Assessing the microbial oxidative stress mechanism of ozone treatment through the responses of Escherichia coli mutants

AIMS

To investigate the effect of the oxidative stress of ozone on the microbial inactivation, cell membrane integrity and permeability and morphology changes of Escherichia coli.

METHODS AND RESULTS

Escherichia coli BW 25113 and its isogenic mutants in soxR, soxS, oxyR, rpoS and dnaK genes were treated with ozone at a concentration of 6 μg ml⁻¹ for a period up to 240 s. A significant effect of ozone exposure on microbial inactivation was observed. After ozonation, minor effects on the cell membrane integrity and permeability were observed, while scanning electron microscopy analysis showed slightly altered cell surface structure.

CONCLUSIONS

The results of this study suggest that cell lysis was not the major mechanism of microbial inactivation. The deletion of oxidative stress-related genes resulted in increased susceptibility of E. coli cells to ozone treatment, implying that they play an important role for protection against the radicals produced by ozone. However, DnaK that has previously been shown to protect against oxidative stress did not protect against ozone treatment in this study. Furthermore, RpoS was important for the survival against ozone.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides important information about the role of oxidative stress in the responses of E. coli during ozonation.

Phase I trial sunitinib plus everolimus in patients with metastatic renal cell carcinoma (mRCC)

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Background: Sunitinib a targeted tyrosine kinase inhibitor and everolimus an mTOR inhibitor both inhibit hypoxia-induced factor-dependent signaling and have activity in advanced renal cell carcinoma (RCC). The safety and maximum tolerated dose (MTD) of sunitinib in combination with everolimus was assessed in this phase I trial.

Methods: Cohorts of 3–6 patients with mRCC received sunitinib at 37.5 or 50 mg daily for 4 weeks followed by 2 weeks off with everolimus administered either daily (2.5 or 5 mg) or weekly (20 or 30 mg). Dose-limiting toxicities (DLTs) were assessed in the first 6-week cycle to determine MTD.

Results: 20 patients (13 clear cell and 7 non-clear cell RCC) were enrolled in five cohorts. Both patients in the 2nd dose level (everolimus 5 mg daily, sunitinib 37.5mg) experienced grade 3 DLT (thrombocytopenia and mucositis; vomiting). With weekly everolimus dosing, the MTD was everolimus 30 mg /sunitinib 37.5 mg (4th dose level). However, only one of six patients at this dose level tolerated treatment beyond 4 cycles. Grades 3 and 4 toxicities observed with chronic treatment included infection, gastrointestinal hemorrhage, and pulmonary embolism. A total of six patients were treated with everolimus 20b mg weekly/37.5 mg sunitinib (3rd dose level) with better tolerance as chronic therapy. Overall, 5 out of 20 patients achieved a partial response including 3 patients with non-clear cell histology.

Conclusions: Partial responses were observed in both clear cell and non-clear cell histologies. However, due to toxicity the combination of sunitinib and everolimus could not be administered at full doses.

[Table: see text]

Optimising management of cancer related anemia

This review article provides the current recommendations and evidence for the correct management of anemia in cancer patients. The various options available include transfusions, iron and erythropoiesis stimulation. The indications, pros and cons of each option are discussed.

A comparison of IMRT and 3DCRT in the treatment planning of patients with distal esophageal cancer

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Background: There is limited data comparing intensity modulated radiation therapy (IMRT) and 3D conformal radiation therapy (3DCRT) in node-negative patients with cancer of the distal esophagus.

Methods: Eight patients with node-negative cancer of the distal esophagus measuring 1-5 cm tumors were selected for this study. Target volumes were generated for all patients based on standard current practice; 3DCRT and IMRT plans optimized to obtain minimum dose to the heart were then created using the using the Eclipse Treatment Planning. Conformality index (CI, the amount of target volume covered by the prescription dose) and conformation number (CN, the amount of normal tissue receiving prescription dose) were calculated. Dose volume histograms also were generated and clinically relevant parameters were extracted and compared for each planning modality using paired T-tests. Each patient served as his or her own control.

