Study of hole-injecting properties in efficient, stable, and simplified phosphorescent organic light-emitting diodes by impedance spectroscopy

Simplified phosphorescent organic light-emitting diodes (OLEDs) using only two kinds of hosts and comprising either a neat MoO(x) hole-injecting layer (HIL) or a MoO(x)-doped 4,4'-bis(carbazol-9-yl)biphenyl (CBP) HIL were studied. The devices having the MoO(x)-doped CBP HIL are superior to the device having the neat MoO(x) HIL in terms of power efficiency and operational lifetime. Impedance spectroscopy studies revealed that both the reduced hole-injecting barrier height at the anode/doped HIL interface and the reduced bulk resistivity in the doped CBP HIL contribute to the improvement in electroluminescence characteristics. When increasing the MoO(x) volume percentage from 5 to 10% and then to 20%, the hole-injecting barrier height is decreased from 0.63 eV to 0.36 eV and then to 0.18 eV. The power efficiency of the device with a 20 vol % of MoO(x)-doped CBP HIL is more than two times that of the device with a neat MoO(x) HIL measured at a driven current of 5 mA/cm(2). Moreover, the lifetime of the device with a 20 vol % of MoO(x)-doped CBP HIL is more than three times that of the device with a neat MoO(x) HIL estimated at an initial luminance of 1000 cd/m(2). The MoO(x)-doped HIL further ensures the feasibility of the simplified phosphorescent OLEDs for potential applications.

Relationships between hair growth rate and morphological parameters of human straight hair: a same law above ethnical origins?

After measurement of individual growth rates, natural hair fibres from Asian and Caucasian subjects were analysed using scanning electron microscopy. In total, more than 1000 hairs were analysed. Measurements of diameter, medulla and interscale distance (average distance between two successive cuticle scales) show these parameters strongly correlated with hair growth rate. A thicker hair fibre corresponds to a faster growth rate, a shorter interscale distance and greater probability to have a medulla, and vice versa, a thin hair fibre shows slower growth rate, a larger interscale distance and a lower probability to have a medulla. Very interestingly, this finding appears to be unrelated to the ethnic origin of the subjects, suggesting a common characteristic of human hair, at least for the straight or semi-straight hair studied. From a practical viewpoint, this finding clearly suggests an alternative method for measuring hair growth rates, by measuring the interscale distance, which appears easier than using common laboratory equipments.

Polymorphisms in the toll-like receptor 9 gene associated with sepsis and multiple organ dysfunction after major blunt trauma

BACKGROUND

Toll-like receptor (TLR) 9 is the pattern recognition receptor for microbial DNA. Genetic variation within pattern recognition receptors for bacterial endotoxin and exotoxin has been shown to be associated with the risk of sepsis and organ dysfunction in critical illness. However, little is known about the clinical relevance of TLR9 gene polymorphisms in critical illness.

METHODS

A total of 557 patients with major blunt trauma were included in the study. Genetic variation data for the entire TLR9 gene were obtained from the HapMap Project. The genotypes of TLR9 gene polymorphisms were determined using a pyrosequencing method. Whole peripheral blood samples obtained immediately after admission were stimulated with bacterial DNA and production of tumour necrosis factor (TNF) α was then determined. Sepsis morbidity rate and multiple organ dysfunction (MOD) scores were assessed.

RESULTS

Of five single-nucleotide polymorphisms (SNPs) genotyped, four (rs187084, rs352139, rs352140 and rs352162) existed as common SNPs and were in strong linkage disequilibrium. Both rs187084 and rs352162 were significantly associated with TNF-α production by peripheral blood leucocytes in response to bacterial DNA stimulation and a higher sepsis morbidity rate in patients with major trauma. In addition, the rs352162 polymorphism was significantly associated with MOD scores, whereas rs187084 showed a trend to be associated with MOD score.

CONCLUSION

TLR9 polymorphisms rs187084 and rs352162 might be used to provide relevant risk estimates for the development of sepsis and MOD in patients with major trauma.

Roles of HAUSP-mediated p53 regulation in central nervous system development

The deubiquitinase HAUSP (herpesvirus-associated ubiquitin-specific protease; also called USP7) has a critical role in regulating the p53-Mdm2 (murine double minute 2) pathway. By using the conventional knockout approach, we previously showed that hausp inactivation leads to early embryonic lethality. To fully understand the physiological functions of hausp, we have generated mice lacking hausp specifically in the brain and examined the impacts of this manipulation on brain development. We found that deletion of hausp in neural cells resulted in neonatal lethality. The brains from these mice displayed hypoplasia and deficiencies in development, which were mainly caused by p53-mediated apoptosis. Detailed analysis also showed an increase of both p53 levels and p53-dependent transcriptional activation in hausp knockout brains. Notably, neural cell survival and brain development of hausp-mutant mice can largely be restored in the p53-null background. Nevertheless, in contrast to the case of mdm2- and mdm4 (murine double minute 4)-mutant mice, inactivation of p53 failed to completely rescue the neonatal lethality of these hausp-mutant mice. These results indicate that HAUSP-mediated p53 regulation is crucial for brain development, and also suggest that both the p53-dependent and the p53-independent functions of HAUSP contribute to the neonatal lethality of hausp-mutant mice.

