Suppression of crosstalk in multielectrode arrays with local shielding

Electrical crosstalk can constrain the performance of multielectrode arrays in electro- and neurophysiology, in terms of both stimulation and recording. This is especially so at high electrode density, desirable for spatiotemporal mapping of bioelectrical signals from multiple cells. Channel interference due to crosstalk is currently only partially addressed, via continuous interleaved sampling or post-data acquisition spike sorting. Here, we show that a locally-shielded electrode architecture significantly suppresses crosstalk, and enables multi-site recording at high electrode density without the need for spike sorting. Arrays of shielded electrodes, prepared by micro- and nanofabrication techniques in a vertically-oriented coaxial geometry, demonstrate at least a 400 times improvement in spatial density over the unshielded case.

Towards spectrally selective catastrophic response

We study the large-amplitude response of classical molecules to electromagnetic radiation, showing the universality of the transition from linear to nonlinear response and breakup at sufficiently large amplitudes. We demonstrate that a range of models, from the simple harmonic oscillator to the successful Peyrard-Bishop-Dauxois type models of DNA, which include realistic effects of the environment (including damping and dephasing due to thermal fluctuations), lead to characteristic universal behavior: formation of domains of dissociation in driving force amplitude-frequency space, characterized by the presence of local boundary minima. We demonstrate that by simply following the progression of the resonance maxima in this space, while gradually increasing intensity of the radiation, one must necessarily arrive at one of these minima, i.e., a point where the ultrahigh spectral selectivity is retained. We show that this universal property, applicable to other oscillatory systems, is a consequence of the fact that these models belong to the fold catastrophe universality class of Thom's catastrophe theory. This in turn implies that for most biostructures, including DNA, high spectral sensitivity near the onset of the denaturation processes can be expected. Such spectrally selective molecular denaturation could find important applications in biology and medicine.

Variability in sleep disturbance, physical activity and quality of life by level of depressive symptoms in women with Type 2 diabetes

AIMS

To examine (1) the prevalence of depressive symptoms in women with Type 2 diabetes, (2) the associations between depressive symptoms and the following dependent variables: sleep disturbance; physical activity; physical health-related; and global quality of life, and (3) the potential moderating effects of antidepressants and optimism on the relationship between depressive symptoms and dependent variables.

METHODS

Participants in the Women's Health Initiative who had Type 2 diabetes and data on depressive symptoms (N=8895) were included in the analyses. In multivariable linear regression models controlling for sociodemographic, medical and psychosocial covariates, we examined the main effect of depressive symptoms, as well as the interactions between depressive symptoms and antidepressant use, and between depressive symptoms and optimism, on sleep disturbance, physical activity, physical health-related quality of life; and global quality of life.

RESULTS

In all, 16% of women with Type 2 diabetes reported elevated depressive symptoms. In multivariable analyses, women with depressive symptoms had greater sleep disturbance (P<0.0001) and lower global quality of life (P<.0001). We found evidence of significant statistical interaction in the models for quality-of-life outcomes: the increased risk of poor physical health-related quality of life associated with antidepressant use was stronger in women without vs with depressive symptoms, and the association between greater optimism and higher global quality of life was stronger in women with vs without depressive symptoms.

CONCLUSIONS

To improve health behaviours and quality of life in women with Type 2 diabetes, sociodemographic and medical characteristics may identify at-risk populations, while psychosocial factors including depression and optimism may be important targets for non-pharmacological intervention.

Abstract P1-15-05: Is absolute lymphocyte count associated with platinum-sensitivity? A phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in triple negative breast cancer

Background: Platinum-based chemotherapy is still considered investigational for the treatment of sporadic triple negative breast cancer (TNBC). Since patients with TNBC have a high rate of chemotherapy resistance, it is critical to identify platinum-sensitive individuals prior to initiating therapy. Higher absolute lymphocyte count (ALC) is associated with improved clinical response to anthracycline-based chemotherapy, the current standard of care in TNBC. We report the initial results of a phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in TNBC. We also report results of an exploratory analysis assessing whether ALC can be used to predict pathologic complete response (pCR) after treatment with platinum-based chemotherapy.

Patients and Methods: 78 patients with clinical stage II or III TNBC have been enrolled in this ongoing study evaluating the efficacy of neoadjuvant carboplatin and docetaxel (NCT201404107). Patients received docetaxel 75 mg/m2 and carboplatin AUC 6 every three weeks for a total of 6 cycles. Blood samples were collected prior to each cycle, and a posttreatment sample was collected &gt; 3 weeks after completing cycle 6. pCR was defined as no residual invasive disease in the breast, with or without ductal carcinoma in situ, and no tumor deposits in sampled lymph nodes. Baseline characteristics of patients were summarized with descriptive statistics. Univariate and multivariate logistic regression analyses were used to identify factors associated with pCR.

