Stability of buoyant convection in a layer submitted to acoustic streaming

The linear stability of the flows induced in a fluid layer by buoyant convection (due to an applied horizontal temperature gradient) and by acoustic streaming (due to an applied horizontal ultrasound beam) is studied. The vertical profiles of the basic flows are determined analytically, and the eigenvalue problem resulting from the temporal stability analysis is solved by a spectral Tau Chebyshev method. Pure acoustic streaming flows are found to be sensitive to a shear instability developing in the plane of the flow (two-dimensional instability), and the thresholds for this oscillatory instability depend on the normalized width Hb of the ultrasound beam with a minimum for Hb=0.32 . Acoustic streaming also affects the stability of the buoyant convection. For a centered beam, effects of stabilization are obtained at small Prandtl number Pr for large beam widths Hb (two-dimensional shear instability) and for moderate Pr (three-dimensional oscillatory instability), but destabilization is also effective at small Pr for small beam widths Hb and at large Pr with a spectacular decrease of the thresholds of the three-dimensional steady instability. An adequate decentring of the ultrasound beam can enhance the stabilization. Insight into the stabilizing and destabilizing mechanisms is gained from the analysis of the fluctuating energy budget associated with the disturbances at threshold. The modifications affecting the two-dimensional shear instability thresholds are strongly connected to modifications of the velocity fluctuations when acoustic streaming is applied. Concerning the three-dimensional steady instability, the spectacular decrease of the thresholds is explained by the extension of the zone with inverse stratification in the lower half of the layer.

Erythropoiesis-stimulating agents in oncology: a study-level meta-analysis of survival and other safety outcomes

BACKGROUND: Cancer patients often develop the potentially debilitating condition of anaemia. Numerous controlled studies indicate that erythropoiesis-stimulating agents (ESAs) can raise haemoglobin levels and reduce transfusion requirements in anaemic cancer patients receiving chemotherapy. To evaluate recent safety concerns regarding ESAs, we carried out a meta-analysis of controlled ESA oncology trials to examine whether ESA use affects survival, disease progression and risk of venous-thromboembolic events.

METHODS: This meta-analysis included studies from the 2006 Cochrane meta-analysis, studies published/updated since the 2006 Cochrane report, and unpublished trial data from Amgen and Centocor Ortho Biotech. The 60 studies analysed (15 323 patients) were conducted in the settings of chemotherapy/radiochemotherapy, radiotherapy only treatment or anaemia of cancer. Data were summarised using odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS: Results indicated that ESA use did not significantly affect mortality (60 studies: OR=1.06; 95% CI: 0.97–1.15) or disease progression (26 studies: OR=1.01; 95% CI: 0.90–1.14), but increased the risk for venous-thromoboembolic events (44 studies: OR=1.48; 95% CI: 1.28–1.72).

CONCLUSION: Though this meta-analysis showed no significant effect of ESAs on survival or disease progression, prospectively designed, future randomised clinical trials will further examine the safety and efficacy of ESAs when used according to the revised labelling information.

Disease mongering: expanding the boundaries of treatable disease

Traditionally, the promotional activities of medical industries have been product specific. In recent years, however, there have been examples where companies have worked through partnerships, which have included clinicians, to expand the boundaries of treatable disorders. The main motivation appears to be to increase sales of commercial products. The term 'disease mongering' has been applied to these activities. Whereas some disease awareness programmes may bring benefits in the form of improved recognition and management of disorders, the presence of strong commercial interests probably distorts the traditional processes by which treatable diseases have been defined. This can result in individual patients being exposed to potential harms, with little expectation of benefit and will place an unwarranted burden on the publicly funded health-care system. None of this can happen without the collaboration of the medical profession that needs to be aware of the risks of becoming involved in commercially supported 'consensus' groups that are reviewing the definition and management of diseases.

