ADAM9 drives the immunosuppressive microenvironment by cholesterol biosynthesis-mediated activation of IL6-STAT3 signaling for lung tumor progression

Chronic inflammation associated with lung cancers contributes to immunosuppressive tumor microenvironments, reducing CD8+ T-cell function and leading to poor patient outcomes. A disintegrin and metalloprotease domain 9 (ADAM9) promotes cancer progression. Here, we aim to elucidate the role of ADAM9 in the immunosuppressive tumor microenvironment. A bioinformatic analysis of TIMER2.0 was used to investigate the correlation of ADAM9 and to infiltrate immune cells in the human lung cancer database and mouse lung tumor samples. Flow cytometry, immunohistochemistry, and RNA sequencing (RNA-seq) were performed to investigate the ADAM9-mediated immunosuppressive microenvironment. The coculture system of lung cancer cells with immune cells, cytokine array assays, and proteomic approach was used to investigate the mechanism. By analyzing the human LUAD database and the mouse lung cancer models, we showed that ADAM9 was associated with the immunosuppressive microenvironment. Additionally, ADAM9 released IL6 protein from cancer cells to inhibit IL12p40 secretion from dendritic cells, therefore leading to dendritic cell dysfunction and further affecting T-cell functions. Proteomic analysis indicated that ADAM9 promoted cholesterol biosynthesis and increased IL6-STAT3 signaling. Mechanistically, ADAM9 reduced the protein stability of LDLR, resulting in reduced cholesterol uptake and induced cholesterol biosynthesis. Moreover, LDLR reduction enhanced IL6-STAT3 activation. We reveal that ADAM9 has a novel biological function that drives the immunosuppressive tumor microenvironment by linking lung cancer's metabolic and signaling axes. Thus, by targeting ADAM9 an innovative and promising therapeutic opportunity was indicated for regulating the immunosuppression of lung cancer.

Inhibition of ADAM9 promotes the selective degradation of KRAS and sensitizes pancreatic cancers to chemotherapy

Kirsten rat sarcoma virus (KRAS) signaling drives pancreatic ductal adenocarcinoma (PDAC) malignancy, which is an unmet clinical need. Here, we identify a disintegrin and metalloproteinase domain (ADAM)9 as a modulator of PDAC progression via stabilization of wild-type and mutant KRAS proteins. Mechanistically, ADAM9 loss increases the interaction of KRAS with plasminogen activator inhibitor 1 (PAI-1), which functions as a selective autophagy receptor in conjunction with light chain 3 (LC3), triggering lysosomal degradation of KRAS. Suppression of ADAM9 by a small-molecule inhibitor restricts disease progression in spontaneous models, and combination with gemcitabine elicits dramatic regression of patient-derived tumors. Our findings provide a promising strategy to target the KRAS signaling cascade and demonstrate a potential modality to enhance sensitivity to chemotherapy in PDAC.

Interim Analysis of a Non-Randomized Prospective Trial Comparing Hypofractionated Post-Mastectomy Radiotherapy (HF-PMRT) to Conventional Post-Mastectomy Radiotherapy (CF-PMRT) for Breast Cancer (BC) Patients

PURPOSE/OBJECTIVE(S)

The standard of care for treatment for LABC patients who have undergone modified radical mastectomy (MRM) is PMRT. Post-mastectomy RT (PMRT) for LABC patients has been established in three trials to improve locoregional control and overall survival (OS). A published trial from China showed that HF-PMRT was non-inferior to CF-PMRT. This study was conducted to determine if HF-PMRT can provide similar efficacy and toxicity.

MATERIALS/METHODS

A non-randomized prospective trial design was employed to compare HF-PMRT and CF-PMRT in post-MRM BC patients. Patients with pathologically proven BC who underwent MRM without positive margins and with less than 8 positive nodes were included. Informed consent was obtained. Patients decided which treatment they will receive. They received either HF-PMRT of 43.2 Gy in 16 fractions (fx) [2.7 Gy/fx] or CF-PMRT of 50-50.4 Gy in 1.8-2.0 Gy/fx to both chest wall and regional nodes (axillary and supraclavicular) in both regimens. Primary endpoints were 2-year OS and 2-year local recurrence free survival (LRFS). Secondary endpoints include acute and late toxicities. Analysis was done as intention-to treat. An interim analysis of 2-year results is presented.

RESULTS

A total of 37 patients were enrolled in two separate cohorts: a single-arm cohort that recruited 10 HF-PMRT patients from 2014-2015 and a two-arm prospective trial that started recruitment last 2019 and included 12 HF-PMRT and 15 CF-PMRT patients. Median follow-up was 35 months. There were more Stage IIB and Stage III for the CF-PMRT arm [p = 0.040]. Treatment interruptions were more frequent in the CF-PMRT arm (100% vs 68%, p = 0.028). The duration of interruption was also longer in CF-PMRT (median 8 vs 3 days) [p < 0.003]. Acute and late toxicities were not statistically different. There was one patient each with RTOG Grade 2 acute skin toxicity in the HF-PMRT (4.55%) and CF-PMRT arms (6.67%) [p = 0.703]. For late toxicities, the HF-PMRT arm had 6 Grade 1 late skin toxicities and 1 Grade 3 late skin toxicity vs 1 Grade 1 late skin toxicity for CF-PMRT arm [p = 0.196]. 2-year OS rate (86.3% vs 100%, p = 0.403) 2-year DFS rate (68.18% and 73.33%, p = 0.126) were both not statistically different. There were no reported locoregional recurrences (LCR).

CONCLUSION

In terms of local control, both arms have showed no LCRs. 2-year OS and DFS rate were no different. As the study has not yet reached the adequate sample size, the non-inferiority of HF-PMRT cannot be definitively concluded. Acute and late toxicities were no different. There was a significantly higher rate of treatment interruptions in the CF-PMRT compared to the HF-PMRT arm. The results of this interim analysis prove to be promising and patients will continue to be accrued. The final results of this study might have tremendous implications in local practice.

Inhibition of CDCP1 by 8-isopentenylnaringenin synergizes with EGFR inhibitors in lung cancer treatment

CUB domain-containing protein 1 (CDCP1) contributes to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance by regulating EGFR signaling pathways and is a potential target in lung cancer treatment. This study aims to identify a CDCP1 reducer that synergistically improves TKI treatment. Utilizing a high-throughput drug screening system, a phytoestrogen 8-isopentenylnaringenin (8PN) was identified. Upon 8PN treatment, CDCP1 protein levels and malignant features were reduced. 8PN exposure caused the accumulation of lung cancer cells in G0/G1 phase and increased the proportion of senescent cells. In EGFR TKI-resistant lung cancer cells, the combination of 8PN and TKI synergistically reduced cell malignance, inhibited downstream EGFR pathway signaling and exerted additive effects on cell death. Moreover, combination therapy effectively reduced tumor growth and enhanced tumor necrosis in tumor xenograft mice models. Mechanistically, 8PN increased interleukin (IL)6 and IL8 expression, induced neutrophil infiltration, and enhanced neutrophil-mediated cytotoxicity to attenuate lung cancer cell growth. In conclusion, 8PN enhances the anti-cancer efficacy of EGFR TKI on lung cancer, and triggers neutrophil-dependent necrosis, highlighting the potential to overcome TKI resistance in lung cancer patients who have EGFR mutation.

