A phase Ib study of selumetinib (AZD6244, ARRY-142886) in combination with sorafenib in advanced hepatocellular carcinoma (HCC)

BACKGROUND

Treatment with sorafenib, although associated with inhibition of tumour growth and angiogenesis in in vivo studies, leads to up-regulation of pERK. The addition of MEK inhibition could potentially abrogate this effect and potentiate anti-tumour activity. This phase I study investigated the maximum tolerated dose (MTD), safety, tolerability, pharmacokinetics (PK) and biomarker correlates of selumetinib combined with sorafenib in patients with advanced hepatocellular carcinoma (HCC).

METHODS

Patients with Child-Pugh (CP) score ≤7 were treated with 400 mg twice daily of sorafenib with escalating doses of selumetinib in a 3 + 3 study design. The dose-limiting toxicity (DLT) evaluation period was 28 days. PK of selumetinib was determined. Angiogenic effect was evaluated with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

RESULTS

Twenty-seven patients of Asian ethnicity were enrolled. The MTD was selumetinib 75 mg daily with sorafenib 400 mg twice daily. DLT included grade 3 transaminitis, diarrhoea and fatigue. Most common treatment-related adverse events at MTD (all grades) were diarrhoea (85%), rash (59%), hypertension (44%), fatigue (30%), anorexia (22%) and hand-foot syndrome (22%). Four patients (15%) had PR and 13 (48%) had SD. PR or SD was observed for ≥6 months in seven patients. The median overall survival was 14.4 months. Selumetinib exposures in combination with sorafenib were comparable to other monotherapy studies. A reduction in permeability-surface area product noted in DCE-MRI with treatment correlated with worse survival outcomes.

CONCLUSION

The MTD of selumetinib was 75 mg daily when combined with sorafenib 400 mg twice a day in CP ≤7 HCC. Acceptable adverse events and encouraging anti-tumour activity warrant further evaluation. DCE-MRI findings deserve prospective evaluation.

CLINICALTRIALSGOV IDENTIFIER

NCT01029418.

Analysis of imprinted messenger RNA expression in deceased transgenic cloned goats

Genomic imprinting is an important epigenetic mechanism that has vital effects on fetal growth and development. We observed the differences in four tissues (heart, spleen, liver, and kidney) from dead transgenic cloned goats using hematoxylin and eosin (H&E) staining. Eight imprinted genes in the tissues of dead transgenic cloned and normal goats were analyzed using reverse transcription polymerase chain reaction. H&E staining results from the abortion group indicated the lack of obvious morphological changes in heart and spleen tissues, while inflammatory cell infiltration and glomerular nephritis characteristics were observed in liver and kidney tissues, respectively. Compared to the control group, CDKN1C, H19, IGF2R, and SNRPN were significantly (P < 0.05) overexpressed in the heart tissue of the abortion group, while XIST was significantly reduced. In the liver tissues, CDKN1C and DLK1 expression decreased, while GNAS, H19, IGF2R, PEG3, and XIST expression increased significantly. In the spleen tissues, DLK1 expression increased, while GNAS, H19, IGF2R, PEG3, SNRPN, and XIST expression decreased. In the kidney tissues, CDKN1C, DLK1, GNAS, IGF2R, and PEG3 expression increased, while H19 and XIST expression decreased. The overall expression of imprinted genes was abnormal in different tissues of transgenic cloned goats, and the degree of abnormal genomic imprinting was more severe in the abortion group compared to the death and control groups. These results suggest that abnormal expression of imprinted genes may cause developmental defects in transgenic cloned goats. Moreover, abnormal epigenetic modifications may affect the reprogramming of transgenic donor cells.

Phase I and biomarker study of OPB-51602, a novel signal transducer and activator of transcription (STAT) 3 inhibitor, in patients with refractory solid malignancies

BACKGROUND

The aim of this study was to determine the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of OPB-51602, an oral, direct signal transduction activator of transcription 3 (STAT3) inhibitor, in patients with refractory solid tumors.

PATIENTS AND METHODS

Three cohorts were studied: cohort A, a sequential dose escalation of OPB-51602 administered intermittently (days 1-14 every 21 days); cohort B, an expansion cohort evaluating the dose lower than the MTD; cohort C, evaluating continuous daily dosing.

