Carbon trading for phosphorus gain: the balance between rhizosphere carboxylates and arbuscular mycorrhizal symbiosis in plant phosphorus acquisition

Two key plant adaptations for phosphorus (P) acquisition are carboxylate exudation into the rhizosphere and mycorrhizal symbioses. These target different soil P resources, presumably with different plant carbon costs. We examined the effect of inoculation with arbuscular mycorrhizal fungi (AMF) on amount of rhizosphere carboxylates and plant P uptake for 10 species of low-P adapted Kennedia grown for 23 weeks in low-P sand. Inoculation decreased carboxylates in some species (up to 50%), decreased plant dry weight (21%) and increased plant P content (23%). There was a positive logarithmic relationship between plant P content and the amount of rhizosphere citric acid for inoculated and uninoculated plants. Causality was indicated by experiments using sand where little citric acid was lost from the soil solution over 2 h and citric acid at low concentrations desorbed P into the soil solution. Senesced leaf P concentration was often low and P-resorption efficiencies reached >90%. In conclusion, we propose that mycorrhizally mediated resource partitioning occurred because inoculation reduced rhizosphere carboxylates, but increased plant P uptake. Hence, presumably, the proportion of plant P acquired from strongly sorbed sources decreased with inoculation, while the proportion from labile inorganic P increased. Implications for plant fitness under field conditions now require investigation.

Functionalized mesoporous silica particles for application in drug delivery system

In these years, ordered mesoporous silica materials have shown promising applications in drug delivery system as drug carriers. These carriers with stable mesoporous structure, large surface area, good biocompatibility and tailored size of mesopores exhibit significant property of higher drug loading. However, silica-based mesoporous materials cannot control the release of the loaded drug without modifications. In this paper, we review the recent research work discussing functionalization of mesoporous materials by various components and methods for application in drug delivery systems. All the examples show that these functionalized mesoporous silica-based systems have great potential for a variety of drug delivery applications, specifically in the fields of the drug targeted and controlled delivery systems.

Vitreous surgery for macular hole-related retinal detachment after phacoemulsification cataract extraction: 10-year retrospective review

PURPOSE

To evaluate the visual and anatomical results of surgery for macular hole-related retinal detachment (MHRD) after phacoemulsification cataract extraction.

METHODS

Data for all patients who underwent surgery for MHRD after phacoemulsification cataract extraction from 1 December 1998 to 30 September 2008 in one hospital were evaluated. Patient characteristics, best-corrected visual acuity (VA) preoperatively and at last examination, surgical technique, anatomical success, and follow-up period were extracted and analysed statistically.

RESULTS

A total of 13 625 eyes of 10 076 patients who had phacoemulsification cataract surgery were included. In the follow-up period, 10 cases of MHRD in nine patients were observed, of which seven eyes had high myopia. The mean axial length was 30.97 ± 1.36 mm (29.19, 32.97) and mean myopia was-19.35 ± 1.93 (-7.5,-3.5) dioptres. Overall anatomical success was achieved in 90% (9 out of 10 eyes). There was no statistically significant difference (P=0.240) between the logarithm of the MAR VA before the phacoemulsification cataract extraction and after MHRD surgical repair. VA increased in three eyes but decreased in the other seven after MHRD surgery.

CONCLUSIONS

As a primary procedure, vitreous surgery combined with other necessary adjunct procedures such as membrane peeling and retinal tamponade seems to be successful in achieving anatomical success. However, VA improvement is dependent on the type of macular lesion and not the surgical procedure.

Abstract 1111: Synthetic microRNA (miR)-181a nanoparticles (NP) target RAS and sensitize cells to daunorubicin (DNR) in acute myeloid leukemia (AML)

Most AML patients (pts) fail to achieve long-term survival with current treatments. New therapeutic options are needed. We recently showed that high miR-181a expression is associated with better outcome in AML pts with normal karyotype, but the mechanisms underlying this achievement are unknown. Aberrant activation of RAS due to mutations or overexpression is frequent in human malignancies, including AML. MiR-181a has been shown to target KRAS. In this study, we show that it also targets NRAS. With luciferase reporter constructs spanning the predicted binding site in NRAS we found a 25% decrease in luciferase activity after co-transfection with miR-181a vs scramble control (sc) in 293T cells. Reduced KRAS & NRAS levels were found in miR-181a vs sc transfected OCI-AML3 and KG1a at mRNA (1.9 & 1.4 and 3.2 & 2.9 fold, respectively) & protein levels (2.2 & 1.5 and 1.7 & 1.3 fold, respectively). Thus increasing miR-181a may improve outcome in AML pts by inhibiting RAS signaling. Free synthetic miRs are degraded in bio-fluid & have limited cellular uptake. We developed a novel non-viral delivery system for synthetic miRs that overcomes these limitations. Polyethylenimine was used to capture synthetic miRs & form a polyplex core. An outside lipid layer of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, linoleic acid & 1,2-dimyristoyl-sn-glycerol-3-phosphoethanolamine, methoxypolyethylene glycol protected the miRs from degradation & clearance & facilitated their uptake. Since AML cells overexpress the transferrin (Tf) receptor, we conjugated the NPs with Tf for targeted delivery. Mature miR-181a in OCI-AML3 & KG1a cells were measured by qPCR after treatment with TfNP encapsulating precursor miR-181a (pM181a) molecules (TfNP181a) or sc (TfNPsc) at 0.5 nM. At 24h mature miR-181a levels increased 50 fold in OCI-AML3 & 15 fold in KG1a cells, while the levels of unrelated miR-140 remained unchanged. We found that delivered pM181a downregulated levels of KRAS & NRAS at mRNA and protein levels (OCI-AML3: 2 & 3 fold and 4.4 & 11.3 fold; KG1a: 1.7 & 1.6 fold, and 5 & 2.7 fold, respectively) vs. TfNPsc treatment. To analyze downstream effects we measured MAPK & p-MAPK protein & observed a TfNP181a-mediated decrease of p-MAPK by 2.9 & 3.2 fold in OCI-AML3 & KG1a vs. TfNPsc treatment. Next we tested if TfNP181a sensitized AML cells to chemotherapy (DNR). After priming with 0.5 nM TfNP181a or TfNPsc (for 48h) OCI-AML3 cells were treated with 0.2 uM DNR (for 72h). MTS assays showed decreased cell viability for priming: 44.5% vs 82.5% (p<0.01). We confirmed these findings in primary pt blasts 62.4% (TfNP181a) vs. 96.5% (TfNPsc) (p<0.01). In conclusion we report an effective NP-based delivery system for miRs. TfNP181a treatment showed RAS downregulation, RAS signaling inhibition & increased sensitivity to DNR in AML cells. TfNP181a may be a new therapeutic in AML & other malignancies involving RAS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1111. doi:1538-7445.AM2012-1111

