RGD peptide-decorated micelles assembled from polymer-paclitaxel conjugates towards gastric cancer therapy.

Development of polymer-drug conjugate capable of controlled drug release is urgently needed for gastric cancer therapy. Herein, arginine-glycine-aspartic acid (RGD)-decorated polyethylene glycol (PEG)-paclitaxel (PTX) conjugates containing disulfide linkage were synthesized. The amphiphilic PEG-PTX conjugates were found to assemble into micelles (RGD@Micelles), which would be decomposed under the reduction of glutathione (GSH) and finally release PTX in weakly acidic conditions characteristic of intracellular environment. The RGD@Micelles were spherical nanoparticles with an average hydrodynamic size of ˜50 nm, which were stable in physiological environment. The release of PTX from the micelles in response to GSH was investigated. In vitro cell assay suggested that the RGD@Micelles could target the gastric cancer cells and inhibit cell proliferation by inducing apoptosis. In vivo experiments indicated that the RGD@Micelles could be delivered to the tumor site and inhibit the tumor growth efficiently by releasing PTX inside the tumor cells. This type of micelles exhibited high therapeutic efficacy and low side effects, providing new insights into targeted drug delivery for gastric cancer therapy.

Expression of Synthetic Phytoene Synthase Gene to Enhance ß-Carotene Production in Scenedesmus sp. CPC2.

ß-carotene is a valuable pigment abundant in some microalgal species but the low ß-carotene productivity of microalgae has become the major obstacles against its commercialization. This work aims to improve the productivity of algae-based ß-carotene via genetic engineering approaches. First, a synthetic psy gene construct (891 bp) encoding 297 amino acids is expressed in Scenedesmus sp. CPC2 host to enhance the ß-carotene production. The synthetic psy gene is designed by considering the highest consensus of amino acids (i.e., 62% identity) from Chlamydomonas reinhardtii, Dunaliella salina, and Mariella zofingiensis. The original ß-carotene content in wild-type Scenedesmus sp. CPC2 is 10.8 mg g-1 -cell when grown on BG11 medium under 2% CO2 aeration, 150 µmol m-2 s-1 light intensity and 25°C. After transformation of the psy gene into the microalgal host, the ß-carotene content of the best recombinant strain (i.e., transformant CPC2-4) significantly increased to over 30 mg g-1 -cell. The optimal production of ß-carotene with the CPC2-4 recombinant strain was achieved when the strain is grown on BG11 medium amended with 0.075 g of MgSO4 , giving approximately 3-fold higher ß-carotene content than that of the wild-type strain. The best cellular ß-carotene content obtained (i.e., 31.8 mg g-1 ) is superior to most algae-based ß-carotene production performance reported in the literature.

Controllable release of nitric oxide and doxorubicin from engineered nanospheres for synergistic tumor therapy.

NaYF4:Yb,Er upconversion nanoparticles (UCNPs) capped with long-chain carboxylic acid were synthesized and then conjugated with chitosan (CS) in the aid of N-hydroxysuccinimide. The resultant nanocompound was integrated with doxorubicin (DOX) and Roussin's black salt (RBS), a photosensitive nitric oxide (NO) donor to produce stimuli-responsive UCNPs(DOX)@CS-RBS nanospheres as nanocarriers for controllable drug delivery. On the one hand, the encapsulated UCNPs can efficiently absorb NIR photons and convert them into visible photons to trigger NO release. On the other hand, the entrapped DOX can be released at lowered pH from the swollen nanospheres caused by stretched oleoyl-CS chains under acidic conditions. The UCNPs(DOX)@CS-RBS nanospheres exhibit great therapeutic efficacy, which is attributable to the combination of NO and DOX releases based on NO dose-dependent mechanisms. This study highlights the controllable release of NO and DOX from the same nanocarriers and the synergistic therapeutic effect on tumors, which could give new insights into improving cancer nanotherapeutics. STATEMENT OF SIGNIFICANCE: In this paper, core-shell structured UCNPs(DOX)@CS-RBS nanospheres have been designed and synthesized via a step-by-step procedure. The stimuli-responsive UCNPs(DOX)@CS-RBS nanospheres act as nanocarriers for controllable drug delivery towards cancer therapy. The encapsulated UCNPs can efficiently absorb NIR photons and convert them into visible light to trigger NO release. Meanwhile, the entrapped DOX can be released from the swollen nanospheres caused by stretched oleoyl-CS chains at lowered pH typical of intracellular environment. Synergistic cancer therapy will be achieved through the combination of NO and DOX releases based on NO dose-dependent mechanisms. This study provides new drug nanocarriers with high antitumor efficacy for synergistic cancer therapy.