Inhibition of cervical cancer cell growth in vitro and in vivo with dual shRNAs

RNA interference (RNAi)-based gene silencing is widely used in laboratories for gene function studies and also holds a great promise for developing treatments for diseases. However, in vivo delivery of RNAi therapy remains a key issue. Lentiviral vectors have been employed for stable gene transfer and gene therapy and therefore are expected to deliver a stable and durable RNAi therapy. But this does not seem to be true in some disease models. Here, we showed that lentivirus delivered short-hairpin RNA (shRNA) against human papillomavirus (HPV) E6/E7 oncogenes were effective for only 2 weeks in a cervical cancer model. However, using this vector to carry two copies of the same shRNA or two shRNAs targeting at two different but closely related genes (HPV E6 and vascular endothelial growth factor) was more effective at silencing the gene targets and inhibiting cell or even tumor growth than their single shRNA counterparts. The cancer cells treated with dual shRNA were also more sensitive to chemotherapeutic drugs than single shRNA-treated cells. These results suggest that a multi-shRNA strategy may be a more attractive approach for developing an RNAi therapy for this cancer.

A rapid assay for simultaneous detection of Spiroplasma eriocheiris and white spot syndrome virus in Procambarus clarkii by multiplex PCR

AIMS

To establish a multiplex PCR method for simultaneous and rapid detection of Spiroplasma eriocheiris and white spot syndrome virus (WSSV) in Procambarus clarkii with recommendations for application to other crustacea.

METHODS AND RESULTS

Three primer sets were mixed at a ratio of 1:3:1 to amplify specific fragments of the S. eriocheiris, WSSV, P. clarkii crayfish (control organism) genomes, respectively. S. eriocheiris and WSSV were used to challenge the susceptible crustacea in the experimental groups. Total DNA of the samples was purified and detected by multiplex PCR. The PCR-amplified products produced four groups of results as follows. One fragment of 1195 bp, amplified by the primer set ITS-crayfish/28S-crayfish, served as an internal control, showed no pathogen detection, thus confirming the specificity of our positive tests. Two groups represented by: (i) samples challenged by S. eriocheiris alone, or (ii) challenged by WSSV alone, yielded two fragments each; i.e. those from S. eriocheiris (271 bp) plus the internal control and those from WSSV (530 bp) plus the internal control. Finally, for the fourth group, in cases of double challenged treatments, all three amplified products were detected simultaneously.

CONCLUSIONS

Simultaneous and rapid detection of two pathogens in P. clarkii is important to maintain productive and healthy crayfish in aquaculture. The direct detection of S. eriocheiris and WSSV from P. clarkii is practicable with multiplex PCR.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study shows that the two pathogens are simultaneously and rapidly detected in P. clarkii by multiplex PCR, thus increasing the efficiency of pathogen detection.

Kinetic analysis of oxytetracycline residues in Chinese mitten crab, Eriocheir sinensis, muscle following intramuscular administration

Crab culture is a very important economic industry in China. An epidemic of tremor disease of Chinese mitten crabs, Eriocheir sinensis, has become a serious problem in recent years. A spiroplasm has been proved to be the causative agent of this disease. Oxytetracycline (OTC) is used widely in aquaculture and was confirmed to be very effective against this pathogen. In this study, the distribution and depletion patterns of OTC in crab muscle were evaluated following single intramuscular doses of 2, 8 and 40 mg kg(-1) body weight. OTC was detected with a validated HPLC method. Concentration-time profiles were well described by a three-compartment model with first-order absorption after a single dose of 8 and 40 mg kg(-1). For comparison, a non-compartment model was employed. A withdrawal time of 48.29 and 55.92 days was suggested prior to consumption after receiving 8 and 40 mg kg(-1). A recommended therapeutic dose of OTC in theory was calculated to be 36.37 mg kg(-1). OTC was distributed well throughout the body. The elimination of OTC in muscle was slower compared with fish and other crustaceans. A dose of 40 mg kg(-1) is suggested for practical use.

Dynamic nucleotide mutation gradients and control region usage in squamate reptile mitochondrial genomes

Gradients of nucleotide bias and substitution rates occur in vertebrate mitochondrial genomes due to the asymmetric nature of the replication process. The evolution of these gradients has previously been studied in detail in primates, but not in other vertebrate groups. From the primate study, the strengths of these gradients are known to evolve in ways that can substantially alter the substitution process, but it is unclear how rapidly they evolve over evolutionary time or how different they may be in different lineages or groups of vertebrates. Given the importance of mitochondrial genomes in phylogenetics and molecular evolutionary research, a better understanding of how asymmetric mitochondrial substitution gradients evolve would contribute key insights into how this gradient evolution may mislead evolutionary inferences, and how it may also be incorporated into new evolutionary models. Most snake mitochondrial genomes have an additional interesting feature, 2 nearly identical control regions, which vary among different species in the extent that they are used as origins of replication. Given the expanded sampling of complete snake genomes currently available, together with 2 additional snakes sequenced in this study, we reexamined gradient strength and CR usage in alethinophidian snakes as well as several lizards that possess dual CRs. Our results suggest that nucleotide substitution gradients (and corresponding nucleotide bias) and CR usage is highly labile over the approximately 200 m.y. of squamate evolution, and demonstrates greater overall variability than previously shown in primates. The evidence for the existence of such gradients, and their ability to evolve rapidly and converge among unrelated species suggests that gradient dynamics could easily mislead phylogenetic and molecular evolutionary inferences, and argues strongly that these dynamics should be incorporated into phylogenetic models.