Results: Out of the 78 enrolled patients, 60 have completed all 6 treatment cycles and surgery. The preliminary pCR rate is 46.7%. Age, race, clinical stage, and tumor grade determined at time of diagnosis were not significantly different between pCR patients and non-pCR patients. In univariate analyses, patients with higher ALCs at the posttreatment time point were more likely to have pCR than those who had lower ALCs (OR 5.5, 95% CI 1.5-20.7, p=0.011). Additionally, patients who had higher minimum ALCs were also more likely to have pCR (OR 9.1, 95% CI 1.5-54.9, p=0.016). Baseline ALC values were not associated with pCR. The associations of posttreatment and minimum ALCs to pCR remained statistically significant even after controlling for age and clinical stage at time of diagnosis (posttreatment ALC OR 7.6, 95% CI 1.7-34.8, p=0.009; minimum ALC OR 9.0, 95% CI 1.5-55.2, p=0.018).

Conclusion: The pCR rate of our cohort is similar to that of other trials evaluating neoadjuvant platinum-based chemotherapy in TNBC. Baseline ALC did not predict which patients would achieve pCR. However, the associations of posttreatment and minimum ALCs with pCR indicate patients who are able to maintain a robust population of circulating lymphocytes throughout treatment with platinum-based chemotherapy are more likely to respond favorably. The link between patient immunity and platinum-based chemotherapy suggests addition of immunotherapy agents to neoadjuvant chemotherapy may improve patient outcomes.

Citation Format: Chen I, Guo F, Summa T, Luo J, Ellis MJ, Ma CX, Weilbaecher KN, Naughton MJ, Suresh R, Peterson LL, Cherian MA, Bose R, Frith AE, Hernandez-Aya LF, Gillanders WE, Ademuyiwa FO. Is absolute lymphocyte count associated with platinum-sensitivity? A phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-05.

Abstract P2-09-09: The effects of treatment-induced symptoms, depression and age on sexuality in premenopausal women with early breast cancer receiving adjuvant endocrine therapy

Background: In premenopausal women with breast cancer any treatment that causes abrupt, premature ovarian failure increases the risk of sexual problems. Randomized-controlled trials in this population reported a worsening in sexual functioning over time irrespective of adjuvant endocrine treatment. We investigated key symptoms related to endocrine therapy, depression and age as predictors of sexual problems in premenopausal women with early breast cancer treated in the IBCSG TEXT/SOFT trials over the first two years of endocrine therapy.

Methods: A subset of patients (pts) enrolled by centers with English as primary language to TEXT (1027 of 2672 pts) and SOFT (1260 of 3066 pts) completed a questionnaire consisting of global and symptom-specific quality of life indicators, the CES-Depression (CES-D) and the MOS- Sexual Problems (MOS-SP) measures at baseline, 6, 12 and 24 months. The analysis considered 5 cohorts of pts according to chemotherapy use (yes/no), trial (SOFT/TEXT) and endocrine treatment assignment (tamoxifen alone [T], T or exemestane [E] with ovarian function suppression [OFS]). Mixed modeling was used to test the effect of the following on changes in sexual problems (MOS-SP total score) over two years: changes in treatment-induced symptoms (hot flushes, vaginal dryness, sleep disturbances, bone/joint pain, troubled by weight gain, tiredness, nausea/vomiting) from baseline to 6 months; depression at 6 months; and age at randomization. The model included severity groups of symptoms, depression (all dichotomized by median) and age (&lt; 40 vs ≥40 years), 5 cohorts, time points (6, 12, 24 months), baseline covariates, and interactions of symptoms, timepoints and cohorts.

Results: Overall across cohorts, pts with more severe worsening of vaginal dryness and sleep disturbances at 6 months reported a greater increase in sexual problems at all timepoints (p&lt;.0001). The effect of vaginal dryness on sexual problems was most pronounced in the cohort of pts who received T+OFS or E+OFS without chemotherapy; the effect of sleep disturbances was most pronounced in the cohort with prior chemotherapy and T alone. All other symptoms had a smaller impact on differences in changes of sexual problems. Significant effects were only seen in the short-term and varied according to cohort. Severity of depression at six months did not predict sexual problems at the later timepoints in the overall population. In the cohort that received T+OFS or E+OFS without chemotherapy, pts who had more severe depression scores at 6 months reported significantly worse sexual problems at all timepoints (p&lt;.05). No differences were found for younger vs. older pts with respect to sexual problems at any timepoint.

Conclusion: Among several key symptoms related to endocrine therapy, only vaginal dryness and sleep disturbances significantly predicted sexual problems during the first two years in pts who received adjuvant endocrine therapy with or without chemotherapy. Depression predicted sexual problems only in the cohort of pts who received combined endocrine treatment without chemotherapy. Early identification of vaginal dryness, sleep disturbances and depression is important for timely and tailored interventions.