Spatiotemporal evolution of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect under initial pulselike disturbances

The spatiotemporal evolution of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect is investigated by carrying out fully nonlinear two-dimensional numerical simulations initiated by a pulselike disturbance. The traveling wave packets for positive as well as negative separation factors psi are obtained numerically for ethanol-water-like mixtures (Prandtl number Pr=10 , Lewis number Le=0.01) and selected combinations of Rayleigh and Reynolds numbers at psi=0.01, 0.1 and psi=-0.1. The characteristics of the wave fronts and the transitions observed between absolute and convective instabilities when changing the parameters are compared with the results previously obtained by linear spatiotemporal stability analysis. The simulations are in very good agreement with the stability results, which confirms the validity of both approaches. Finally, in order to characterize the possible interaction between the two wave packets of the so-called downstream and upstream modes for psi<0, the spatiotemporal stability analysis is used to detect a boundary curve in the (Re, Ra) parameter region beyond which the two wave packets will never completely separate. Numerical simulations illustrate the different evolutions of the wave packets on both sides of this boundary.

Phase III study of standard triweekly versus dose-dense biweekly capecitabine (C) + oxaliplatin (O) + bevacizumab (B) as first-line treatment for metastatic colorectal cancer (mCRC): XELOX-A-DVS (dense versus standard): Interim analysis

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Background: Every 3 week (Q3W) COB has been shown to be highly active and non-inferior to FOLFOX+B in first-line mCRC. Phase II data suggest that dose-dense every 2 week (Q2W) COB may be significantly more active and better tolerated than Q3W COB. Methods: XELOXA-DVS was a phase III, open-label study of 435 patients with chemonaive mCRC who met standard eligibility criteria. Patients were randomized to Q3W: C 850 mg/m2 BID d1–14 + O 130 mg/m2 d1 + B 7.5 mg/kg d1 or Q2W: C 1500 mg/m2 BID d1–7 + O 85 mg/m2 d1 + B 5 mg/kg d1 for up to 72 weeks. Complete surgical resection was allowed using pre-defined criteria. The primary endpoint, progression-free survival (PFS), was estimated using the Kaplan- Meier method, while the hazard ratio and 95% CI were estimated using Cox regression analysis, based on the intent-to-treat population. No formal statistical testing was conducted. Results: The median PFS was 8.4 months (Q2W) and 9.7 months (Q3W) (hazard ratio [HR]=0.84; 95% CI=0.62–1.13). The median PFS (on-treatment) was 9.1 months and 10.2 months, respectively (HR=0.81). Of the 72 and 73 patients with disease progression (DP), the median time to DP was 9.4 and 10.8 months, respectively (HR=0.86). The objective response rates were 21.7% vs 29.4%, respectively (HR=1.05). Patients in the Q2W vs Q3W group experienced higher rates of grade 3/4 diarrhea (29% vs 24%), hand-foot syndrome (12% vs 8%), and treatment discontinuation rates (40% vs 20%), respectively. Other grade 3/4 toxicities (>5%, Q2W vs Q3W) included fatigue (13% vs 13%), dehydration (12% vs 10%), nausea (8% vs 9%), peripheral neuropathy (5% vs 9%), anorexia (5% vs 7%), and abdominal pain (5% vs 7%). Conclusions: At the dose and schedule used, dose-dense Q2W COB was not superior to standard Q3W COB. These data further confirm the activity and tolerability of Q3W COB. The activity and tolerability of a lower C dose Q2W, with more aggressive dose reduction, combined with B and O or irinotecan is currently being evaluated (X-BIO).

[Table: see text]

Influence of acoustic streaming on the stability of a laterally heated three-dimensional cavity

The flows induced by acoustic streaming in a three-dimensional side-heated parallelepiped cavity of length Ax representative of crystal growth configurations are numerically studied. Both the structure of the flows and their stability properties are determined. The flows have different symmetries, belonging to the group D4 for pure streaming, Z2xZ2 for pure buoyancy, and Z2 for the mixed case, but these symmetries are generally broken at the first bifurcation points. Bifurcation diagrams are obtained which show that the flows become oscillatory periodic at a Hopf bifurcation, either directly on the primary steady solution branch, or on a secondary branch which bifurcates from the primary branch at a steady bifurcation point. The critical Grashof numbers for these bifurcation points are calculated as a function of the cavity length Ax, the Prandtl number Pr and the acoustic streaming parameter A. The thresholds are generally found to increase when the acoustic streaming contribution is enhanced, which indicates a stabilizing effect induced by acoustic streaming and may explain the observed improvement of the crystal quality when ultrasound waves are applied during the growth process. Destabilization effects are, however, found in some parameter range.

