Targeting PARG induces tumor cell growth inhibition and antitumor immune response by reducing phosphorylated STAT3 in ovarian cancer

BACKGROUND

Ovarian cancer is the most lethal gynecological malignancy, with limited treatment options after failure of standard therapies. Despite the potential of poly(ADP-ribose) polymerase inhibitors in treating DNA damage response (DDR)-deficient ovarian cancer, the development of resistance and immunosuppression limit their efficacy, necessitating alternative therapeutic strategies. Inhibitors of poly(ADP-ribose) glycohydrolase (PARG) represent a novel class of inhibitors that are currently being assessed in preclinical and clinical studies for cancer treatment.

METHODS

By using a PARG small-molecule inhibitor, COH34, and a cell-penetrating antibody targeting the PARG's catalytic domain, we investigated the effects of PARG inhibition on signal transducer and activator of transcription 3 (STAT3) in OVCAR8, PEO1, and Brca1-null ID8 ovarian cancer cell lines, as well as in immune cells. We examined PARG inhibition-induced effects on STAT3 phosphorylation, nuclear localization, target gene expression, and antitumor immune responses in vitro, in patient-derived tumor organoids, and in an immunocompetent Brca1-null ID8 ovarian mouse tumor model that mirrors DDR-deficient human high-grade serous ovarian cancer. We also tested the effects of overexpressing a constitutively activated STAT3 mutant on COH34-induced tumor cell growth inhibition.

RESULTS

Our findings show that PARG inhibition downregulates STAT3 activity through dephosphorylation in ovarian cancer cells. Importantly, overexpression of a constitutively activated STAT3 mutant in tumor cells attenuates PARG inhibitor-induced growth inhibition. Additionally, PARG inhibition reduces STAT3 phosphorylation in immune cells, leading to the activation of antitumor immune responses, shown in immune cells cocultured with ovarian cancer patient tumor-derived organoids and in immune-competent mice-bearing mouse ovarian tumors.

CONCLUSIONS

We have identified a novel antitumor mechanism underlying PARG inhibition beyond its primary antitumor effects through blocking DDR in ovarian cancer. Furthermore, targeting PARG activates antitumor immune responses, thereby potentially increasing response rates to immunotherapy in patients with ovarian cancer.

POLD1 DEDD Motif Mutation Confers Hypermutation in Endometrial Cancer and Durable Response to Pembrolizumab

BACKGROUND

Mutations in the DNA polymerase delta 1 (POLD1) exonuclease domain cause DNA proofreading defects, hypermutation, hereditary colorectal and endometrial cancer, and are predictive of immunotherapy response. Exonuclease activity is carried out by two magnesium cations, bound to four highly conserved, negatively charged amino acids (AA) consisting of aspartic acid at amino acid position 316 (p.D316), glutamic acid at position 318 (p.E318), p.D402, and p.D515 (termed DEDD motif). Germline polymorphisms resulting in charge-discordant AA substitutions in the DEDD motif are classified as variants of uncertain significance (VUSs) by laboratories and thus would be considered clinically inactionable. We hypothesize this mutation class is clinically pathogenic.

METHODS

A review of clinical presentation was performed in our index patient with a POLD1(p.D402N) heterozygous proband with endometrial cancer. Implications of this mutation class were evaluated by a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review, in silico analysis with orthogonal biochemical confirmation, and whole-exome and RNA sequencing analysis of the patient's tumor and engineered cell lines.

RESULTS

Our systematic review favored a Mendelian disease mutation class associated with endometrial and colorectal cancers. In silico analysis predicted defective protein function, confirmed by biochemical assay demonstrating loss of nuclease activity. A POLD1-specific mutational signature was found in both the patient's tumor and POLD1(p.D402N) overexpressing cell. Furthermore, paired whole-exome/transcriptome analysis of endometrial tumor demonstrated hypermutation and T cell-inflamed gene expression profile (GEP), which are joint predictive biomarkers for pembrolizumab. Our patient showed a deep, durable response to immune checkpoint inhibitor (ICI).

CONCLUSION

Charge-discordant AA substitution in the DEDD motif of POLD1 is detrimental to DNA proofreading and should be reclassified as likely pathogenic and possibly predictive of ICI sensitivity.