Citation Format: Ribi K, Luo W, Burstein HJ, Naughton MJ, Chirgwin J, Ansari RH, Walley BA, Salim M, van der Westhuizen A, Abdi E, Francis PA, Budman DR, Kennecke H, Harvey VJ, Giobbie-Hurder A, Fleming GF, Pagani O, Regan MM, Bernhard J. The effects of treatment-induced symptoms, depression and age on sexuality in premenopausal women with early breast cancer receiving adjuvant endocrine therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-09-09.

Abstract P5-08-09: Differential patient stratification by the breast cancer index HoxB13/IL17BR ratio vs recurrence score (RS) plus quantitative ER expression in hormone receptor positive, node negative breast cancer

Background: Second generation genomic biomarkers for patients with early stage breast cancer are based on integration of proliferative and estrogen signaling-related gene expression, which has led to data applicable in the extended (post-5 year) endocrine therapy setting. The Breast Cancer Index (BCI) assay interrogates these two signaling pathways, significantly stratified patients into high (13.4%) or low (3.5%) risk of late (5-10y) distant recurrence in TransATAC , and includes a gene expression signature (HoxB13/IL17BR, H/I) that predicted benefit from extended endocrine therapy in MA.17. The 21-gene assay has recently been investigated in combination with quantitative estrogen receptor (qER) expression, wherein a subset of approximately 20% of patients with a high recurrence score (RS) and qER above 9.1 had a higher prognostic risk for late distant recurrence (12.6%) than those with Low RS (4.7%) or intermediate RS (4.1%) (Wolmark, ASCO 2014). The objective of this study was to compare patient stratification with H/I and RS+qER.

Methods: Consecutive cases submitted for BCI clinical testing from lymph node-negative breast cancer patients with available RS scores and qER &gt;9.1 abstracted from pathology reports (N=115) were analyzed. Cohen's kappa statistic was used to test agreement between H/I and RS+qER for patient stratification.

Results: No statistically significant agreement was observed between H/I stratification and RS+qER prognostic risk stratification with respect to identifying patients for extended endocrine therapy (Cohen's kappa = -0.002, p = 0.51). H/I identified 36 cases (34%) as High likelihood to benefit from extended endocrine therapy compared to 3 cases (3%) classified as by RS+qER as having high risk of late recurrence (Table). Of the 69 cases (66%) classified as RS+qER Low risk, 19 were identified as High likelihood to benefit from extended endocrine therapy by H/I.

Table Low H/I PredictiveHigh H/I PredictiveTotalRS+qER Low Risk50 (48%)19 (18%)69 (66%)RS+qER Inter Risk17 (16%)16 (15%)33 (31%)RS+qER High Risk2 (2%)1 (1%)3 (3%)Total69 (66%)36 (34%) 

Conclusions: This retrospective analysis of clinical cases shows that H/I and RS+qER identify distinct subsets of patients, and highlights that the underlying biology of risk stratification differs from that of endocrine responsiveness. Comparatively, findings indicate that the H/I identifies additional patients that may be considered for extended endocrine therapy.

Citation Format: Naughton MJ, Schroeder BE, Operana TN, Zhang Y, Schnabel CA. Differential patient stratification by the breast cancer index HoxB13/IL17BR ratio vs recurrence score (RS) plus quantitative ER expression in hormone receptor positive, node negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-09.

Hot electron plasmon-protected solar cell

A solar cell based on a hot electron plasmon protection effect is proposed and made plausible by simulations, non-local modeling of the response, and quantum mechanical calculations. In this cell, a thin-film, plasmonic metamaterial structure acts as both an efficient photon absorber in the visible frequency range and a plasmonic resonator in the IR range, the latter of which absorbs and protects against phonon emission the free energy of the hot electrons in an adjacent semiconductor junction. We show that in this structure, electron-plasmon scattering is much more efficient than electron-phonon scattering in cooling-off hot electrons, and the plasmon-stored energy is recoverable as an additional cell voltage. The proposed structure could become a prototype of a new generation of high efficiency solar cells.

Spectroscopic evidence for negative electronic compressibility in a quasi-three-dimensional spin-orbit correlated metal

Negative compressibility is a sign of thermodynamic instability of open or non-equilibrium systems. In quantum materials consisting of multiple mutually coupled subsystems, the compressibility of one subsystem can be negative if it is countered by positive compressibility of the others. Manifestations of this effect have so far been limited to low-dimensional dilute electron systems. Here, we present evidence from angle-resolved photoemission spectroscopy (ARPES) for negative electronic compressibility (NEC) in the quasi-three-dimensional (3D) spin-orbit correlated metal (Sr1-xLax)3Ir2O7. Increased electron filling accompanies an anomalous decrease of the chemical potential, as indicated by the overall movement of the deep valence bands. Such anomaly, suggestive of NEC, is shown to be primarily driven by the lowering in energy of the conduction band as the correlated bandgap reduces. Our finding points to a distinct pathway towards an uncharted territory of NEC featuring bulk correlated metals with unique potential for applications in low-power nanoelectronics and novel metamaterials.