Linear temporal and spatiotemporal stability analysis of two-layer falling films with density stratification

A detailed temporal and spatiotemporal stability analysis of two-layer falling films with density and viscosity stratification is performed by using the Chebyshev collocation method to solve the full system of linear stability equations. From the neutral curves Re(k) for the surface mode and the interface mode of instability, obtained for different density ratios gamma of the upper layer to the lower layer, it is found that smaller density ratios make the surface mode and the short-wave interface mode much more stable, and can even make the short-wave interfacial instability disappear. Moreover, through the study of the local growth rates of the spatiotemporal instability as a function of the ray velocity V , it is found that for not too small incline angles like theta=0.2, the two-layer flow is always convectively unstable, and there is a transition between long- and short-wave instabilities which is determined by the Briggs-Bers collision criterion. Due to the existence of the absolute Rayleigh-Taylor instability for gamma>0 and theta=0, a transition from convective to absolute instability can be detected at small incline angles, and the corresponding boundary curves are plotted for different Reynolds numbers, viscosity ratios, and incline angles. It is found that there exists a limit Reynolds number above which the two-layer film flow can only be convectively unstable for a fixed small incline angle. The spatial amplification properties of the convective waves are finally presented for both surface and interface modes.

Multiple flow transitions in a box heated from the side in low-Prandtl-number fluids

The determination of the flow transitions in a cavity heated from the side in low-Prandtl-number fluids has been a challenge for many years. Contrarily to the Rayleigh-Bénard situation, these transitions occur in already very intense convective flows, and the problem has been up to now mainly treated in two-dimensional situations. Thanks to a performing numerical method, the thresholds corresponding to the first flow transition in a three-dimensional (3D) parallelepipedic cavity have been determined for a wide range of aspect ratios and Prandtl number values. We obtain a kind of map of the transitions involved. Such a map of transitions is quite usual for Rayleigh-Bénard or Marangoni-Bénard situations, but completely new for 3D cavities heated from the side. The most striking result is the very frequent change of stability branches when the aspect ratios or Prandtl number are changed, which indicates different flow structures triggered at the thresholds, either steady or oscillatory, and breaking some of the symmetries of the problem.

Epoetin-alfa initiation at Hb 10–11 or Hb <10 g/dL: Analysis of safety and efficacy

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Background: Current guidelines recommend consideration of epoetin alfa (EPO) therapy for chemotherapy-induced anemia (CIA) either when Hb <11 g/dL (National Comprehensive Cancer Network) or when Hb < 10g/dL (ASCO/ASH 2002). The objective was to evaluate the safety and efficacy of EPO in patients (pts) with CIA when EPO was initiated at Hb 10–11 or at <10 g/dL. Methods: A post hoc analysis was performed on data from randomized, well-controlled trials conducted from 2002–2006. Trials in which EPO therapy was initiated at the approved dose of 40,000 Units weekly in male and female pts with Hb <11g/dL and =1 post-baseline Hb value were included. Two trials were identified, T1 and T2. Safety was assessed by the proportion of pts experiencing clinically relevant thrombovascular events (CR- TVEs) who received =1 dose of EPO. Efficacy was assessed by RBC transfusion requirements (Day 1 - end of treatment [EOT] and Day 29 - EOT) and achievement of durable Hb response (Hb =11 g/dL for =2 consecutive weeks). Results: Baseline (BL) characteristics (age, gender, platinum-based therapy, ECOG PS, and tumor type) were similar between the Hb 10–11 and <10 g/dL groups. BL Hb was 10.53 and 9.29 g/dL in T1 and 10.28 and 9.53 g/dL in T2 for the Hb 10–11 and Hb<10 g/dL subsets, respectively. Results are summarized below ( table ). Conclusions: These results show that patients treated with EPO at an Hb of 10–11 g/dL appear to have a lower incidence of CR-TVEs compared to patients treated at Hb <10 g/dL. In addition, patients who started EPO treatment at an Hb of 10–11 g/dL had fewer RBC transfusions and higher durable Hb response. Trial 1 - Waltzman et al. The Oncologist. 2005;10:642–650. Trial 2 - Henry et al. Curr Med Res Opin. 2006;22:1403–1413.

