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J Klijn

Publications and source records attributed to J Klijn.

14 recordsLinked to original sources
PubMed2003

Direct measurement of the local density of states of a disordered one-dimensional conductor.

One-dimensional electron systems (1DESs) containing two and one occupied subbands are found below the different types of [11;2] steps of the InAs(110) surface. Using low-temperature scanning tunneling spectroscopy, we determined the subband energies, the disorder potential, and the local density of states of these 1DESs. The rather complete knowledge of the 1DES allowed us to compare the measured LDOS with a single-particle calculation. Surprisingly, we did not find significant deviations from the calculation albeit the electron-electron interaction in the 1DESs is stronger than the electron-disorder interaction.

Journal Article↗
PubMed2003

Real-space observation of drift States in a two-dimensional electron system at high magnetic fields.

The local density of states of the adsorbate-induced two-dimensional electron system is studied in magnetic fields up to B=6 T. Landau quantization is observed and drift states with a width of about the magnetic length are found in agreement with theoretical predictions. At the tails of the Landau levels the states form closed paths indicating localization. These states show the expected energy dependence. A multifractal analysis applied to the data results in a nice parabolic shape of the characteristic f(alpha) spectra, but we find only a slight displacement of the origin from alpha=2.0 for the states in the center of the Landau level.

Journal Article↗
PubMed2003

Continuing chemotherapy or not after the induction treatment in advanced breast cancer patients. clinical outcomes and oncologists' preferences.

The optimal duration of cytostatic treatment for metastatic breast cancer is still a matter of debate. Possible gain in the duration of remission has to be weighed against the side-effects of treatment. Our aim was to define the optimal duration of cyclophosphamide, methotrexate, 5-fluorouracil (CMF) treatment by studying the time to treatment failure, overall survival and using a Q-TWiST analysis. The treating physician's opinion was asked. The European Organization for Research and Treatment of Cancer (EORTC) Breast Cancer Group conducted a randomised trial in 204 non-progressing metastatic breast cancer patients after induction chemotherapy (CMF) to stop or continue treatment. Progression-free (PFS) and overall survival (OS) were studied. To gain more insight into the burden of treatment-related side-effects, Q-TWiST was analysed. In addition, we asked for oncologists' preferences as patients are likely to be influenced by their physicians' opinion. Continuation of CMF had a significantly longer time to treatment failure (TTF) 5.2 versus 3.5 months (P=0.011). There was no overall survival (OS) difference 14.0 versus 14.4 months (P=0.77). Mean quality-adjusted survival time was equal to 8.4 months for no further treatment and decreased to 7.9 months for continuation of CMF (95% Confidence Interval (CI) of difference equals 0.5+/-2.5 months). Almost half of the oncologists said they would favour continuous treatment for a 3-month gain in time to progression-a difference which was not found in this study. Based on these data, an interruption of chemotherapy (CMF), if this is the wish of the patient, is justified.

Adult↗
PubMed2002

Direct comparison between potential landscape and local density of states in a disordered two-dimensional electron system.

The local density of states (LDOS) of the adsorbate-induced two-dimensional electron system (2DES) on n-InAs(110) is studied by scanning tunneling spectroscopy. In contrast to a similar 3DES, the 2DES LDOS exhibits 20 times stronger corrugations and rather irregular structures. Both results are interpreted as consequences of weak localization. Fourier transforms of the LDOS reveal that the k values of the unperturbed 2DES still dominate the 2DES, but additional lower k values contribute. To clarify the origin of the LDOS patterns, we measure the potential landscape of the 2DES area. We use it to calculate the expected LDOS and find reasonable agreement between calculation and experiment.

Journal Article↗
PubMed2000

Identification and interpretation of clinical and quality of life prognostic factors for survival and response to treatment in first-line chemotherapy in advanced breast cancer.

The aim of the project was to identify clinical and quality of life (QL) factors that together predict survival and response to chemotherapy in advanced breast cancer. Potential prognostic factors were studied in 187 women with baseline QL data from a trial of paclitaxel versus doxorubicin as first-line chemotherapy. Demographic and clinical factors studied were age, performance status, dominant site of disease and preceding disease-free interval (DFI). Factors from the EORTC QLQ-C30 were all function scales, fatigue, nausea/vomiting, pain, dyspnoea, insomnia, loss of appetite and global QL. The proportional hazards regression model with stratification for treatment, and the logistic regression model adjusting for treatment arm were used for univariate and multivariate analyses of survival and response to treatment, respectively. For survival, multiple sites of visceral disease, pain, global QL and fatigue were significant prognostic factors in the univariate analysis. The final multivariate model predicted poor survival with multiple sites of visceral disease (P=0.003), DFI </=2 years (P=0.026) and pain (P=0.003). For response, age, dyspnoea, fatigue and global QL were significant predictive factors in the univariate analysis. The final multivariate model for response selected DFI (P=0.009), multiple sites of visceral disease (P=0.037) and dyspnoea (P=<0.001) using forward selection, but model instability was indicated by the inclusion of fatigue and emotional function in the final model when backward selection was used. In addition to known clinical factors, patient-assessed QL variables appear to be prognostic for survival and response to chemotherapy in women with advanced breast cancer. However, identification of prognostic factors from responses to questionnaires may be unstable, and their reliability and clinical utility should be tested prospectively.

Adolescent↗
PubMed2000

EORTC 10941: A phase II study of liarozole in postmenopausal patients with 'chemotherapy-resistant' or 'potentially hormone sensitive' metastatic breast cancer.