Nanoscope based on nanowaveguides

The far field spatial resolution of conventional optical lenses is of the order of the wavelength of light, due to loss in the far field of evanescent, near electromagnetic field components. We show that subwavelength details can be restored in the far field with an array of divergent nanowaveguides, which map the discretized, subwavelength image of an object into a magnified image observable with a conventional optical microscope. We demonstrate in simulations that metallic nanowires, nanocoaxes, and nanogrooves can be used as such nanowaveguides. Thus, an optical microscope capable of subwavelength resolution - a nanoscope - can be produced, with possible applications in a variety of fields where nanoscale optical imaging is of value.

Phase II trial of temsirolimus in patients with metastatic breast cancer

Preclinical models suggested that activating mutations of the PIK3CA gene are associated with sensitivity to inhibitors of the mammalian target of rapamycin (mTOR). In breast cancers, PIK3CA mutations are associated with estrogen receptor (ER) positivity. We therefore performed an open-label single arm phase II study of the rapamycin analog, temsirolimus, at a dose of 25 mg weekly, in women with pretreated breast cancers that were positive for ER, PR, or HER2. Archived formalin-fixed paraffin embedded tumor was collected for immunohistochemical evaluation of components of the PI3K/Akt/mTOR pathway and PIK3CA mutation analysis. Thirty-one patients were enrolled. There were no major objective responses; however, three patients had stable disease for over 24 weeks. Twenty-three tumor samples were available for mutational analysis. There were five tumors with PIK3CA mutations; no association was found between prolonged stable disease and PIK3CA mutation or any immunohistochemical marker. There was a trend toward improved progression free survival (PFS) for patients with positive nuclear staining for phospho-Akt308. One patient remains on study four and a half years after starting therapy; her tumor did not have a PIK3CA mutation. We conclude that single agent temsirolimus has minimal activity in a population of women with heavily pretreated breast cancer. We found no evidence that either absence of immunohistochemical staining for PTEN or mutations in the hotspot domains of PIK3CA in the primary tumor were associated with clinical benefit.

Enhanced ductile behavior of tensile-elongated individual double-walled and triple-walled carbon nanotubes at high temperatures

We report exceptional ductile behavior in individual double-walled and triple-walled carbon nanotubes at temperatures above 2000 degrees C, with tensile elongation of 190% and diameter reduction of 90%, during in situ tensile-loading experiments conducted inside a high-resolution transmission electron microscope. Concurrent atomic-scale microstructure observations reveal that the superelongation is attributed to a high temperature creep deformation mechanism mediated by atom or vacancy diffusion, dislocation climb, and kink motion at high temperatures. The superelongation in double-walled and triple-walled carbon nanotubes, the creep deformation mechanism, and dislocation climb in carbon nanotubes are reported here for the first time.

Symptom clusters in irradiated brain tumor survivors

8581

Background: Symptom clusters, whereby ≥2 symptoms coexist within patients, occur with cancer and its treatment. Identification and treatment of symptom clusters may improve functional status and health-related quality of life (HRQL). We report the characterization of symptom clusters occurring in irradiated brain tumor survivors. Materials/Methods: 34 adult survivors of primary or metastatic brain tumors following partial or whole brain irradiation ≥6 months prior were enrolled in an open-label Phase II study of donepezil, an acetylcholinesterase inhibitor (Rapp et al and Shaw et al, Neuro-Oncology 6:357 and 358, 2004). Eligibility criteria included life expectancy ≥30 weeks, no imaging evidence of progressive brain disease ≥3 months, stable/decreasing steroid dose, Karnofsky Performance Status (KPS) ≥70, and no brain tumor therapy during the study period. Patients received donepezil 5mg/day for 6 weeks, then 10mg/day for 18 weeks, followed by 6 weeks observation off drug. Symptoms were assessed at baseline, 6, 12, 24, and 30 weeks with the Functional Assessment of Cancer Therapy - Brain (FACT-Br) and Profile of Mood States (POMS). Factor analysis, multidimensional scaling and multivariate cluster analysis were used to characterize symptom clustering. Results: Of 34 patients enrolled, 24 remained on study for 24 weeks and 21 remained for the entire 30 weeks. Utilizing the HRQL data, all three methods of analysis demonstrated 3 distinct symptom clusters: mood, cognition and energy. The factor analysis table below illustrates such findings. Conclusions: Three symptom clusters with symptoms related to mood, cognitive function and energy were identified in this group of irradiated brain tumor survivors. Further research should focus on therapeutic interventions for symptom clusters rather than the traditional emphasis on single-symptom therapy. This study was supported by NCI grant 1 U10 CA81851.