Abstract 921: Liposomal bortezomib improves chemosensitivity and inhibits cell proliferation in part through BCR/ABL downregulation in CML

The t(9;22) Philadelphia chromosome translocation fuses the BCR gene to the c-ABL proto-oncogene resulting in a chimeric BCR/ABL protein. Although BCR/ABL inhibitor imatinib has shown unprecedented efficacy for treatment of chronic myeloid leukemia (CML), resistance to this agent due to BCR/ABL mutations or increased protein expression poses a significant clinical problem, thereby arguing for novel therapeutic approaches. BCR/ABL gene amplification frequently occurs in blast crisis and BCR/ABL expression is required for its mutation. BCR promoter contains Sp1 binding sites and proteasome inhibitor bortezomib (BORT) disrupts Sp1 transactivation, therefore, we hypothesized that BORT could abolish BCR/ABL expression leading to disrupted kinase activity. However, the fast clearance and the inability to reach target cells in vivo have limited its application. As such, we designed a liposomal BORT (L-BORT) and transferrin receptor (TfR)-targeted L-BORT (Tf-L-BORT) for the objective of enhancing BORT delivery efficiency. We observed that there were 3.6-fold and 10.4-fold increases in cellular uptake of L-BORT and Tf-L-BORT, respectively, compared to that of the free drug. We evidenced a 2.7-fold augmented chemosensitivity to doxorubicin (DOX) in cells exposed to subtoxic concentration of BORT, with a decrease in IC50 from 8 μM to 300 nM. Tf-L-BORT further reduced IC50 of DOX to 90 nM. These data indicated the enhanced chemosensitizing efficacy of the L-BORT formulations. When single tumor cells from K562 tumor bearing mice were treated by subtoxic L-BORT combined with DOX, a synergy of toxicity was evidenced by 70-fold increased chemosensitivity (p<0.05). Tf-L-BORT was more effective in chemosensitizing tumor single cells than L-BORT, with decreased IC50 of DOX to 94 nM. Pharmacokinetic study in mice after i.v. bolus injection showed that L-BORT had slower tissue distribution (T1/2α, 7.3 min vs. 2.9 min), increased elimination phase half-life (T1/2α, 82.9 h vs. 68.3 h), decreased clearance (CL, 4.2 mL/h vs. 27.7 mL/h), and increased area under the plasma concentration-time curve (AUC, 4714.1 h·ng/mL vs. 721.4 h·ng/mL) compared to the free drug. This indicated a significant and potentially beneficial change in BORT pharmacokinetics in vivo. Mechanistically, when K562 cells were exposed to L-BORT (0, 10, 30 and 60nM) or DOX (0, 100, 200 and 500nM) for 48h, BCR/ABL protein was significantly decreased in a dose-dependent manner. Interestingly, the combination of L-BORT with DOX synergistically abrogated BCR/ABL and Sp1 protein expression. Altogether, these results highlight the therapeutic relevance of disrupting BCR/ABL protein expression and strongly support the utilization of L-BORT alone or in combination with DOX to treat CML patients harboring overexpressed BCR/ABL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 921. doi:1538-7445.AM2012-921

Prophylaxis and management of acute radiation-induced skin reactions: a systematic review of the literature

Radiation therapy is a common treatment for cancer patients. One of the most common side effects of radiation is acute skin reaction (radiation dermatitis) that ranges from a mild rash to severe ulceration. Approximately 85% of patients treated with radiation therapy will experience a moderate-to-severe skin reaction. Acute radiation-induced skin reactions often lead to itching and pain, delays in treatment, and diminished aesthetic appearance-and subsequently to a decrease in quality of life. Surveys have demonstrated that a wide variety of topical, oral, and intravenous agents are used to prevent or to treat radiation-induced skin reactions. We conducted a literature review to identify trials that investigated products for the prophylaxis and management of acute radiation dermatitis. Thirty-nine studies met the pre-defined criteria, with thirty-three being categorized as prophylactic trials and six as management trials.For objective evaluation of skin reactions, the Radiation Therapy Oncology Group criteria and the U.S. National Cancer Institute Common Toxicity Criteria were the most commonly used tools (65% of the studies). Topical corticosteroid agents were found to significantly reduce the severity of skin reactions; however, the trials of corticosteroids evaluated various agents, and no clear indication about a preferred corticosteroid has emerged. Amifostine and oral enzymes were somewhat effective in preventing radiation-induced skin reactions in phase II and phase III trials respectively; further large randomized controlled trials should be undertaken to better investigate those products. Biafine cream (Ortho-McNeil Pharmaceuticals, Titusville, NJ, U.S.A.) was found not to be superior to standard regimes in the prevention of radiation-induced skin reactions (n = 6).In conclusion, the evidence is insufficient to support the use of a particular agent for the prevention and management of acute radiation-induced skin reactions. Future trials should focus on comparing agents and approaches that, in phase I and II trials, suggest efficacy. These future phase III randomized controlled trials must clearly distinguish between preventive and management strategies for radiation-induced dermatitis. Only then can evidence-based guidelines be developed, with the hope of standardizing the approach across centres and of improving the prevention and management of radiation-induced dermatitis.