ADAM9 functions as a transcriptional regulator to drive angiogenesis in esophageal squamous cell carcinoma

Hypoxia and angiogenesis play key roles in the pathogenesis of esophageal squamous cell carcinoma (ESCC), but regulators linking these two pathways to drive tumor progression remain elusive. Here we provide evidence of ADAM9's novel function in ESCC progression. Increasing expression of ADAM9 was correlated with poor clinical outcomes in ESCC patients. Suppression of ADAM9 function diminished ESCC cell migration and in vivo metastasis in ESCC xenograft mouse models. Using cellular fractionation and imaging, we found a fraction of ADAM9 was present in the nucleus and was uniquely associated with gene loci known to be linked to the angiogenesis pathway demonstrated by genome-wide ChIP-seq. Mechanistically, nuclear ADAM9, triggered by hypoxia-induced translocation, functions as a transcriptional repressor by binding to promoters of genes involved in the negative regulation of angiogenesis, and thereby promotes tumor angiogenesis in plasminogen/plasmin pathway. Moreover, ADAM9 suppresses plasminogen activator inhibitor-1 gene transcription by interacting with its transcription factors at the promoter. Our findings uncover a novel regulatory mechanism of ADAM9 as a transcriptional regulator in angiogenesis and highlight ADAM9 as a promising therapeutic target for ESCC treatment.

Involvement of c-Myc in low dose radiation-induced senescence enhanced migration and invasion of unirradiated cancer cells

Ionizing radiation is known to cause cell apoptosis at high dose range, but little is known about the cellular response to low dose radiation. In this study, we found that conditioned medium harvested from WI-38 lung fibroblasts and H1299 lung adenocarcinoma cells exposed to 0.1Gy to 1Gy could enhance the migration and invasion of unirradiated H1299 cells in both 2D and 3D culturing circumstances. Low dose radiation did not induce apoptosis, but induced senescence in irradiated cells. We next examined the expression of immediately early genes including c-Myc and K-Ras. Although both genes could be up-regulated by low dose radiation, induction of c-Myc was more specific to low dose range (0.5Gy) at transcriptional and translational levels. Knockdown of c-Myc by shRNA could repress the senescence induced by low dose radiation. The conditioned medium of irradiated cells induced migration of unirradiated cells was also repressed by knockdown of c-Myc. The c-Myc inhibitor 10058-F4 could suppress low dose radiation induced cell senescence, and the conditioned medium harvested from irradiated cells pretreated with 10058-F4 also lost the ability to enhance the migration of unirradiated cells. The cytokine array analysis revealed that immunosuppressive monocyte chemoattractant protein-1 increased by low dose radiation could be repressed by 10058-F4. We also showed that 10058-F4 could suppress low dose radiation induced tumor progression in a xenograft tumor model. Taken together, current data suggest that -Myc is involved in low dose radiation induced cell senescence and potent bystander effect to increase the motility of unirradiated cells.

Identification of theranostic factors for patients developing metastasis after surgery for early-stage lung adenocarcinoma

Rationale: Lung adenocarcinoma (LUAD) is an aggressive disease with high propensity of metastasis. Among patients with early-stage disease, more than 30% of them may relapse or develop metastasis. There is an unmet medical need to stratify patients with early-stage LUAD according to their risk of relapse/metastasis to guide preventive or therapeutic approaches. In this study, we identified 4 genes that can serve both therapeutic and diagnostic (theranostic) purposes.

Methods: Three independent datasets (GEO, TCGA, and KMPlotter) were used to evaluate gene expression profile of patients with LUAD by unbiased screening approach. Upon significant genes uncovered, functional enrichment analysis was carried out. The predictive power of their expression on patient prognosis were evaluated. Once confirmed their theranostic roles by integrated bioinformatics, we further conducted in vitro and in vivo validation.

Results: We found that four genes (ADAM9, MTHFD2, RRM2, and SLC2A1) were associated with poor patient outcomes with an increased hazard ratio in LUAD. Knockdown of them, both separately and simultaneously, suppressed lung cancer cell proliferation and migration ability in vitro and prolonged survival time in metastatic tumor mouse models. Moreover, these four biomarkers were found to be overexpressed in tumor tissues from LUAD patients, and the total immunohistochemical staining scores correlated with poor prognosis.

Conclusions: These results suggest that these four identified genes could be theranostic biomarkers for stratifying high-risk patients who develop relapse/metastasis in early-stage LUAD. Developing therapeutic approaches for the four biomarkers may benefit early-stage LUAD patients after surgery.

Targeting positive feedback between BASP1 and EGFR as a therapeutic strategy for lung cancer progression

Rationale: Brain metastasis in patients with lung cancer is life-threatening. However, the molecular mechanism for this catastrophic disease remains elusive, and few druggable targets are available. Therefore, this study aimed to identify and characterize proteins that could be used as therapeutic targets.

Methods: Proteomic analyses were conducted to identify differentially expressed membrane proteins between brain metastatic lung cancer cells and primary lung cancer cells. A neuronal growth-associated protein, brain acid soluble protein 1 (BASP1), was chosen for further investigation. The clinical relevance of BASP1 in lung adenocarcinoma was first assessed. Tyrosine kinase activity assays and in vitro and in vivo functional assays were conducted to explore the oncogenic mechanisms of BASP1.

Results: The protein levels of BASP1 were positively associated with tumor progression and poor prognosis in patients with lung adenocarcinoma. Membrane-bound BASP1 increased EGFR signaling and stabilized EGFR proteins by facilitating their escape from the ubiquitin-proteasome pathway. Reciprocally, activation of EGFR recruited more BASP1 to the plasma membrane, generating a positive feedback loop between BASP1 and EGFR. Moreover, the synergistic therapeutic effects of EGFR tyrosine kinase inhibitor and arsenic trioxide led to a reduction in the level of BASP1 protein observed in lung cancer cells with acquired resistance to EGFR inhibitors.

Conclusions: The reciprocal interaction between BASP1 and EGFR facilitates EGFR signaling in brain metastatic lung cancer. Targeting the newly identified BASP1-EGFR interaction could open new venues for lung cancer treatment.

Abstract 5796: Therapeutic effects of statins against lung adenocarcinoma via mutant p53 mediated apoptosis

Introduction The p53 gene is well known as an important tumor suppressor gene. Mutant p53 genes account for about half of all lung cancer cases. There is increasing evidence for the anti-tumor effects of statins via inhibition of the mevalonate pathway. However, the cancer prevention and protection effects of statinsin population-based studies are controversial. Previous population-based studies have shown protective effects of statins in advanced lung cancer patients; however, the effects in early lung cancer patients are unclear.

Methods We investigated the correlation between statin use and lung cancer prognosis using the Taiwanese National Health Insurance Research Database retrospectively, mainly focusing on early-stage lung cancer. Cell viability, lipid raft changes, and motile activity from simvastatin-treated cell lines were examined to determine the effect of simvastatin under different p53 mutations. Apoptotic pathways and autophagy in lung cancer cells treated with simvastatin were analyzed using a western blot assay.