The multiple levels of regulation by p53 ubiquitination

p53 is a central integrator of a plethora of signals and outputs these signals in the form of tumor suppression. It is well accepted that ubiquitination plays a major part in p53 regulation. Nonetheless, the molecular mechanisms by which p53 activity is controlled by ubiquitination are complex. Mdm2, a RING oncoprotein, was once thought to be the sole E3 ubiquitin ligase for p53, however recent studies have shown that p53 is stabilized but still degraded in the cells of Mdm2-null mice. Although the essential role of Mdm2 in p53 regulation is well established, there are an increasing number of other E3 ligases implicated in Mdm2-independent regulation of p53 by ubiquitination. The different types of ubiquitination on p53 by various E3 ligases have been linked to its differential effects on p53-mediated stress responses. In addition to proteasome-mediated degradation, ubiquitination of p53 acts as signals for degradation-independent functions, such as nuclear export. The function of ubiquitinated p53 varies in the nucleus and cytosol underlying the many potential contributions ubiquitinated p53 may have in promoting cell proliferation or death. Thus, p53 requires multiple layers of regulatory control to ensure correct temporal and spatial functions.

Inactivation of HAUSP in vivo modulates p53 function

Hausp is a deubiquitinase that has been shown to regulate the p53-Mdm2 pathway. Cotransfection of p53 and Hausp stabilizes p53 through the removal of ubiquitin moieties from polyubiquitinated p53. Interestingly, knockout or RNA interference-mediated knockdown of Hausp in human cells also resulted in the stabilization of p53 due to the destabilization of Mdm2, suggesting a dynamic role of Hausp in p53 activation. To understand the physiological functions of Hausp, we generated hausp knockout mice. Hausp knockout mice die during early embryonic development between embryonic days E6.5 and E7.5. The hausp knockout embryos showed p53 activation, but no apparent increase in apoptosis. Embryonic lethality was caused by a dramatic reduction in proliferation and termination in development, in part due to p53 activation and/or abrogation of p53-independent functions. Although deletion of p53 did not completely rescue the embryonic lethality of the hausp knockout, embryonic development was extended in both hausp and p53 double knockout embryos. These data show that Hausp has a critical role in regulating the p53-Mdm2 pathway.

Syphilis co-infection does not affect HIV disease progression

HIV and syphilis are often seen as co-infections since they share a common mode of transmission. During episodes of syphilis, CD4 counts transiently decrease and HIV viral loads increase; however, the effect of syphilis co-infection on HIV disease progression (time to AIDS or death) is unclear. We analysed prospectively collected information on 2239 persons with estimated dates of HIV seroconversion (205 [9.2%] with confirmed syphilis and 66 [2.9%] with probable syphilis) in order to determine the effect of syphilis co-infection on HIV disease progression. In multivariate models censored at highly active antiretroviral therapy (HAART) initiation or last visit, adjusting for CD4 count, age, race, gender, and hepatitis B and C status, syphilis (confirmed + probable) was not associated with increased hazard of AIDS or death (hazard ratio 0.99, 95% CI 0.73-1.33). Treating HAART as a time-varying covariate or limiting the analysis to only confirmed syphilis cases did not significantly alter the results. Despite transient changes in CD4 counts and viral loads, syphilis does not appear to affect HIV disease progression.

Type 2 diabetes mellitus associated with increased risk for colorectal cancer: evidence from an international ecological study and population-based risk analysis in China

OBJECTIVE

To study the association between type 2 diabetes mellitus (T2DM) and colorectal cancer (CRC).

STUDY DESIGN

An international ecological study and a population-based risk analysis.

METHODS

Prevalence data for T2DM and incidence data for CRC were collected from 170 countries, and Spearman's correlation was calculated between T2DM and CRC. In the Nan-Hu district of Jia-Xing city, Zhejiang province, China, the incidence of CRC among T2DM patients between 1 January 2002 and 30 June 2002 was identified through record linkage between the Diabetic Surveillance and Registry Database with the Cancer Surveillance and Registry Database. Standardized incidence ratios (SIRs) and 95% confidence intervals were used to estimate the risk of CRC among T2DM patients.

RESULTS

Significant positive correlations (r(s)=0.534 and 0.597 in males and females, respectively) were found between the prevalence of T2DM and the incidence of CRC. Sixty-four cases of CRC were found among 7938 T2DM patients. The SIR for CRC among T2DM patients was 1.588 (95% CI 1.199-1.977). For male T2DM patients, the SIR for CRC was 1.821 (95% CI 1.234-2.408), compared with 1.364 (95% CI 0.85-1.879) among female T2DM patients. Significant increased risks for colon cancer were found, with an SIR of 1.899 (95% CI 1.139-2.658) in male T2DM patients. Female T2DM patients showed a borderline significant risk for colon cancer, with an SIR of 1.687 (95% CI 0.948-2.426). However, no significant associations were found between T2DM and risk for rectal cancer among males (SIR 1.723, 95% CI 0.786-2.66) or females (SIR 0.906, 95% CI 0.235-1.578) (all P>0.05).

