Dose and dose intensity as determinants of outcome in the adjuvant treatment of breast cancer. The Cancer and Leukemia Group B

BACKGROUND: Both total dose and dose intensity of adjuvant chemotherapy are postulated to be important variables in the outcome for patients with operable breast cancer. The Cancer and Leukemia Group B study 8541 examined the effects of adjuvant treatment using conventional-range dose and dose intensity in female patients with stage II (axillary lymph node-positive) breast cancer. METHODS: Within 6 weeks of surgery (radical mastectomy, modified radical mastectomy, or lumpectomy), 1550 patients with unilateral breast cancer were randomly assigned to one of three treatment arms: high-, moderate-, or low-dose intensity. The patients received cyclophosphamide, doxorubicin, and 5-fluorouracil on day 1 of each chemotherapy cycle, with 5-fluorouracil administration repeated on day 8. The high-dose arm had twice the dose intensity and twice the drug dose as the low-dose arm. The moderate-dose arm had two thirds the dose intensity as the high-dose arm but the same total drug dose. Disease-free survival and overall survival were primary end points of the study. RESULTS: At a median follow-up of 9 years, disease-free survival and overall survival for patients on the moderate- and high-dose arms are superior to the corresponding survival measures for patients on the low-dose arm (two-sided P<.0001 and two-sided P = .004, respectively), with no difference in disease-free or overall survival between the moderate- and the high-dose arms. At 5 years, overall survival (average +/- standard error) is 79% +/- 2% for patients on the high-dose arm, 77% +/- 2% for the patients on the moderate-dose arm, and 72% +/- 2% for patients on the low-dose arm; disease-free survival is 66% +/- 2%, 61% +/- 2%, and 56% +/- 2%, respectively. CONCLUSION: Within the conventional dose range for this chemotherapy regimen, a higher dose is associated with better disease-free survival and overall survival.     

A successful system of scientific data audits for clinical trials. A report from the Cancer and Leukemia Group B

OBJECTIVE: To report on data collected during on-site audits of source documents in the Cancer and Leukemia Group B (CALGB). DESIGN: A retrospective review of audit reports in four audit cycles. SETTING: A cooperative group of institutions conducting clinical trials in cancer treatment. PARTICIPANTS: Patients taking part in clinical trials at collaborating CALGB institutions, members of the CALGB Data Audit Committee, and group chairmen of CALGB. MAIN OUTCOME MEASURE: The results of 691 institutional audits conducted by the CALGB in 1982 through 1992 with comparisons of main CALGB institutions vs affiliates. RESULTS: In four full reviews of all participating institutions in the CALGB, 3787 patients have had their on-site medical records compared with data submitted to the CALGB Data Management Center. Compliance with federal regulations for oversight by an institutional review board improved from a deficiency rate of 28.0% among the main institutions and 49.6% of the affiliate institutions in the first audit cycle to respective figures of 13.3% and 28.2% in the fourth cycle. Consent form deficiencies also dropped overall from 18.5% in the first cycle to 3.9% in the fourth. Patient eligibility was verified by auditors in 94.5%, and assessment of tumor changes in response to treatment was verified in 96.4% in the fourth cycle; both figures were only slightly lower in the first cycle. Two instances of scientific impropriety were discovered for a rate of only 0.28% of all audits. Both occurred prior to 1984, and none have occurred since. Major protocol deviations in drug dosing have held steady at about 11% over four audit cycles. Over the 11-year period of audits, three main institutions and 96 affiliate institutions have discontinued CALGB membership due solely, or at least partly, to unfavorable audit results. CONCLUSION: Scientific improprieties have occurred very rarely in clinical trials conducted by the CALGB. Protocol compliance in assessing patient eligibility and tumor responses has been high. Attention to administrative matters of consent forms, institutional review board approval, and ancillary data submission has measurably improved in the CALGB, which is at least partly due to the pressure from this on-site peer review of investigator performance.     

Active Site Mutations as a Suitable Tool Contributing to Explain a Mechanism of Aristolochic Acid I Nitroreduction by Cytochromes P450 1A1, 1A2 and 1B1