Results Statin treatments reduced the 5-year mortality (odds ratio, 0.43; 95% confidence interval [CI], 0.37-0.49;P&lt; 0.001) in this population-based study. Simvastatin inhibited cell growth, especially in mutant p53 lung cancer cell lines. Significantly higher levels of cellular apoptosis and decreased lipid rafts were shown in mutant p53 lung cancer cells treated with simvastatin. Further, simvastatin increased activity of the caspase-dependent apoptotic pathway in lung cancer cells containing mutant p53. In addition, simvastatin reduced migration in cells with a mutated p53 gene.

Conclusion This study reports the protective effects of statin use in early-stage lung cancer patients regardless of chemotherapy. Simvastatin induced cellular apoptosis and regulated lipid raft content; further, motile activity was reduced in lung cancer cells with p53 missense mutations. These data suggest that statin use in selected lung cancer patients may have clinical benefits.

Citation Format: Cheng-wei Chou, Ching-Heng Lin, Tzu-Hung Hsiao, Chia-Chien Lo, Chih-Ying Hsieh, Cheng-Chung Huang, Yuh-Pyng Sher. Therapeutic effects of statins against lung adenocarcinoma via mutant p53 mediated apoptosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5796.

Therapeutic effects of statins against lung adenocarcinoma via p53 mutant-mediated apoptosis

The p53 gene is an important tumour suppressor gene. Mutant p53 genes account for about half of all lung cancer cases. There is increasing evidence for the anti-tumour effects of statins via inhibition of the mevalonate pathway. We retrospectively investigated the correlation between statin use and lung cancer prognosis using the Taiwanese National Health Insurance Research Database, mainly focusing on early-stage lung cancer. This study reports the protective effects of statin use in early-stage lung cancer patients regardless of chemotherapy. Statin treatments reduced the 5-year mortality (odds ratio, 0.43; P < 0.001) in this population-based study. Significantly higher levels of cellular apoptosis, inhibited cell growth, and regulated lipid raft content were observed in mutant p53 lung cancer cells treated with simvastatin. Further, simvastatin increased the caspase-dependent apoptotic pathway, promotes mutant p53 protein degradation, and decreased motile activity in lung cancer cells with p53 missense mutations. These data suggest that statin use in selected lung cancer patients may have clinical benefits.

ADAM9 enhances CDCP1 by inhibiting miR-1 through EGFR signaling activation in lung cancer metastasis

MicroRNAs (miRNAs), which are endogenous short noncoding RNAs, can regulate genes involved in important biological and pathological functions. Therefore, dysregulation of miRNAs plays a critical role in cancer progression. However, whether the aberrant expression of miRNAs is regulated by oncogenes remains unclear. We previously demonstrated that a disintegrin and metalloprotease domain 9 (ADAM9) promotes lung metastasis by enhancing the expression of a pro-migratory protein, CUB domain containing protein 1 (CDCP1). In this study, we found that this process occurred via miR-1 down-regulation. miR-1 expression was down-regulated in lung tumors, but increased in ADAM9-knockdown lung cancer cells, and was negatively correlated with CDCP1 expression as well as the migration ability of lung cancer cells. Luciferase-based reporter assays showed that miR-1 directly bound to the 3′-untranslated region of CDCP1 and inhibited its translation. Treatment with a miR-1 inhibitor restored CDCP1 protein levels and enhanced tumor cell mobility. Overexpression of miR-1 decreased tumor metastases and increased the survival rate in mice. ADAM9 knockdown reduced EGFR signaling and increased miR-1 expression. These results revealed that ADAM9 down-regulates miR-1 via activating EGFR signaling pathways, which in turn enhances CDCP1 expression to promote lung cancer progression.

Reaching the quantum limit of sensitivity in electron spin resonance

The detection and characterization of paramagnetic species by electron spin resonance (ESR) spectroscopy is widely used throughout chemistry, biology and materials science, from in vivo imaging to distance measurements in spin-labelled proteins. ESR relies on the inductive detection of microwave signals emitted by the spins into a coupled microwave resonator during their Larmor precession. However, such signals can be very small, prohibiting the application of ESR at the nanoscale (for example, at the single-cell level or on individual nanoparticles). Here, using a Josephson parametric microwave amplifier combined with high-quality-factor superconducting microresonators cooled at millikelvin temperatures, we improve the state-of-the-art sensitivity of inductive ESR detection by nearly four orders of magnitude. We demonstrate the detection of 1,700 bismuth donor spins in silicon within a single Hahn echo with unit signal-to-noise ratio, reduced to 150 spins by averaging a single Carr-Purcell-Meiboom-Gill sequence. This unprecedented sensitivity reaches the limit set by quantum fluctuations of the electromagnetic field instead of thermal or technical noise, which constitutes a novel regime for magnetic resonance. The detection volume of our resonator is ∼ 0.02 nl, and our approach can be readily scaled down further to improve sensitivity, providing a new versatile toolbox for ESR at the nanoscale.

Hybrid optical-electrical detection of donor electron spins with bound excitons in silicon

Electrical detection of spins is an essential tool for understanding the dynamics of spins, with applications ranging from optoelectronics and spintronics, to quantum information processing. For electron spins bound to donors in silicon, bulk electrically detected magnetic resonance has relied on coupling to spin readout partners such as paramagnetic defects or conduction electrons, which fundamentally limits spin coherence times. Here we demonstrate electrical detection of donor electron spin resonance in an ensemble by transport through a silicon device, using optically driven donor-bound exciton transitions. We measure electron spin Rabi oscillations, and obtain long electron spin coherence times, limited only by the donor concentration. We also experimentally address critical issues such as non-resonant excitation, strain, and electric fields, laying the foundations for realizing a single-spin readout method with relaxed magnetic field and temperature requirements compared with spin-dependent tunnelling, enabling donor-based technologies such as quantum sensing.

Abstract 2260: c-Myc induced senescence is dependent on transactivation of actin depolymerizing factor (ADF)/cofilin to mediate potent bystander effect

Oncogene-induced senescence may prevent unlimited proliferation and lead to cell death. This phenomenon is likely to be associated with up-regulation of p53 and p16INK4 tumor suppressor. Morphological transformation is also an important feature of senescence that exhibits enlarged cell volume and flat morphology. In this study, we found that c-Myc was co-upregulated with cofilin-1, an actin-binding protein essential for actin dynamics and morphological maintenance in replicative senescence. Additionally, oxidative stress induced senescent phenotypes also accompanied by up-regulation of both c-myc and cofilin-1. Knockdown of cofilin-1 was sufficient to minimize the cell shapes and senescence associated β-galactosidase marker that was induced by over-expressed c-myc or oxidative stress. Over-expression of cofilin-1 was also sufficient to induce senescence in the absence of p53 and p16INK4, but was unable to influence c-Myc level. On the other hand, over-expression of c-Myc could induce cofilin-1 expression. We next found that c-myc was able to induce the transactivation of cofilin-1 gene according to results of quantitative polymerase chain reaction (qPCR) and luciferase reporter gene assay. Furthermore, the results of ChIP assay provided evidence that c-myc can bind to two proximal E-box elements nearby the transcriptional initiation on cofilin-1 gene promoter. Although c-myc promoted cellular senescence in vitro, the conditional medium from c-myc over-expressing A549 cells accelerated migration and proliferation in separate cultured cells without c-myc over-expression. Knockdown of cofilin-1 also alleviated this bystander effect caused by over-expression of c-myc. Therefore, c-myc oncogene may require cofilin-1 for cell senescence that influences the growth of other tumor cells. Taken together, current data provide evidence that c-myc/cofilin-1 signaling pathway is a novel mechanism on promoting oncogene-induced cellular senescence and tumor progression.