CONCLUSIONS

T2DM was associated with increased risk for CRC, and this association was more evident for colon cancer and among male diabetic patients.

A pilot study of biological markers (BM) as predictors for response and prognosis in patients (pts) with R0 resected gastric cancer (GC)

e22076

Background: To evaluate clinical value of biological markers and their prognostic significance in gastric cancer as well as prediction to clinic outcome; To select preference marker for targeted therapy in high risk patients hence to guide personalized treatment. Methods: Retrieved from total 394 patients treated during the period of Jan 2004 to June 2006 of Cancer Hospital, Fudan University with complete medical records and follow up data, 84 patients with pre- and post- operative biological markers examined were selected. All of these patients underwent R0 gastrectomy, 61 (72.6%) patients underwent D2 resection. Forty- one (48.8%) patients received ≥ 4 cycles adjuvant chemotherapy. Preoperative tumor markers include: CEA, AFP, CA199, CA50, CA72–4, CA24–2 and postoperative immunohistochemical examination include: Bax, Bcl-2, P27, CyclinD1, TOPO2, MDR, GST-π, Ki67, AgNOR, EGFR, P21, P53, PCNA, C-myc and Neu were analyzed. Univariate, multivariate and Logistic regression analysis were performed and Kapan-Meier estimates were calculated. Results: For the whole group, 2-year OS and PFS were 76% and 66% respectively. Logistic regression analysis showed bcl-2, ki67, c-myc2 and Neu were relative with more nodal involvement. Patients with lower level of CEA, CA72–4 and higher level of cyclin D1 suivived longer than the other patients. There were different clinical significance with those biomarkers. Patients with lower level of cyclinD1, CEA had more local regional recurrence (p=0.026) while patients with higher PCNA experienced more distant metastasis (p=0.005). Univariate analysis showed that clinical staging, level of cyclinD1 and CEA were correlated with OS (p<0.05). Conclusions: Biological markers may be helpful in predicting the clinical outcome and prognosis for R0 resected gastric cancer patients. Further study are needed to confirm their clinical significance.

No significant financial relationships to disclose.

Dissecting roles of ubiquitination in the p53 pathway

Posttranslational modification of proteins by mono- or polyubiquitination represents a central mechanism to modulate a wide range of cellular functions like protein stability, intracellular transport, protein interactions, and transcriptional activity. Analogous to other posttranslational modifications, ubiquitination is a reversible process counteracted by deubiquitinating enzymes (DUBs), which cleave the isopeptide linkage between protein substrate and the ubiquitin residue. The p53 tumor suppressor is a sequence-specific DNA-binding transcriptional factor that plays a central role in regulating growth arrest and apoptosis during the stress response. Notably, recent studies indicate that both the stability and the subcellular localization of p53 are tightly regulated by ubiquitination; p53 is mainly ubiquitinated by Mdm2 but other ubiquitin ligases such as ARF-BP1/HectH9/MULE are also involved in p53 regulation in vivo. Moreover, a deubiquitinase HAUSP was initially identified in p53 deubiquitination but more recent studies showed that both Mdm2 and Mdmx are also bona fide substrates of HAUSP. In this article, we review our latest understanding of ubiquitination in modulating the p53 tumor suppression pathway.

CNV and nervous system diseases--what's new?

Several new genomic disorders caused by copy number variation (CNV) of genes whose dosage is critical for the physiological function of the nervous system have been recently identified. Dup(7)(q11.23) patients carry duplications of the genomic region deleted in Williams-Beuren syndrome, they are characterized by prominent speech delay. The phenotypes of Potocki-Lupski syndrome and MECP2 duplication syndrome were neuropsychologically examined in detail, which revealed autism as an endophenotype and a prominent behavioral feature of these disorders. Tandem duplication of LMNB1 was reported to cause adult-onset autosomal dominant leukodystrophy. PAFAH1B1/LIS1 and YWHAE, which were deleted in isolated lissencephaly (PAFAH1B1/LIS1 alone) and Miller-Dieker syndrome (both genes), were found to be duplicated in patients with developmental delay. Finally, two novel microdeletion syndromes affecting 17q21.31 and 15q13.3, as well as their reciprocal duplications, were also identified. In this review, we provide an overview of the phenotypic manifestation of these syndromes and the rearrangements causing them.