[Table: see text]

No significant financial relationships to disclose.

Quality of life (QOL) companion to CALGB 9840: A phase III study of paclitaxel (P) via weekly 1 hour (hr) versus standard 3 hour infusion every 3 weeks with trastuzumab in the treatment of patients with/without HER-2/neu-overexpressing metastatic breast cancer

674

Background: This study determined if adding trastuzumab (Herceptin, T) to P modified the QOL of HER-2 non-overexpressors and examined QOL differences between patients treated with weekly versus standard P. Methods: Of the 585 patients treated in CALGB 9840, 394 provided QOL data. Eligibility criteria and main trial results were reported, indicating greater efficacy in weekly versus standard P, but no greater efficacy with T in HER-2 negatives (Seidman AD et al., Proc ASCO 2004, Vol. 22, No 14S, abstract 512). HER-2 non-overexpressors were randomized to 1 of 4 groups: 1) P 175 mg/m2 over 3 hrs every 3 wks; 2) P 80 mg/m2 over 1 hr weekly; 3) P 175 mg/m2 over 3 hrs every 3 wks + T 4 mg/kg load, then 2 mg/kg weekly; and 4) P l 80 mg/m2 over 1 hr weekly + T 4 mg/kg load, then 2 mg/kg weekly, all IV. All HER-2 overexpressors received T and were randomized to group 3 or 4. Patients completed QOL interviews prior to randomization, and at 3, 6, and 9 months. Main outcome measures were the EORTC-C30 with the Breast Module (QLQ-BR23). Data were analyzed using general linear models for repeated measures, with the following covariates: treatment arm, assessment point, patient age, race, education, marital status, performance status, prior chemotherapy, and prior radiation therapy. Results: HER-2 negative patients receiving weekly P with/without T as compared to standard P with/without T reported better global QOL (p=.022) and fewer cancer symptoms (p=.036). No QOL differences were observed among the HER-2 overexpressors. The use of T in the HER-2 negatives, regardless of P schedule, resulted in better role (p=.002) and emotional functioning (p=.039), and fewer arm (p=.045) and breast (p=.033) symptoms than HER-2 negative patients not receiving T. No differences in physical, social, and cognitive functioning were observed across any of these treatment groups. Conclusions: Both weekly P and T improved the QOL of HER-2 negative patients. There were no QOL differences by P schedule among the HER-2 overexpressors. The higher QOL in HER-2 negatives receiving T was unexpected, inconsistent with clinical data, and needs further exploration in the dataset.

[Table: see text]

Field-enhanced diamagnetism in the pseudogap state of the cuprate Bi2Sr2CaCu2O(8+delta) superconductor in an intense magnetic field

In hole-doped cuprates, Nernst experiments imply that the superconducting state is destroyed by spontaneous creation of vortices which destroy phase coherence. Using torque magnetometry on Bi2Sr2CaCu2O(8+delta), we uncover a field-enhanced diamagnetic signal M above the transition temperature Tc that increases with applied field to 32 Tesla and scales just like the Nernst signal. The magnetization results above Tc distinguish M from conventional amplitude fluctuations and strongly support the vortex scenario for the loss of phase coherence at Tc.

Coexistence of superconductivity and antiferromagnetism probed by simultaneous nuclear magnetic resonance and electrical transport in (TMTSF)2PF6 system

We report simultaneous NMR and electrical transport experiments in the pressure range near the boundary of the antiferromagnetic spin density wave (SDW) insulator and the metallic/superconducting (SC) phase in (TMTSF)2PF6. Measurements indicate a tricritical point separating a line of second-order SDW/metal transitions from a line of first-order SDW/metal(SC) transitions with coexistence of macroscopic regions of SDW and metal(SC) order, with little mutual interaction but strong hysteretic effects. NMR results quantify the fraction of each phase.

Magic angle effects and angular magnetoresistance oscillations as dimensional crossovers

Interference effects between velocity and density of states, which occur as electrons move along open orbits in the extended Brillouin zone in anisotropic conductors, result in a change of wave functions' dimensionality at magic angle (MA) directions of a magnetic field. In particular, these 1D-->2D dimensional crossovers result in the appearance of sharp minima in a resistivity component rho perpendicular (H,alpha), perpendicular to conducting layers. This explains the main qualitative features of MA and angular magnetoresistance oscillations' phenomena observed due to the existence of quasi-one-dimensional sheets of Fermi surface in (TMTSF)2X, (DMET-TSeF)2X, and kappa-(ET)2Cu(NCS)(2) conductors.