Changes of serum omentin levels and relationship between omentin and adiponectin concentrations in type 2 diabetes mellitus

BACKGROUND

Omentin has recently been characterized as a potent insulin-sensitizing adipokine, but its pathophysiologic roles in humans remain largely unknown.

OBJECTIVE

To investigate the change of fasting serum omentin levels and evaluate the relationship of omentin with adiponectin in patients with type 2 diabetes mellitus.

DESIGN

35 patients with newly diagnosed type 2 diabetes (T2DM), 35 patients with impaired glucose regulation (IGT) and 35 patients with normal glucose tolerance (NGT) participated in this study. Fasting serum omentin and adiponectin levels were measured by enzyme-linked immunosorbent assay. The relationship between serum omentin, serum adiponectin levels and metabolic parameters was also analyzed.

RESULTS

Fasting serum omentin levels were significantly lower in T2DM and IGT groups than in NGT group (16.75±1.71 vs. 18.62±1.22 vs. 24.60±1.43 ng/ml, all P<0.01). Obesity subjects had significantly lower serum omentin levels than normal body weight subjects ( P<0.01 or P<0.05). Female subjects had moderately higher fasting serum omentin levels than male subjects. Fasting serum adiponectin levels showed a similar variation trend to omentin in T2DM and NGT groups, obesity and normal body weight subjects, female and male subjects. Fasting serum omentin levels were negatively correlated with HOMA-IR and positively correlated with adiponectin. Moreover, HOMA-IR and adiponectin were the independently predictors of fasting serum omentin levels.

CONCLUSIONS

Serum omentin levels possibly play an important role in the pathogenesis of insulin resistance and diabetes. More importantly, there is such a close connection between serum omentin and adiponectin levels that regulation of omentin may be dependent on adiponectin.

Extramammary Paget disease: review of patients seen in a non-melanoma skin cancer clinic

Extramammary Paget disease (EMPD) is a rare skin disease commonly found in the anogenital region. In this study, we aimed to identify EMPD patients seen in the non-melanoma skin cancer clinic at Odette Cancer Centre and to describe the treatments delivered and outcomes achieved. From 2000 to 2009, 14 patients were seen. Initial treatment recommendations included imiquimod and surgical excision, although half the patients required more than one treatment modality, highlighting the difficulty of achieving complete eradication of this disease.

Expression profiling identifies new function of collapsin response mediator protein 4 as a metastasis-suppressor in prostate cancer

Metastasis is the chief cause of mortality from cancer, but the mechanisms leading to metastasis are poorly understood. We used a proteomics approach to screen for metastasis-associated proteins and found that collapsin response mediator protein-4 (CRMP4) expression was inversely associated with the lymph node metastasis of prostate cancer (PCa). Subsequent in vitro and in vivo studies revealed that overexpression of CRMP4 not only suppressed the invasion ability of PCa cells, but also strongly inhibited tumor metastasis in an animal model. Furthermore, methylation of a CpG island within the promoter region of the CRMP4 gene is responsible for downregulation of CRMP4 expression. Thus, in this study, we show new function of CRMP4 as a metastasis-suppressor in PCa. The findings provide new mechanistic insights into metastasis and therapeutic potential for this most common male cancer.

Targeted delivery of antisense oligodeoxynucleotide by transferrin conjugated pH-sensitive lipopolyplex nanoparticles: a novel oligonucleotide-based therapeutic strategy in acute myeloid leukemia

Therapeutic use of oligodeoxynucleotides (ODNs) that hybridize to and downregulate target mRNAs encoding proteins that contribute to malignant transformation has a sound rationale, but has had an overall limited clinical success in cancer due to insufficient intracellular delivery. Here we report a development of formulations capable of promoting targeted delivery and enhanced pharmacologic activity of ODNs in acute myeloid leukemia (AML) cell lines and patient primary cells. In this study, transferrin (Tf) conjugated pH-sensitive lipopolyplex nanoparticles (LPs) were prepared to deliver GTI-2040, an antisense ODN against the R2 subunit of ribonucleotide reductase that has been shown to contribute to chemoresistance in AML. LPs had an average particle size around 110 nm and a moderately positive zeta potential at approximately 10 mV. The ODN encapsulation efficiency of LPs was >90%. These nanoparticles could release ODNs at acidic endosomal pH and facilitate the cytoplasmic delivery of ODNs after endocytosis. In addition, Tf-mediated targeted delivery of GTI-2040 was achieved. R2 downregulation at both mRNA and protein levels was improved by 8-fold in Kasumi-1 cells and 2- to 20-fold in AML patient primary cells treated with GTI-2040-Tf-LPs, compared to free GTI-2040 treatment. Moreover, Tf-LPs were more effective than nontargeted LPs, with 10 to 100% improvement at various concentrations in Kasumi-1 cells and an average of 45% improvement at 3 microM concentration in AML patient primary cells. Treatment with 1 microM GTI-2040-Tf-LPs sensitized AML cells to the chemotherapy agent cytarabine, by decreasing its IC(50) value from 47.69 nM to 9.05 nM. This study suggests that the combination of pH sensitive LP formulation and Tf mediated targeting is a promising strategy for antisense ODN delivery in leukemia therapy.