The p53--Mdm2--HAUSP complex is involved in p53 stabilization by HAUSP

The ubiquitin-specific protease HAUSP is a critical component of the p53-Mdm2 pathway by acting as a specific deubiquitinase for both p53 and Mdm2. Recent structural studies have indicated that p53 and Mdm2 bind to the N-terminal TRAF-like domain of HAUSP in a mutually exclusive manner. To understand the mechanism of HAUSP-mediated effects, we have created a p53 mutant that lacks HAUSP binding based on the crystal structure analysis. Indeed, this mutant p53 protein can be degraded by Mdm2 but fails to interact with HAUSP both in vitro and in vivo. Surprisingly, however, we have found that direct interaction between HAUSP and p53 is not absolutely required for it to antagonize efficiently Mdm2-mediated ubiquitination of p53 and that HAUSP is capable of enzymatically functioning in trans on p53 by using Mdm2 as a bridge. Further, we show that a trimeric protein complex containing p53, Mdm2 and HAUSP can exist in vivo, despite mutually exclusive binding, with Mdm2 serving as a binding mediator for p53 and HAUSP. These findings reveal the complication of HAUSP-mediated effects in the p53-Mdm2 interplay. It also has important implications for the development of novel chemotherapeutic compounds aimed at blocking this protein-protein interaction.

The use of activated charcoal for the removal of PCR inhibitors from oyster samples

Activated charcoal is a carbonaceous adsorbent with a high internal porosity, and hence a large internal surface area. Cells of a strain of Escherichia coli O157:H7 seeded into oyster tissue homogenates were completely bound to untreated charcoal after an incubation period of 15 min at room temperature. In contrast, activated charcoal particles coated with cells of Pseudomonas fluorescens resulted in 92.6%+/-3.7 recovery of E. coli O157:H7. This allowed the successful use of the coated activated charcoal for the absorption of PCR inhibitors from seeded tissue samples. With coated charcoal, real-time PCR was able to detect 1x10(3) CFU of E. coli 0157:H7/g of tissue which was equivalent to 50 genomic targets per real-time PCR. In contrast, without the use of treated charcoal, the real-time PCR failed to detect 10(7) CFU/g. This is a promising, and convenient technology that can be applied to increase the sensitivity of the PCR assay without selective enrichment, for the detection of low numbers of pathogenic microorganisms in complex matrices such as foods, clinical, and environmental samples, which frequently exhibit high levels of PCR inhibition.

Cytotoxic benzo[j]fluoranthene metabolites from Hypoxylon truncatum IFB-18, an endophyte of Artemisia annua

Two new benzo[j]fluoranthene-based secondary metabolites named daldinone C (1) and daldinone D (2), along with two known metabolites, altechromone A and (4S)-5,8-dihydroxy-4-methoxy-alpha-tetralone, were isolated from the CHCl3/MeOH (1:1) extract of a solid culture of the endophyte Hypoxylon truncatum IFB-18 harbored inside the symptomless stem tissue of Artemisia annua. The structures of the new compounds were elucidated by MS and 1D and 2D NMR spectra and by X-ray diffraction analysis. Their absolute configurations were determined unambiguously by a combination of their CD data and the established exciton chirality rule. Compounds 1 and 2 were substantially cytotoxic against SW1116 cells, with IC50 values of 49.5 and 41.0 microM, respectively, comparable to that (37.0 microM) of 5-fluorouracil. The biosynthetic pathway for 1 and 2 was postulated with the natural occurrence of benzo[j]fluoranthene analogues discussed in brief.

ARF-BP1 as a potential therapeutic target

In this review, we discuss the recent identification of ARF-BP1 (also known as Mule, UREB1, E3^histone, LASU1, and HectH9). ARF-BP1, a HECT domain-containing E3 ubiquitin ligase, interacts with ARF and p53. Its ubiquitin ligase activity is inhibited by ARF. Inactivation of ARF-BP1 stabilised p53 and induced apoptosis. Notably, inactivation of ARF-BP1 also caused cell growth repression in p53-null cells and breast cancer cells with mutant p53. Thus, ARF-BP1 emerges as a novel therapeutic target against cancer regardless of p53 status.

Inhibition of cervical cancer cell growth in vitro and in vivo with lentiviral-vector delivered short hairpin RNA targeting human papillomavirus E6 and E7 oncogenes

In this study, we investigated the suppressive effect of a short hairpin RNA delivered by a lentiviral vector (LV-shRNA) against human papillomavirus (HPV) type 18 E6 on the expression of the oncogenes E6 and E7 in cervical cancer HeLa cells both in vitro and in vivo. The LV-shRNA effectively delivered the shRNA to HeLa cells and lead to a dose-dependent reduction of E7 protein and the stabilization of E6 target proteins, p53 and p21. Low-dose infection of HeLa cells with LV-shRNA caused reduced cell growth and the induction of senescence, whereas a high-dose infection resulted in specific cell death via apoptosis. Transplant of HeLa cells infected with a low dose of LV-shRNA into Rag-/- mice significantly reduced the tumor weight, whereas transplant of cells infected with a high dose resulted in a complete loss of tumor growth. Systemic delivery of LV-shRNA into mice with established HeLa cell lung metastases led to a significant reduction in the number of tumor nodules. Our data collectively suggest that lentiviral delivery is an effective way to achieve stable suppression of E6/E7 oncogene expression and induce inhibition of tumor growth both in vitro and in vivo. These results encourage further investigation of this form of RNA interference as a promising treatment for cervical cancer.