RESULTS

Fifty-one patients were studied at 2, 4, and 5 mg per day dosing. The MTD was 5 mg; first-cycle dose-limiting toxicities (DLTs) were grade 3 hyponatremia in one patient, and grade 3 dehydration in another. Intermittent dosing of both 2 and 4 mg doses were tolerable, and the recommended phase II dose was 4 mg. Cohort B investigated 4 mg intermittently, whereas cohort C investigated 4 mg continuously. Common toxicities included fatigue, nausea/vomiting, diarrhea, anorexia, and early-onset peripheral neuropathy. Drug-induced pneumonitis occurred in two patients in cohort C. Continuous dosing was associated with a higher incidence of peripheral neuropathy and a lower mean relative dose intensity, compared with intermittent dosing. Steady-state pharmacokinetics was characterized by high oral clearance, mean elimination half-life ranging from 44 to 61 h, and a large terminal-phase volume of distribution. An active metabolite, OPB-51822, accumulated to a greater extent than OPB-51602. Flow cytometry of peripheral blood mononuclear cells demonstrated pSTAT3 (Tyr(705)) inhibition following exposure. Two patients achieved partial responses at 5 mg intermittently and 4 mg continuously; both had epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) with prior EGFR tyrosine kinase inhibitor exposure.

CONCLUSION

OPB-51602 demonstrates promising antitumor activity, particularly in NSCLC. Its long half-life and poorer tolerability of continuous dosing, compared with intermittent dosing, suggest that less frequent dosing should be explored.

CLINICALTRIALSGOV IDENTIFIER

NCT01184807.

Polymorphisms of vascular endothelial growth factor on prognosis in hepatocellular carcinoma patients receiving transcatheter arterial chemoembolization treatment

We conducted a cohort study to investigate the prognostic significance of vascular endothelial growth factor (VEGF) polymorphisms in hepatocellular carcinoma (HCC) patients after transcatheter arterial chemoembolization (TACE). In total, 156 patients with histologically confirmed HCC within 2 months were collected from January 2007 to January 2008. The genotypes of VEGF-2578C/A, -1154G/A, -634C/G, and -1498T/C were determined from blood extracted using a blood kit on a 384-well plate. The survival rate at 5 years was 55.47%. Multivariate analysis revealed that only tumor-node-metastasis (TNM) stage, metastasis, and the VEGF-2578 AA and -1154 AA genotypes were independent prognostic factors. Patients with TNM stage III-IV and metastasis showed a greatly increased risk of death from HCC, with hazard ratios (HRs) [95% confidence interval (CI)] of 3.64 (1.67-6.79) and 2.91 (1.30-6.27), respectively. Moreover, the VEGF-2578 AA and -1154 AA genotypes showed a significantly increased risk of death compared with the wild-type genotype (HR = 3.65, 95%CI = 1.35-11.13; HR = 7.13, 95%CI = 1.46-65.8). These results will be helpful for predicting clinical outcomes of HCC patients.

Anesthesia treatment in cases of infant epiglottis cyst emergency extirpation operations

Congenital epiglottic cyst is a rare embryonic disease. As a congenital laryngeal mucocele, its clinical manifestations include repeated sudden dyspneic respiration and even suffocation accompanied by laryngeal stridor after birth. During food intake, bucking and vomiting is a key feature. Delay in diagnosis and treatment of the disease affects growth and the development of neonatorum leading to suffocation and death. This study was designed to investigate the safety of anesthesia in infants with congenital epiglottic cyst during operation to reduce the occurrence of its complications. The treatment of operations on 12 infants with congenital epiglottic cysts were retrospectively analyzed. Twelve cases of infants with epiglottic cysts received emergency enucleation. Owing to adequate preanesthetic preparation, cystectomies were successfully performed with microwave cauterization under suspension laryngoscopy. None of the 12 patients showed apparent suffocation during anesthesia, the surgical results were good, and after 6 months to 1 year of follow-up, the disease had not recurred. Because of the acute onset of the disease and its severe symptoms and complications, attention should be paid to improve preoperative preparation. Careful selection of proper anesthesia is the key to achieving a successful operation.