Citation Format: Shih-Ting Lin, Cheng-Han Tsai, Yi-Jang Lee, Chia-Chien Lo, Yen-Ting Chou. c-Myc induced senescence is dependent on transactivation of actin depolymerizing factor (ADF)/cofilin to mediate potent bystander effect. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2260. doi:10.1158/1538-7445.AM2014-2260

Abstract 440: The sublethal dose radiation induces cellular senescence and potent bystander effects through c-Myc oncogene

The sublethal dose radiation may induce cellular senescence and promote secondary maligancy during radiotherapy. However, the molecular mechanisms are unclear. It has been reported that a variety of early response oncogenes can be up-regulated by the low dose radiation. Because oncogene-induced senescence (OIS) has been considered important for tumor development, we are interested in investigating whether the sublethal dose radiation also raises OIS to affect the malignancy. To this end, human diploid fibroblasts WI-38 cells and human non-small lung cancer H1299 cells were exposed to less than 2Gy of X-rays delivered by the RS2000 X-rays machine. Both cell types exhibited senescent phenotypes within a dose-dependent manner using the senescence-associated β-galactosidase (SA-β-gal) staining. Subsequently, we investigated the expression of c-Myc and c-Ras oncogenes, and the results showed that sublethal dose radiation could induce c-Myc, but not c-Ras, in both transcriptional and translational levels. Additionally, up-regulated c-Myc exhibited transcriptional activity as demonstrated by the promoter-based reporter gene assys. Although the sublethal dose radiation caused cellular senescence and growth delay in exposed cells, the collected culture medium could increase the motility of non-irradiated H1299 cancer cells using the wound healing assay. Interestingly, the culture medium obtained from irradiated H1299 cancer cells caused higher motility in non-irradiated cells than that from irradiated WI-38 fibroblasts. Furthermore, the sublethal dose radiation induced senescent phenotype was suppressed in cells treated with siRNA against c-Myc. Meanwhile, the motility of non-irradiated cells was not increased by the cultured medium obtained from irradiated c-Myc silenced cells. Taken together, the current data suggest that the sublethal dose radiation causes a c-Myc oncogene induced senescence, and this event may promote the bystandard effects that influence the motility of non-irradiated cancer cells.

Citation Format: Chia-Chien Lo, Yen-Ting Chou, Su-Jun Chiu, Jeng-Jung Hwang, Yi-Jang Lee. The sublethal dose radiation induces cellular senescence and potent bystander effects through c-Myc oncogene. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 440. doi:10.1158/1538-7445.AM2013-440

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Enhanced cellular radiosensitivity induced by cofilin-1 over-expression is associated with reduced DNA repair capacity

PURPOSE

A previous report has indicated that over-expression of cofilin-1 (CFL-1), a member of the actin depolymerizing factor (ADF)/cofilin protein family, enhances cellular radiosensitivity. This study explores the involvement of various DNA damage responses and repair systems in the enhanced cellular radiosensitivity as well as assessing the role of CFL-1 phosphorylation in radiosensitivity.

MATERIALS AND METHODS

Human non-small lung cancer H1299 cells harboring a tet-on gene expression system were used to induce exogenous expression of wild-type CFL-1. Colony formation assays were used to determine cell survival after γ-ray exposure. DNA damage levels were determined by Comet assay. DNA repair capacity was assessed by fluorescence-based DNA repair analysis and antibody detection of various repair proteins. The effects of CFL-1 phosphorylation on radiation responses were explored using two mutant CFL-1 proteins, S3D and S3A. Finally, endogenous CFL-1 phosphorylation levels were investigated using latrunculin A (LA), cytochalasin B (CB) and Y27632.

RESULTS

When phosphorylatable CFL-1 was expressed, radiosensitivity was enhanced after exposure to γ-rays and this was accompanied by DNA damage. Phosphorylated histone H2AX (γ-H2AX) and p53-binding protein-1 (53BP1) foci, as well as Chk1/2 phosphorylation, were apparently suppressed, although ataxia telangiectasia mutated (ATM) kinase activation was apparently unaffected. In addition, two radiation-induced double-strand break (DSB) repair systems, namely homologous recombination repair (HRR) and non-homologous end joining (NHEJ), were suppressed. Moreover, over-expression of CFL-1 S3D and CFL-1 S3A both enhanced radiosensitivity. However, enhanced radiosensitivity and reduced γ-H2AX expression were only detected in cells treated with LA which increased endogenous phospho-CFL-1, and not in cells treated with Y27632, which dephosphorylates CFL-1.

CONCLUSION

CFL-1 over-expression enhances radiosensitivity and this is associated with reduced DNA repair capacity. Although phosphorylated CFL-1 seems to be involved in radiosensitivity, further studies are required to address the importance of CFL-1 activity to the regulation of radiosensitivity.

All-electrical nuclear spin polarization of donors in silicon

We demonstrate an all-electrical donor nuclear spin polarization method in silicon by exploiting the tunable interaction of donor bound electrons with a two-dimensional electron gas, and achieve over two orders of magnitude nuclear hyperpolarization at T=5 K and B=12 T with an in-plane magnetic field. We also show an intricate dependence of nuclear polarization effects on the orientation of the magnetic field, and both hyperpolarization and antipolarization can be controllably achieved in the quantum Hall regime. Our results demonstrate that donor nuclear spin qubits can be initialized through local gate control of electrical currents without the need for optical excitation, enabling the implementation of nuclear spin qubit initialization in dense multiqubit arrays.

A multiobjective hybrid genetic algorithm for the capacitated multipoint network design problem

The capacitated multipoint network design problem (CMNDP) is NP-complete. In this paper, a hybrid genetic algorithm for CMNDP is proposed. The multiobjective hybrid genetic algorithm (MOHGA) differs from other genetic algorithms (GAs) mainly in its selection procedure. The concept of subpopulation is used in MOHGA. Four subpopulations are generated according to the elitism reservation strategy, the shifting Prufer vector, the stochastic universal sampling, and the complete random method, respectively. Mixing these four subpopulations produces the next generation population. The MOHGA can effectively search the feasible solution space due to population diversity. The MOHGA has been applied to CMNDP. By examining computational and analytical results, we notice that the MOHGA can find most nondominated solutions and is much more effective and efficient than other multiobjective GAs.