Abstract 3558: The natural product silvestrol decreases oncogenic FLT3 and miR-155 levels in FLT3-ITD positive Acute Myeloid Leukemia (AML) cells

Despite improvement in our understanding of leukemogenic mechanisms, the majority of AML patients (pts) fail to achieve long-term survival and die of their disease. Therefore, new therapeutic options are needed. Silvestrol, a natural product isolated from Aglaia foveolata, has been shown to have potent antitumor activity, most likely through inhibition of initiation of translation. Promising synergistic effects of silvestrol with chemotherapy were shown in AML, but the exact mechanism mediating the antileukemic activity remains to be fully elucidated. Recently, microRNAs (miRs), short non-coding RNAs, have been recognized to contribute to leukemogenesis by inhibiting expression of targeted tumor suppressor genes. Therefore, we hypothesized that the antileukemic effect of silvestrol may at least be partly mediated by activity on miRs. We investigated the effects of silvestrol on the expression of a panel of miRs previously linked to AML (miR-29a, miR-29b, miR-29c, miR-181a, miR-34a & miR-155) by quantitative RT-PCR in representative AML cell lines (MV4-11, Kasumi-1, K562). Among the miRs measured, miR-155 was the only one found to be altered, with &gt;40% reduction from baseline following 24h silvestrol treatment (50nM). MiR-155 has a known oncogenic effect in leukemia and is up-regulated in FLT3-ITD (internal tandem duplication)-positive blasts. FLT3 encodes a tyrosine kinase membrane receptor, and the FLT3-ITD mutation is carried by ∼30% of all AML pts. FLT3-ITD supports abnormal myeloid blast proliferation and survival, and predicts dismal outcome. Silvestrol treatment of FLT3-ITD-positive MV4-11 cells resulted in a sustained 40% decrease of miR-155 expression observed as early as 6h post-treatment, as well as down-regulation (80%) of FLT3 mRNA and protein expression compared with vehicle-treated controls as measured by quantitative RT-PCR and immunoblotting respectively. We confirmed this finding by demonstrating a significant reduction of FLT3 surface expression by flow cytometry. These effects were associated with a significant antiproliferative and apoptotic activity of silvestrol on MV4-11 cells (IC50 &lt;10nM at 48h) as measured by MTS assays and annexin/PI staining. We conclude that silvestrol has a potent cytotoxic activity on mir-155 and FLT3-ITD expressing AML cells. The finding that FLT3-ITD expression was down-regulated not only at the protein level but also at the RNA level suggests that the effect of silvestrol on FLT3 mutants may be in part mediated by previously unreported mechanisms other than translational inhibition. Our data support further investigation to elucidate these novel aspects of the antileukemic activity of silvestrol in specific subsets of AML and the design of therapeutic studies testing this compound alone and/or in combination with other tyrosine kinase inhibitors in FLT3-ITD-driven AML.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3558.

Sp1/NFkappaB/HDAC/miR-29b regulatory network in KIT-driven myeloid leukemia

The biologic and clinical significance of KIT overexpression that associates with KIT gain-of-function mutations occurring in subsets of acute myeloid leukemia (AML) (i.e., core binding factor AML) is unknown. Here, we show that KIT mutations lead to MYC-dependent miR-29b repression and increased levels of the miR-29b target Sp1 in KIT-driven leukemia. Sp1 enhances its own expression by participating in a NFkappaB/HDAC complex that further represses miR-29b transcription. Upregulated Sp1 then binds NFkappaB and transactivates KIT. Therefore, activated KIT ultimately induces its own transcription. Our results provide evidence that the mechanisms of Sp1/NFkappaB/HDAC/miR-29b-dependent KIT overexpression contribute to leukemia growth and can be successfully targeted by pharmacological disruption of the Sp1/NFkappaB/HDAC complex or synthetic miR-29b treatment in KIT-driven AML.

Self-complementary AAV-mediated gene therapy restores cone function and prevents cone degeneration in two models of Rpe65 deficiency

To test whether fast-acting, self-complimentary (sc), adeno-associated virus-mediated RPE65 expression prevents cone degeneration and/or restores cone function, we studied two mouse lines: the Rpe65-deficient rd12 mouse and the Rpe65-deficient, rhodopsin null ('that is, cone function-only') Rpe65(-/-)::Rho(-/-) mouse. scAAV5 expressing RPE65 was injected subretinally into one eye of rd12 and Rpe65(-/-)::Rho(-/-) mice at postnatal day 14 (P14). Contralateral rd12 eyes were injected later, at P35. Rd12 behavioral testing revealed that rod vision loss was prevented with either P14 or P35 treatment, whereas cone vision was only detected after P14 treatment. Consistent with this observation, P35 treatment only restored rod electroretinogram (ERG) signals, a result likely due to reduced cone densities at this time point. For Rpe65(-/-)::Rho(-/-) mice in which there is no confounding rod contribution to the ERG signal, cone cells and cone-mediated ERGs were also maintained with treatment at P14. This work establishes that a self-complimentary AAV5 vector can restore substantial visual function in two genetically distinct models of Rpe65 deficiency within 4 days of treatment. In addition, this therapy prevents cone degeneration but only if administered before extensive cone degeneration, thus supporting continuation of current Leber's congenital amaurosis-2 clinical trials with an added emphasis on cone subtype analysis and early intervention.

Comparison of the MMSE and RUDAS cognitive screening tools in an elderly inpatient population in everyday clinical use

We compared test score and performance times of Folstein's Mini Mental State Examination (MMSE) and the Rowland Universal Dementia Assessment Scale (RUDAS). Forty-six patients were recruited. The mean score was 20.6 for the MMSE and 20.5 for the RUDAS. Linear regression analysis revealed an r value of 0.83 (P < 0.05). The mean performance time was 9.4 min for both the MMSE and the RUDAS. Patient satisfaction was similar for both tests. Surveyed clinicians preferred the MMSE because of greater familiarity. We concluded that the RUDAS correlates well with the MMSE and is no more time-consuming to perform. It has good clinical utility as a cognitive screening tool.