Feasibility of combining pelvic reconstruction with gynecologic oncology-related surgery

INTRODUCTION AND HYPOTHESIS

At our institution, every patient seen by the gynecologic oncology service is screened for pelvic floor dysfunction. This study was aimed at determining if a combined surgical approach by gynecologic oncology and urogynecology services at our institution was feasible and safe for this patient population.

METHODS

We performed a retrospective review of patients undergoing combined surgery by gynecologic oncology and urogynecology services at our institution from 2013 to 2021. Perioperative variables, postoperative adverse events, and long-term outcomes were assessed, and descriptive statistics were performed.

RESULTS

From 20 December 2013 to 29 January 2021, a total of 102 patients underwent concurrent surgical repair of pelvic organ prolapse and/or stress urinary incontinence. Seventy-three patients (71.6%) had normal/benign pathologic conditions, and 29 (28.4%) had premalignant/malignant pathologic conditions. Ten patients (9.8%) had a postoperative complication, including reoperation for exposed midurethral sling (4.9%), urinary retention requiring midurethral sling release (2.9%), reoperation for hemoperitoneum (1.0%), and anemia requiring blood transfusion (1.0%). Nine complications occurred in patients with benign/normal pathologic conditions (12.3%), and one complication occurred in patients with pre-malignant/malignant pathologic conditions (3.4%).

CONCLUSIONS

In our single-institution experience, concurrent gynecologic oncology and pelvic floor reconstructive surgery were safe and feasible in combination with no reported major morbidity events.

Phase I trial of daily subcutaneous SPL-108 injections in combination with paclitaxel in patients with platinum resistant CD44+ advanced ovarian epithelial cancer

OBJECTIVE

Preclinical evidence and early clinical trials have demonstrated the activity of SPL-108, a targeted agent that inhibits CD44 mediated induction of multidrug resistance specifically to paclitaxel and platinum agents. We conducted a phase I, open label, dose escalation study of the safety and tolerability of the combination of SPL-108 with weekly paclitaxel in patients with platinum resistant CD44+ ovarian, primary peritoneal, or fallopian tube cancer.

METHODS

Patients with platinum resistant histologically proven epithelial ovarian, primary peritoneal, or fallopian tube cancers and measurable disease according to RECIST (Response Evaluation Criteria in Solid Tumours) version 1.1 were selected. Tumors were tested for CD44 expression for eligibility, defined as strong (+++) or moderate (++) staining in ≥20% of the tumor tissue or diffuse + staining. Patients were treated with daily and then twice daily SPL-108 subcutaneous injections and weekly intravenous paclitaxel on days 1, 8, and 15 of a 28 day cycle. Endpoints included safety, determination of maximum tolerated dose, and efficacy. Tumors underwent comprehensive genomic profiling, and cell lines and western blotting were used to study markers of response.

RESULTS

We screened 16 patients, and 14 were enrolled based on CD44+ expression. A total of 86% of patients had high grade serous tumors and all had received multiple prior therapies. There were no grade 4-5 toxicities. One patient had grade 3 peripheral sensory neuropathy attributed to paclitaxel and one patient developed presumed colonic perforation attributed to the study drug. No dose reductions or treatment discontinuations were required. All patients tolerated the maximum planned dose; no maximum tolerated dose was reached. Overall response rate was 36%; 5 (36%) patients had partial response and 5 (36%) patients had stable disease.

CONCLUSIONS

The combination of SPL-108 with weekly paclitaxel was safe and well tolerated. Encouraging antitumor activity was observed, with 72% of patients deriving a clinical benefit.

TRIAL REGISTRATION

NCT03078400.