Chemotherapy for tumors: an analysis of the dynamics and a study of quadratic and linear optimal controls

We investigate a mathematical model of tumor-immune interactions with chemotherapy, and strategies for optimally administering treatment. In this paper we analyze the dynamics of this model, characterize the optimal controls related to drug therapy, and discuss numerical results of the optimal strategies. The form of the model allows us to test and compare various optimal control strategies, including a quadratic control, a linear control, and a state-constraint. We establish the existence of the optimal control, and solve for the control in both the quadratic and linear case. In the linear control case, we show that we cannot rule out the possibility of a singular control. An interesting aspect of this paper is that we provide a graphical representation of regions on which the singular control is optimal.

Mixed immunotherapy and chemotherapy of tumors: modeling, applications and biological interpretations

We develop and analyze a mathematical model, in the form of a system of ordinary differential equations (ODEs), governing cancer growth on a cell population level with combination immune, vaccine and chemotherapy treatments. We characterize the ODE system dynamics by locating equilibrium points, determining stability properties, performing a bifurcation analysis, and identifying basins of attraction. These system characteristics are useful not only to gain a broad understanding of the specific system dynamics, but also to help guide the development of combination therapies. Numerical simulations of mixed chemo-immuno and vaccine therapy using both mouse and human parameters are presented. We illustrate situations for which neither chemotherapy nor immunotherapy alone are sufficient to control tumor growth, but in combination the therapies are able to eliminate the entire tumor.

Congenital dermatofibrosarcoma protuberans with fibrosarcomatous and myxoid change

This report describes a case of congenital dermatofibrosarcoma protuberans (DFSP) with fibrosarcomatous (FS) and myxoid areas. Immunohistochemical results showed that tumour cells in ordinary DFSP areas were diffusely positive for CD34, whereas in the FS and myxoid areas, few tumour cells were positive for this antigen. Ki-67 positive tumour cell numbers were greater in the FS (11.8%) and myxoid areas (19.8%) relative to ordinary DFSP areas (2.2%). Reverse transcription polymerase chain reaction and sequence analysis showed the presence of an identical COL1A1-PDGFB fusion transcript in ordinary DFSP (plaque-like area), FS, and myxoid areas of DFSP. These results indicate that the three components of DFSP have a common histogenesis. This study documents the first application of gene analysis involving the myxoid area of DFSP.

Measurement of dijet azimuthal decorrelations at central rapidities in pp collisions at sqrt s =1.96 TeV

Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (-)p collisions at a center-of-mass energy sqrt[s]=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.

Inhibitory effect of recombinant adenovirus carrying melittin gene on hepatocellular carcinoma

OBJECTIVES

To search for a new clinical application of melittin (Mel): treating hepatocellular carcinoma with Mel gene.

METHODS

Recombinant adenoviruses carrying the Mel gene and alpha-fetoprotein (AFP) promoter (Ad-rAFP-Mel) were constructed through a bacterial homologous recombinant system. The efficiency of adenovirus-mediated gene transfer and the inhibitory effect of Ad-rAFP-Mel on the proliferation of hepatocarcinoma cells were determined by X-gal stain and MTT assay, respectively. The tumorigenicity of hepatocarcinoma cells transfected by Ad-rAFP-Mel and the antitumor effect of Ad-rAFP-Mel on transplanted tumor in nude mice were detected in vivo.

RESULTS

The Mel mRNA was transcribed in BEL-7402 hepatocellular carcinoma cells transducted by Ad-rAFP-Mel. The efficiency of adenovirus-mediated gene transferred to BEL-7402 cells was 100% when the multiplicity of infection of Ad-rAFP-Mel was 10 in vitro, and was also high in vivo. The inhibitive rates of Ad-rAFP-Mel and Ad-rAFP for BEL7402 cells were 66.2 +/- 2.7% and 2.9 +/- 2.3% (t=30.83, P=6.6 x 10(-6)) by MTT assay. The inhibitive rates of Ad-CMV-Mel for BEL7402, SMMC7721 and L02 cells were 58.9 +/- 9.6%, 65.9 +/- 3.8% and 31.7 +/- 1.2%, respectively, and of Ad-rAFP-Mel were 66.2 +/- 2.7%, 16.1 +/- 6.6% and 7.5 +/- 3.3%, respectively (t=1.27, P=0.27; t=11.31, P=3.5 x 10(-4); and t=12.12, P=2.7 x 10(-4) versus the Ad-CMV-Mel group in the same cells). The tumorigenicity rates of hepatocarcinoma cells transfected by Ad-rAFP-Mel were decreased. A significant antineoplastic effect was detected on transplanted tumor in nude mice by intratumoral injection of Ad-rAFP-Mel.

CONCLUSIONS

Ad-rAFP-Mel can inhibit specifically proliferation of AFP-producing human hepatocarcinoma cells in vitro and in vivo. This suggests that animal toxin gene can be used as an antitumor gene.

LGI1: a gene involved in epileptogenesis and glioma progression?

The leucine-rich, glioma inactivated gene 1 (LGI1) gene on human chromosome 10q24 was first identified as a candidate tumor suppressor gene for glioma. Surprisingly, mutations in LGI1 were also shown to cause an idiopathic epilepsy syndrome, autosomal dominant lateral temporal lobe epilepsy (ADLTE). LGI1 is one of the only two currently known non-ion channel genes whose mutations cause idiopathic epilepsy in humans. In this review we summarize the current data on structure and function of the LGI1 protein and discuss clinical aspects of ADLTE and their correlation with LGI1. We also propose that the evidence supporting the tumor suppressor role of LGI1 in malignant gliomas is weak and that further work is necessary to establish LGI1 role in glial cells.

