were retrieved from the Shandong Cancer Hospital (Jinan, China) database. A total of 89 patients were included, 50 of whom were treated with the 1st-line CHT/2nd-line TKI regimen and the remaining 39 patients underwent a 1st-line TKI/2nd-line CHT regimen. The differences in total PFS time between the two regimens were analyzed. The median total PFS time was 14.28 months with the 1st-line CHT/2nd-line TKI regimen and 17.77 months with the 1st-line TKI/2nd-line CHT regimen (adjusted hazard ratio, 0.96; 95% confidence interval (CI), 0.56-1.66; P=0.886). A significant difference in PFS time was revealed between the two strategies when comparing only the 1st-line or 2nd-line treatments (all P<0.001). The objective response rate (RR) was 52.0% for those treated with 1st-line CHT/2nd-line TKI and 38.5% for the reverse regimen. After adjusting for associated factors, the odds ratio for the RR was 2.77 (95% CI: 0.77-9.90; P=0.117). The current results revealed that there was no significant difference between the total PFS time of patients with NSCLC undergoing the 1st-line CHT/2nd-line TKI regimen compared with patients with NSCLC undergoing the 1st-line TKI/2nd-line CHT regimen.

PQQ ameliorates D-galactose induced cognitive impairments by reducing glutamate neurotoxicity via the GSK-3ß/Akt signaling pathway in mouse.

Oxidative stress is known to be associated with various age-related diseases. D-galactose (D-gal) has been considered a senescent model which induces oxidative stress response resulting in memory dysfunction. Pyrroloquinoline quinone (PQQ) is a redox cofactor which is found in various foods. In our previous study, we found that PQQ may be converted into a derivative by binding with amino acid, which is beneficial to several pathological processes. In this study, we found a beneficial glutamate mixture which may diminish neurotoxicity by oxidative stress in D-gal induced mouse. Our results showed that PQQ may influence the generation of proinflammatory mediators, including cytokines and prostaglandins during aging process. D-gal-induced mouse showed increased MDA and ROS levels, and decreased T-AOC activities in the hippocampus, these changes were reversed by PQQ supplementation. Furthermore, PQQ statistically enhanced Superoxide Dismutase SOD2 mRNA expression. PQQ could ameliorate the memory deficits and neurotoxicity induced by D-gal via binding with excess glutamate, which provide a link between glutamate-mediated neurotoxicity, inflammation and oxidative stress. In addition, PQQ reduced the up-regulated expression of p-Akt by D-gal and maintained the activity of GSK-3ß, resulting in a down-regulation of p-Tau level in hippocampus. PQQ modulated memory ability partly via Akt/GSK-3ß pathway.

Modulation of glycine sites enhances social memory in rats using PQQ combined with d-serine.

The aim of study was to investigate the effects of pyrroloquinoline quinone (PQQ) combined with d-serine on the modulation of glycine sites in the brain of rats using social recognition test. Rats were divided into seven groups (n=10) and given repeated intraperitoneal (ip) injections of saline, MK-801 (0.5mg/kg), clozapine (1mg/kg), haloperidol (0.1mg/kg), d-serine (0.8g/kg), PQQ (2.0µg/kg), or d-serine (0.4g/kg) combined with PQQ (1.0µg/kg) for seven days. A social recognition test, including assessment of time-dependent memory impairment, was performed. A non-competitive NMDA receptor antagonist, MK-801, significantly impaired social memory, and this impairment was significantly repaired with an atypical antipsychotic (clozapine) but not with a typical antipsychotic (haloperidol). Likewise, d-serine combined with PQQ significantly improved MK-801-disrupted cognition in naïve rats, whereas haloperidol was ineffective. The present results show that the co-agonist NMDA receptor treated with PQQ and d-serine enhances social memory and may be an effective approach for treating the cognitive dysfunction observed in schizophrenic patients. PQQ stimulates glycine modulatory sites by which it may antagonize indirectly by removing glycine from the synaptic cleft or by binding the unsaturated site with d-serine in the brain, providing the insights into future research of central nervous system and drug discovery.

Pyrroloquinoline quinone prevents MK-801-induced stereotypical behavior and cognitive deficits in mice.