Liarozole is an imidazole compound that inhibits enzymes involved in steroid hormone aromatisation and retinoid metabolism. The IDBBC branch of the EORTC has performed a series of phase II studies of the agent in four groups of postmenopausal women with metastatic breast cancer. This paper reports the results of the first two groups: 'Chemotherapy Resistant' (unrestricted ER status, 1 or 2 prior chemotherapy regimens, 0-2 prior hormonal therapies) and 'Potentially Hormone Sensitive' (ER positive or unknown, 1 or 2 prior hormonal therapies with a substantial disease free interval or progression free survival, and no history of chemotherapy for metastatic disease). Liarozole was administered at 150-300 mg orally bid. The objective response rate was 12% in the 'Chemotherapy Resistant' group (n = 34), and 22% in the 'Potentially Hormone Sensitive' group (n = 37), with median response durations of 9 and 14 months, respectively. Median time to treatment failure was only 2 months in both groups, due largely to the significant percentage (24%) of patients who ceased treatment following excessive mucocutaneous and gastrointestinal toxicity. This adverse event profile will limit its use in breast cancer. Results of the 'ER negative' and 'Tamoxifen Refractory' groups will be reported in a future paper.

Adult↗
PubMed1998

Vorozole (Rivizor): an active and well tolerated new aromatase inhibitor for the treatment of advanced breast cancer patients with prior tamoxifen exposure. Investigational Drug Branch of the European Organization for Research and Treatment of Cancer (EORTC) Breast Cancer Cooperative Group.

Vorozole (Rivizor) is a potent and stereospecific inhibitor of aromatase having shown promising endocrine effects in phase I studies. In the present trial, 27 postmenopausal patients with advanced breast cancer, measurable lesions, presumably hormone responsive (ER or PR+, or ER? with disease-free survival longer than 1 year, or prior documented response to tamoxifen), were treated with vorozole one tablet 2.5 mg daily. All had been previously treated with tamoxifen as adjuvant (two patients) or for advanced disease (24 patients), or both (one patient). Objective remissions were observed in eight patients (30%) with two complete responses (CR) and six partial responses (PR) lasting for a median of 14.3 months (range 6.8-40.6); nine stabilizations were also recorded (median 7.9 months; range 3.7-40.1). Median time to progression for the 27 patients was 5.9 months. Sites of response were skin (three patients), lymph nodes (two patients), lung (two patients) and chest wall plus lymph nodes (one patient). Treatment was very well tolerated: mild hot flushes (four patients), gastrointestinal complaints (four patients) and no significant toxicity (common toxicity criteria grade above 2) or drug-related severe adverse event. It is concluded that vorozole is an active second-line endocrine treatment, deserving consideration for randomized comparison with other agents such as aminoglutethimide, megestrol acetate or medroxyprogesterone acetate.

Adult↗
PubMed1997

Corticosteroids significantly delay the onset of docetaxel-induced fluid retention: final results of a randomized study of the European Organization for Research and Treatment of Cancer Investigational Drug Branch for Breast Cancer.

PURPOSE: To confirm the efficacy of docetaxel in patients with breast cancer previously treated with one chemotherapy regimen for advanced or metastatic disease and to compare the incidence of fluid retention (FR) and skin toxicity when docetaxel is administered with and without prophylactic corticosteroids. PATIENTS AND METHODS: Eighty-three patients, pretreated with one chemotherapy regimen for metastatic breast cancer (MBC) with bidimensionally measurable and progressive disease, were eligible for this randomized trial. Docetaxel with prophylactic oral antihistamine was administered at a dose of 50 mg/m2 as a 1-hour infusion on days 1 and 8 every 21 days and patients were randomized to receive methylprednisolone (40 mg days -1, 0, 1, 7, 8, and 9 of each cycle) (arm A) or no methylprednisolone (arm B). RESULTS: Twenty-eight patients (34%, 95% confidence interval [CI], 23% to 45%) achieved on objective response. The median time to disease progression and median overall survival time were 5 and 13.5 months, respectively. In total, 415 cycles of docetaxel were administered (arm A: N = 219, median = six; arm B: N = 196, median = five). The most common toxicity observed was grade 3 or 4 neutropenia, which occurred in 79% of patients. Clinically significant nonhematologic side effects included skin reactions and asthenia. In an intent-to-treat analysis, patients who received methylprednisolone premedication had a delayed onset of FR (median time to onset of FR: arm A, 84 days; arm B, 62 days; P = .01) and received a higher median cumulative dose of docetaxel before the onset of FR (arm A, 333 mg/m2; arm B, 215 mg/m2; P = .001). There was no statistically significant difference in the incidence of skin toxicity between the two arms. CONCLUSION: Docetaxel, at this dose and schedule, has definite antitumor activity in pretreated MBC patients. Moreover, this is the first randomized trial to show that corticosteroids have a favorable impact on docetaxel-induced FR.

Adult↗
PubMed1996

An ongoing European organization for research and treatment of cancer crossover trial comparing single-agent paclitaxel and doxorubicin as first- and second-line treatment of advanced breast cancer.

The activity of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in advanced breast cancer patients who have failed doxorubicin treatment is well established, but the optimal sequence between these two important agents remains to be determined. The European Organization for Research and Treatment of Cancer therefore designed a prospective randomized clinical trial in which patients not exposed to anthracyclines in the adjuvant setting received either first-line paclitaxel, given as a 3-hour infusion at a dose of 200 mg/m2 followed at the time of disease progression by second-line doxorubicin, given as a bolus injection at a dose of 75 mg/m2 or the reverse sequence. The target accrual is 330 patients. Interim results on 207 evaluable patients of 289 randomized are presented.

Adenocarcinoma↗