MicroRNA-29b induces global DNA hypomethylation and tumor suppressor gene reexpression in acute myeloid leukemia by targeting directly DNMT3A and 3B and indirectly DNMT1

Aberrant DNA hypermethylation contributes to myeloid leukemogenesis by silencing structurally normal genes involved in hematopoiesis. MicroRNAs (miRNAs) are noncoding RNAs that regulate gene expression by targeting protein-coding mRNAs. Recently, miRNAs have been shown to play a role as both targets and effectors in gene hypermethylation and silencing in malignant cells. In the current study, we showed that enforced expression of miR-29b in acute myeloid leukemia cells resulted in marked reduction of the expression of DNA methyltransferases DNMT1, DNMT3A, and DNMT3B at both RNA and protein levels. This in turn led to decrease in global DNA methylation and reexpression of p15(INK4b) and ESR1 via promoter DNA hypomethylation. Although down-regulation of DNMT3A and DNMT3B was the result of a direct interaction of miR-29b with the 3' untranslated regions of these genes, no predicted miR-29b interaction sites were found in the DNMT1 3' untranslated regions. Further experiments revealed that miR-29b down-regulates DNMT1 indirectly by targeting Sp1, a transactivator of the DNMT1 gene. Altogether, these data provide novel functional links between miRNAs and aberrant DNA hypermethylation in acute myeloid leukemia and suggest a potentially therapeutic use of synthetic miR-29b oligonucleotides as effective hypomethylating compounds.

Transferrin receptor-targeted lipid nanoparticles for delivery of an antisense oligodeoxyribonucleotide against Bcl-2

Antisense oligonucleotide G3139-mediated down-regulation of Bcl-2 is a potential strategy for overcoming chemoresistance in leukemia. However, the limited efficacy shown in recent clinical trials calls attention to the need for further development of novel and more efficient delivery systems. In order to address this issue, transferrin receptor (TfR)-targeted, protamine-containing lipid nanoparticles (Tf-LNs) were synthesized as delivery vehicles for G3139. The LNs were produced by an ethanol dilution method, and lipid-conjugated Tf ligand was then incorporated by a postinsertion method. The resulting Tf-LNs had a mean particle diameter of approximately 90 nm and G3139 loading efficiency of 90.4%. Antisense delivery efficiency of Tf-LNs was evaluated in K562, MV4-11, and Raji leukemia cell lines. The results showed that Tf-LNs were more effective than nontargeted LNs and free G3139 (p < 0.05) in decreasing Bcl-2 expression (by up to 62% at the mRNA level in K562 cells) and in inducing caspase-dependent apoptosis. In addition, Bcl-2 down-regulation and apoptosis induced by Tf-LN G3139 were shown to be blocked by excess free Tf and thus were TfR-dependent. Cell lines with higher TfR expression also showed greater Bcl-2 down-regulation. Furthermore, up-regulation of TfR expression in leukemia cells by iron chelator deferoxamine resulted in a further increase in antisense effect (up to 79% Bcl-2 reduction in K562 at the mRNA level) and in caspase-dependent apoptosis (by approximately 3-fold) by Tf-LN. Tf-LN-mediated delivery combined with TfR up-regulation by deferoxamine appears to be a potentially promising strategy for enhancing the delivery efficiency and therapeutic efficacy of antisense oligonucleotides.

A LC-MS/MS method for the analysis of intracellular nucleoside triphosphate levels

PURPOSE

To simultaneously quantify intracellular nucleoside triphosphate (NTP) and deoxynucleoside triphosphate (dNTP) pools and to assess their changes produced by interfering with ribonucleotide reductase (RNR) expression in leukemia cells.

METHODS

A HPLC-MS/MS system was used to quantify intracellular NTP and dNTP pools.

RESULTS

The assay was linear between 50 nM, the lower limit of quantification (LLOQ), and 10 muM in cell lysate. The within-day coefficients of variation (CVs, n = 5) were found to be 12.0-18.0% at the LLOQ and 3.0-9.0% between 500 and 5,000 nM for dNTPs and 8.0-15.0% and 2.0-6.0% for NTPs. The between-day CVs (n = 5) were 9.0-13.0% and 3.0-11.0% for dNTPs and 9.0-13.0% and 3.0-6.0% for NTPs. The within-day accuracy values were 93.0-119.0% for both NTPs and dNTPs. ATP overlapped with dGTP and they were analyzed as a composite. This method was applied to measure basal intracellular dNTPs/NTPs in five leukemia cell lines exposed to the RNR antisense GTI-2040. Following drug treatment, dCTP and dATP levels were found to decrease significantly in MV4-11 and K562 cells. Additionally, perturbation of dNTP/NTP levels in bone marrow sample of a patient treated with GTI-2040 was detected.

CONCLUSIONS

This method provides a practical tool to measure intracellular dNTP/NTP levels in cells and clinical samples.

Modulation of DNA methylation by a sesquiterpene lactone parthenolide

Hypermethylation of 5'-cytosine-guanosine islands of tumor suppressor genes resulting in their silencing has been proposed to be a hallmark of various tumors. Modulation of DNA methylation with DNA methylation inhibitors has been shown to result in cancer cell differentiation or apoptosis and represents a novel strategy for chemotherapy. Currently, effective DNA methylation inhibitors are mainly limited to decitabine and 5-azacytidine, which still show unfavorable toxicity profiles in the clinical setting. Thus, discovery and development of novel hypomethylating agents, with a more favorable toxicity profile, is essential to broaden the spectrum of epigenetic therapy. Parthenolide, the principal bioactive sesquiterpene lactone of feverfew, has been shown to alkylate Cys(38) of p65 to inhibit nuclear factor-kappaB activation and exhibit anti-tumor activity in human malignancies. In this article, we report that parthenolide 1) inhibits DNA methyltransferase 1 (DNMT1) with an IC(50) of 3.5 microM, possibly through alkylation of the proximal thiolate of Cys(1226) of the catalytic domain by its gamma-methylene lactone, and 2) down-regulates DNMT1 expression possibly associated with its SubG(1) cell-cycle arrest or the interruption of transcriptional factor Sp1 binding to the promoter of DNMT1. These dual functions of parthenolide result in the observed in vitro and in vivo global DNA hypomethylation. Furthermore, parthenolide has been shown to reactivate tumor suppressor HIN-1 gene in vitro possibly associated with its promoter hypomethylation. Hence, our study established parthenolide as an effective DNA methylation inhibitor, representing a novel prototype for DNMT1 inhibitor discovery and development from natural structural-diversified sesquiterpene lactones.