Niraparib-induced STAT3 inhibition increases its antitumor effects

Recently, poly(ADP-ribosyl)ation polymerase inhibitors (PARPis), which induce synthetic lethality of tumor cells with DNA damage repair defects, have emerged as a promising therapy for ovarian, breast, and pancreatic cancer. Although the PARPi Olaparib is limited to treating cancer patients with DNA repair deficiencies, the PARPi Niraparib is FDA approved to treat ovarian cancer patients regardless of their status in DNA repair pathways. Despite differences in the affinity to PARP enzymes, the rationale behind the clinical use of Niraparib in patients without DNA repair deficiencies is still lacking. Moreover, only Olaparib has been approved for pancreatic ductal adenocarcinoma (PDAC) patients with BRCA mutations, accounting for only 5-7% of total PDACs. It remains unclear whether Niraparib could be beneficial to PDACs without BRCA mutations. We found that Niraparib inhibits ovarian and PDAC tumor cell growth, regardless of BRCA mutational status, more effectively than Olaparib. Unlike Olaparib, which is known to activate STAT3, Niraparib inhibits STAT3 activity in ovarian and PDAC cancer cell lines and patient tumors. Moreover, Niraparib regulates the expression of several STAT3 downstream genes involved in apoptosis. Overexpression of a constitutively activated STAT3 mutant rescues Niraparib-induced cancer cell apoptosis. Our results suggest that Niraparib inhibits pSTAT3 by interfering with SRC tyrosine kinase. Collectively, our studies provide a mechanism underlying Niraparib's ability to induce tumor cell apoptosis without BRCA mutations, suggesting the potential use of Niraparib for treating PDAC patients regardless of BRCA status.

PARP Inhibition Activates STAT3 in Both Tumor and Immune Cells Underlying Therapy Resistance and Immunosuppression In Ovarian Cancer

Despite the promising activity of poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) in many cancer types with defects in the DNA damage response the majority of the treated patients acquire PARPi resistance and succumb to their diseases. Consequently, there is an urgent need to identify the mechanisms of PARPi resistance. Here, we show that PARPi treatment promotes STAT3 activation in ovarian cancer cells, tumor-associated immune cells and fibroblasts, resulting in PARPi resistance and immunosuppression. Comparison of ovarian cancer patient-matched tumor biopsies before and after PARPi therapy revealed that STAT3 activity was significantly higher in tumor cells and tumor-associated immune cells and fibroblasts post PARPi treatment. Moreover, one-time PARPi treatment activated STAT3 both in tumor cells as well as diverse immune subsets and fibroblasts. PARPi-treated immune cells exhibited decreased expression of immunostimulatory interferon (IFN)-γ and Granzyme B while increasing immunosuppressive cytokine IL-10. Finally, we demonstrate that the acquisition of PARPi resistance in ovarian cancer cells was accompanied by increased STAT3 activity. Ablating STAT3 inhibited PARPi-resistant ovarian tumor cell growth and/or restored PARPi sensitivity. Therefore, our study has identified a critical mechanism intrinsic to PARPi that promotes resistance to PARPi and induces immunosuppression during PARPi treatment by activating STAT3 in tumor cells and tumor-associated immune cells/fibroblasts.

PIPAC for the Treatment of Gynecologic and Gastrointestinal Peritoneal Metastases: Technical and Logistic Considerations of a Phase 1 Trial

BACKGROUND

Peritoneal metastases (PM) from ovarian, gastric, appendiceal, or colorectal origin can be treated via cytoreductive surgery with or without the addition of hyperthermic intraperitoneal chemotherapy (HIPEC) for selected patients. Unfortunately, not all patients are candidates for aggressive surgical debulking. For these patients, pressurized intraperitoneal aerosolized chemotherapy (PIPAC) has emerged as an alternative method for intraperitoneal (IP) chemotherapy administration. This report presents the design and implementation of the first phase 1 trial to evaluate the safety and efficacy of PIPAC in the United States.

METHODS

This is an ongoing prospective phase 1 clinical trial of PIPAC for patients who have histologically confirmed ovarian, uterine, gastric, appendiceal, or colorectal cancer with PM and have progressed to at least one evidence-based chemotherapeutic regimen. The trial has two clinical arms. The patients in arm 1 have gynecologic and gastric malignancies treated with IP cisplatin and doxorubicin, and the arm 2 patients have colorectal and appendiceal malignancies treated with intravenous fluorouracil and leucovorin followed by IP oxaliplatin. All the patients are monitored for dose-limiting toxicities and adverse events.

RESULTS

Practical and technical considerations for the phase 1 PIPAC trial are presented. These considerations include patient selection, operating room setup, and technical details for successful aerosolized chemotherapy delivery. The phase 1 study results will be reported separately at completion of the trial.

CONCLUSIONS

The PIPAC treatment is a feasible, minimally invasive approach that permits IP delivery of chemotherapy. Once completed, the ongoing phase 1 trial will help to provide safety and initial efficacy data.

