[Reducing the use of medication in the elderly; why or why not?]

Many healthcare providers agree that reduction or stopping of medication, so-called deprescribing, would be good in vulnerable people with polypharmacy. However, deprescribing is not yet widely conducted. Physicians and pharmacists experience barriers, such as lack of evidence and guidance to support this process. There is also a tendency to maintain the status quo when there are no acute problems. Patients do want fewer pills but the proposal to stop certain medication can lead to resistance or confusion. The needs and concerns from a patient's perspective are a good starting point for desprescribing. It is important to set new goals and to prioritize together which medication can be stopped. It is not only relevant to react to existing problems but also to act proactively when the potential benefits no longer outweigh the medication burden or risks. Recently, more guidance and tools to support deprescribing became available in the Netherlands.

Manipulating duckweed through genome duplication

Significant inter- and intraspecific genetic variation exists in duckweed, thus the potential for genome plasticity and manipulation is high. Polyploidy is recognised as a major mechanism of adaptation and speciation in plants. We produced several genome-duplicated lines of Landoltia punctata (Spirodela oligorrhiza) from both whole plants and regenerating explants using a colchicine-based cocktail. These lines stably maintained an enlarged frond and root morphology. DNA ploidy levels determined by florescence-activated cell sorting indicated genome duplication. Line A4 was analysed after 75 biomass doublings. Frond area, fresh and dry weights, rhizoid number and length were significantly increased versus wild type, while the growth rate was unchanged. This resulted in accumulation of biomass 17-20% faster in the A4 plants. We sought to determine if specific differences in gene products are found in the genome duplicated lines. Non-targeted ultra performance LC-quadrupole time of flight mass spectrometry was employed to compare some of the lines and the wild type to seek identification of up-regulated metabolites. We putatively identified differential metabolites in Line A65 as caffeoyl hexoses. The combination of directed genome duplication and metabolic profiling might offer a path for producing stable gene expression, leading to altered production of secondary metabolites.

Caputo standard α-family of maps: fractional difference vs. fractional

In this paper, the author compares behaviors of systems which can be described by fractional differential and fractional difference equations using the fractional and fractional difference Caputo standard α-Families of maps as examples. The author shows that properties of fractional difference maps (systems with falling factorial-law memory) are similar to the properties of fractional maps (systems with power-law memory). The similarities (types of attractors, power-law convergence of trajectories, existence of cascade of bifurcations and intermittent cascade of bifurcations type trajectories, and dependence of properties on the memory parameter α) and differences in properties of falling factorial- and power-law memory maps are investigated.

Universal fractional map and cascade of bifurcations type attractors

We modified the way in which the Universal Map is obtained in the regular dynamics to derive the Universal α-Family of Maps depending on a single parameter α>0, which is the order of the fractional derivative in the nonlinear fractional differential equation describing a system experiencing periodic kicks. We consider two particular α-families corresponding to the Standard and Logistic Maps. For fractional α<2 in the area of parameter values of the transition through the period doubling cascade of bifurcations from regular to chaotic motion in regular dynamics corresponding fractional systems demonstrate a new type of attractors--cascade of bifurcations type trajectories.

Regulation of protein metabolism: Coupling of photosynthetic electron transport to in vivo degradation of the rapidly metabolized 32-kilodalton protein of the chloroplast membranes

In Spirodela oligorrhiza, mature chloroplasts copiously synthesize and degrade a 32-kilodalton membrane protein. The rates of synthesis and degradation are controlled by light intensity, the protein being unstable in the light and stable in the dark. Light-driven synthesis, but not degradation, is dependent on ATP. Degradation is blocked by herbicides inhibiting photosystem II electron transport, such as diuron and atrazine. Thus, both anabolism and catabolism of the 32-kilodalton protein are photoregulated, with degradation coupled to electron transport rather than phosphorylation.