Electrically detected magnetic resonance of neutral donors interacting with a two-dimensional electron gas

We have measured the electrically detected magnetic resonance of donor-doped silicon field-effect transistors in resonant X- (9.7 GHz) and W-band (94 GHz) microwave cavities. The two-dimensional electron gas resonance signal increases by 2 orders of magnitude from X to W band, while the donor resonance signals are enhanced by over 1 order of magnitude. Bolometric effects and spin-dependent scattering are inconsistent with the observations. We propose that polarization transfer from the donor to the two-dimensional electron gas is the main mechanism giving rise to the spin resonance signals.

Electrically detected magnetic resonance in a W-band microwave cavity

We describe a low-temperature sample probe for the electrical detection of magnetic resonance in a resonant W-band (94  GHz) microwave cavity. The advantages of this approach are demonstrated by experiments on silicon field-effect transistors. A comparison with conventional low-frequency measurements at X-band (9.7  GHz) on the same devices reveals an up to 100-fold enhancement of the signal intensity. In addition, resonance lines that are unresolved at X-band are clearly separated in the W-band measurements. Electrically detected magnetic resonance at high magnetic fields and high microwave frequencies is therefore a very sensitive technique for studying electron spins with an enhanced spectral resolution and sensitivity.

Adsorption of ethyl violet dye in aqueous solution by regenerated spent bleaching earth

The adsorption of basic dye (i.e., ethyl violet or basic violet 4) from aqueous solution onto the regenerated spent bleaching earth (RSBE) was carried out by varying the process parameters such as initial concentration, pH, and temperature. As analytical comparisons, activated bleaching earth (ABE) was also used as adsorbent for the adsorption of the basic dye at various initial concentrations. The experimental results showed that the adsorption process can be well described with the pseudo-second-order reaction model and less fitted by the intra-particle diffusion model. The kinetic parameters of both models obtained in the present work are in line with pore properties of the two adsorbents. According to the equilibrium adsorption capacity from the fitting of pseudo-second-order reaction model, it was further found that the both models of Langmuir and Freundlich appeared to fit well the isotherm data. In addition, the thermodynamic parameters were evaluated based on the pseudo-second-order rate constants, showing that the adsorption of ethyl violet onto the RSBE is endothermic in nature.

Removal of herbicide paraquat from an aqueous solution by adsorption onto spent and treated diatomaceous earth

A spent diatomaceous earth from the beer brewery has been tentatively activated by sodium hydroxide at about 100 degrees C. The resulting product was used as a novel adsorbent for the adsorption of herbicide paraquat from an aqueous solution in a continuously stirred adsorber and batch flasks, respectively. The results showed that the adsorption process could be well described by the pseudo-second-order reaction model. From the view of the negatively charged surface of diatomaceous earth and cationic property of paraquat, the results were also reasonable to be explained by physical adsorption in the ion-exchange process under the effects of pH and temperature. Further, it was found that the Freundlich model appeared to fit the isotherm data better than the Langmuir model.

Endoscopic balloon dilatation is a safe method in the management of common bile duct stones

BACKGROUNDS AND AIMS

Endoscopic sphincterotomy is a widely accepted treatment for patients with common bile duct stones. Despite improvement in this technique, endoscopic sphincterotomy is still associated with some biliary complications. Endoscopic balloon dilatation is a less traumatic and sphincter preserving method for removal of common bile duct stones. However, the results of controlled studies in comparison with these two methods are contradictory. The aim of this study is to compare the safety and efficacy of endoscopic balloon dilatation and endoscopic sphincterotomy in Chinese patients.

PATIENTS AND METHODS

A total of 104 patients with common bile duct stones on endoscopic retrograde cholangiopancreatography were enrolled. They were randomly assigned to endoscopic balloon dilatation or endoscopic sphincterotomy. Endoscopic balloon dilatation was performed by using a balloon dilator to dilate the sphincter for 5 min. The common bile duct stones were then removed by a Dormia basket after endoscopic balloon dilatation or endoscopic sphincterotomy. Mechanical lithotripsy was performed if the stones were difficult to remove by Dormia basket. After discharge, patients were regularly followed up for biliary complications.

RESULTS

The successful bile duct stone clearance rate was 94.1% in endoscopic balloon dilatation group and 100% in endoscopic sphincterotomy group. Post-procedural significant haemorrhage was higher in endoscopic sphincterotomy group than in endoscopic balloon dilatation group (14/53 versus 1/48, P < 0.001). The bleeding patient from endoscopic balloon dilatation group was a case of uremia and bleeding occurred 48 h after endoscopic balloon dilatation. All the patients with post-procedural haemorrhage were controlled endoscopically. The post-procedural serum amylase level showed no significant difference in both groups and none of them developed clinical pancreatitis. After a mean 16 months follow-up, three patients (6.3%) in endoscopic balloon dilatation group and four patients (7.5%) in endoscopic sphincterotomy group developed recurrent common bile duct stones. The recurrent common bile duct stones were multiple and muddy in consistency. They were successfully removed endoscopically.

CONCLUSION

Both endoscopic balloon dilatation and endoscopic sphincterotomy are safe and effective techniques for the treatment of common bile duct stones. Endoscopic balloon dilatation can be safely applied in patients with coagulopathy and does not increase the incidence of pancreatitis or bleeding.

Endoscopic 13C-urea breath test for the diagnosis of Helicobacter pylori infection

BACKGROUND

Endoscopic 13C-urea breath test may avoid contamination of oral urease and rapidly discriminate Helicobacter pylori-positive and Helicobacter pylori-negative patients.

AIMS

To compare the accuracy of endoscopic 13C-urea breath test with conventional invasive methods in diagnosis of Helicobacter pylori infection.

PATIENTS

One hundred patients who attended for routine upper gastrointestinal endoscopy were included.

METHODS

13C-urea was applied to the stomach through the working channel of endoscope at the end of endoscopic examination. Breath samples were collected before endoscopy and 2, 4, 6, 8, 10 min after consumption of 100 or 50 mg 13C-urea. Helicobacter pylori infection was defined as those with positive culture or positive results of both histology and CLO test.

RESULTS

The accuracy of 100 mg endoscopic 13C-urea breath test was significantly higher than that of culture and CLO test (100% vs. 88% and 92%, p = 0.02 and 0.03, respectively). The accuracy of 50 mg endoscopic 13C-urea breath test was higher than that of histology and CLO test (98% vs. 90% and 96%, respectively), although the differences were not statistically significant.

CONCLUSIONS

Endoscopic 13C-urea breath test has a higher accuracy compared with biopsy-based modalities. It may be a good choice to diagnose Helicobacter pylori infection if endoscopy is indicated for a dyspeptic patient.

Effect of storage time and temperature on stallion sperm DNA and fertility

We used the sperm chromatin structure assay (SCSA) to study the change in stallion sperm DNA susceptibility to denaturation after exposure of extended semen to three different storage temperatures (5, 20, or 37 degrees C) at 7, 20, 31, and 46 h. In addition, we compared the rates of sperm DNA denaturation in fertile and subfertile stallions. Among fertile stallions, spermatozoa stored at 20 and 37 degrees C showed a significant (P < 0.05) rise in the SCSA measures (Mean(alpha1), S.D.(alpha(t)), and percent cells outside the main population-COMP(alpha(t))) overtime, with the degree of rise being more dramatic at 37 degrees C. Over all stallions, samples stored at 5 degrees C showed no significant (P > 0.05) changes in the SCSA values measured over time, indicating maintenance of chromatin quality for up to 46 h. The COMP(alpha(t)) from stallions classified as subfertile showed an increased susceptibility to denaturation or decline in chromatin quality between 20 and 31 h when stored at 5 degrees C; however, spermatozoa from fertile stallions did not change during the time intervals analyzed. These data suggest that sperm DNA from some subfertile stallions may decline at a greater rate than spermatozoa from fertile stallions when exposed to similar storage conditions.