Dynamic covalent linked triblock copolymer micelles for glutathione-mediated intracellular drug delivery.

Redox-responsive linkages dispersed in the backbones of the synthetic polymers, while young in the current spectrum of the biomedical application, are rapidly extending into their niche. In the present work, triblock copolymer PEG-PLA-PEG synthesized and characterized by 1H -NMR and SEC can self-assemble into redox-responsive micelles in aqueous media with nanosized 33nm and 47nm. And the copolymers PEG2000-PLA3000-PEG2000 and PEG2000-PLA5000-PEG2000 present lower CMC with 0.034 and 0.022mg/mL, and higher DLC of 4.28% and 5.14% respectively, compared with that of diblock copolymer. Moreover, drug release from the micelles can be triggered and significantly accelerated in reductive environment. The low cytotoxicity of redox-responsive micelles was confirmed by MTT assay against NIH 3T3 cells. All of these results demonstrated that these polymeric micelles self-assembled from double-disulfide tethered block copolymers are promising carriers for the redox-responsive intracellular delivery of hydrophobic anticancer drugs.

Chitosan-based core-shell nanomaterials for pH-triggered release of anticancer drug and near-infrared bioimaging.

As a naturally-abundant biopolymer, chitosan (CS) exhibit pH-sensitive structural transformation within a narrow pH range. Integrating hydrophobic groups to CS molecules gives modified CS polymers with more adjustable pH responsiveness. In this paper, near-infrared (NIR) photoluminescent Ag2S QDs capped by long-chain carboxylic acid were synthesized and then conjugated with CS via esterification reaction. The anticancer drug doxorubicin (DOX) has an affinity for the hydrophobic oleoyl groups and was entrapped by them to produce Ag2S(DOX)@CS nanospheres. A variety of experiments were performed to characterize the nanospheres. In vitro and in vivo experiments showed that the nanospheres can release DOX at lowered pH in tumor cells and have high antitumor efficacy. In addition, the strong NIR signal derived from the encapsulated Ag2S QDs makes real-time monitoring of the nanosphere distribution in a body possible. This study provides a new CS-based nanocomposite drug carrier for efficient cancer therapy.

Synthesis and evaluations of an acid-cleavable, fluorescently labeled nucleotide as a reversible terminator for DNA sequencing.

An acid-cleavable linker based on a dimethylketal moiety was synthesized and used to connect a nucleotide with a fluorophore to produce a 3'-OH unblocked nucleotide analogue as an excellent reversible terminator for DNA sequencing by synthesis.

Design and synthesis of fluorescence-labeled nucleotide with a cleavable azo linker for DNA sequencing.

A cleavable azo linker was synthesized and reacted with 5-(6)-carboxytetramethyl rhodamine succinimidyl ester, followed by further reactions with di(N-succinimidyl) carbonate and 5-(3-amino-1-propynyl)-2'-deoxyuridine 5'-triphosphate [dUTP(AP3)] to obtain the terminal product dUTP-azo linker-TAMRA as a potential reversible terminator for DNA sequencing by synthesis with no need for 3'-OH blocking.

Redox-responsive micelles self-assembled from dynamic covalent block copolymers for intracellular drug delivery.

Redox-responsive micelles self-assembled from dynamic covalent block copolymers with double disulfide linkage in the backbone have been developed successfully. The amphiphilic block copolymers PEG-PLA associated with complementary H-bonding sequences can self-assemble into spherical micelles in aqueous media with sizes from 34 nm to 107 nm with different molar mass of PEG and PLA. Moreover, in vitro drug release analyses indicate that reductive environment can result in triggered drug release profiles. The glutathione (GSH) mediated intracellular drug delivery was investigated against HeLa human cervical carcinoma cell line. Flow cytometry and fluorescence microscopy measurements demonstrated that the micelles exhibited faster drug release in glutathione monoester (GSH-OEt) pretreated HeLa cells than that in the nonpretreated cells. Cytotoxicity assay of DOX-loaded micelles indicated the higher cellular proliferation inhibition against 10 mM of GSH-OEt pretreated HeLa cells than that of the nonpretreated ones. These reduction-responsive, biodegradable and biocompatibility micelles could provide a favorable platform to construct excellent drug delivery systems for cancer therapy.