Magnetic determination of H(c2) under accurate alignment in (TMTSF)2ClO4

Cantilever magnetometry has been used to measure the upper critical magnetic field H(c2) of the quasi-one-dimensional molecular organic superconductor (TMTSF)2ClO4. From simultaneous resistivity and torque magnetization experiments conducted under precise field alignment, H(c2) at low temperature is shown to reach 5 T, nearly twice the Pauli paramagnetic limit imposed on spin singlet superconductors. These results constitute the first thermodynamic evidence for a large H(c2) in this system and provide support for spin triplet pairing in this unconventional superconductor.

Interference commensurate oscillations in quasi-one-dimensional conductors

We suggest an analytical theory to describe angular magnetoresistance oscillations recently discovered in the quasi-one-dimensional conductor (TMTSF)2PF6 [see Phys. Rev. B 57, 7423 (1998)]] and define the positions of the oscillation minima. The origin of these oscillations is related to interference effects resulting from Bragg reflections which occur as electrons move along quasiperiodic and periodic ("commensurate") electron trajectories in the extended Brillouin zone. We reproduce via calculations existing experimental data and predict some novel effects.

Intersubband transport in quantum wells in strong magnetic fields mediated by single- and two-electron scattering

We show theoretically that in quantum wells subjected to a strong magnetic field the intersubband current peaks at magnetic field values, which reveal the underlying specific intersubband scattering mechanism. We have designed and grown a superlattice structure in which such current oscillations are clearly visible, and in which the transition from the purely single-electron to the mixed single- and two-electron scattering regimes can be observed by tuning the applied voltage bias. The measurements were conducted in ultrahigh magnetic fields (up to 45 T) to obtain the full spectrum of the current oscillations.

Critical field enhancement near a superconductor-insulator transition

We have discovered a phenomenon where the orbital pair breaking effect is reduced, if not eliminated. It appears as a striking enhancement in the upper critical field H(c2) for (TMTSF)2PF6 and a strong upward curvature in the critical field versus temperature in the region of pressure-temperature phase space near the superconductor-spin density wave insulator boundary. A simple model based on self-consistently dividing the superconductor into layers explains the observations remarkably well and provides a unique way around orbital frustration and toward higher critical fields.

The health-related quality of life and survival of small-cell lung cancer patients: results of a companion study to CALGB 9033

The purposes of this study were 2-fold: to evaluate the impact of the schedule dependency of etoposide (3-day IV short course vs. a 21-day oral prolonged course) with cisplatin on the quality of life of small-cell lung cancer (SCLC) patients; and to examine the effect of baseline quality of life variables on long-term survival, after adjustment for known demographic and clinical prognostic factors. Participants were 70 patients enrolled in the cancer and leukemia group B (CALGB) protocol 9033. Quality of life was assessed at baseline, 6 and 12 weeks by: the EORTC QLQ-30, the Centers for epidemiology studies--Depression short form, the medical outcomes study (MOS) social support questionnaire, and a scale of sleep quality. Contrary to expectations, study results suggested no significant differences in the patients' life quality and treatment response based on whether they received etoposide in a 3-day IV vs. a 21-day oral regimen. The use of the baseline variables in predicting overall survival indicated that patients who were non-white and with liver involvement had decreased survival. Brain involvement, being male, and higher depressive symptoms were also found to be borderline significant in predicting decreased survival in this patient population.

Triplet superconductivity in an organic superconductor probed by NMR Knight shift

The nature of the superconducting state in quasi-one-dimensional organic conductors has remained controversial since its discovery. Here we present results of (77)Se NMR Knight shift (K(s)) experiments in (TMTSF)(2)PF(6) under 7 kbar of pressure with a magnetic field aligned along the most conducting a axis. We find no noticeable shift in K(s) upon cooling through the superconducting transition. Since K(s) directly probes the spin susceptibility chi(s), the fact that chi(s) remains unchanged through the superconducting transition strongly suggests spin-triplet superconductivity.

Promoting adherence and retention to clinical trials in special populations: a women's health initiative workshop

This paper describes a Women's Health Initiative workshop on promoting adherence and retention in randomized clinical trials among ethnic minority women, participants of lower socioeconomic status, and older women. Workshop objectives were: (1) to increase knowledge of demographic and cultural characteristics of diverse groups, (2) to increase awareness of how diversity can affect interactions in clinical research, (3) to explore how research staff behavior can influence adherence and retention, and (4) to increase knowledge of strategies to enhance adherence and retention in special populations. The workshop emphasized the importance of understanding beliefs, values, and experiences that are common in diverse groups of individuals, while at the same time recognizing and respecting individual differences that result from varying life circumstances and experiences. We discuss strategies to increase cultural competence, reduce stereotypes and discrimination, and create a culturally relevant and sensitive research environment.