GDF15 is a potential predictive biomarker for TPF induction chemotherapy and promotes tumorigenesis and progression in oral squamous cell carcinoma

BACKGROUND

Randomized trials have not shown major survival benefits when induction chemotherapy plus standard therapy is compared with standard therapy alone in patients with oral squamous cell carcinoma (OSCC). Induction chemotherapy is likely to be effective for biologically distinct subgroups and biomarker development may lead to identification of patients whose tumors are likely to respond to a particular treatment.

PATIENTS AND METHODS

We evaluated immunohistochemical staining for GDF15 in pretreatment biopsy specimens of 230 of 256 OSCC patients who were treated in a prospective, randomized, phase III trial on induction chemotherapy including docetaxel, cisplatin and 5-fluorouracil (TPF). Relationship between GDF15 intervention and cell proliferation, migration, invasion, colony formation and tumorigenicity was analyzed using in vitro and in vivo OSCC models.

RESULTS

Low GDF15 expression predicted a better survival in OSCC patients, especially overall survival [P = 0.049, hazard ratio (HR) = 0.597] and distant metastasis-free survival (DMFS; P = 0.031, HR = 0.562). cN+ patients with low GDF15 expression benefitted from induction TPF in overall survival (P = 0.039, HR = 0.247) and DMFS (P = 0.039, HR = 0.247), cN- patients with high GDF15 expression benefitted from induction TPF in overall survival (P = 0.019, HR = 0.231), disease-free survival (P = 0.011, HR = 0.281), locoregional recurrence-free survival (P = 0.035, HR = 0.347) and DMFS (P = 0.009, HR = 0.197). Decreased GDF15 expression in OSCC lines significantly inhibited cell proliferation, migration, invasion, colony formation and tumorigenesis through increased phosphorylation of AKT and ERK1/2 (P < 0.05). Likewise, overexpression of GDF15 significantly promoted cell proliferation, migration, invasion and colony formation through decreased phosphorylation of AKT and ERK1/2 (P < 0.05).

CONCLUSIONS

GDF15 expression can be used as a prognostic biomarker for OSCC, and as a predictive biomarker for benefitting from TPF induction chemotherapy. GDF15 promotes tumorigenesis and progression through phosphorylation of AKT and ERK1/2 in OSCC. The clinical trial in this study was registered with www.ClinicalTrials.gov (NCT01542931).

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Oct4 and Sox2 overexpression improves the proliferation and differentiation of bone mesenchymal stem cells in Xiaomeishan porcine

Mesenchymal stem cells derived from bone marrow (BMSCs) are a population of self-renewing multipotent cells that are capable of differentiating into various cellular lineages, and are widely employed in tissue engineering and cell therapy. Recently, clinical research involving BMSCs has become increasingly popular. In order to conduct appropriate research, it is first necessary to amplify large amounts of functional BMSCs in vitro. However, after several passages of expanding in vitro, the proliferation and differentiation potential of BMSCs gradually decline. To determine whether overexpression of Oct4 or Sox2 might prevent this decline, we transfected Oct4 or Sox2, which are essential for the pluripotency and self-renewal of embryonic stem cells, into BMSCs of Xiaomeishan porcine by a lentivirus. The results showed that overexpression of Sox2 or Oct4 BMSCs in culture media containing a basic fibroblast growth factor resulted in higher proliferation and differentiation compared to controls, suggesting that genetic modification of stemness-related genes is an efficient way to maintain the proliferation and differentiation potential of BMSCs.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

Intraosseous Venous Malformations of the Facial Bone: A Retrospective Study in 11 Patients

Objectives:

To investigate the clinical symptoms, computed tomography (CT) features and treatments of intraosseous venous malformations (IVM) that occur in the facial bone.

Methods and Results:

Eleven patients with facial IVM were treated with two surgical techniques, excision ( n = 4) or curettage ( n = 7). No recurrence was encountered at follow-up (45.8 ± 16.0 months). Postoperative deformities were left in two paediatric patients who were treated with excision.

Conclusions:

The diagnosis of IVM can be difficult and is mainly based on clinical symptoms and CT features. IVM should be differentiated from other lesions, including ameloblastoma, odontogenic cysts, osteosarcoma, aneurysmal bone cysts and arteriovenous malformations, among others. Conventional block biopsy should be replaced by fine needle aspiration cytology for further diagnosis. Curettage is a more appropriate method for IVM compared with excessive en-bloc osteotomy, while transosseous embolo-sclerotherapy may be a promising alternative method. Finally, the terminological confusion between ‘intraosseous haemangioma’ and ‘intraosseous venous malformation’ should be avoided according to the binary classification.