Abstract 2432: Somatic mutations in the STAT3 activation pathway are associated with improved survival in gynecologic malignancies and provide a molecular rationale for therapeutic targeting

Background: Signal transducer and activator of transcription 3 (STAT3) activation promotes tumor cell survival, immune evasion, metastasis, and drug resistance in PARP inhibitors and platinum-based chemotherapy.

Objective: Based on our in-vitro findings of the tumoricidal potential of STAT3 inhibition in BRCAwild-type and PARP inhibitor-resistant tumor cells, we sought to evaluate whether ovarian and uterine cancer patients with somatic mutations in the STAT3 activation pathway had improved overall survival (OS) compared to those with intact STAT3 activation pathway-related genes.

Method: We induced Olaparib resistance in BRCAwild-type ovarian cancer cell lines (OVCAR8 and A2780) and treated both parental and PARP inhibitor-resistant cell lines with various STAT3 inhibitors. We then attempted to establish clinical correlations of our in-vitro studies and queried the Cancer Genome Atlas (TCGA) Pan-Cancer Atlas for uterine and ovarian cancers. OS in patients with somatic mutations in the STAT3 gene and/or associated STAT3 activation genes (IL6ST, GNAS, JAK1, JAK2) was compared to OS in patients with intact STAT3 pathway-related genes. Kaplan-Meier survival curves were compared using the log-rank test.

Results: In-vitro, STAT3 inhibition demonstrated potent, tumoricidal propensity in all cell lines (EC50: 0.34uM-0.46uM) including A2780parental, A2780parpi-resistant, OVCAR8parental, and OVCAR8parpi-resistant. Clinically, 1,154 total patients were identified in TCGA, including 571 high-grade serous ovarian carcinoma, 397 uterine endometrioid adenocarcinomas, 109 uterine serous carcinoma/uterine papillary serous carcinomas, 56 uterine carcinosarcomas/uterine malignant mixed Mullerian tumors, and 21 uterine mixed endometrial carcinomas. When pooling all uterine and ovarian cancer patients, median survival (MS) was 52 months (0-185) in patients with intact STAT3 (n=1,007) compared to not reached (NR, 0-225) in the STAT3 mutated group (n=147) with a Hazard Ratio (HR) of 0.25 and Confidence Interval (CI) 0.20-0.32 (p<0.001). In ovarian cancer patients, MS was 45 months (0-180) in patients with intact STAT3 (n=551) compared to 95 months (0-145) in the STAT3 mutated group (n=20) with a HR of 0.48 and CI 0.29-0.80 (p=0.038). In uterine cancer patients, MS was 112 months (0-185) in patients with intact STAT3 (n=456) compared to NR (0-225) in the STAT3 mutated group (n=127) with a HR of 0.40 and CI 0.25-0.64 (p=0.003).

Conclusion: Pharmacologic and genetic (siRNA) inhibition of the STAT3 activation pathway killed PARP inhibitor-resistant ovarian cancer cells in-vitro. Clinically, somatic mutations in the STAT3 activation pathway were associated with improved OS in both ovarian and uterine cancer. These findings provide a rationale for the therapeutic targeting of this pathway in gynecologic malignancies.

Citation Format: Adrian Kohut, Antons Martincuks, Thanh Dellinger, Hua Yu, Lorna Rodriguez-Rodriguez. Somatic mutations in the STAT3 activation pathway are associated with improved survival in gynecologic malignancies and provide a molecular rationale for therapeutic targeting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2432.

Criminal Justice Involvement and Abnormal Cervical Cancer Screening Results Among Women in an Urban Safety Net Hospital

OBJECTIVE

The aim of the study was to elucidate the risk factors underlying abnormal cytology-based cervical cancer screening (Pap testing) in justice-involved women (JIW) compared with non-JIW in an urban safety net hospital.

METHODS

Retrospective chart review of women with a history of correctional involvement who received care at Grady Health System between 2010 and 2018 and had a Pap test was performed (n = 191). An age-matched cohort of women with no correctional involvement and had a Pap test at Grady served as the control (n = 394). Variables of interest were age, HIV, smoking, race, mental health history, and history of incarceration. Outcomes of interests were rate of abnormal Pap tests and follow-up. χ2 and logistic regression models evaluated associations between the variables of interest and outcomes.