Involving minority and underrepresented women in clinical trials: the National Centers of Excellence in Women's Health

Recent attention to reducing health disparities among population groups has focused on the need to include in clinical studies, especially clinical trials, participants who represent the diversity of the populations to which study results will be applied. While scientists generally applaud the goal of broadening the characteristics of participants in clinical trials, they are faced with multiple challenges as they seek to include historically underrepresented populations in their research. This article examines the historical and sociocultural context of participation by underrepresented groups, especially women and minorities, in clinical trials, identifies major barriers and challenges facing researchers, and suggests strategies for meeting these challenges. The article draws upon the experiences of the investigators affiliated with the National Centers of Excellence of Women's Health (CoEs).

Bone marrow staging in patients with non-Hodgkin's lymphoma: is flow cytometry a useful test?

BACKGROUND

Flow cytometric analysis of bone marrow often is used as an adjunct to morphologic evaluation in the staging of patients with non-Hodgkin's lymphoma (NHL). The goal of this study was to define objectively the benefit of flow cytometry in this setting.

METHODS

The authors reviewed retrospectively all bone marrow specimens submitted between January 1992 and December 1994 to the Washington University Department of Pathology for flow cytometric immunophenotyping to rule out NHL. Results of morphologic examination and flow cytometry were reviewed independently and the ability to detect bone marrow involvement compared.

RESULTS

Two hundred and seventy-three bone marrow specimens from 190 patients with an established diagnosis of NHL were submitted for flow cytometric analysis at initial presentation, restaging, and/or recurrence. Morphologic evaluation was negative in 69%, positive in 23%, and equivocal in 8%. Flow cytometry was negative in all but 1 morphologically negative bone marrow specimens and 40% of morphologically involved bone marrow specimens. Two of 23 morphologically equivocal bone marrow specimens were positive by flow cytometry. An additional 86 specimens were obtained to rule out NHL in patients without an established diagnosis of NHL. The majority of patients had a history of human immunodeficiency virus infection, cytopenia, or unexplained fevers. Morphologically, one specimen was involved with NHL, 5 were equivocal, and 80 were negative. All specimens were negative by flow cytometry.

CONCLUSIONS

In this study, flow cytometric analysis improved the detection of NHL in bone marrow in only 3 of 273 samples, 2 of which were suspicious morphologically. Flow cytometry of bone marrow aspirates has a limited role in the routine staging and follow-up of patients with an established diagnosis of NHL.

Quality of life in geriatric patients with lower urinary tract dysfunction

Lower urinary tract dysfunctions, such as urinary incontinence, detrusor instability, and benign prostatic hyperplasia, are prevalent in older adults. These conditions, which can occur alone or in combination, result in irritative or obstructive symptoms that can interfere with everyday functioning, leading to negative consequences on health-related quality of life. The nature and severity of these symptoms and the perception of their impact on daily activities can be quite variable. Until recently, relatively little was known about the effect of lower urinary tract dysfunctions on general health status and quality of life. An increasing research base is now available that shows the impact of different urologic dysfunctions in clinical and general populations. This article will provide a brief background on the definition and measurement of health-related quality of life and will summarize the literature about the quality of life of community-dwelling elderly patients with urinary incontinence or prostate conditions. Implications to guide clinical practice and future research will be derived.

Assessment of health-related quality of life in orthopaedic outcomes' studies

The assessment of health-related quality of life is becoming increasingly important in evaluating the effectiveness of orthopaedic interventions. This report provides an overview of issues related to the assessment of quality of life in orthopaedic populations. Discussed are the definition and dimensions of health-related quality of life: the usefulness of collecting quality of life data; methodological considerations in designing outcomes' studies; the selection of quality of life instruments; modes of instrument administration; and scoring.

Laparoscopic ligation of the umbilical cord of an acardiac fetus

We performed umbilical cord ligation using laparoscopic technique in twins with twin reversed arterial perfusion sequence.

DPB1 locus PCR-RFLP typing of the fourth Asia-Oceania Histocompatibility Workshop cell panel reveals a novel DPB1 allele

DPB1 locus typing of the 155 cell 4AOHW panel was performed using a PCR-RFLP method. Ambiguity of allele assignment was resolved by amplification using sequence-specific primers. Of the 150 cells for which typings were achieved, three exhibited unusual restriction enzyme fragment patterns, suggesting the possibility of novel DPB1 alleles. Sequence analysis revealed one allele present in the currently reported 46, one novel allele (4AOHW/107) not present among the 46, and one from a non-human primate which is being investigated. Twenty-six (26) of the 34 10IHW cells have been studied previously by cDNA RFLP, and strong haplotypic associations have been demonstrated between DPA1 and DPB1 locus alleles. It is proposed that exploitation of intron polymorphisms making haplotypes will be an integral part of future DPB1 typing as a "first-pass' stratification process to minimize the requirement for sequence-based methods to definitively assign DPB1 alleles.