Design and synthesis of new acid cleavable linkers for DNA sequencing by synthesis.

A new kind of acid sensitive tetrahydrofuranyl (THF) linker was synthesized and then reacted with 5-(6)-carboxytetramethylrhodaminesuccinimidyl ester (5(6)-TAMRA, SE), followed by di(N-succinimidyl) carbonate (DSC) and modified 2'-deoxyuridine triphosphate (dUTP); the final product, as a reversible terminator for DNA sequencing by synthesis (DNA SBS), was given obtained and confirmed by 1H-NMR, 31P-NMR, and HRMS with purity of up to 99%. The synthesized dye-labeled terminator incorporated into DNA strand successfully, and the fluorophore was cleaved completely under acidic conditions. The preliminary results encourage us to explore more acid-sensitive linkers for DNA SBS to increase the cleavage efficiency under weakly acidic conditions.

Synthesis and 188Re radiolabelling of dendrimer polyamide amine (PAMAM) folic acid conjugate.

Folic acid receptors (FR) are usually over expressed in many cancer cells and are considered as potential targeted therapy agent. Generation of five polyamido amine (PAMAM) dendrimer folic acid conjugate was synthesised and radiolabelled with (188)Re, furthermore the in vitro/in vivo stability was evaluated accordingly. The labelling yield of the conjugate G5-FA-DTPA-(188)Re was 67.1% and its radiochemical purity exceeded 95%. The conjugate also showed high in vitro stability and potential value for further structure modifications and evaluations.

Oral absorbable fat-soluble vitamin formulation in pediatric patients with cholestasis.

OBJECTIVE: Fat-soluble vitamin (FSV) deficiencies are common complications in pediatric patients with chronic cholestasis. The aim of the present study was to evaluate the status of FSV deficiencies in patients under present practice and to test the effect of an oral, absorbable, fat-soluble vitamin formulation (OAFSV) in these patients. METHODS: We recruited a total of 23 pediatric patients receiving conventional FSV supplementation in a single medical center, with diagnosis of biliary atresia (10), progressive familial intrahepatic cholestasis (9), Alagille syndrome (2), and other conditions (2). Ten patients switched to OAFSV and continued for 3 months. Plasma levels of vitamins A, D, and E and an international normalized ratio (INR) for prothrombin time (PT), a surrogate marker for vitamin K deficiency, were measured. RESULTS: The proportion of patients with FSV A, D, E, and K deficiencies under conventional supplementation was 73.9%, 81.8%, 91.3%, and 20.0%, respectively. In patients with total bilirubin levels ≥3.0  mg/dL, the proportion of at least 1 FSV deficiency was 100%; and the deficiency rates of vitamin A, D, E, and K were 78.6%, 100.0%, 100.0% and 21.4%, respectively. Of the 10 patients receiving standard daily dose of OAFSV for 3 months, no adverse events or overdose effects were found. The rates of vitamin A, D, and E deficiency in the patients receiving OAFSV decreased from 80.0%, 100%, and 100%, respectively, to 70.0%, 60.0%, and 60.0% after 3 months of oral supplementation. CONCLUSIONS: High rates of FSV deficiency were found in pediatric patients with chronic cholestasis under present follow-up. OAFSV supplementation is safe and potentially effective in pediatric patients with cholestasis.

Characteristics and incidences of pediatric Crohn's disease in the decades before and after 2000.