The effect on maternal temperature of delaying initiation of the epidural component of combined spinal-epidural analgesia for labor: a pilot study

BACKGROUND

Labor epidural analgesia is associated with maternal hyperthermia. This pilot study compared the effects on maternal temperature during labor of different timing of initiation of the epidural component of combined spinal-epidural analgesia.

METHODS

After induction of analgesia with intrathecal bupivacaine 2 mg and fentanyl 20 μg, healthy term nulliparas in spontaneous labor were randomized to receive immediate epidural analgesia (n=26) or delayed epidural analgesia after the return of pain (n=28), by patient-controlled epidural analgesia with 0.125% bupivacaine and fentanyl 1 μg/mL. Maternal tympanic temperature, visual analog scale pain score and dermatome block level were measured hourly during labor.

RESULTS

The duration of labor for most parturients (83.3%) was <5 h. Mean maternal temperature gradually increased over time but did not significantly differ from either from baseline or between the two groups. There was no significant difference in the incidence of maternal fever (≥38°C) between the two groups. At 2 h post spinal analgesia the visual analog scale score was higher (P=0.03) and the dermatome block level was lower (P=0.005) in the delayed epidural analgesia group compared to the immediate epidural analgesia group.

CONCLUSIONS

Delaying the epidural component of combined spinal-epidural analgesia did not significantly affect maternal temperature in the study population of whom 83.3% had a labor of <5 h. However, this study was underpowered to detect a difference in the incidence of fever and a larger prospective study is required.

Decreased expression of profilin 2 in oral squamous cell carcinoma and its clinicopathological implications

Profilins are small proteins essential for many normal cellular dynamics and constitute one of the crucial components of actin-based cellular motility. Several recent studies have implicated a role for the profilin (PFN) family in cancer pathogenesis and progression. However, their expression and promising functions are largely unknown in oral squamous cell carcinoma (OSCC). In this study, we analyzed the correlation between PFN1 and PFN2 expression in vitro and in vivo. The protein expression levels were roughly compared between cell lines (HIOEC, HB96) with the employment of mass spectrometry. PFN2 was singled out as one of the significantly down-regulated genes in the cancerous HB96 cells. The expression levels of PFN1 and PFN2 in vitro were validated by RT-PCR, real-time PCR and Western blotting. Laser scanning confocal microscopy was used for the first time to assess the localization of PFN2 expression. In subsequent experiments, we observed the relationship between PFN2 expression levels and the proliferation of transfected HB96 cancer cells. VASP, N-WASP and P27 expression was also examined in the PFN2-transfected or non-transfected HB96 cells. In vivo, antigen expression was determined by immunohistochemical analyses in 88 paired tissue specimens. Decreased protein expression was confirmed in cancerous tissues from 88 OSCC patients compared with paracancerous normal mucous epithelia. Tumors with weak PFN2 expression were associated with a significantly worse prognosis than strongly expressed tumours (P<0.001). Other statistical analyses were performed to assess the differences in expression and their clinical and pathological significance. In conclusion, PFN2 can be utilized as both a potential suppressor marker and a prognostic protein for OSCC. The function of PFN2 may be to regulate the N-WASP/Arp2/3 signaling pathway.

Malignant solitary fibrous tumors of the head and neck: a clinicopathological study of nine consecutive patients

Malignant solitary fibrous tumor (MSFT) is one of the angiosarcomas arising from or resembling the components of blood vessels. Because of its rarity, the diagnosis is difficult. Between 1998 and 2008, 24 patients were diagnosed as having hemangiopericytomas (16) and solitary fibrous tumors (8). Nine of them were confirmed to be MSFT and treated at the Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. All patients were treated with surgery as the primary modality. Eight patients received postoperative adjuvant radiation therapy. The average follow-up duration was 4.6 years (range: 6 months-10 years). Of the nine patients reviewed in this study, three died of locoregional or distant metastasis, six survived 6 months-6 years (four survived over 4 years). The size of primary tumor, the number of mitoses per 10 high powered fields and cervical lymph node metastasis seemed to be correlated with poor prognosis in MSFT patients, although the small number of patients did not permit the performance of statistical analysis.