Search for supersymmetry with gauge-mediated breaking in diphoton events at D0

We report the results of a search for supersymmetry (SUSY) with gauge-mediated breaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle.

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).

Observation and properties of the X(3872) decaying to J/psipi(+)pi(-) in pp collisions at sqrt[s]=1.96 TeV

We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in pp collisions at sqrt[s]=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.

Search for doubly charged higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in pp collisions at sqrt[s]=1.96 TeV

A search for pair production of doubly charged Higgs bosons in the process pp -->H(++)H(--) -->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of sqrt[s]=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H(+/-+/-)(L))>118.4 GeV/c(2) and M(H(+/-+/-)(R))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs.

Assessment of arbovirus vector infection rates using variable size pooling

Pool testing of vector samples for arboviruses is widely used in surveillance programmes. The proportion of infected mosquitoes (Diptera: Culicidae) is often estimated from the minimum infection rate (MIR), based on the assumption of only one infected mosquito per positive pool. This assumption becomes problematic when pool size is large and/or infection rate is high. By relaxing this constraint, maximum likelihood estimation (MLE) is more useful for a wide range of infection levels that may be encountered in the field. We demonstrate the difference between these two estimation approaches using West Nile virus (WNV) surveillance data from vectors collected by gravid traps in Chicago during 2002. MLE of infection rates of Culex mosquitoes was as high as 60 per 1000 at the peak of transmission in August, whereas MIR was less than 30 per 1000. More importantly, we demonstrate roles of various pooling strategies for better estimation of infection rates based on simulation studies with hypothetical mosquito samples of 18 pools. Variable size pooling (with a serial pool sizes of 5, 10, 20, 30, 40 and 50 individuals) performed consistently better than a constant size pooling of 50 individuals. We conclude that variable pool size coupled with MLE is critical for accurate estimates of mosquito infection rates in WNV epidemic seasons.

[Estimation of vector prevalence by using pool sampling]

AIM

To investigate theoretically the feasibility of the pool sampling method in estimating the vector prevalence.

METHODS

The probability distribution of infected individuals in a given pool was analyzed using binomial distribution, based upon the upper limit of predicted vector infectivity. The maximal pool size was determined in case that the probability of only one infected individual within this positive pool is larger than a predetermined significance level, in this way infection rate is estimated by the number of positive pools and the judgment of predicted prevalence was addressed by the threshold of positive pool ratio.

RESULTS

In comparison with the pool sampling based on the positive pool ratio the method suggested in the present paper poses a variance and precision of estimates independent on pool sizes although it requires a predicted prevalence to determine the maximal pool size. In situations of limited samples and a high prevalence this pooling method has higher estimation efficiency.

CONCLUSION

Theoretically the estimation of vector prevalence using pooling methods is feasible. The estimation based on positive pool ratio is suitable for situations of lacking epidemiological data and rough precision estimation, whereas the method based on the maximum pool size provides more accurate estimates and needs a prior predicted infection rate.

Quantitative trait loci for bone density in mice: the genes determining total skeletal density and femur density show little overlap in F2 mice

Bone mineral density variation is a highly heritable trait and is the best predictor of skeletal fragility. Total skeletal density was determined by PIXIMUS, and femur density was determined by pQCT. The data were analyzed for quantitative trait loci (QTL) to determine if bone density at a specific skeletal site (femur) would identify new gene loci or the same gene loci as total body (PIXIMUS). In order to show concordance and differences in QTL for total body bone density versus femur bone density, we performed a genome-wide scan from 633 (MRL x SJL) F2 mice. The bone mineral density (BMD) data from pQCT were used to identify nine QTL on chromosomes 1, 3, 4, 9, 12, 17, and 18, while nine QTL on chromosomes 1, 2, 4, 9, 11, 14, and 15 were identified by PIXIMUSdata, accounting for 32.5% and 30.4% variation in F2 mice, respectively. QTL on chromosomes 1, 2, 3, 9, 11, 12, 14, 15, 17, and 18 are unique to our study, as they have never been described before. Chromosome 1 (D1Mit33 and D1Mit362) had similar QTL between pQCT and PIXIMUS. Several QTL were identified for both femur and total body BMD but only two QTL were common for both of these phenotypes. This suggests that genes regulating bone density differ depending on the skeletal site analyzed.

Opposing changes in osteocalcin levels in bone vs serum during the acquisition of peak bone density in C3H/HeJ and C57BL/6J mice

Our knowledge of the developmental changes in the concentration of serum and bone osteocalcin (OC) is limited. To investigate the interrelationship between skeletal and circulatory OC during acquisition of peak bone density in mice, we examined the temporal changes in the concentration of serum and bone OC from 3 to 12 weeks of age between C3H/HeJ (C3H) and C57BL/6J (B6), two commonly used inbred strains of mice with a large difference in bone density. We have demonstrated an increase in bone and decrease in serum OC during the acquisition of peak bone density in C3H and B6 mice which parallels an increase in bone mineral density. These two strains exhibited differential changes in the concentration of OC. C3H mice retained more OC in bone and secreted less into serum compared with B6, which coincides with the large differences in bone density between these two strains. These opposite changes of OC levels in bone and serum between C3H and B6 stress the importance of defining the genetic mechanisms underlying the differences in OC metabolism, differences that could be relevant to the acquisition and maintenance of bone mass in mice.