OBJECTIVE: The increasing incidence of pediatric Crohn's disease (CD) is well known in Western countries in the last two decades. This study was conducted to delineate the trends of incidence during this period and clinical patterns of pediatric CD in Taiwan. METHODS: All children admitted to National Taiwan University Hospital between 1990 and 2009 who met the Porto Criteria for CD were included. Annual enrollment and clinical characteristics were retrospectively reviewed. The incidence was calculated by dividing the number of index cases by total hospitalized pediatric cases to minimize the bias caused by the growing number of hospitalized patients there. We quoted data and statistics from the Department of Health, Executive Yuan, Taiwan, and Accounting and Statistics, Executive Yuan, Taiwan, to present the social-economic changes in Taiwan in the recent decades. RESULTS: The cumulative hospital-based incidence of CD rose from 13.2 per 100,000 to 25.4 per 100,000 children admitted to this hospital in the past two decades. The median age of diagnosis in the first decade of this study was less than that of the second decade. The other study parameters, including gender, disease activity at diagnosis, duration from disease onset to diagnosis, anatomic location and disease behavior, and symptoms at diagnosis, were not different. CONCLUSIONS: This study showed that the hospital-based incidence of pediatric CD has been increasing in Taiwan in recent decades. Factors contributing to such an increase could be physicians' awareness of the disease, easier access to health care, and environmental factors.

Radiosynthesis, biodistribution and micro-SPECT imaging study of dendrimer-avidin conjugate.

Partially acetylated generation five polyamidoamine (PAMAM) dendrimer (G5-Ac) was reacted with biotin and 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetria minepentaacetic acid (1B4M-DTPA), respectively to form the complex Bt-G5-Ac-1B4M which was further conjugated with avidin to give the conjugate Av-G5-Ac-1B4M. Then both of the conjugates were radiolabeled with technetium-99m ((99m)Tc), respectively. Their in vitro cellular uptake study shows that the conjugate of Av-G5-Ac-1B4M-(99m)Tc exhibits much higher cellular uptake in HeLa cells than that of Bt-G5-Ac-1B4M-(99m)Tc. Accordingly the following evaluation such as in vitro/in vivo stability, biodistribution and micro-SPECT imaging was observed only for the conjugate of Av-G5-Ac-1B4M-(99m)Tc.

[Tragus cartilage tympanoplasty for treatment of adhesive otitis media].

OBJECTIVE: To evaluate the efficacy of cartilage tympanoplasty in the treatment of adhesive otitis media. METHODS: From June to October, 2008, 18 patients with adhesive otitis media (18 ears) were treated with tragus cartilage tympanoplasty. The air-bone gap changes and the self-perceived symptomatic improvement were evaluated at 1 month and 1 year after the operation. RESULTS: All the patients showed dry ear within 6 weeks after the operation. Tympanic membrane healing was achieved in 17 cases, and 1 case presented with a inferior-anterior fissure in the tympanic membrane. With the average preoperative air-bone gap (at 0.25, 0.5, 1.0, and 2.0 kHz) of 44.65 dB, the patients showed an obvious decrease of the air-bone gap by over 10 dB at 1 month after the operation and by over 25 dB at one year. Symptomatic improvements were achieved in these cases, including alleviated ear discomforts (3/15 cases), total tinnitus relief (1/11 cases), and alleviated tinnitus (10/11 cases). High-frequency tinnitus was noted in 1 case (1/7 cases), and the tympanic membrane appeared normal in 17 cases. CONCLUSION: Tympanic membrane reconstruction using the tragus cartilage can be feasible for treatment of secretory otitis media, but the surgical indications should be carefully controlled.

Synthesis and binding affinities of Re(I) and (99m)Tc(I)-containing 16alpha-substituted estradiol complexes: Models for potential breast cancer imaging agents.

To develop technetium and rhenium-labeled imaging agents for estrogen receptor (ER) positive breast tumors, we have synthesized tridentate metal tricarbonyl chelates substituted at the 16alpha-position of estradiol. Their structures were characterized by IR, (1)H NMR, (13)C NMR, HRMS or elemental analysis. The rhenium complex 7b showed the highest ER binding affinity (RBA=25.7) among these compounds, so ligand 6b was selected to be labeled by the precursor [(99m)Tc(H(2)O)(3)(CO)(3)](+) to yield technetium(I)-99m complex 7b' with good radiochemical yields. The lipophilicity of corresponding technetium(I)-99m complex 7b' was appropriately reduced, which might be favorable to target tissue selectivity in vivo. The stability of complex 7b' is excellent in 1mM histidine, 1mM cysteine, PBS and bovine serum within 6h in vitro.