Pyrroloquinoline quinone (PQQ), an essential nutrient, antioxidant, redox modulator, and nerve growth factor, prevents cognitive deficits associated with oxidative stress-induced neurodegeneration. Previous molecular imaging studies also demonstrate that PQQ binds to N-methyl D-aspartate (NMDA) receptors. In this study, we investigated the effects of PQQ on stereotypical behaviors and cognitive deficits induced by MK-801, a non-competitive NMDA antagonist used to model schizophrenia. Mice were given repeated injections of MK-801 (0.5mg/kg/d) and PQQ (0.2, 2.0, or 20 µg/kg/d) for 60 days. Behavior was evaluated using a variety of motor, social, and cognitive tests. We found that PQQ administration significantly attenuated MK-801-induced increases in stereotypical behavior and ataxia, suggesting a protective role of PQQ against MK-801-induced neuronal dysfunction and psychiatric disorders. Future studies are necessary to elucidate the underlying mechanisms of PQQ.

[Study of chemical kinetics between pyrroloquinoline quinine and D-serine in body by ion-pair liquid chromatography].

As a new neurotransmitter present in the glial cells, D-serine (DSer) plays an important role in central nervous system diseases. Pyrroloquinoline quinine (PQQ) can promote the production of the nerve growth factor and has a protective effect on nerve injuries. The chemical kinetics of PQQ and DSer was studied by determining the free contents of PQQ using ion-pair liquid chromatography (LC), so it can provide important information for the mechanisms of PQQ in the regulation of neurotransmitter. The PQQ and the production of the incubation were separated on an Amethyst C18-P column using tetrabutylammonium bromide as ion-pair reagent. The average recoveries were between 94.2% and 99.3%, and the relative standard deviations were between 1.05% and 2.03%. The average rate constants (K) of PQQ with DSer were 0.032, 0.07 and 0.17 h(-1) at 25, 37 and 50 degrees C, respectively. The average activation energy (E(a)) was 54.7 kJ/mol. The values of half life (t1/2) were 22.0, 9.8 and 3.99 h at 25, 37 and 50 degrees C, respectively. The results showed that PQQ can regulate the balance of DSer in the brain. The method is simple and reliable.

Safety, tolerability, pharmacokinetics and pharmacodynamics of recombinant human parathyroid hormone after single- and multiple-dose subcutaneous administration in healthy Chinese volunteers.

Recombinant human parathyroid hormone [rhPTH(1-84)] represents a new class of anabolic agents for the treatment of osteoporosis. The present study was designed to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of rhPTH(1-84) after single- and multiple-dose subcutaneous administration in healthy Chinese volunteers. Six cohorts of 32 volunteers received a single dose of rhPTH(1-84) at 0.5-5.0 µg/kg, and two cohorts of 12 volunteers received 2.0 and 3.0 µg/kg of rhPTH(1-84) once daily for 7 consecutive days to assess its safety and tolerability. The results indicated that rhPTH(1-84) appeared to be safe and well tolerated. Additionally, pharmacokinetics of rhPTH(1-84) and its active N-terminal fragment rhPTH(1-34) were investigated after administration of single 1.0, 2.0 and 4.0 µg/kg doses of rhPTH(1-84) in 30 other volunteers and after multiple doses of 2.0 µg/kg once daily for 7 consecutive days. The pharmacokinetic parameters for rhPTH(1-84) and rhPTH(1-34) after subcutaneous administration of a single dose of 1.0, 2.0 and 4.0 µg/kg were as follows: Cmax = (110.54 ± 59.18), (149.70 ± 50.61) and (372.52± 94.96) pg/mL; (53.93±6.27), (61.12±11.28) and (89.04 ± 7.08) pg/mL, respectively. AUC0-10 = (268.87 ± 47.72), (538.93 ± 146.89) and (1364.11 ± 176.82) pg hr/mL; (197.20 ± 50.78), (207.15 ± 72.08) and (344.05 ± 77.06) pg hr/mL, respectively. t1/2 = (2.34 ± 1.93), (2.58 ± 1.18) and (2.74 ± 1.31) hr; (3.37 ± 1.82), (4.39 ± 3.79), and (3.99 ± 1.85) hr, respectively. Plasma Cmax and AUC values of rhPTH(1-84) and rhPTH(1-34) were found to be dose proportional. The pharmacokinetic parameters for rhPTH(1-84) and rhPTH(1-34) after administration of multiple doses of 2.0 µg/kg were as follows: Css_max = (164.96 ± 52.61) and (75.05 ± 7.31) pg/mL; Css_min = (6.99 ± 7.73) and (2.05 ± 2.82) pg/mL; AUCss = (567.26 ± 118.41) and (306.02 ± 77.55) pg hr/mL; t1/2 = (1.81 ± 0.89) and (2.27 ± 1.11) hr; DF = (6.93 ± 2.64) and (6.00 ± 1.37), respectively. After multiple doses, the pharmacokinetic parameters for rhPTH(1-84) were consistent with those after single dose. However, the mean Cmax and AUC0-10 of rhPTH(1-34) after multiple dosing were significantly higher than the corresponding values obtained after single-dose administration. Serum total calcium and phosphate concentrations increased and decreased significantly at 4 hr post-dosing, respectively.