Results: The difference in CI ranged from 0-0.01, indicating equivalent target coverage for each patient. IMRT produced superior CN (mean CN = 0.74) vs. the 3DCRT plans (mean CN = 0.45). Heart V40 and the maximum dose to spinal cord were lower for IMRT (mean difference in heart V40 = 34.5%, p=0.0006 and mean difference in the maximum dose to the spinal cord = 18.1 Gy, p=0.0005) but lung V5 and V20 were lower for 3DCRT (mean difference in lung V5 = -21.3%, p=0.0026 and mean difference in lung V20 = -5.2%, p=0.0014).

Conclusions: When optimized to minimize dose to the heart, IMRT plans were substantially more conformal to the target structures with less dose to the heart as compared to 3DCRT plans; however this occurred at the expense of increased dose delivered to the lung.

No significant financial relationships to disclose.

Synthesis and Antimicrobial Screening of Pyrazolo-3-Aryl Quinazolin-4(3H)ones

2-thio-3-aryl quinazolin-4(3H)one (1) was synthesized by reacting anthranilic acid with thiocarbamate salts of substituted aniline and carbon disulphide, which on reflux with excess of hydrazine hydrate to form 2-hydrazino quinazolin-4(3H)one derivatives (2). The reaction of (2) with variously substituted aryl aldehydes gave the corresponding hydrazones (3). Further, the cyclization of compound (3) in acetic anhydride gave tricyclic pyrazoloquinazolinones (4). All newly synthesized compounds have been tested for their antibacterial activity against gram +ve bacteria B. substilis, S. aureus and gram –ve bacteria E. coli, P. vulgaris. The species used for antifungal activity are Aspergillus niger and Phytophora. Introduction of -OCH3, -OH and -Cl groups to the heterocyclic frame work enhanced antibacterial and antifungal activities.

Abstract P6-12-09: A Phase I-II Trial of Dasatinib (D) in Combination with Weekly (w) Paclitaxel (P) for Patients (Pts) with Metastatic Breast Carcinoma (MBC)

Background: Inhibition of SRC is a novel approach for MBC. D is an inhibitor of multiple tyrosine kinases, including the SRC family. Pre-clinical data show D inhibits multiple breast cancer cell lines, including those of “basal-like” subtype. In preclinical models D + P had superior antitumor activity to either agent alone. We designed this phase I-II study to translate this observation.

Methods: For phase I: pts with MBC, ECOG PS 0-1, normal hepatic, renal, marrow function were eligible. Pts with pleural/pericardial effusions were excluded. For phase II: pts had measurable, HER2-negative MBC, ≥2 prior rx for MBC. Prior taxanes, stable brain metastases and baseline neuropathy grade ≥1 were allowed. Cycle (C) consisted of wP 80 mg/m2 IV 3/4 weeks + D 70mg orally daily; escalating to 100 mg, 120 mg and 150 mg in cohorts of 3pts. Toxicity was assessed by CTCAE v3.0, response by RECIST.

Results: 17 pts enrolled (15 phase I; 2 phase II); median age 54 (range 35-74), median PS=1 (range 0-1). 12 (71%) pts rcvd prior adjuvant chemoRx. Pts rcvd a median of 3 prior rx for MBC (range 0-12). Pts rcvd median of 2 C of D + P (range 1-14). One DLT occurred at 150mg (G3 fatigue); this cohort was expanded with no further DLTs. However 3 pts on this dose level withdrew;1 pt delayed hypersensitivity rash (grade 1), 1 pt febrile neutropenia (grade 3), 1 pt paclitaxel pneumonitis (grade 3). Therefore the phase II dose is D 120mg. Overall the most common toxicities have been hematologic and low G (table). 13 pts are assessable for response; 4 patients (31%) had a PR, including 3 patients previously treated with taxanes. 5 pts (29%) had stable disease.

Toxicities > Grade 1

Conclusion: Treatment with wP and D is feasible in pts with MBC. In the phase I study, 1 DLT occurred at D 150mg but due to cumulative toxicities the recommended dose for the ongoing phase II study is 120mg. Preliminary evidence of activity has been seen in taxane-pretreated pts at the phase II dose. Identification of biomarkers to select appropriate pts for this therapeutic approach is the subject of ongoing correlative studies.