Synthesis, biodistribution, and microsingle photon emission computed tomography (SPECT) imaging study of technetium-99m labeled PEGylated dendrimer poly(amidoamine) (PAMAM)-folic acid conjugates.

Three conjugates based on dendrimer PAMAM generation five were synthesized and radiolabeled successfully. To investigate their tumor targeting, the in vitro and in vivo stability, cell uptake, in vivo biodistribution, and micro-SPECT imaging were evaluated, respectively. The conjugate of (99m)Tc labeled PEGylated dendrimer PAMAM folic acid conjugate ((99m)Tc-G5-Ac-pegFA-DTPA) shows much higher uptake in KB cancer cells and accumulated more in the tumor area than that of the other two conjugates. The uptake in KB cells depends on the incubation time. The results of in vivo biodistribution agree with the data obtained from micro-SPECT imaging. These studies show that PEGylation of PAMAM dendrimer folic acid conjugate improves the tumor targeting. Folate-conjugated dendrimer maybe developed to be potential radiopharmaceuticals and targeted drug delivery systems.

Design, synthesis, and evaluation of cyclofenil derivatives for potential SPECT imaging agents.

To develop technetium- and rhenium-labeled nonsteroidal estrogen imaging agents for estrogen receptor (ER) positive breast tumors, two groups of rhenium and technetium cyclofenil derivatives were synthesized and characterized. The binding affinities of the rhenium complexes for ERs were determined. The tricarbonyl rhenium complex showed the highest binding affinity for ERs (81.2 for ERbeta, 16.5 for ERalpha). Tricarbonyl technetium cyclofenil complexes were obtained in high radiochemical purity and radiochemical yields. The results of studies of their octanol/water partition and in vitro stability are presented. These results demonstrate that these radiolabeled cyclofenil derivatives may be considered as potential breast cancer imaging agents.

Radiosynthesis and micro-SPECT imaging of 99mTc-dendrimer poly(amido)-amine folic acid conjugate.

Acetylated (Ac) dendrimer poly(amido)-amine (PAMAM) generation 5 (G5) reacted with folic acid (FA), followed by reacting with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetria minepentaacetic acid (1B4M DTPA) to form the conjugate of Ac-G5-FA-1B4M DTPA which was further radiolabeled with (99m)Tc. The radiochemical yield is up to 98.9% with excellent in vitro/in vivo stability, rapid blood clearance and certain tumor accumulation which was further confirmed by micro-SPECT imaging study.

Early development of acute myeloid leukemia following treatment of osteosarcoma: a case report and review of the literature.

We report a case of treatment-related acute myeloid leukemia (t-AML) in a 16-year-old male following treatment for osteosarcoma (OS). He had been treated with a protocol comprising neoadjuvant chemotherapy, definitive surgery with wide excision and adjuvant chemotherapy for OS. Four months after completion of the treatment, a routine hemogram showed hyperleukocytosis with 90% blasts. Bone marrow aspirate and a chromosomal analysis disclosed acute myeloid leukemia (AML), M5b with 46, XY, t(11;19)(q23;p13.3). The t-AML was characterized by early development (just 4 months after completion of chemotherapy for OS) and generalized leukemia cutis. The patient received an alkylating agent (ifosfamide) and DNA topoisomerase II-targeted drugs (etoposide and doxorubicin). In terms of latency, cytogenetics, and presentation, DNA topoisomerase II-targeted drug-related leukemia seemed likely for this patient. Clinically, his leukemia cutis had developed during a nadir in white blood cell count after the first induction of chemotherapy for AML. The rapid progression and its refractoriness to chemotherapy were poor prognostic signs.

Synthesis and antimicrobial evaluation of bile acid tridentate conjugates.

Two series of novel bile acid tridentate conjugates with different linkers were synthesized and characterized, and their biological activities in vitro were evaluated. The procedure was straightforward and efficient to be carried out with high overall yield. The antimicrobial activity of the synthesized compounds against Saccharomyces cerevisiae, Aspergillus niger, Escherichia coli and Staphylococcus aureus was investigated in vitro. The best activity of minimal inhibitory concentrations (MICs) for 1c, 1c', 2c and 2c' against S. cerevisiae was up to 0.125 microg/mL.