Sequential changes of gastric hyperplastic polyps following endoscopic ligation

BACKGROUND

Endoscopic ligation has been extensively applied in the management of esophageal and gastric varices with or without bleeding. The varices are automatically eradicated through the use of ligation. However, whether avascular necrosis will occur in a gastrointestinal polyp when the base is ligated remains unclear. The aims of this pilot study were to investigate the sequential changes of gastric hyperplastic polyps following endoscopic detachable snare ligation and to determine the possibility of induction of avascular necrosis in these lesions following ligation.

METHODS

Eleven patients with eighteen gastric hyperplastic polyps were treated with endoscopic detachable-snare ligation. The polyps were observed for 5 minutes and biopsies were then conducted. At 14 days after endoscopic ligation, follow-up endoscopies were performed to assess the outcome of the strangulated polyps.

RESULTS

After being strangulated by the detachable snares, a majority of the polyps immediately congested (94%), and then developed cyanotic change (89%) approximately 4 minutes later. Pathological examination revealed severe venous congestion in the lamina propria of the strangulated polyps. On follow-up endoscopy 2 weeks later, all the snares had dropped off, and avascular necrosis occurred in sixteen polyps (89%). All of the polyps with avascular necrosis were detected to have developed cyanotic changes in initial endoscopy. No complications occurred during or following the ligation procedure.

CONCLUSIONS

Most gastric hyperplastic polyps develop avascular necrosis following ligation by detachable snare. Cyanotic change is an important predictor of the outcomes of the lesions following endoscopic ligation. The application of this ligation technique in treatment of bleeding or non-bleeding gastrointestinal polyps deserves further investigation.

Clinical significance of oral urease in diagnosis of Helicobacter pylori infection by [13C]urea breath test

This study was performed to evaluate the effect of oral flora on [13C]urea breath test in detecting H. pylori infection and find an optimal method and timing for sample collection. Forty-five volunteers were included in this study. The [13C]urea breath test was performed using mouthwash, endoscopic administration, and conventional methods. According to the receiver-operating characteristic curves, the earliest optimal time for discriminating H. pylori-positive and H. pylori-negative patients was at 25 min with the mouthwash method with 78% sensitivity and 82% specificity, at 2 min with the endoscopic administration method with 100% sensitivity and 100% specificity, and at 6 min with the conventional method with 100% sensitivity and 95% specificity. The study shows a significant effect of oral urease on the results of the [13C]urea breath test. The timing of sampling collection can be shortened to 6 min with the conventional method or to 2 min through endoscopic administration.

Determination of tetracycline and streptomycin in mixed fungicide products by capillary zone electrophoresis

A method of capillary zone electrophoresis (CZE) was used to determine tetracycline and streptomycin content in commercial agriculture products. The results indicated that this method was capable of analyzing the mixed fungicide in formulated products with instrument detection limit (IDL) of 0.50 microg/mL and a method detection limit (MDL) of 0.52 microg/mL for tetracycline, and IDL of 1.00 microg/mL and MDL of 1.22 microg/mL for streptomycin. Precision expressed by relative standard deviation (RSD) ranged from 1.44 to 4.37% of tetracycline and 1.00 to 4.20% of streptomycin. Recoveries were in the region of 98.2-102.5% for tetracycline and 95.3--103.0% for streptomycin. The low detection limit, the low RSD values, and the high percentage of recovery confirmed that the CZE technique is a sensitive and selective method. And the CZE method can analyze both tetracycline and streptomycin at the same time without complicated extraction and further derivative reaction.

Comparison of clinical, serological and histological findings between non-ulcer dyspepsia patients with and without Helicobacter pylori infection

BACKGROUND AND AIMS

The role of Helicobacter pylori (H. pylori) infection in non-ulcer dyspepsia (NUD) remains controversial. This study investigates the clinical, serological and histological differences between patients with H. pylori-positive and -negative NUD.

METHODS

One hundred and eighty consecutive patients with NUD were enrolled from January to December 1998. The severity of symptoms was evaluated by the Tucci's scoring system. The histological changes of gastric mucosa were assessed according to the Updated Sydney System, and a fasting blood sample was obtained to test the serum gastrin and pepsinogen I levels.

RESULTS

The H. pylori-positive NUD patients were notably older than H. pylori-negative NUD patients (48.2 +/- 15.9 vs 39.8 +/- 15.7 years, P= 0.001). There were no differences in other clinical factors between the two NUD groups. The serum pepsinogen I levels were considerably higher in H. pylori-positive NUD patients than in H. pylori-negative NUD patients (78.9 +/- 42.2 vs 61.5 +/- 43.3 ng/mL, P<0.01). However, no significant differences in serum gastrin levels were discovered between the two groups. The antrum histological scores for chronic inflammation, acute inflammation, gland atrophy and lymphoid follicles were higher in H. pylori-positive NUD patients than in H. pylori-negative NUD patients (2.09 vs 1.01, P<0.001; 1.22 vs 0.36, P<0.001; 0.76 vs 0.36, P<0.01; 0.33 vs 0.13, P<0.01, respectively).

CONCLUSIONS

The present study discovered marked differences in age, serum pepsinogen I levels, histological grades of acute inflammation, chronic inflammation, gland atrophy and lymphoid tissue formation between H. pylori-positive and H. pylori-negative NUD patients. Further investigation of the clinical prognosis of the two groups of patients is necessary.

Eradication of Helicobacter pylori prevents ulcer development in patients with ulcer-like functional dyspepsia

BACKGROUND

Although the eradication of Helicobacter pylori infection benefits patients with gastric or duodenal ulcers, the value of eradicating the infection in the patients with functional dyspepsia (FD) remains controversial.

AIMS

To determine whether eradicating H. pylori can prevent the subsequent development of ulcers or relieve the symptoms of functional dyspepsia patients.

METHODS

In a double-blind, placebo-controlled trial, 161 patients infected with H. pylori who had functional dyspepsia were randomly assigned to 7 days of treatment with a lansoprazole-based triple therapy or placebo and then followed for 1 year. The main outcome measures were the development of peptic ulcers and the resolution of symptoms.

RESULTS

H. pylori was eradicated in 63 out of 81 patients (78%) in the treatment group and none of the 80 patients (0%) in the placebo group. During the follow-up period, two patients in the treatment group and six patients in the placebo group developed peptic ulcers at repeat endoscopy (2.5% vs. 7.5%; 95% CI: -12 to 2). The reduction in ulcer rates was statistically significant in the 'ulcer-like' sub-group (0% vs. 16.7%; 95% CI: -32 to -2), but not in the 'dysmotility-like' and 'unclassifiable' sub-groups. Regarding symptom response, the resolution rates of symptoms were similar between the treatment and placebo groups (58.0% vs. 55.0%, 95% CI: -12 to 18). Additionally, no significant differences existed in the symptom responses between the treatment and control arms in each of the dyspepsia sub-groups.