PXR, CAR and HNF4alpha genotypes and their association with pharmacokinetics and pharmacodynamics of docetaxel and doxorubicin in Asian patients

Previously studied candidate genes have failed to account for inter-individual variability of docetaxel and doxorubicin disposition and effects. We genotyped the transcriptional regulators of CYP3A and ABCB1 in 101 breast cancer patients from 3 Asian ethnic groups, that is, Chinese, Malays and Indians, in correlation with the pharmacokinetics and pharmacodynamics of docetaxel and doxorubicin. While there was no ethnic difference in docetaxel and doxorubicin pharmacokinetics, ethnic difference in docetaxel- (ANOVA, P=0.001) and doxorubicin-induced (ANOVA, P=0.003) leukocyte suppression was observed, with Chinese and Indians experiencing greater degree of docetaxel-induced myelosuppression than Malays (Bonferroni, P=0.002, P=0.042), and Chinese experiencing greater degree of doxorubicin-induced myelosuppression than Malays and Indians (post hoc Bonferroni, P=0.024 and 0.025). Genotyping revealed both PXR and CAR to be well conserved; only a PXR 5'-untranslated region polymorphism (-24381A>C) and a silent CAR variant (Pro180Pro) were found at allele frequencies of 26 and 53%, respectively. Two non-synonymous variants were identified in HNF4alpha (Met49Val and Thr130Ile) at allele frequencies of 55 and 1%, respectively, with the Met49Val variant associated with slower neutrophil recovery in docetaxel-treated patients (ANOVA, P=0.046). Interactions were observed between HNF4alpha Met49Val and CAR Pro180Pro, with patients who were wild type for both variants experiencing least docetaxel-induced neutropenia (ANOVA, P=0.030). No other significant genotypic associations with pharmacokinetics or pharmacodynamics of either drug were found. The PXR-24381A>C variants were significantly more common in Indians compared to Chinese or Malays (32/18/21%, P=0.035) Inter-individual and inter-ethnic variations of docetaxel and doxorubicin pharmacokinetics or pharmacodynamics exist, but genotypic variability of the transcriptional regulators PAR, CAR and HNF4alpha cannot account for this variability.

Effects of intrathecal and i.v. small-dose sufentanil on the median effective dose of intrathecal bupivacaine for Caesarean section

BACKGROUND

Spinal anaesthesia with bupivacaine combined with sufentanil has been widely used for Caesarean section. However, the main site of action (spinal vs central) of intrathecal (IT) sufentanil is controversial. The aim of this study was to examine the predominant mechanism of action of IT, small-dose sufentanil when added to bupivacaine for Caesarean section, by comparing the effects of IT and i.v. sufentanil 2.5 microg on the median effective dose (ED50) of bupivacaine.

METHODS

Ninety parturients undergoing elective Caesarean section with a combined spinal-epidural technique were enrolled into this prospective, double-blind, up-down sequential allocation study. According to the up-down sequential allocation, parturients received varying doses of bupivacaine alone (C group) or co-administered with i.v. sufentanil 2.5 microg group (IVS group; n = 30) or IT sufentanil 2.5 microg group (ITS group; n = 30). The possible maternal or neonatal adverse effects were also recorded.

RESULTS

The ED(50) of bupivacaine was 6.3 mg (95% CI 6.2-6.5) in the C group, 5.2 mg (95% CI 5.1-5.4) in the IVS group, and 3.0 mg (95% CI 2.9-3.1) in the ITS group. The ED50 in the ITS group was significantly lower as compared with the other two groups (P < 0.0005). With the exception of pruritus that exclusively occurred in the ITS group (P = 0.011, compared with the other two groups), no significant differences among groups were observed regarding the frequencies of the maternal or neonatal adverse effects.

CONCLUSIONS

Compared with an equal dose of sufentanil i.v., intrathecally administered sufentanil 2.5 microg has a significant local anaesthetic-sparing effect via a predominantly spinal mechanism for Caesarean section.