No significant financial relationships to disclose.

[Table: see text]

Randomized study of early intervention compared to standard intervention with darbepoetin-alpha (DA) for chemotherapy-induced anemia (CIA) in early stage breast cancer (ESBC)

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Background: Dose dense chemotherapy (DDC) with sequential doxorubicin/ cyclophosphamide followed by paclitaxel Q 14 days has an established place in the treatment of ESBC. However, moderate/severe CIA is a common consequence and therapeutic intervention is frequent. We sought to determine if early intervention at the onset of anemia with DA could reduce the emergence of more severe anemia during therapy and maintain quality of life compared to later intervention. Material and Methods: Non-iron deficient (ferritin > 50) patients (pts) with hemoglobin (Hb) levels >11.0 g/dl scheduled to receive adjuvant or neoadjuvant DDC for ESBC were recruited. Pts were randomly assigned prior to chemotherapy to initiate treatment with DA 200 μg q2w SQ when Hb < 11.5 g/dl (early intervention, EARLY), or DA 200 μg q2w SQ when Hb < 10.0 g/dl (standard intervention, STD) with end of treatment defined as 14 days after the last cycle of chemotherapy. Dose escalation for inadequate response of < 1 g/dl after 6 weeks of DA and dose withholding/reduction for Hb >13 g/dl were pre-specified. Results: The complete sample of 149 pts have been accrued (median age of 53.1, range 28.7 - 74.5). Analysis of fatigue ratings show a trend towards lower fatigue scores in EARLY at Hb nadir, and at end of study,(ANOVA, Group x Time interaction, p=.07). Discussion: Early intervention with DA significantly reduces the risk of developing moderate/severe CIA and increases time spent in the target range during DDC for ESBC.

[Table: see text]

No significant financial relationships to disclose.

The mechanism of human angiosarcoma drug resistance

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Background: Angiosarcoma (AS) is a malignant neoplasm of endothelial cells. AS has an extremely poor outcome since it can metastasize widely and rapidly becomes chemoresistant. Understanding the mechanism of this resistance is important not only because of the critical need for new therapeutic strategies in sarcoma, but also since it sheds light on important pathways in endothelial growth that may help understand tumor angiogenesis. Methods/Results: We have established and characterized stable pre-chemotherapy (named B8) and chemotherapy-resistant (named D3) angiosarcoma cell lines from an individual patient with primary (non radiated) breast angiosarcoma prior to initiation of chemotherapy and later after development of resistance to adriamycin, ifosfamide, gemcitabine, docetaxel, paclitaxel, interferon, thalidomide and bevacizumab. D3 cells differ dramatically from B8s in morphology and function. Prechemotherapy B8 cells assume a polygonal morphology reminiscent of native endothelial cells, the D3 cells throw out long processes that span several cell lengths, and do not appear to contact-inhibit. Migration and invasion assays confirm the highly motile nature of these cells. Although it is not surprising that the D3 cells were doxorubicin resistant, we found that unlike the B8 cells, the D3 cells actively transcribe VEGF. In keeping with this, D3 cells are relatively more sensitive to growth inhibition by the anti-VEGF drug bevacizumab than chemonaïve B8 cells. Conclusion: These studies reveal two avenues to target chemoresistant human angiosarcoma; via agents affecting cell migration and those agents that target the VEGF pathway.

No significant financial relationships to disclose.

Darbepoetin alfa administered at varying intervals compared with weekly epoetin alfa for treating chemotherapy-induced anemia: A pooled analysis of 20 clinical trials