RESULTS

Rates of abnormal Pap tests were significantly higher in JIW (35.6%) than controls (18.5%, p < .0001). Compared with controls, JIW were significantly more likely to have high-grade cervical cytology (odds ratio [OR] = 3.89, p < .0005) and be lost to gynecologic follow-up (OR = 8.75, p < .0001) and a history of severe mental illness (29.5% vs 4.3%, p < .0001). Those with abnormal Pap tests were likely to be HIV-positive (OR = 20.7, p < .001) and have a history of incarceration (OR = 2.33, p < .001). Predictors of high-grade Pap test were smoking history (OR = 0.16, p = .014), HIV-positive (OR = 3.66, p = .025), and history of incarceration (OR = 3.96, p < .0005).

CONCLUSIONS

Justice-involved women represent a high-risk subpopulation with significantly increased rates of high-grade cytology and lost to follow-up. This underscores the need for attention to screening programs and follow-up interventions for JIW.

A Bibliometric Analysis of Citation Classics in the Journal of Ultrasound in Medicine

OBJECTIVES

A bibliometric analysis of articles in the Journal of Ultrasound in Medicine (JUM) identified the journals' most impactful articles.

METHODS

A bibliometric analysis of citation classics that were published in the JUM from its inception in 1982 to 2019 was performed. All citation classics, defined as articles cited 100 or more times, were evaluated for the number of citations, citations per year, publication year, subspecialty, design, and country of origin. Characteristics were compared before and after 1998 by the Mann-Whitney test for unpaired data and 2-sample z tests of sample proportions. The Kruskal-Wallis test for nonparametric continuous data was used to compare the median number of citations per year by decade of publication.

RESULTS

A total of 7868 articles were published in the JUM between 1982 and 2019; 54 (0.7%) were citation classics. The median citation classics year of publication was 1998 (interquartile range [IQR], 1991-2003). Most citation classics originated from the United States (36 of 54 [66.7%]), were observational (47 of 54 [87%]), and were related to obstetric and gynecologic topics (16 of 54 [29.6%]). Citation classics after 1998 received significantly more citations per year (9.3 versus 4.7; P < .001), with no other differences noted. The median number of citations per year increased for each decade, with medians of 4 citations (IQR, 3.6-4.7) in 1982 to 1991 and 11.2 citations (IQR, 9-13.9) in 2002 to 2012 (P < .001).

CONCLUSIONS

This list provides insight into the most influential articles that were published in the JUM. Most citation classics were observational, were from the United States, and covered obstetric and gynecologic topics. Citation classics received more citations per year after 1998.

Primary colonic extrauterine endometrial stromal sarcoma: A case and review of the literature

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Primary colonic extrauterine endometrial stromal sarcoma is a rare entity and diagnosis of this tumor can be challenging.

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There is a common gene translocation specific to the tumors, our case was confirmed by identifying it.

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Classifying these tumors correctly is important for treatment.

Evaluating unplanned readmission and prolonged length of stay following minimally invasive surgery for endometrial cancer

OBJECTIVE

To evaluate risk factors for 30-day unplanned readmission and increased length of stay (LOS) following minimally invasive surgery (MIS) for endometrial cancer.

METHODS

This was a retrospective, case-control study using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). Multivariable logistic regression was used to assess perioperative variables associated with readmission and increased LOS after MIS for endometrial cancer.

RESULTS

The study population included 10,840 patients who met the criteria of having undergone MIS with a resultant endometrial malignancy confirmed on postoperative pathology. Common reasons for readmission included organ/space surgical site infection (65 cases), sepsis/septic shock (19 cases), and venous thromboembolism (20 cases). Notable risk factors for readmission included (Odds Ratio, Confidence Interval, p-value): dialysis dependence (6.77, 2.51-17.80, <0.01), increased length of stay (3.00, 2.10-4.10, <0.01), and preoperative weight loss (2.80, 1.06-7.17, 0.03); notable risk factors for increased LOS: ascites (8.51, 2.00-36.33, <0.01), operation duration >5 h (6.93, 5.29-9.25, <0.01), and preoperative blood transfusion (5.37, 2.05-14.04, <0.01).