VEGF-Targeted RNA Interference Suppresses Angiogenesis and Tumor Growth of Retinoblastoma

Vascular endothelial growth factor (VEGF) is one of the most important angiogenic growth factors for tumor angiogenesis which has been verified to be involved in neovascularization of retinoblastoma. Here, we sought to explore whether RNA interference (RNAi) targeting VEGF could inhibit retinoblastoma angiogenesis and tumor growth. Stable transfection of the two human retinoblastoma cell lines SO-RB50 and HXO-RB44 with VEGF-targeted small interfering RNA (siRNA) expression plasmid significantly inhibited VEGF expression determined by real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay and Western blot, whereas the control transfection showed no effects. The chemically synthesized VEGF siRNA dramatically suppressed tumor angiogenesis (CD34 immunohistochemistry) and tumor growth in the SO-RB50 subcutaneous xenograft model. Significant downregulation of VEGF expression both on messenger RNA and protein levels in VEGF-siRNA-treated SO-RB50 subcutaneous xenograft was confirmed by real-time PCR and Western blot compared to control. Our data demonstrate the suppression function on angiogenesis and tumor growth of retinoblastoma by VEGF-targeted RNAi. This novel therapeutic strategy promises to play a part in the clinical management of retinoblastoma.

A multicentre randomised phase II study of carboplatin in combination with gemcitabine at standard rate or fixed dose rate infusion in patients with advanced stage non-small-cell lung cancer

BACKGROUND

Intracellular gemcitabine triphosphate (dFdCTP) levels can be optimised by administering gemcitabine at a fixed dose rate infusion.

PATIENTS AND METHODS

Patients with chemonaive advanced non-small cell lung cancer (NSCLC) were randomised to receive gemcitabine at a fixed dose rate gemcitabine 750 mg/m(2) over 75 min (arm A) or gemcitabine 1000 mg/m(2) over 30 min (arm B) on days 1 and 8 every three week cycle. Carboplatin at AUC of 5 was administered in both treatment arms on day 1 of each cycle. End points were activity, tolerability and pharmacokinetics of plasma and intracellular gemcitabine.

RESULTS

76 patients were randomised. Response rate was 34% in arm A and 42% in arm B. Toxicity and quality of life scores were similar for both treatment arms. Mean plasma Cmax(gemcitabine) and mean dFdCTP AUC in arm A was 20.8 microM +/- 17.2 microM and 35,079 +/- 18,216 microM*min respectively and in arm B, 41.2 +/- 13.9 microM and 32 249 +/- 11 267 microM*min respectively. dFdCTP saturation was reached in Arm B but not in Arm A.

CONCLUSION

The saturability of dFdCTP accumulation in Arm A suggests optimal delivery of gemcitabine is achieved using fixed rate infusion compared to 30-min infusion. Fixed dose rate gemcitabine is active and feasible, supporting the concept of fixed dosing rate of gemcitabine in advanced NSCLC. However, this entails a longer infusion time with associated higher costs involved.

Periodic Mesoporous Organosilica Hollow Spheres with Tunable Wall Thickness

Periodic mesoporous organosilica (PMO) hollow spheres with tunable wall thickness have been successfully synthesized by a new vesicle and a liquid crystal "dual templating" mechanism, which may be applicable for drug and DNA delivery systems, biomolecular encapsulation, as well as nanoreactors for conducting biological reactions at the molecular levels.

Novel mechanism of inhibition of HIV-1 reverse transcriptase by a new non-nucleoside analog, KM-1