Efficient induction and selection of chloroplast-encoded antibiotic-resistant mutants in Nicotiana

A high rate of plastome-encoded mutations was induced in Nicotiana by exposing seeds to N-nitroso-N-methylurea. Seeds then were subjected to nutritional and in vitro selection procedures for systematic isolation of plastome-dependent antibiotic-resistant plants. Multiple flowering lines resistant to streptomycin, spectinomycin, lincomycin, or chloramphenicol were obtained. A detailed analysis of the streptomycin-resistant lines is presented. Sexual hybridization, cybrid formation following protoplast fusion, and in organello protein synthesis were used to rigorously assign the mutations to the chloroplast genome. The efficient rates of mutagenesis combined with the in vitro mass-screening procedures described here should facilitate investigation of fundamental aspects of chloroplast genetics in higher plants.

Satellite-rich DNA in cucumber: hormonal enhancement of synthesis and subcellular identification

Cucumber hypocotyl DNA in neutral CsCl distributes into a mainband comprising 59% of the total, and two large satellite bands which contribute 41% to the DNA pattern. Organelle enrichment studies show that the densities of mitochondrial and chloroplast DNA coincide with those of the satellite bands. At least 12-19% of total cucumber DNA is associated with the cytoplasmic organelles. These values, which are several times larger than those usually quoted for higher plants, are correlated with an unusually low amount of DNA per haploid nucleus in cucumber. Synthesis of the satellite DNAs, as well as mainband DNA, is appreciably stimulated in vivo by application of the plant hormone, gibberellin. Endogenous and hormone-enhanced synthesis of the satellite DNAs is proportionately greater in target tissue showing a high rate of organelle synthetic activity.

Fractional dissipative standard map

Using kicked differential equations of motion with derivatives of noninteger orders, we obtain generalizations of the dissipative standard map. The main property of these generalized maps, which are called fractional maps, is long-term memory. The memory effect in the fractional maps means that their present state of evolution depends on all past states with special forms of weights. Already a small deviation of the order of derivative from the integer value corresponding to the regular dissipative standard map (small memory effects) leads to the qualitatively new behavior of the corresponding attractors. The fractional dissipative standard maps are used to demonstrate a new type of fractional attractors in the wide range of the fractional orders of derivatives.

Superdiffusion in the dissipative standard map

We consider transport properties of the chaotic (strange) attractor along unfolded trajectories of the dissipative standard map. It is shown that the diffusion process is normal except for the cases when a control parameter is close to some special values that correspond to the ballistic mode dynamics. Diffusion near the related crises is anomalous and nonuniform in time; there are large time intervals during which the transport is normal or ballistic, or even superballistic. The anomalous superdiffusion seems to be caused by stickiness of trajectories to a nonchaotic and nowhere dense invariant Cantor set that plays a similar role as cantori in Hamiltonian chaos. We provide a numerical example of such a sticky set. Distribution function on the sticky set almost coincides with the distribution function (SRB measure) of the chaotic attractor.

Problem of transport in billiards with infinite horizon

We consider particles transport in the Sinai billiard with infinite horizon. The simulation shows that the transport is superdiffusive in both continuous and discrete time. Also, it is shown that the moments do not converge to the Gaussian moments even in the logarithmically renormalized time scale, at least for a fairly long computational time. These results are discussed with respect to the existent rigorous theorems. Similar results are obtained for the stadium billiard.

Dynamics of the chain of forced oscillators with long-range interaction: from synchronization to chaos

We consider a chain of nonlinear oscillators with long-range interaction of the type 1l(1+alpha), where l is a distance between oscillators and 0<alpha<2. In the continuous limit, the system's dynamics is described by a fractional generalization of the Ginzburg-Landau equation with complex coefficients. Such a system has a new parameter alpha that is responsible for the complexity of the medium and that strongly influences possible regimes of the dynamics, especially near alpha=2 and alpha=1. We study different spatiotemporal patterns of the dynamics depending on alpha and show transitions from synchronization of the motion to broad-spectrum oscillations and to chaos.