Phase I study of GTI-2040, an antisense to ribonucleotide reductase, in combination with high-dose cytarabine in patients with acute myeloid leukemia

PURPOSE

Inhibition of ribonucleotide reductase reduces the availability of the endogenous pool of deoxycytidine and may increase cytarabine (AraC) cytotoxicity. We performed a phase I dose escalation trial of AraC combined with GTI-2040, a 20-mer antisense oligonucleotide shown in preclinical studies to decrease levels of the R2 subunit of ribonucleotide reductase, to determine the maximum tolerated dose in adults with relapsed/refractory acute myeloid leukemia.

EXPERIMENTAL DESIGN

Twenty-three adults (ages 18-59 years) were enrolled in this dose escalation phase I trial, receiving high-dose AraC twice daily combined with infusional GTI-2040. An ELISA-based assay measured plasma and intracellular concentrations of GTI-2040. R2 protein changes were evaluated by immunoblotting in pretreatment and post-treatment bone marrow samples.

RESULTS

The maximum tolerated dose was 5 mg/kg/d GTI-2040 (days 1-6) and 3 g/m2/dose AraC every 12 hours for 8 doses. Neurotoxicity was dose limiting. Eight patients (35%) achieved complete remission. Mean bone marrow intracellular concentration of GTI-2040 were higher at 120 hours than at 24 hours from the start of GTI-2040 (P = 0.002), suggesting intracellular drug accumulation over time. Reductions in bone marrow levels of R2 protein (>50%) were observed at 24 and 120 hours. Higher baseline R2 protein expression (P = 0.03) and reductions after 24 hours of GTI-2040 (P = 0.04) were associated with complete remission.

CONCLUSIONS

GTI-2040 and high-dose AraC were coadministered safely with successful reduction of the intended R2 target and encouraging clinical results. The clinical efficacy of this combination will be tested in an upcoming phase II study.

Bortezomib induces DNA hypomethylation and silenced gene transcription by interfering with Sp1/NF-kappaB-dependent DNA methyltransferase activity in acute myeloid leukemia

Bortezomib reversibly inhibits 26S proteasomal degradation, interferes with NF-kappaB, and exhibits antitumor activity in human malignancies. Zinc finger protein Sp1 transactivates DNMT1 gene in mice and is functionally regulated through protein abundance, posttranslational modifications (ie, ubiquitination), or interaction with other transcription factors (ie, NF-kappaB). We hypothesize that inhibition of proteasomal degradation and Sp1/NF-kappaB-mediated transactivation may impair aberrant DNA methyltransferase activity. We show here that, in addition to inducing accumulation of polyubiquitinated proteins and abolishment of NF-kappaB activities, bortezomib decreases Sp1 protein levels, disrupts the physical interaction of Sp1/NF-kappaB, and prevents binding of the Sp1/NF-kappaB complex to the DNMT1 gene promoter. Abrogation of Sp1/NF-kappaB complex by bortezomib causes transcriptional repression of DNMT1 gene and down-regulation of DNMT1 protein, which in turn induces global DNA hypomethylation in vitro and in vivo and re-expression of epigenetically silenced genes in human cancer cells. The involvement of Sp1/NF-kappaB in DNMT1 regulation is further demonstrated by the observation that Sp1 knockdown using mithramycin A or shRNA decreases DNMT1 protein levels, which instead are increased by Sp1 or NF-kappaB overexpression. Our results unveil the Sp1/NF-kappaB pathway as a modulator of DNA methyltransferase activity in human cancer and identify bortezomib as a novel epigenetic-targeting drug.

Targeting AML1/ETO-Histone Deacetylase Repressor Complex: A Novel Mechanism for Valproic Acid-Mediated Gene Expression and Cellular Differentiation in AML1/ETO-Positive Acute Myeloid Leukemia Cells

In t(8;21) acute myeloid leukemia (AML), the AML1/ETO fusion protein promotes leukemogenesis by recruiting class I histone deacetylase (HDAC)-containing repressor complex to the promoter of AML1 target genes. Valproic acid (VPA), a commonly used antiseizure and mood stabilizer drug, has been shown to cause growth arrest and induce differentiation of malignant cells via HDAC inhibition. VPA causes selective proteasomal degradation of HDAC2 but not other class I HDACs (i.e., HDAC 1, 3, and 8). Therefore, we raised the question of whether this drug can effectively target the leukemogenic activity of the AML1/ETO fusion protein that also recruits HDAC1, a key regulator of normal and aberrant histone acetylation. We report here that VPA treatment disrupts the AML1/ETO-HDAC1 physical interaction, stimulates the global dissociation of AML1/ETO-HDAC1 complex from the promoter of AML1/ETO target genes, and induces relocation of both AML1/ETO and HDAC1 protein from nuclear to perinuclear region. Furthermore, we show that mechanistically these effects associate with a significant inhibition of HDAC activity, histone H3 and H4 hyperacetylation, and recruitment of RNA polymerase II, leading to transcriptional reactivation of target genes (i.e., IL-3) otherwise silenced by AML1/ETO fusion protein. Ultimately, these pharmacological effects resulted in significant antileukemic activity mediated by partial cell differentiation and caspase-dependent apoptosis. Taken together, these data support the notion that VPA might effectively target AML1/ETO-driven leukemogenesis through disruption of aberrant HDAC1 function and that VPA should be integrated in novel therapeutic approaches for AML1/ETO-positive AML.