CONCLUSIONS

Identification of risk factors for adverse postoperative outcomes is necessary to inform and improve standards of care in MIS for endometrial cancer. Using nationally reported data from the ACS NSQIP, this study identifies independent risk factors for unplanned readmission and prolonged LOS, and in doing so, highlights potential avenues for quality improvement.

From plasma to nanoparticles: optical and particle emission of a spark discharge generator

The increased demand for high purity nanoparticles (NPs) of defined geometry necessitates the continuous development of generation routes. One of the most promising physical techniques for producing metal, semiconductor or alloy NPs in the gas phase is spark discharge NP generation. The technique has a great potential for up-scaling without altering the particles. Despite the simplicity of the setup, the formation of NPs in a spark discharge takes place via complex multi-scale processes, which greatly hinders the investigation via conventional NP measurement techniques. In the present work, time-resolved optical emission spectroscopy (OES) was used to provide information on the species present in the spark from as early as approximately 100 ns after the initiation of the discharge. We demonstrate that operando emission spectroscopy can deliver valuable insights into NP formation. The emission spectra of the spark are used to identify, among others, the main stages of material erosion and to calculate the quenching rate of the generated metal vapour. We demonstrate that the alteration of key control parameters, that are typically used to optimize NP generation, clearly affect the emission spectra. We report for Cu and Au NPs that the intensity of spectral lines emitted by metal atoms levels off when spark energy is increased above an energy threshold, suggesting that the maximum concentration of metal vapour produced in the generator is limited. This explains the size variation of the generated NPs. We report a strong correlation between the optical and particle emission of the spark discharge generator, which demonstrate the suitability of OES as a valuable characterization tool that will allow for the more deliberate optimization of spark-based NP generation.

Ogilvie's Syndrome after Robotic-Assisted Radical Hysterectomy for Cervical Cancer

Acute colonic pseudo-obstruction (ACPO), also known as Ogilvie's syndrome, is defined by poor peristaltic activity of the colon that mimics mechanical obstruction in the absence of any mechanical occlusive gut lesion. This case report is the first to be published on ACPO occurring after robotic-assisted radical hysterectomy. Given that robotic-assisted laparoscopic surgery has become the next major stage of advancement for a range of operations, especially in gynecologic oncology surgery, this report emphasizes the importance of recognizing precipitating factors associated with this syndrome, including minimally invasive surgery.

MDR1 (C3435T) polymorphism: relation to the risk of breast cancer and therapeutic outcome

P-glycoprotein (PGP), the product of the MDR1 gene, is a transmembrane active efflux pump for a variety of carcinogens and cytostatics. It has been suggested that MDR1 polymorphisms contribute to the variability in cancer risk and therapeutic outcome. We examined the relevance of C3435T polymorphism in relation to breast cancer susceptibility, clinical and pathological characteristics of breast carcinoma, the therapeutic response and hematologic toxicities after anthracycline-based chemotherapy. A significant association between allele frequencies and histological type, stage and histological grade was observed (P=0.024, 0.014, 0.006, respectively, chi(2)-test or Fisher's exact test). We also found significantly higher (P=0.019, chi(2)-test) T allele frequency in breast cancer patients (n=221) than in controls (n=113). A significantly enhanced therapeutic outcome after neoadjuvant therapy (n=38; P=0.021, Fisher's exact test) and longer time to progression after anthracycline-based chemotherapy (n=102; P=0.049, log-rank test) were observed in CC homozygotes. However, no significant association between hematologic toxicities and C3435T polymorphism was detectable.

Mechanism of silver ion reduction in concentrated solutions of amphiphilic invertible polyesters in nonpolar solvent at room temperature

Fast formation and efficient stabilization of silver nanoparticles from [Ag(NH3)2]OH are achieved in concentrated nonpolar solutions of amphiphilic invertible polyesters based on poly(ethylene oxide) (PEO) and aliphatic dicarboxylic acids. Surface-modified silver nanoparticles able to be dispersed in both a polar and nonpolar medium are developed in the form of a ready-to-use colloidal solution with an enhanced silver concentration. The PEO fragments of polyesters form cavities (also called pseudo-crown ester structures) that can bind metal ions. The reduction of bound metal ions proceeds via oxidation of polyoxyethylene fragments. No chemical reducing agents are necessary in this approach. The polyesters act simultaneously as an efficient reducing agent and stabilizer. The main focus of the present research is to clarify the chemical mechanism of silver ion reduction in amphiphilic polyester solutions. A one-electron reduction mechanism is proposed to explain the formation of silver nanoparticles. The effect of the poly(ethylene oxide) fragment length and the polyester concentration are explored by examining several amphiphilic polyesters.