Pemetrexed plus cetuximab in patients (pts) with recurrent non-small cell lung cancer (NSCLC): A phase I-IIa dose-ranging study from the Hoosier Oncology Group

7698

Background: Both pemetrexed (P) and cetuximab (C) have single agent activity in NSCLC, non-overlapping toxicities and different mechanisms of action, making the combination of P and C an attractive option to evaluate. This study evaluates the feasibility of combining these agents, and tests the activity and toxicity of this regimen in pts with recurrent NSCLC. Methods: Eligible pts had stage IIIB/IV NSCLC, previously treated ≥ 1 prior platinum containing regimen, PS 0–1. Prior use of EGFR tyrosine kinase inhibitors was permitted. The phase I portion determined the MTD (Bedano Proc ASCO et al., 2006). The primary endpoint of the phase II portion was to estimate TTP using Kaplan-Meier analysis (5% alpha, 80% beta), requiring 25 pts to demonstrate a TTP of ≥ 24 weeks vs. historical control of 12 weeks. Following a loading dose of C at 400 mg/m2 on week 1, pts received P at 750 mg/m2 iv q3wks and C at 250 mg/m2 iv weekly. Cycles were repeated every 21 days. After completing at least 4 cycles, pts with non-progressive disease (PD) were allowed to continue C alone until PD. Results: Eligible and treated phase II pts (n=23) received a median of 4 cycles (range 1–12). Pt characteristics: M:F 57%:43%; median age 64 (range 43–80), stage IIIB: IV 17%:83%; adeno:squamous cell 61%:30%; smoking status: current/former/never: 29%/62%/10%. Prior regimens, median 2 (range 1–6). G3/4/5 toxicities included: 4.3% neutropenia, 13% infection, 4.3% hemorrhage, 22% skin. There were no G3/4 episodes of anemia, TCP, febrile neutropenia, liver toxicity or diarrhea. Response data was available for 18 patients. Partial responses were seen in 2 pts (8.7 %), SD in 8 patients (34.8%). Median TTP was 25 weeks. Conclusion: It is feasible and safe to combine P at 750 mg/m2 every 21 days and C at 400 mg/m2 week 1 and 250 mg/m2 weekly thereafter. This combination resulted in longer TTP when compared with historical controls of P at 500 mg/m2 alone.

No significant financial relationships to disclose.

Elderly subgroup analysis of a randomized phase 3 trial of gemcitabine (G) in combination with carboplatin (Cb) or paclitaxel (P) compared to paclitaxel plus carboplatin in advanced (stage IIIB, IV) non-small cell lung cancer (NSCLC)

7665

Background: Efficacy and safety of platinum-based chemotherapy doublets in elderly (ELD) NSCLC pts with good PS have been reported to be similar to those in younger pts (N-ELD). However, little data exists about which of the standard regimens are suitable for the ELD. To compare efficacy and safety of doublet regimens in the ELD, we conducted a retrospective age-specific subgroup analysis of our Phase 3 randomized trial comparing 3 regimens for advanced NSCLC (Treat, et al: Abst#7025, Proc ASCO 2005). Methods: A Phase 3 study in advanced (Stage IIIB/IV) NSCLC chemonaive patients with ECOG PS <2 was designed to compare the efficacy of a G-containing platinum regimen GCb (G 1000 mg/m2 IV D 1, 8 plus Cb AUC 5.5, D 1) to a nonplatinum G doublet GP (G 1000 mg/m2 IV D 1,8 plus P 200 mg/m2, D 1) and a reference regimen of PCb (P 225 mg/m2 plus Cb AUC 6.0, D 1). Outcome data of ELD pts (age =70) vs. N-ELD pts (age <70) were compared. Survival (OS) was the primary endpoint with secondary endpoints being response rate (RR), time to progression (TTP) and toxicity. Data from all 3 arms were pooled for this analysis. Results: A total of 314 ELD and 746 N- ELD pts were analyzed (GCb 111/245, GP 100/251, PCb 103/250). There were no significant differences in the OS or TTP distributions in ELD compared to N-ELD pts ( Table 1 ). In general, the incidence and grade of toxicity in ELD vs. N-ELD were comparable. ELD experienced moderately higher incidences of Grade 3–4 constitutional (12.6% vs. 7.1%), neurologic (16.1% vs. 8.9%), and pulmonary (12.3% vs. 7.9%) toxicities compared with N-ELD pts. Conclusion: Use of G-containing doublets as first-line chemotherapy showed similar efficacy to the standard PCb regimen in ELD and N-ELD patients with advanced/metastatic NSCLC as defined by OS, RR, and TTP. ELD tolerated these regimens well despite experiencing slightly more toxicity than younger patients.