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Background: Cancer patients (pts) often develop chemotherapy-induced anemia (CIA), resulting in an increased risk for transfusions and fatigue. The erythropoiesis-stimulating agents (ESAs) epoetin alfa (EA) and darbepoetin alfa (DA) can reduce transfusion requirements, raise hemoglobin (Hb) levels, and decrease fatigue in pts with CIA. The 74-hour half-life of DA allows for flexible dosing with weekly (QW), every-2-week (Q2W), or every-3-week (Q3W) administration. This study evaluated if the dosing interval used to administer DA affected its efficacy. Methods: Data from 20 clinical trials in the CIA setting were pooled, including single-arm, active-controlled, and placebo-controlled trials (a full description of these studies will be presented). Six studies contributed data for DA QW, 7 studies for DA Q2W, and 5 studies for DA Q3W. Controlled studies used either a placebo or EA as the comparator. Logistic regression with treatment as a random effect was used to analyze the clinical trials. Endpoints included the percentage of pts requiring transfusions (from week 1 to end of the treatment period [EOTP] and from week 5 to EOTP), reaching a target Hb of ≥ 11 g/dL, and achieving ≥ 3 point change in FACT-F score from baseline (BL). Percentages were adjusted for BL Hb levels (< 10 vs ≥ 10 g/dL), whether pts received platinum chemotherapy (no vs yes), and for dosage adjustments. Results: The type of ESA used (EA or DA) did not appear to affect the percentage of study pts who achieved clinically meaningful endpoints (see Table ). The results from these analyses also suggest that the dosing interval at which DA was administered did not affect its efficacy in study pts (see Table ). Conclusions: DA administered at dosing intervals of QW, Q2W, or Q3W has comparable efficacy to EA QW. This flexibility allows DA administration to be synchronized with common chemotherapy schedules, which may increase pt convenience by reducing the number of clinic visits.

[Table: see text]

[Table: see text]

Phase II trial of nanoparticle albumin-bound paclitaxel (ABX) + capecitabine (XEL) in first line treatment of metastatic breast cancer (MBC)

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Background: ABX and XEL both have substantial single agent activity in MBC. Taxane and anti-metabolic doublets improve response rate and TTP compared to singlet therapy. ABX given weekly has excellent safety and efficacy profile with maintenance of dose intensity. We designed this study to test the safety and efficacy of ABX + XEL given in a novel combination schedule. Methods: This phase II, multicenter open label study utilized ABX 125 mg/m2 IV on day 1, 8 and with no premeds and Xeloda 825 mg/m2 PO days 1–14 every three weeks. Entry criteria include measurable MBC by RECIST, no prior chemo for metastatic disease, > 6 months since adjuvant fluoropyrimidine and paclitaxel. A total of 50 patients (pts) are scheduled to be enrolled. Primary endpoint is objective response rate. Results: To date, 14 patients have entered on study. Safety analysis prespecified by the protocol is completed in the 1st six patients. No unique, unexpected or grade 4 toxicities have occurred. Two patients have grade 3 hand-foot syndrome, one had grade 3 neutropenia and one had grade 3 fatigue. Enrollment is continuing without change in dose/schedule. Response data is available in the first two cycles of therapy in 8 patients. At this point, two pts have achieved PR, four have stable disease and two have progressive disease. Conclusions: The combination of weekly ABX plus daily XEL orally at clinically effective doses is safe and shows preliminary evidence of efficacy. Complete enrollment of this trial is expected by May 2006 and updated results will be presented.

[Table: see text]

The utility of PET scanning in the management of squamous cell carcinoma of the anus

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Background: PET scanning is an established modality that is useful in the clinical management of squamous cell carcinoma (SCC) of the head and neck and esophagus. This study evaluates the usefulness of PET scans in the management of anal SCC. Methods: Prospective case series of all patients treated for SCC of the anus between 2002 and 2006 in a multi-disciplinary oncology practice group. All patients had staging studies at diagnosis of anal SCC that included CT scan of the chest/abdomen/pelvis and PET scan. All patients with palpable inguinal adenopathy or PET scans positive for inguinal adenopathy underwent fine needle aspiration (FNA) of inguinal nodes. All patients were evaluated by physical exam (PE) and biopsy (Bx), when appropriate, within 3 months of completing treatment. All patients who completed combined chemoradiation for anal SCC and had a post-treatment PET scan were included in this study. Results: 14 of 20 treated patients met criteria for this study. Sensitivity of pre-treatment PET scan was 100% for primary tumor. Extra-pelvic sites with PET SUV<4.0 were uniformly negative for tumor. 66% of inguinal nodes identified by PET scan were FNA positive for metastatic disease. Post-treatment, combined PE and Bx accurately predicted presence or absence of disease in 93%. Post-treatment scans were obtained a mean of 7.6 months after chemoradiation (range 1 to 42 months). In these patients, PET scan sensitivity = 50%, specificity = 72%, predictive value positive (PVP) = 50%, predictive value negative = 80%. 64% of scans were performed within 6 months of treatment; in these, PVP = 33% and PVN = 66%. Conclusions: PET scanning for anal SCC provides accurate staging of disease at presentation and may alter treatment planning by identifying inguinal node involvement not apparent on clinical examination. In this series, PET scan results did not change post-chemoradiation management in any case. Importantly, resolution of primary tumor defined by PET scan was accurate only 80% of the time. PE and Bx within 3 months of treatment were more accurate than PET scan in assessing disease. Post-treatment evaluation of anal SCC should continue to include careful PE, CT scan and Bx when appropriate.