A critical review of dimension-specific measures of health-related quality of life in cross-cultural research

This article reviews six dimension-specific health-related quality of life (HRQL) measures which have been used cross-culturally. The instruments reviewed are: the Beck Depression Inventory (BDI); the McGill Pain Questionnaire (MPQ); the Center for Epidemiologic Studies--Depression (CES-D); the Zung Self-Rating Depression Scale (SDS); the General Health Questionnaire (GHQ); and the Psychological General Well-Being Index (PGWB). These instruments primarily represent the psychological or emotional dimension of HRQL, and are scales that were developed and validated in the USA, Canada or the UK. The review of specific studies for each of the six instruments was not meant to be exhaustive, but rather to give an indication of the ways in which the instruments have been assessed or used in various countries. The focus throughout this article is on the psychometric properties (reliability, validity and responsiveness) of these scales in different cultures, as well as the processes used to translate the instruments from English into another language. Implications of the results of this review for cross-cultural use of dimension-specific HRQL instruments are drawn.

Strategy for definition of DR/DQ haplotypes in the 4AOHW cell panel using noncoding sequence polymorphisms

Our previously described intron-based DQA1-typing method provides 11 allelic and suballelic groups, including the eight alleles encoded at the second exon. Concurrent testing for the presence of the DRB3, DRB4, and DRB5 loci and the Rsa I pattern of the DRw52 group simplifies the typing requirements for allele assignment at the highly polymorphic DRB1 locus. The DRB1-allele-shortlisting process relies on known DR/DQ haplotypes. In addition to reducing the testing requirements for definitive DRB1 allele assignment, this strategy allows inference of the DR/DQ haplotype and assists in recognition of novel and/or unusual associations.

HLA-DQA1 allele and suballele typing using noncoding sequence polymorphisms. Application to 4AOHW cell panel typing

HLA-DQA1 typing of the 4AOHW cell panel is presented using a novel strategy that exploits both intron and exon polymorphisms. Intron sequences adjacent to the variable HLA-DQA1 second exon exhibit stable polymorphisms that are specific for locus alleles and certain suballelic DR/DQ haplotypes. A PCR-RFLP method has been developed that is based on amplification of a 780-bp segment extending from intron 1 through exon 2 to intron 2. Stable sequence polymorphisms provide restriction enzyme sites and confer mobility variations detected on polyacrylamide minigel electrophoresis. Direct band comparison of amplified products and restriction fragments with known standards facilitates pattern comparison, obviating the requirement for accurate molecular weight determination. This method, using only two enzymes, identifies a total of 11 allelic and suballelic groups, including all eight DQA1 alleles encoded at the second exon.

Community trends in CPR training and use: the Minnesota Heart Survey

STUDY OBJECTIVE

To examine community changes in self-reported CPR training and use from 1980-82 to 1985-87 using data obtained from the Minnesota Heart Survey. A comparative investigation of CPR training among blacks and whites in 1985-86 also was completed.

DESIGN

Data were obtained in 1980-81, 1981-82, 1985-86, and 1986-87 from four population-based samples drawn from the seven-county Minneapolis-St Paul metropolitan area. To increase sample sizes and to compare prevalences of CPR training and use in the early 1980s with prevalences in the mid-1980s, the four Minnesota Heart Survey surveys were combined into two time periods, 1980-82 and 1985-87. A separate survey of black individuals was conducted in 1985, and these data were used in the comparisons between blacks and whites in 1985-86.

RESULTS

The prevalence of whites trained in CPR increased significantly between 1980-82 and 1985-87 in both nonhealth professionals (18.5% vs 30.9%) and health professionals (71.9% vs 86.8%). No significant change was observed between the two periods in the percentage of nonhealth professionals who had ever used their CPR skills (9.7% vs 10.7%), whereas use among health professionals increased significantly (40.2% vs 53.4%). Training within the prior two or three years decreased from 1980-82 to 1985-87 among nonhealth professionals, but increases in recent training were observed among health professionals. There were no significant differences between black and white nonhealth professionals in the prevalence of CPR training. Black trainees, however, reported a higher percentage of ever using CPR skills than white trainees (15.4% vs 9.8%, respectively). Black trainees also had higher rates of recent CPR training than white trainees. No differences were observed between black and white health professionals regarding CPR training and use, or recency of certification.

CONCLUSION

These results suggest that the percentage of individuals trained in CPR is increasing. Improvement is needed, however, in the rates of recent certification among nonhealth professionals.