No significant financial relationships to disclose.

[Table: see text]

Subgroup analysis of African American patients from a randomized phase 3 trial of gemcitabine (G) in combination with carboplatin (Cb) or paclitaxel (P) compared to P plus Cb in advanced (stage IIIB, IV) non-small cell lung cancer (NSCLC)

18066

Background: A relationship between race and prognosis in patients with NSCLC has been suggested with African Americans (AA) having higher incidence and lower survival rates compared to whites (W) with a similar stage of disease. However, due to under representation of AA in clinical trials there is little data to substantiate this hypothesis. To investigate the possibility of a race effect on the efficacy and safety of standard chemotherapy doublet regimens in AA pts, we conducted a retrospective subgroup analysis of our Phase 3 randomized trial comparing 3 regimens for advanced NSCLC (Treat, et al: Abst#7025, Proc ASCO 2005). Methods: A Phase 3 study in advanced (stage IIIB/IV) NSCLC chemonaive patients with ECOG PS <2 was designed to compare the efficacy of a G-containing platinum regimen GCb (G 1000 mg/m2 IV D 1, 8 plus Cb AUC 5.5, D 1) to a nonplatinum G doublet GP (G 1000 mg/m2 IV D 1,8 plus P 200 mg/m2, D 1) and a reference regimen of PCb (P 225 mg/m2 plus Cb AUC 6.0, D 1). Outcome and toxicity data of AA pts vs. W pts were compared. Survival (OS) was the primary endpoint with secondary endpoints being response rate (RR), time to progression (TTP) and toxicity. Data from all 3 arms were pooled for this analysis. Results: A total of 128 AA and 906 W pts were analyzed. There were no significant differences in the OS or TTP distributions in AA compared to W pts ( Table 1 ). The incidence and grade of hematologic toxicity in AA vs. W pts were comparable. AA demonstrated slightly lower incidences of Grade 3–4 constitutional (5.1% vs. 9.0%), hemorrhage (1.4 % vs. 2.5 %), and metabolic (4.4% vs. 7.0%) toxicities compared with W pts. Conclusions: Use of standard chemotherapy doublets as first-line chemotherapy in AA pts with advanced NSCLC demonstrated similar efficacy and safety compared to W pts treated under similar conditions.

[Table: see text]

No significant financial relationships to disclose.

Toxicity and survival by sex in patients with advanced non-small cell lung carcinoma (NSCLC) on modern Southwest Oncology Group (SWOG) trials