No significant financial relationships to disclose.

Cooperative partnerships or conflict-of-interest? A national survey of interaction between the pharmaceutical industry and medical organizations

BACKGROUND

There is extensive and varied interaction between the pharmaceutical industry and the medical profession. Most empirical research concerns contact between individual physicians and industry, and reflects North American experience. We sought to clarify the extent and nature of relationships between the pharmaceutical industry and Australian medical organizations.

METHODS

We administered questionnaires to 63 medical organizations concerned with clinical practice, continuing medical education or professional accreditation, or the political representation of medical professionals.

RESULTS

Survey instruments were received from 29 organizations, giving a response rate of 46%. Seventeen of these organizations (59%) had received support from one or more pharmaceutical company in the past financial year. Support was predominantly for annual conferences, with some support for continuing medical education, research, travel and library purchases. The majority of organizations had an academic journal or newsletter, and 10 (34%) accepted revenue from pharmaceutical advertising. Twenty organizations (72%) had policies or guidelines covering their relationship with industry. Few organizations indicated that they would be unable to continue their activities without pharmaceutical industry support.

CONCLUSION

These data indicate a high level of inter-action between the pharmaceutical industry and medical organizations in Australia. While most organizations have policies for guiding their relationship with industry, it is unclear whether these are effective in preventing conflicts of interest and maintaining public trust.

Minimax statistical models for air pollution time series. Application to ozone time series data measured in Bordeaux

This paper deals with the application of l(infinity) (or minimax) optimization techniques to statistical modelling of high frequency air pollution data. The method was applied to ground-level ozone time-series data measured in Bordeaux over 4 years from 1998 to 2001. The aim of model building was to develop predictive models in order to provide forecasts of the maximal daily ground-level ozone concentration. Experimental results from this case study indicate that such techniques could be more appropriate than the commonly used l2 setting if only good estimation of high levels is of interest. When the free parameters are fitted by means of l(infinity) optimization techniques, the forecasting errors are more evenly distributed amongst the data points, resulting in a better estimation of high values. The paper compares the quality of forecasts produced by both a linear and a nonlinear model, using l2 and l(infinity) parameter optimization.

Durable efficacy of metformin/glibenclamide combination tablets (Glucovance) during 52 weeks of open-label treatment in type 2 diabetic patients with hyperglycaemia despite previous sulphonylurea monotherapy

Oral anti-diabetic combinations that address insulin resistance and beta-cell dysfunction (e.g. metformin and glibenclamide) represent a rational therapeutic option for patients uncontrolled on monotherapy. A 52-week, open-label extension to a double-blind study evaluated metformin-glibenclamide combination tablets (Glucovance) in 477 patients with hyperglycaemia despite sulphonylurea therapy. Reductions in HbA1C were maintained, with a mean reduction of -1.7% after 52 weeks, compared with the baseline value for the double-blind trial. Eighty-five patients receiving 4 x 500 mg/2.5 mg tablets daily displayed a marked improvement in HbA1c following up-titration to a regimen of 2 x 500 mg/2.5 mg + 3 x 500 mg/5 mg tablets. Lipid profiles improved significantly. The combination tablets were well tolerated: 11.1% of patients reported hypoglycaemic symptoms (all either mild or moderate severity). No patient withdrew or required pharmacologic intervention for hypoglycaemia. Metformin-glibenclamide combination tablets are an effective and well-tolerated therapeutic option for intensifying oral anti-diabetic therapy.