Polymerized lyotropic liquid crystal assemblies for materials applications

The development of functional materials with nanometer-scale architectures and the effect of these architectures on their chemical and physical properties are currently of great interest in materials design. Polymerizable lyotropic liquid crystal (LLC) assemblies provide a facile entry into this area by allowing one to fix the inherent order in these systems using covalent bonds to create robust, nanostructured materials. The use of the cross-linked inverted hexagonal phase in templated nanocomposite formation and heterogeneous catalysis has been demonstrated. Additionally, the polymerization of LLC mesogens in the regular hexagonal and bicontinuous cubic phases is being targeted for future developments in functional materials. Future directions for new applications of these materials are also discussed.

Detection of sporadic cases of hepatitis E virus (HEV) infection in China using immunoassays based on recombinant open reading frame 2 and 3 polypeptides from HEV genotype 4

We reported previously on the complete sequence of hepatitis E virus (HEV) genotype 4, isolated from patients with sporadic cases of acute HEV infection in China. At least eight HEV genotypes have now been described worldwide, and further isolates await classification. Current immunoassays for the detection of anti-HEV antibodies are based on polypeptides from genotypes 1 and 2 only and may be inadequate for the reliable detection of other genotypes. Because genotypes 1 and 4 predominate in China, we wished to investigate the antigenic reactivities of HEV genotype 4 proteins. Four overlapping regions of open reading frame 2 (ORF2) (FB5, amino acids [aa] 1 to 130; E4, aa 67 to 308; F2-2, aa 288 to 461; E5, aa 414 to 672) and the entire ORF3 product were expressed in Escherichia coli as fusion proteins. Enzyme immunoassays based on each of the five purified polypeptides were evaluated with sera from patients with sporadic cases of acute HEV infection. Individual immunoassays derived from HEV genotype 4 detected more cases of acute hepatitis E than a commercial assay. Some serum samples, which were positive for anti-HEV immunoglobulin G only by assays based on HEV genotype 4, were positive for HEV RNA by reverse transcription-PCR. Polypeptide FB5, from the N terminus of ORF2, had the greatest immunoreactivity with sera from patients with acute hepatitis E. These data indicate that the N terminus of ORF2 may provide epitopes which are highly reactive with acute-phase sera and that assays based on genotypes 1 and 2 alone may be inadequate for the detection of HEV infection in China, where sporadic cases of HEV infection are caused predominantly by HEV genotypes 4 and 1.

Identification of wound healing/regeneration quantitative trait loci (QTL) at multiple time points that explain seventy percent of variance in (MRL/MpJ and SJL/J) mice F2 population

Studies on genetic mechanisms of wound healing in mammals are very few, although injury is a leading cause of the global burden of disease. In this study, we performed a high-density, genome-wide scan using 633 (MRL/MPJ x SJL/J) F(2) intercross at multiple time points (days 15, 21, and 25) to identify quantitative trait loci (QTL) involved in wound healing/regeneration. The hypothesis of the study was that QTL and unique epistatic interactions are involved at each time point to promote wound healing/regeneration. Ten QTL were identified from chromosomes 1, 4, 6, 7, 9, and 13. Of the 10 QTL, eight from chromosomes 1, 4, 6, and 9 were novel as compared to QTL identified in the study. The 10 QTL altogether explained 70% of variance in F(2) mice. The same QTL were identified at each time point, with simple linear correlation between days 15, 21, and 25, showing very high significant relationships (R >0.92, P <0.0001). Unique epistatic interactions were identified at each time point except those from chromosomes 4, 6, 9, and 13 that were found at all three time points, showing that some loci are involved at all the three time points of wound healing (days 15, 21, and 25). Therefore, loci-to-loci interactions may play a major role in wound healing. Information from these studies may help in the identification of genes that could be involved in wound healing/regeneration.

Characterisation of soy isoflavones and screening for novel malonyl glycosides using high-performance liquid chromatography-electrospray ionisation-mass spectrometry

HPLC combined with electrospray ionisation (ESI)-MS and photodiode array detection has been employed to study the isoflavone components of soy. All of the known soy isoflavones separated by HPLC were identified and characterised, and three novel isoflavones were detected and screened out. These minor isoflavones were deduced to be isomers of 6"-O-malonyl isoflavone glycosides, based on the ESI-MS and UV data, in which the malonyl group is attached at a position other than the 6" position of the glycosyl moiety of the molecule. These novel malonyl glycosides are as thermally labile as the 6"-O-malonyl glycosides, being converted into known isoflavone glycosides after heating in aqueous ethanol. The advantages of HPLC-ESI-MS in detection of novel isoflavones from plant extracts are reviewed.