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Background: The older lung cancer clinical trial literature suggests that women have better survival than men, possibly due to sex-related changes in drug metabolism based on estrogen levels. A detailed analysis of this issue has not been conducted in the modern chemotherapy era. Thus, the SWOG Lung Committee analyzed outcomes in recent trials, with the hypotheses that either sex-specific toxicity profiles and/or age (as a surrogate for estrogen level) may explain outcome differences. Methods: A data base of eligible patients with complete toxicity data enrolled on 6 consecutive SWOG phase II or III advanced stage NSCLC trials was formed. Treatment was platin-based, plus either gemcitabine, vinorelbine, or a taxane. Toxicities were categorized by type, number and grade with alpha=0.01 (multiple comparisons). Kaplan-Meier survival estimates and Cox multivariate models were computed (alpha=0.05), plus exploratory age by sex interaction analyses. Results: There were1,324 patients (36% women). No difference by sex was found in either maximum toxicity grade, number of toxicities, or specific toxicity types, except for marginally more severe or worse metabolic (12% vs 9%, p=0.02) and life- threatening or worse neurologic (2% vs 1%, p=0.04) toxicities in women. Median, 1- and 2-year survivals were significantly better for women (11 mos, 46%, 19%) vs men (8 mos, 35%, 13%). After adjustment for prognostic factors, women had 14% reduced risk of death (HR 0.86; 95% CI: 0.75, 0.98; p=0.02). The exploratory age by sex cutpoint analysis found women age 60 or older had better survival (11 vs 8 mos, p=0.006), whereas survival was similar by sex for those under age 60. No other age cutpoint was significant. Conclusions: Women with advanced NSCLC survive longer than men after adjustment for other prognostic factors in the modern chemotherapy era. There was no difference in toxicity profile by sex to explain this finding. The survival benefit for women appeared limited to patients age 60 and older, suggesting that estrogen levels may interact with the efficacy of current chemotherapy prescriptions or other as yet undefined factors. This finding, if validated, could be potentially exploited in designing new therapies.

No significant financial relationships to disclose.

Stochastic web as a generator of three-dimensional quasicrystal symmetry

It is shown that two coupled oscillators perturbed by periodic kicks generate a thin stochastic web in the four-dimensional phase space, which differs from the Arnold web. Under some resonance-type condition the web possesses a quasicrystal-type symmetry. In three-dimensional coordinate space, the web's symmetry corresponds to the icosahedral one and, due to that, the original four-dimensional map can be considered as a dynamical generator of the quasicrystal-type tiling of three-dimensional space.

Chemoradiotherapy (CRT) and gefitinib (G) in stage III non-small cell lung cancer (NSCLC): A CALGB stratified phase II trial

7046

Background: G is a small molecule inhibitor of EGFR with activity in advanced NSCLC and preclinical evidence of being a radiosenitizer. Methods: Patients with stage III NSCLC were assigned to stratum 1 (PS 0–1>5% weight loss and/or PS 2) or stratum 2 (PS 0–1weight loss < 5%). Both strata received induction paclitaxel (P) 200 mg/m2 and carboplatin (C) AUC of 6 IV every three weeks for 2 cycles plus G 250 mg PO/day. G was removed 4/05 from induction therapy as stage IV studies showed no benefit from adding G to P and C. Stratum 1 then received RT 200 cGy for 33 fractions (total dose 6,600 cGy) and G 250 mg PO /day. Stratum 2 received the same RT with concurrent G 250 mg/day, and P 50 mg/m2 plus C AUC of 2 weekly for 7 doses. Maintenance G was started after all toxicities were grade ≤2. Results: Activation was 5/02 and administrative closure 5/04 due to results from SWOG S0023. 64 patients were accrued and 59 (20 stratum 1, 39 stratum 2) were eligible and analyzed: median age 67, male 74%, adeno 30%, squamous 45%, other 25%, IIIA 51%, IIIB 49%. There was no clear increase for acute high-grade infield toxicities compared to CRT alone (reported PASCO 2004). Best response for stratum 1 was PR 29% for induction (RR 29%, 95% CI 10%-56%) and CR 5%, PR 45% full treatment (RR 50%, 95% CI 27%-73%); for stratum 2 PR 13% for induction (RR 13%, 95% CI 3%-34%) and CR 5%, PR 76% full treatment (RR 81%, 95% CI 65%-92%). Stratum 1 “poor risk” median failure free survival (FFS) was 11.5 months (95% CI 5.6–21.2), one year survival 60% (95% CI 33%-79%) and median overall survival (OS) 19.0 months (95% CI 7.2–21.2). Stratum 2 “good risk” median FFS was 9.2 months (95% CI 6.7–12.0), one year survival 47% (95% CI 30%–63%) and median OS was 12.0 months (95% CI 8.5–18.6). EGFR and Ras mutation analysis on tumor biopsies (n = 50) will be presented. Conclusions: Small sample size prevented planned data analysis. Survival of “good risk” patients on stratum 2 (CRT + G) was disappointing. The promising survival of the small number of “poor risk” patients on stratum 1 (RT + G) justifies a follow-up phase II trial of induction chemotherapy followed by RT with a concurrent small molecule EGFR inhibitor.