CONCLUSIONS

Eradicating H. pylori can prevent the subsequent development of peptic ulcers in the patients with 'ulcer-like' functional dyspepsia. However, this approach does not significantly reduce the symptoms of functional dyspepsia patients.

Gender differences in drinking patterns among Hong Kong Chinese youth: a pilot study

About one year before the People's Republic of China regained political control of Hong Kong, a semistructured interview study was conducted among a group of 101 Hong Kong Chinese adolescents to explore their drinking behavior. The purpose of this exploratory study was to look for empirical evidence confirming the general hypothesis that wherever Chinese reside, they are moderate drinkers. Specifically, the study was designed to examine whether male and female adolescents gave different reasons for their drinking and nondrinking behavior, were differentially affected by parents' drinking, and experienced differential consequences resulting from alcohol use. The results confirm that Chinese youth in Hong Kong are moderate drinkers. Only minimal differences exist between the genders. The traditional Chinese normative view of alcohol may partly explain the results, an observation that suggests future research into the sociocultural features that influence drinking among youth.

Drugs and prisoners: treatment needs on entering prison

An interview study was conducted among a group of incoming prisoners in a county jail in Ohio during the summers of 1997 and 1998 to assess their current drug treatment needs. "Incoming prisoners" refers to individuals who were being transferred from this county jail to the state prison system. Marijuana and cocaine were the most commonly tried illegal drugs among the subjects as well as the drugs of choice during the month prior to imprisonment. The Diagnostic Interview Schedule, combined with questions employed in the Drug Use Forecasting (DUF) project, was used to construct the questionnaire for this study. Based on the criteria of DSM-IV diagnoses, 57.5% of those interviewed had exhibited drug dependency at some point in their lives, and 51% were currently dependent on some substance. Thus, more than half of the incoming prisoners were in need of treatment for use of at least one substance. Cocaine dependence was the greatest problem facing this group of inmates, with an especially notable problem among the older females. Younger males were more likely to have current marijuana dependence. The study found that individuals currently dependent on cocaine or opiates perceived that they had a need for drug treatment, while those currently dependent on marijuana did not share this perception.

Effects of timing of diatrizoate (water-soluble contrast medium) administration on pancreatic microcirculatory derangement in cerulein pancreatitis in rats

OBJECTIVE

We investigated whether the timing of administration of contrast medium after onset of acute pancreatitis is critical in determining the magnitude of microcirculatory derangement.

METHODS

An acute pancreatitis model in male Sprague-Dawley rats (225-275 g) was established by continuous infusion of cerulein (15 mg/kg per hour). The mean arterial pressure was monitored continuously by means of a femoral artery catheter. Diatrizoate (Hypaque-76), a water-soluble contrast medium, was delivered through a femoral vein catheter at doses corresponding to those given to humans, either 1, 2, or 3 hours after pancreatitis induction. In vivo microscopy and laser-Doppler flowmetry were used to investigate microcirculatory derangement. The water contents of the pancreas and lung, the malondialdehyde levels of the pancreas, and the trypsinogen activation peptide levels in the serum were measured at the end of the experiment (8 hours after infusion of cerulein).

RESULTS

Early administration of contrast medium (1 hour after pancreatitis induction) resulted in significantly greater changes in microcirculation and mean arterial pressure than did late administration (2 or 3 hours after pancreatitis induction). Rats given contrast medium 1 hour after induction also had highest pancreas and lung water contents, the highest pancreas malondialdehyde levels, and the highest serum trypsinogen activation peptide levels.

CONCLUSION

These results show that a water soluble contrast medium that is often used for computed tomographic imaging of the pancreas can adversely affect the pancreatic microcirculatory parameters, such as tissue perfusion and leukocyte sticking, and hemodynamics in a cerulein-induced model of acute pancreatitis. Early administration seems to cause more severe derangement of the pancreatic microcirculation.

Aminoguanidine attenuates hemodynamic and microcirculatory derangement in rat intestinal ischemia and reperfusion

BACKGROUND

Nitric oxide (NO) participates in the regulation of hemodynamic and microcirculatory changes in intestinal ischemia and reperfusion (I/R). However, the nature of the involvement of an inducible NO release has been controversial. This study evaluates the impact of an inducible NO synthase inhibitor, aminoguanidine, used as a treatment in a rat intestinal I/R model.

METHODS

We investigated the hemodynamics by measuring the mean arterial pressure (MAP), and the microcirculatory responses of the intestine and liver to systemically administered aminoguanidine by use of laser-Doppler flowmetry (LDF), in vivo microscopy, and flow cytometry.

RESULTS

During the 30-min ischemia of the selected 20-cm ileal segment, no MAP change was noted. At reperfusion, a marked decrease of MAP was noted and the lowest levels were noted 3 hours after reperfusion (67 +/- 4% vs. 99 +/- 5% in sham-operated control animals). A marked decrease in liver perfusion as measured by LDF was noted 1 hour after reperfusion and remained low at 5 hours (72 +/- 4% vs. 97 +/- 3% in sham-operated control animals). A marked decrease in intestine perfusion was noted by using LDF 1 hour after reperfusion and remained low at 5 hours (43 +/- 3% vs. 92 +/- 4% in sham-operated control animals). The flow velocity of the postcapillary venules of the intestine was markedly decreased (1.01 +/- 0.62 vs. 2.67 +/- 0.34 mm/s in sham-operated control animals) at 5 hours after reperfusion. The flow velocity of the postsinusoidal venules of the liver was also markedly decreased (1.01 +/- 0.62% vs. 2.67 +/- 0.34% in sham-operated control animals). Leukocyte-endothelial interaction (adhesion) was increased in the postcapillary venules of the intestine (54 +/- 12 vs. 6 +/- 4/microm2 in sham-operated control animals) and in the postsinusoidal venules of the liver (32 +/- 8 vs. 2 +/- 2/microm2 in sham-operated control animals). Concomitantly, the granulocyte count was increased (9.1 +/- 0.6 vs. 2.1 +/- 0.3% of total circulating leukocytes in sham-operated control animals), with an increase of CD 11b expression. Aminoguanidine administration (1 mg/kg) 0.5 hour before ischemia and 1 hour after reperfusion significantly increased MAP, increased intestine and liver perfusion, decreased adhesion, and decreased circulating granulocytes and CD 11b expression.

CONCLUSION

Inhibition of an inducible NO release by aminoguanidine in intestinal I/R can attenuate hemodynamic and microcirculatory derangement.

Determination of the antibiotic fungicide validamycin A in formulated products by micellar electrokinetic chromatography

A micellar electrokinetic capillary chromatographic method (MEKC) was used to determine validamycin A content in commercial products. The results indicated that this method was capable of analyzing the validamycin A content in formulated products with an instrument detection limit of 0.94 microg/mL and a method detection limit of 1. 70 microg/mL. Relative standard deviation (RSD) values of MEKC determination of validamycin A in formulated products ranged from 0. 61 to 2.09%. Recoveries of validamycin A in formulated products were in the region of 99.5-105.1%. All commercial products collected from markets contained validamycin A. The high percentage of recovery, the low detection limit, and the low RSD values confirmed that the MEKC technique is a senstivie and selective method.