Aristolochic acid I (AAI) is a plant drug found in Aristolochia species that causes aristolochic acid nephropathy, Balkan endemic nephropathy and their associated urothelial malignancies. AAI is activated via nitroreduction producing genotoxic N-hydroxyaristolactam, which forms DNA adducts. The major enzymes responsible for the reductive bioactivation of AAI are NAD(P)H:quinone oxidoreductase and cytochromes P450 (CYP) 1A1 and 1A2. Using site-directed mutagenesis we investigated the possible mechanisms of CYP1A1/1A2/1B1-catalyzed AAI nitroreduction. Molecular modelling predicted that the hydroxyl groups of serine122/threonine124 (Ser122/Thr124) amino acids in the CYP1A1/1A2-AAI binary complexes located near to the nitro group of AAI, are mechanistically important as they provide the proton required for the stepwise reduction reaction. In contrast, the closely related CYP1B1 with no hydroxyl group containing residues in its active site is ineffective in catalyzing AAI nitroreduction. In order to construct an experimental model, mutant forms of CYP1A1 and 1A2 were prepared, where Ser122 and Thr124 were replaced by Ala (CYP1A1-S122A) and Val (CYP1A2-T124V), respectively. Similarly, a CYP1B1 mutant was prepared in which Ala133 was replaced by Ser (CYP1B1-A133S). Site-directed mutagenesis was performed using a quickchange approach. Wild and mutated forms of these enzymes were heterologously expressed in Escherichia coli and isolated enzymes characterized using UV-vis spectroscopy to verify correct protein folding. Their catalytic activity was confirmed with CYP1A1, 1A2 and 1B1 marker substrates. Using ³²P-postlabelling we determined the efficiency of wild-type and mutant forms of CYP1A1, 1A2, and 1B1 reconstituted with NADPH:CYP oxidoreductase to bioactivate AAI to reactive intermediates forming covalent DNA adducts. The S122A and T124V mutations in CYP1A1 and 1A2, respectively, abolished the efficiency of CYP1A1 and 1A2 enzymes to generate AAI-DNA adducts. In contrast, the formation of AAI-DNA adducts was catalyzed by CYP1B1 with the A133S mutation. Our experimental model confirms the importance of the hydroxyl group possessing amino acids in the active center of CYP1A1 and 1A2 for AAI nitroreduction.     

压缩感知在城区高分辨率SAR层析成像中的应用

在建筑密集的城区复杂场景中,高分辨率SAR影像中存在严重的叠掩效应,影像解译的难度加大.SAR层析成像可以分离单个分辨单元内混叠的散射体目标,并且获取各个散射体的3维位置和后向散射强度.该文首先论述了3维SAR层析成像的基本原理,针对传统谱估计法获得的高程向分辨率较低的问题,综述了压缩感知方法在城区3维SAR层析成像中的应用,以基追踪和双步迭代收缩阈值法为例,开展了TerraSAR-X聚束模式数据实验,并与传统的奇异值阈值法进行了对比分析.研究结果表明压缩感知方法的高程向超分辨率、旁瓣抑制优势明显,在城区SAR层析成像中具有广阔的应用前景.      

Platinum Cyclooctadiene Complexes with Activity against Gram-positive Bacteria

Antimicrobial resistance is a looming health crisis, and it is becoming increasingly clear that organic chemistry alone is not sufficient to continue to provide the world with novel and effective antibiotics. Recently there has been an increased number of reports describing promising antimicrobial properties of metal-containing compounds. Platinum complexes are well known in the field of inorganic medicinal chemistry for their tremendous success as anticancer agents. Here we report on the promising antibacterial properties of platinum cyclooctadiene (COD) complexes. Amongst the 15 compounds studied, the simplest compounds Pt(COD)X₂ (X=Cl, I, Pt1 and Pt2 ) showed excellent activity against a panel of Gram-positive bacteria including vancomycin and methicillin resistant Staphylococcus aureus. Additionally, the lead compounds show no toxicity against mammalian cells or haemolytic properties at the highest tested concentrations, indicating that the observed activity is specific against bacteria. Finally, these compounds showed no toxicity against Galleria mellonella at the highest measured concentrations. However, preliminary efficacy studies in the same animal model found no decrease in bacterial load upon treatment with Pt1 and Pt2 . Serum exchange studies suggest that these compounds exhibit high serum binding which reduces their bioavailability in vivo, mandating alternative administration routes such as e. g. topical application.     

A new parameter for checking the suitability of α-tocopherol standards

The quality of an α-tocopherol standard can be checked easily by measuring the UV absorbance at minimum (255 nm,A _min) and maximum (292 nm,A _max) wavelengths inn-hexane. If the quotientA _min/A _max exceeds 0.18, the standard contains less than 90% α-tocopherol and the determination at 292 nm will yield inaccurate results.     

Gadolinium enhancement: improved MRI detection of retinoblastoma extension into the optic nerve

We performed T1-, T2-, proton density-weighted, and T1-weighted gadolinium-enhanced MRI on 24 patients with retinoblastoma, using a 1.5 T superconducting unit and head and orbital surface coil imaging. All patients underwent a complete ophthalmologic examination, including B-scan ultrasonography. CT was performed on 10 of 24 patients. Pathologic correlation was obtained in 18 patients who required enucleation. Contrast-enhanced T1-weighted MRI with fat suppression was the sequence most sensitive to optic nerve extension and provided the greatest differentiation between tumor and uninvolved extrascleral tissue. Retinoblastoma demonstrated contrast enhancement.