Preliminary studies of (99m)Tc-memantine derivatives for NMDA receptor imaging.

INTRODUCTION: Novel technetium-labeled ligands, (99m)Tc-NCAM and (99m)Tc-NHAM were developed from the N-methyl-d-aspartate (NMDA) receptor agonist memantine as a lead compound by coupling with N(2)S(2). This study evaluated the binding affinity and specificity of the ligands for the NMDA receptor. METHODS: Ligand biodistribution and uptake specificity in the brain were investigated in mice. Binding affinity and specificity were determined by radioligand receptor binding assay. Three antagonists were used for competitive binding analysis. In addition, uptake of the complexes into SH-SY5Y nerve cells was evaluated. RESULTS: The radiochemical purity of (99m)Tc-labeled ligands was more than 95%. Analysis of brain regional uptake showed higher concentration in the frontal lobe and specific uptake in the hippocampus. (99m)Tc-NCAM reached a higher target to nontarget ratio than (99m)Tc-NHAM. The results indicated that (99m)Tc-NCAM bound to a single site on the NMDA receptor with a K(d) of 701.21 nmol/l and a B(max) of 62.47 nmol/mg. Specific inhibitors of the NMDA receptor, ketamine and dizocilpine, but not the dopamine D(2) and 5HT(1A) receptor partial agonist aripiprazole, inhibited specific binding of (99m)Tc-NCAM to the NMDA receptor. Cell physiology experiments showed that NCAM can increase the viability of SH-SY5Y cells after glutamate-induced injury. CONCLUSIONS: The new radioligand (99m)Tc-NCAM has good affinity for and specific binding to the NMDA receptor, and easily crosses the blood-brain barrier; suggesting that it might be a potentially useful tracer for NMDA receptor expression.

Preparation of 99mTc-PQQ and preliminary biological evaluation for the NMDA receptor.

Pyrroloquinoline quinone (PQQ), an essential nutrient, antioxidant, redox modulator and nerve growth factor found in a class of enzymes called quinoproteins, was labeled with 99mTc by using stannous fluoride (SnF2) method. Radiolabeling qualification, quality control and characterization of 99mTc-PQQ and its biodistribution studies in mice were performed and discussed. Effects of pH values, temperature, time and reducing agents concentration on the radiolabeling yield were investigated. The quality control procedure of 99mTc-PQQ was determined by thin layer chromatography (TLC), radio high-performance liquid chromatography (RHPLC) and paper electrophoresis methods. The average radiolabeling yield was 94 ± 1% under optimum conditions of 0.99 mg of PQQ, 30 µg of SnF2, 0.5 mg of ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) and 18.5 MBq of Na99mTcO4 at pH 6 and 25 °C with a response volume of 1 ± 0.1 mL. 99mTc-PQQ was stable and anionic. Lipid-water partition coefficient of 99mTc-PQQ was -1.49 ± 0.16. The pharmacokinetics parameters of 99mTc-PQQ were t1/2α = 18.16 min, t1/2ß = 100.45 min, K12 = 0.013 min-1, K21 = 0.017 min-1, Ke = 0.016 min-1, AUC (area under the curve) = 1040.78 ID% g-1 min and CL (plasma clearance) = 0.096 mL min-1. The dual-exponential equation was Y = 10.88e-0.038t  + 5.21e-0.0069t . The biodistribution of 99mTc-PQQ was studied in ICR (Institute for Cancer Research 7701 Burhelme Are., Fox Chase, Philadelphia, PA 1911 USA) mice. In vitro autoradiographic studies clearly showed that the 99mTc-PQQ radioactivity accumulated predominantly in the hippocampus and cortex, which had a high density of N-methyl-d-aspartate Receptor (NMDAR). The enrichment can be blocked by NMDAR redox modulatory site antagonists-ebselen (EB) and 99mTc-PQQ is therefore a promising candidate for the molecular imaging of NMDAR. To date, however, there have been no studies characterizing 99mTc-PQQ.