Effect of D57N mutation on membrane activity and molecular unfolding of cobra cardiotoxin

Cobra cardiotoxins (CTXs) are able to adopt a three-fingered beta-strand structure with continuous hydrophobic patch that is capable of interacting with zwitterionic phospholipid bilayer. In addition to the four disulfide bonds that form the rigid core of CTXs, Asp57 near the C-terminus interacts electrostatically with Lys2 near the N-terminus (Chiang et al. 1996. Biochemistry. 35:9177-9186). We indicate herein, using circular dichroism and the time-resolved polarized tryptophan fluorescence measurement, that Asp57 to Asn57 (D57N) mutation perturbs the structure of CTX molecules at neutral pH. The structural stability of the D57N mutant was found to be lower, as evidenced by the reduced effective concentration of the 2,2,2-trifluoethanol (TFE)-induced beta-sheet to alpha-helix transition. Interestingly, the single mutation also allows a greater degree of molecular unfolding, because the rotational correlation time of the TFE-induced unfolding intermediate is larger for the D57N mutant. It is suggested that the electrostatic interaction between N- and C-termini also contributes to the formation of the functionally important continuous hydrophobic stretch on the distant end of CTX molecules, because both the binding to anilinonaphthalene fluorescent probe and the interaction with phospholipid bilayer were also reduced for D57N mutant. The result emphasizes the importance of the hydrophobic amino acid residues near the tip of loop 3 as a continuous part of the three-fingered beta-strand CTX molecule and indicates how a distant electrostatic interaction might be involved. It is also implicated that electrostatic interaction plays a role in expanding the radius of gyration of the folding/unfolding intermediate of proteins.

Are women heavier drinkers than we thought they were?

OBJECTIVE

This study intended (1) to examine whether men are more likely to experience "male-type" problems related to drinking and women are more likely to encounter "female-type" problems and (2) to discover whether male or female collegians have higher blood alcohol concentrations (BACs) at a typical drinking session.

METHOD

A questionnaire was administered to students enrolled in introductory courses in departments of social sciences at two state universities, situated in the Midwest and the South, in the spring term of 1994. Of the 2,056 students who constituted the sample of the present study, about 54% were women and 92.6% were white. The subject collegians' BACs during drinking episodes were indirectly estimated by three variables-quantity of alcohol consumed, individual body weight and duration of drinking session.

RESULTS

The data indicate that men achieve a higher BAC than do females while drinking. When the incidence of various alcohol-related problems (both gender-biased and gender-neutral problems) was measured, it was found that, after drinking levels are controlled, gender becomes a significant factor in whether some alcohol-related problems will occur.

CONCLUSIONS

Findings indicate that gender socialization may partly explain gender differences in the alcohol-related problems reported.

The facilitating and enhancing roles Greek associations play in college drinking

A quasi-longitudinal, retrospective survey was used to examine the relationship of Greek affiliation and intensity of drinking in college. Explanations of higher levels of drinking among Greeks usually revolve around subcultural support, differential association, and reference group behavior. That is, association with pro-drinking students in a drinking subculture increases the members' drinking level. In this study, students' high-schooling drinking patterns were used to partially explain the decision to join Greek groups in order to continue prior drinking habits. Greek affiliation was found to serve as both a facilitating and enhancing factor in collegiate alcohol use.

The effects of internal and external control factors on college students' marijuana use and cessation of use

The purpose of this study was to examine how selected internal and external control variables influence lifetime use, frequency of use, and cessation of use of marijuana. The internal control factor, comprising the variables 1) perceived risk of marijuana use and 2) attitudes toward prohibition of marijuana use, refers to a built-in personal tendency toward conventionality. The external control factor refers to social-environmental forces which discourage marijuana use. External control is indicated by factors including the number of extra-curricular activities in which an individual is involved; place of residence; the availability of marijuana; peer attitudes toward marijuana use; the number of an individual's friends who use marijuana; and the number of occasions on which an individual has observed others using marijuana. The study's results show that both internal and external control factors are significant predictors of the frequency of marijuana use. The external control factor, however, plays a more important role in explaining lifetime marijuana use and cessation of marijuana use.

Observations on predicted brain influx rates of neurotransmitter precursors. Effects of tumor, operative stress with tumor removal, and postoperative TPN of varying amino acid compositions

Effects of tumor, operative stress and tumor removal, and postoperative TPN of varying amino acid compositions on brain levels of tryptophan or tyrosine as predicted by their brain influx rates were studied in normals and in malnourished cancer patients. Concentrations of the large neutral amino acids (LNAA) were determined in patients before and after tumor removal, and in postoperative patients before and after receiving either a standard TPN solution (STD-TPN), or a branched-chain amino acid solution (BCAA-TPN). The LNAA were altered in all groups versus normals. Brain influx rates showed the following: in preoperative patients, predicted brain tryptophan levels were below normal (P less than 0.001), whereas tyrosine levels were within or above normal; no significant differences between pre- and postoperative tryptophan or tyrosine levels; postoperative STD-TPN did not change predicted brain tryptophan concentration from preinfusion values, but BCAA-TPN decreased it (P less than 0.001), underscoring the common transport carrier; and preinfusion predicted brain tyrosine levels were decreased (P less than 0.001) by both types of TPN solutions. These results imply low substrate levels for brain serotonin and catecholamine synthesis, possibly affecting functions dependent on their control.

Protein requirements of men in a hot climate: decreased urinary nitrogen losses concomitant with increased sweat nitrogen losses during exposure to high environmental temperature

In two separate experiments 8 healthy young men were given an egg-milk formula at a level of 0.7 g protein/kg per day, and were exposed to high environmental temperature (34--37 C, 7 hours daily) or cool temperature (21--26 C, all day), alternately. In the first experiment a 16-day hot period was followed by a 20-day cool period and finally by a 20-day hot period. Daily urinary nitrogen (N) loss of the last 8 days of cool period, 82.2 mg/kg, was significantly higher than that of the last 8 days of the 20-day hot period 69.7 mg/kg. Daily skin N loss was significantly lower during the last 8 days of the cool period (3.5 mg/kg) than during the last 8 days of the 20-day hot period (11.9 mg/kg). Urinary N and skin N lossess were negatively correlated (r equal to -0.905) in these periods. In the second experiment a 28 day hot period was followed by a 20-day cool period. Skin N loss diminished from 12.3 mg/kg daily during the last 12 days of the 28-day hot period to 4.1 mg/kg during the last 12-days of the cool period. At the same time, urinary N loss increased significantly from 81.4 mg/kg during the 28-day hot period to 95.2 mg/kg during a cool period. Urinary N and skin N losses were again negatively correlated (r equal to -0.620) during these periods. Results of these studies indicate that when skin N loss increases during high temperature, urinary N loss decreases gradually, but total N loss does not increase.