Broken bones and fractures - an audit of patients' perceptions

INTRODUCTION

'Have I got a fracture or a break doctor?' remains a commonly posed question in fracture clinics, suggesting that patients frequently feel a 'fracture' and a 'break' are two separate entities. This apparent misconception amongst fracture clinic patients may result in confusion and occasionally anger that doctors appear to have inconsistent views on the severity of their injury. Compliance and outcome of patient care can also be affected by poor communication.

PATIENTS AND METHODS

Our questionnaire-based study was conducted in two stages. The initial objective was to establish whether this misconception surrounding the words 'fracture' and 'break' is commonly held amongst our out-patient trauma patients. The second stage of the audit was to determine whether a patient information leaflet on fractures/broken bones could help reduce this misconception.

RESULTS

The preliminary audit involving 50 new patients attending our fracture clinic showed that 84% thought there was a difference between a 'fracture' and a 'break', with 68% believing a 'break' to be worse than a 'fracture'. Following the introduction of an information leaflet, a re-audit of 61 new patients took place. This time 67% felt there was a difference between a 'fracture' and a 'break', with 65% believing a 'break' to be worse than a 'fracture'. Only 21% had read the supplied information leaflet, and 69% of those still believed there was a difference between a 'fracture' and a 'break'.

CONCLUSIONS

The majority of patients believed that there was a difference between a 'fracture' and a 'break'. Access to information leaflets did not appear to alter this misconception. Verbal communication and explanation may be more beneficial and practical than visual aids and leaflets in overcoming this problem.

Anticancer Activity of 5-Benzylidene-2-Phenylimino-1, 3-Thiazolidin-4-one (BPT) Analogs

We recently identified two compounds of 5-benzylidene-2-phenylimino-1,3-thiazolidin-4-one (BPT) analog, 5-(4-methylbenzylidene)-2-phenylamino-1,3-thiazolidin-4-one (MMPT) and 5-(2,4-dihydroxybenzylidene)-2-phenylimino-1,3-thiazolidin-4-one (DBPT), that can effectively induce apoptosis in cancer cells but not in normal cells, independently of P-glycoprotein status. To further investigate the antitumor activity of BPT analogs, we obtained 18 commercially available analogs of BPT and synthesized 7 analogs in our lab, and analyzed their antitumor activity in various cancer cells, including paclitaxel- and vinorelbine-sensitive and -resistant human lung cancer cells. Two of the compounds were more potent than MMPT or DBPT in induction of apoptosis in certain cancer cell lines and remained tumor selective. Seven compounds did not induce any cytotoxic effects in any of the cell lines tested at the highest concentration tested (31 microM). The other compounds induced cytotoxic effects in some cancer cells but not in others or were less potent than MMPT and DBPT. Cell uptake studies showed that analogs that effectively induced cell killing in paclitaxel- and vinorelbine-resistant cells could be taken up easily by those cells despite their high levels of P-glycoprotein expression. These data further demonstrate that thiazolidinone analogs are not P-glycoprotein substrates and could be useful for treatment of P-glycoprotein overexpressing refractory cancers.

NMDA receptor activation induces mitochondrial dysfunction, oxidative stress and apoptosis in cultured neonatal rat cardiomyocytes

Glutamate is a well-characterized excitatory neurotransmitter in the central nervous system (CNS). Recently, glutamate receptors (GluRs) were also found in peripheral tissues, including the heart. However, the function of GluRs in peripheral organs remains poorly understood. In the present study, we found that N-methyl-D-aspartate (NMDA) could increase intracellular calcium ([Ca(2+)]i) level in a dose-dependent manner in cultured neonatal rat cardiomyocytes. NMDA at 10(-4) M increased the levels of reactive oxygen species (ROS), cytosolic cytochrome c (cyto c), and 17-kDa caspase-3, but depolarized mitochondrial membrane potential, leading to cardiomyocyte apoptosis. In addition, NMDA treatment induced an increase in bax mRNA but a decrease in bcl-2 mRNA expression in the cardiomyocytes. The above effects of NMDA were blocked by the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801), and by ROS scavengers glutathione (GSH) and N-acetylcystein (NAC). These results suggest that stimulation of NMDA receptor in the cardiomyocyte may lead to apoptosis via a Ca(2+), ROS, and caspase-3 mediated pathway. These findings suggest that NMDA receptor may play an important role in myocardial pathogenesis.

Light-induced transient ion flux responses from maize leaves and their association with leaf growth and photosynthesis

Net fluxes of H+, K+ and Ca2+ ions from maize (Zea mays L.) isolated leaf segments were measured non-invasively using ion-selective vibrating microelectrodes (the MIFE technique). Leaf segments were isolated from the blade base, containing actively elongating cells (basal segments), and from non-growing tip regions (tip segments). Ion fluxes were measured in response to bright white light (2600 micromoles m-2 s-1) from either the leaf segments or the underlying mesophyll (after stripping the epidermis). Fluxes measured from the mesophyll showed no significant difference between basal and tip regions. In leaf segments (epidermis attached), light-induced flux kinetics of all ions measured (H+, Ca2+ and K+) were strikingly different between the two regions. It appears that epidermal K+ fluxes are required to drive leaf expansion growth, whereas in the mesophyll light-induced K+ flux changes are likely to play a charge balancing role. Light-stimulated Ca2+ influx was not directly attributable either to leaf photosynthetic performance or to leaf expansion growth. It is concluded that light-induced ion flux changes are associated with both leaf growth and photosynthesis.

Physiological aspects of vetiver grass for rehabilitation in abandoned metalliferous mine wastes

Physiological aspects of why vetiver grass (Vetiveria zizanioides L.) can be tolerant to heavy metals and be used as an alternative method for rehabilitation of abandoned metalliferous mine wastelands have been investigated. The results showed that high proportions of lead and zinc (Pb/Zn) tailing greatly inhibited the leaf growth, dry matter accumulation, and photosynthesis of leaves, but stimulated the accumulation of proline and abscisic acid (ABA), and enhanced the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), implying that different mechanisms to detoxify active oxygen species (AOS) existed in different parts of plants. Physiological responses to heavy metal treatments differed greatly between roots and shoots. Nitrogen fertilizer application could greatly alleviate the adverse effects of high proportions of Pb/Zn tailing on vetiver grass growth.