[Table: see text]

Chaotic and pseudochaotic attractors of perturbed fractional oscillator

We consider a nonlinear oscillator of the Duffing type with fractional derivative of the order 1<alpha<2. In this system replacement of the regular derivative by the fractional one leads to decaying solutions. The main feature of the system is that decay is asymptotically the powerwise situation that appears in different applications. Perturbed by a periodic force, the system exhibits chaotic motion called fractional chaotic attractor (FCA). The FCA is compared to the "regular" chaotic attractor that exists in the periodically forced Duffing oscillator. The properties of the FCA are discussed and the "pseudochaotic" case is demonstrated numerically for the case of the "dying attractor." We call "pseudochaos" the case when the randomness exists with zero Lyapunov exponent, i.e., the dispersion of initially close trajectories is subexponential.

Polynomial dispersion of trajectories in sticky dynamics

Hamiltonian chaotic dynamics is, in general, not ergodic and the boundaries of the ergodic or quasiergodic area (stochastic sea, stochastic layers, stochastic webs, etc.) are sticky, i.e., trajectories can spend an arbitrarily long time in the vicinity of the boundaries with a nonexponentially small probability. Segments of trajectories imposed by the stickiness are called flights. The flights have polynomial dispersion that can lead to non-Gaussian statistics of displacements and to anomalous transport in phase space. In particular, the presence of flights influences the distribution of Poincaré recurrences. We use the distribution function of (l,t;epsilon, epsilon0) -separation of trajectories that at time instant t and trajectory length l are separated for the first time by epsilon<<1, being initially at a distance epsilon0 <<epsilon. The connection of this function, called the complexity function [Afraimovich and Zaslavsky, Chaos 13, 519 (2003)], with the distribution of Poincaré recurrences is established for three cases: (i) for the case of superdiffusion in standard and web maps for which the stickiness is defined by the boundaries of hierarchical sets of islands; (ii) for the case of the Sinai billiard with infinite horizon, where the stickiness is defined by zero-measure slits in the phase space; (iii) for the square billiard with a slit (bar-in-square billiard) where the Lyapunov exponent is zero and the stickiness is defined by the vicinity of the trajectory to the closest periodic trajectories obtained from the Diophantine approximation. Finally, the powerwise asymptotics of the Poincaré recurrences can be connected, in some cases, to the anomalous transport exponent.

Topological instability along invariant surfaces and pseudochaotic transport

The paper describes the complex topological structure of invariant surfaces that appears in a quasi-stationary regime of the tokamak plasma, and it considers in detail anomalous transport of particles along the invariant surfaces (isosurfaces) that have topological genus greater than 1. Such dynamics is pseudochaotic; i.e. it has a zero Lyapunov exponent. Simulations discover such surfaces in confined plasmas under a fairly low ratio of pressure to the magnetic field energy (beta). The isosurfaces correspond to quasi-coherent structures called "streamers" and the streamers are connected by filaments. We study distribution of time of particle separation, Poincaré; recurrences of trajectories, and first time arrival to the system's edge. A model of a multibar-in-square billiard, introduced by Carreras et al. [Chaos 13, 1175 (2003)] is studied with renormalization group method to obtain a distribution of the first time of particles arrival to the edge as a function of the number of bars, which appears to be power-like. The characteristic exponent of this distribution is discussed with respect to its dependence on the number of filaments that connect adjacent streamers.