2-Naphthalenesulfonic acid (4-hydroxy-7-[[[[5-hydroxy-6-[(4 cinnamylphenyl)azo]-7-sulfo-2-naphthalenyl]amino]-carbonyl]amino]-3-[(4-cinnamylphenyl)]azo (KM-1)) is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) that was designed to bind at an unconventional site on human immunodeficiency virus type 1 reverse transcriptase (RT) (Skillman, A. G., Maurer, K. W., Roe, D. C., Stauber, M. J., Eargle, D., Ewing, T. J., Muscate, A., Davioud-Charvet, E., Medaglia, M. V., Fisher, R. J., Arnold, E., Gao, H. Q., Buckheit, R., Boyer, P. L., Hughes, S. H., Kuntz, I. D., and Kenyon, G. L. (2002) Bioorg. Chem. 30, 443-458). We have investigated the mechanism by which KM-1 inhibits wild-type human immunodeficiency virus type 1 RT by using pre-steady state kinetic methods to examine the effect of KM-1 on the parameters governing the single nucleotide incorporation catalyzed by RT. Analysis of the pre-steady-state burst phase of dATP incorporation showed that KM-1 decreased the amplitude of the reaction as previously shown for other NNRTIs, because of the slow equilibration of the inhibitor with RT. In the ternary enzyme-DNA-KM-1 complex (E-DNA-I), incorporation of the next nucleotide onto the primer is blocked. However, unlike conventional NNRTIs, the inhibitory effect was caused primarily by weakening the DNA binding affinity and displacing DNA from the enzyme. Wild-type RT binds a 25/45-mer DNA duplex with an apparent K(d) of 3 nm, which was increased to 400 nm upon saturation with KM-1. Likewise, the apparent K(d) for KM-1 binding to RT increased at higher DNA concentrations. We therefore conclude that KM-1 represents a new class of inhibitor distinct from nevirapine and related NNRTIs. KM-1 can bind to RT in both the absence and presence of DNA but weakens the affinity for DNA 140-fold so that it favors DNA dissociation. The data suggest that KM-1 distorts RT conformation and misaligns DNA at the active site.

Sensitive high-performance liquid chromatography/mass spectrometry method for determination of steviol in rat plasma

The main toxicological concern of stevioside, a highly potent sweetener from S. rebaudiana, is its main metabolite, steviol. To determine very low levels of steviol in in vivo experiments, a sensitive liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) method was developed for quantifying steviol in rat plasma after oral administration of a single dose of stevioside (0.5 g/kg). The sample preparation uses liquid-liquid extraction with tert-butyl methyl ether in an acidic environment. The retention time of steviol was 10.5 min. The assay was linear over the range 2-1000 ng/mL with a lower limit of detection of 1 ng/mL. The intra- and inter-day precision were <5 and <7%, respectively, and the accuracy was in the range 95-108%. The steviol concentration profile in rat plasma was determined.

Quantitation of paclitaxel in micro-sample rat plasma by a sensitive reversed-phase HPLC assay

A sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of paclitaxel in micro-samples of rat plasma in order to study the mechanism of enhanced systemic exposure of paclitaxel co-administered with P-glycoprotein inhibitors. The assay involved solid-phase extraction procedures using 2'-methylpaclitaxel as the internal standard. Chromatographic separations were achieved using a ZORBAX ODS C18 column and mobile phase consisting of acetonitrile, methanol and ammonium acetate buffer (10 mM, pH 5.0) (48.5:16.5:35) pumped at 0.8 ml/min. The effluents were measured for UV absorption at 227 nm, with retention times of 8.5 and 11.0 min for paclitaxel and 2'-methylpaclitaxel, respectively. The chromatographic separation was excellent, with no endogenous interference. The standard curves showed a good linearity (r=0.9994) over the concentration ranges of 10-1,000 ng/ml. At 1,000 ng/ml, the absolute recoveries of paclitaxel and 2'-methylpaclitaxel are 89 and 90%, respectively. The intra- and inter-day variabilities of paclitaxel were both less than 15%. This validated method for the assay of paclitaxel in micro-sample rat plasma made it feasible to study the pharmacokinetics of the drug in a single rat.

A rapid and sensitive liquid chromatography/tandem mass spectrometry method for determination of docetaxel in human plasma

A novel, rapid and sensitive isocratic liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for quantification of docetaxel in human plasma with paclitaxel as internal standard. The high sensitivity and specificity of MS/MS detection enabled the use of a small volume of plasma (0.05 mL) and a simple liquid-liquid extraction procedure. Furthermore, a very short run-time (3 min) fulfilled the need for monitoring plasma levels of docetaxel from large-scale clinical studies. The calibration curve for docetaxel was linear over the range 5-1000 ng/mL with coefficients of correlation >0.999 using only 0.05 mL plasma. The intra- and inter-day precisions (CV) of analysis were <7%, and accuracy ranged from 96 to 110%. The applicability of the method was demonstrated in a pharmacokinetic study of a 1-h infusion of docetaxel with dosages of 75 mg/m(2). Possible conjugated metabolites of docetaxel were not detected in patients' samples.