Alfentanil infusion as a component of intravenous anaesthesia for coronary artery bypass surgery with "fast-track" recovery

Alfentanil and propofol total intravenous anaesthesia was assessed in 25 patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB). A manually controlled alfentanil infusion, calculated from estimated lean body mass and published pharmacokinetic data, was effective in achieving target plasma concentrations, while the "Diprifusor" system was used to vary propofol target concentrations according to changes in haemodynamics and anaesthetic requirement. The effects of CPB on alfentanil plasma concentrations were offset by changes in protein binding and free-fraction of the drug. With the use of only two target plasma concentrations for alfentanil (changed after CPB), a pre-determined infusion profile ensured effective plasma concentrations during surgery and concentrations unlikely to inhibit extubation within six hours of sternal closure.

Subluminous phase velocity of a focused laser beam and vacuum laser acceleration

It has been found that for a focused laser beam propagating in free space, there exists, surrounding the laser beam axis, a subluminous wave phase velocity region. Relativistic electrons injected into this region can be trapped in the acceleration phase and remain in phase with the laser field for sufficiently long times, thereby receiving considerable energy from the field. Optics placed near the laser focus are not necessary, thus allowing high intensities and large energy gains. Important features of this process are examined via test particle simulations. The resulting energy gains are in agreement with theoretical estimates based on acceleration by the axial laser field.

Effects of alcohol on blood pressure and production of vascular aldosterone and corticosterone

AIMS

The aims of this study were to search for the role of alcohol in blood pressure regulation in rats and to investigate the effects of alcohol on the production of vascular aldosterone and corticosterone.

METHODS

Male Wistar rats received alcohol 0.7 g x kg(-1) x day(-1) (alcohol-treated group 1) or 1.4 g x kg(-1) x day(-1) (alcohol-treated group 2) or 2.1 g x kg(-1) x day(-1) (alcohol-treated group 3), orally, for 3 months, and blood pressure was monitored by a pressure transducer. Systolic blood pressure increased in Wistar rats treated with alcohol compared to control rats. Mesenteric artery perfusion ex vivo was performed and pressor responses to norepinephrine were determined. The pressor responses to norepinephrine in mesenteric arteries treated with alcohol were significantly increased. The perfusate from the mesenteric arteries was collected and applied to a Sep-Pak C 18 cartridge column for reverse-phase high-performance liquid chromatography and aldosterone and corticosterone levels were determined by radioimmunoassay, aldosterone was decreased but corticosterone was increased in the perfusate from arteries treated with alcohol.

RESULTS

Reverse transcriptase polymerase chain reaction showed that alcohol inhibited the expression of 11beta-HSD2 and CYP11B2 mRNA in mesenteric arteries.

CONCLUSIONS

These results reveal that alcohol is able to induce hypertension and provide evidence that alcohol inhibits the transcriptions of both 11beta-HSD2 and CYP11B2 in the vasculature, leading to lower aldosterone and higher corticosterone production in vessels, and increased vasoconstrictor responses to norepinephrine.

Clinicopathological report of retinitis pigmentosa with vitamin E deficiency caused by mutation of the alpha-tocopherol transfer protein gene

PURPOSE

To discuss the clinicopathological findings in a patient with retinitis pigmentosa (RP) accompanied by a vitamin E deficiency caused by an H101Q mutation in the alpha-tocopherol transfer protein (alpha-TTP) gene.

CASE

The clinical course of this patient was followed by conventional ophthalmological examinations over a 3-year period. After the patient died from pancreatic cancer, the eyes were obtained, and examined by light and electron microscopy.

OBSERVATIONS

The patient complained of night blindness subsequent to adult-onset ataxia, although the ataxia was very mild. His visual acuity was 0.6 OU, and ophthalmoscopy revealed RP sine pigmento. Ring scotomas were detected, and the electroretinography, electro-oculography, and dark-adaptation were altered. Fluorescein angiography showed granular hyperfluorescence around the macula. No progression of the visual and neurological symptoms was observed during the 10 years he was taking oral vitamin E. Histopathological examination revealed the loss of the outer and inner segments of the photoreceptors in the area corresponding to the ring scotoma, as well as a disorganization and shortening of the outer segments in the peripheral retina.

CONCLUSIONS

We conclude that the clinical and pathological findings in the eyes of this patient having RP with vitamin E deficiency caused by an H101Q mutation are similar to those of common autosomal recessive RP. However, special attention is required in making a diagnosis of RP with vitamin E deficiency because RP with vitamin E deficiency is medically treatable. The mild Friedreich-type ataxia accompanying the RP may be helpful in identifying this disease.

Cloning and characterization of Ginkgo biloba levopimaradiene synthase which catalyzes the first committed step in ginkgolide biosynthesis

Levopimaradiene synthase, which catalyzes the initial cyclization step in ginkgolide biosynthesis, was cloned and functionally characterized. A Ginkgo biloba cDNA library was prepared from seedling roots and a probe was amplified using primers corresponding to conserved gymnosperm terpene synthase sequences. Colony hybridization and rapid amplification of cDNA ends yielded a full-length clone encoding a predicted protein (873 amino acids, 100,289 Da) similar to known gymnosperm diterpene synthases. The sequence includes a putative N-terminal plastid transit peptide and three aspartate-rich regions. The full-length protein expressed in Escherichia coli cyclized geranylgeranyl diphosphate to levopimaradiene, which was identical to a synthetic standard by GC/MS analysis. Removing 60 or 79 N-terminal residues increased levopimaradiene production, but a 128-residue N-terminal deletion lacked detectable activity. This is the first cloned ginkgolide biosynthetic gene and the first in vitro observation of an isolated ginkgolide biosynthetic enzyme.