Chaos-induced intensification of wave scattering

Sound-wave propagation in a strongly idealized model of the deep-water acoustic waveguide with a periodic range dependence is considered. It is investigated how the phenomenon of ray and wave chaos affects the sound scattering at a strong mesoscale inhomogeneity of the refractive index caused by the synoptic eddy. Methods derived in the theory of dynamical and quantum chaos are applied. When studying the properties of wave chaos we decompose the wave field into a sum of Floquet modes analogous to quantum states with fixed quasi-energies. It is demonstrated numerically that the "stable islands" from the phase portrait of the ray system reveal themselves in the coarse-grained Wigner functions of individual Floquet modes. A perturbation theory has been derived which gives an insight into the role of the mode-medium resonance in the formation of Floquet modes. It is shown that the presence of a weak internal-wave-induced perturbation giving rise to ray and wave chaos strongly increases the sensitivity of the monochromatic wave field to an appearance of the eddy. To investigate the sensitivity of the transient wave field we have considered variations of the ray travel times--arrival times of sound pulses coming to the receiver through individual ray paths--caused by the eddy. It turns out that even under conditions of ray chaos these variations are relatively predictable. This result suggests that the influence of chaotic-ray motion may be partially suppressed by using pulse signals. However, the relative predictability of travel time variations caused by a large-scale inhomogeneity is not a general property of the ray chaos. This statement is illustrated numerically by considering an inhomogeneity in the form of a perfectly reflecting bar.

Callus induction and regeneration in Spirodela and Lemna

The development of tissue culture systems in duckweeds has, to date, been limited to species of the genus Lemna. We report here the establishment of an efficient tissue culture cycle (callus induction, callus growth and plant regeneration) for Spirodela oligorrhiza Hegelm SP, Spirodela punctata 8717 and Lemna gibba var. Hurfeish. Significant differences were found among the three duckweed species pertaining to carbohydrate and phytohormone requirements for callus induction, callus growth and frond regeneration. In vitro incubation with poorly assimilated carbohydrates such as galactose ( S. oligorrhiza SP and L. gibba var. Hurfeish) and sorbitol ( S. punctata 8717) as sole carbon source yielded high levels of callus induction on phytohormone-supplemented medium. Sorbitol is required for optimal callus growth of S. oligorrhiza SP and S. punctata 8717, while sucrose is required for callus growth of L. gibba var. Hurfeish. Sucrose either alone ( S. oligorrhiza SP, L. gibba var. Hurfeish) or in addition to sorbitol ( S. punctata 8717) is required for frond regeneration.

Topological instability along filamented invariant surfaces

In dynamical systems with a zero Lyapunov exponent, weak mixing can be governed by a specific topological structure of some surfaces that are invariant with respect to particle dynamics. In particular, when the genus of the invariant surfaces is more than one, they may have weak mixing and the corresponding fractional kinetics. This possibility is demonstrated by using a typical example from plasma physics, a three-dimensional resistive pressure-gradient-driven turbulence model. In a toroidal geometry and with a low-pressure gradient, this model shows the emergence of quasicoherent structures. In this situation, the isosurfaces of the velocity stream function have a web structure with filamentary surfaces emerging from the outer region of the torus and covering the inner region. The filamentary surfaces can result in stochastic jets of particles that cause a "topological instability." In such a situation, particle transport along the surfaces is of the anomalous superdiffusion type.