An effective way to stabilize colloidal particles dispersed in polar and nonpolar media

This article offers a new approach to building up self-adjustable invertible polymer coatings at solid surfaces. The approach is based on a two-step process. In the first step, the surface of dispersed TiO2 has been functionalized with the aid of toluene diisocyanate (TDI) as a coupling agent. In the second step, the chains of amphiphilic oligoester have been covalently grafted to the titanium dioxide surface functionalized with isocyanate groups. It is shown that the titania modified in this way can form stable suspensions in both polar (water) and nonpolar (toluene) media. Multiple redispersion cycles show the ability of the modified titanium dioxide particles, after their removal from one type of dispersion and consequent drying, to be redispersed in dispersing media strongly differing by polarity from the previous.

Design of a new invertible polymer coating on a solid surface and its effect on dispersion colloidal stability

This article presents a new approach to building up self-adjustable invertible polymer coatings at solid surfaces. The approach is based on a two-step process. In the first step, the surface of dispersed TiO2 or silicon wafers was functionalized with the aid of a reactive copolymer, viz., poly(styrene-alt-maleic anhydride) (PSM), to which, in the second step, the chains of amphiphilic oligoester have been tethered. The latter contains both hydrophilic poly(ethylene glycol) and hydrophobic aliphatic dibasic acid moieties being alternately distributed along the oligomer chains. It is shown that the titania modified in this way can form stable suspensions in both polar (water) and nonpolar (toluene) media. Moreover, multiple drying/redispersion cycles demonstrate the ability of the modified titania particles, after their removal from one type of dispersion and consequent drying, to be redispersed in dispersing media strongly differing by polarity from that of the previous medium. An environmentally induced switching of the surface properties has been observed via the measurement of the wetting contact angles and scanning force microscopy (SFM) of silicon wafers covered by PSM with tethered oligoester chains. These experiments give strong support for the predicted capability of such polymer coatings to switch their environmental appearance (i.e., to behave as a self-adjustable invertible interface because of the ability of the tethered amphiphilic oligoester chains to change their conformations in response to environmental changes in such a manner so as to adapt and enhance their compatibility with the surrounding media).

Polymorphism of the p53 gene within the codon 72 in lung cancer patients

We tested the codon 72 single nucleotide polymorphism (SNP) of the tumor suppressor gene p53 for association with lung cancer. In our hospital-based case-control study, 168 lung cancer patients (134 males and 34 females) and 148 controls without malignant diseases were recruited. The genotype characteristics were determined by PCR-based RFLP method using DNA extracted from peripheral blood. Only in lung cancer patients but not in the controls we found both significant decrease of A1 allele of the p53 codon 72 (p=0.024, OR 0.56, 95% CI 0.43-0.72) and A1/A1 homozygous genotype (p=0.006, OR 0.27,95% CI 0.15-0.51). The results of this study suggest a protective effect of A1 allele against lung cancer.

Consequences of reducing nonresponse in a national telephone survey

Critics of public opinion polls often claim that methodological shortcuts taken to collect timely data produce biased results. This study compares two random digit dial national telephone surveys that used identical questionnaires but very different levels of effort: a "Standard" survey conducted over a 5-day period that used a sample of adults who were home when the interviewer called, and a "Rigorous" survey conducted over an 8-week period that used random selection from among all adult household members. Response rates, computed according to AAPOR guidelines, were 60.6 percent for the Rigorous and 36.0 percent for the Standard study. Nonetheless, the two surveys produced similar results. Across 91 comparisons, no difference exceeded 9 percentage points, and the average difference was about 2 percentage points. Most of the statistically significant differences were among demographic items. Very few significant differences were found on attention to media and engagement in politics, social trust and connectedness, and most social and political attitudes, including even those toward surveys.