ZD0473 treatment in lung cancer: an overview of the clinical trial results

Three open-label, non-comparative, multicentre Phase II trials have examined the efficacy and tolerability of ZD0473 as first-and second-line therapy in non-small-cell lung cancer (NSCLC) patients and second-line therapy in small-cell lung cancer (SCLC) patients. Patients with second-line NSCLC or SCLC were evaluated as either platinum-sensitive or -resistant, based upon their time to relapse/progression after platinum-based therapy. First-line NSCLC patients (n = 18) received a total of 60 treatment cycles (median number per patient 2.5) whilst second-line NSCLC (n = 50) and SCLC (n = 48) patients both received a total of 127 treatment cycles (median number per patient 2.0). Grade 3/4 anaemia, neutropenia and thrombocytopenia was observed in: 38.8%, 22.2% and 27.7% of first-line NSCLC patients; 12.0%, 24.0% and 50% of second-line NSCLC patients; and 10.4%, 25.0% and 47.9% of second-line SCLC patients, respectively. The most common grade 3/4 non-haematological toxicities in all three trials were lethargy and dyspnoea. No clinically significant oto-, nephro- or neurotoxicity was observed. The first-line treatment of NSCLC produced an overall response rate (OR) of 6.3%. No OR was seen after second-line treatment of NSCLC, while ORs of 15.4% and 8.3% were seen in the platinum-resistant and -sensitive second-line SCLC patients, respectively.

Chaos and flights in the atom-photon interaction in cavity QED

We study dynamics of the atom-photon interaction in cavity quantum electrodynamics, considering a cold two-level atom in a single-mode high-finesse standing-wave cavity as a nonlinear Hamiltonian system with three coupled degrees of freedom: translational, internal atomic, and the field. The system proves to have different types of motion including Lévy flights and chaotic walkings of an atom in a cavity. The corresponding equations of motion for expectation values of the atom and field variables have two characteristic time scales: fast Rabi oscillations of the internal atomic and field quantities and slow translational oscillations of the center of the atom mass. It is shown that the translational motion, related to the atom recoils, is governed by an equation of a parametric nonlinear pendulum with a frequency modulated by the Rabi oscillations. This type of dynamics is chaotic with some width of the stochastic layer that is estimated analytically. The width is fairly small for realistic values of the control parameters, the normalized detuning delta and atomic recoil frequency alpha. We consider the Poincaré sections of the dynamics, compute the Lyapunov exponents, and find a range of the detuning, |delta| less, similar 3, where chaos is prominent. It is demonstrated how the atom-photon dynamics with a given value of alpha depends on the values of delta and initial conditions. Two types of Lévy flights, one corresponding to the ballistic motion of the atom and the other corresponding to small oscillations in a potential well, are found. These flights influence statistical properties of the atom-photon interaction such as distribution of Poincaré recurrences and moments of the atom position x. The simulation shows different regimes of motion, from slightly abnormal diffusion with <x(2)> approximately tau(1.13) at delta=1.2 to a superdiffusion with <x(2)> approximately tau(2.2) at delta=1.92 that corresponds to a superballistic motion of the atom with an acceleration. The obtained results can be used to find new ways to manipulate atoms, to cool and trap them by adjusting the detuning delta.

Quantification of protein surfaces, volumes and atom-atom contacts using a constrained Voronoi procedure

MOTIVATION

Geometric representations of proteins and ligands, including atom volumes, atom-atom contacts and solvent accessible surfaces, can be used to characterize interactions between and within proteins, ligands and solvent. Voronoi algorithms permit quantification of these properties by dividing structures into cells with a one-to-one correspondence with constituent atoms. As there is no generally accepted measure of atom-atom contacts, a continuous analytical representation of inter-atomic contacts will be useful. Improved geometric algorithms will also be helpful in increasing the speed and accuracy of iterative modeling algorithms.

RESULTS

We present computational methods based on the Voronoi procedure that provide rapid and exact solutions to solvent accessible surfaces, volumes, and atom contacts within macromolecules. Furthermore, we define a measure of atom-atom contact that is consistent with the calculation of solvent accessible surfaces, allowing the integration of solvent accessibility and inter-atomic contacts into a continuous measure. The speed and accuracy of the algorithm is compared to existing methods for calculating solvent accessible surfaces and volumes. The presented algorithm has a reduced execution time and greater accuracy compared to numerical and approximate analytical surface calculation algorithms, and a reduced execution time and similar accuracy to existing Voronoi procedures for calculating atomic surfaces and volumes.