Distinct Driver Pathway Enrichments and a High Prevalence of TSC2 Mutations in Right Colon Cancer in Chile: A Preliminary Comparative Analysis

Colorectal cancer (CRC) is the second leading cause of cancer deaths globally. While ethnic differences in driver gene mutations have been documented, the South American population remains understudied at the genomic level, despite facing a rising burden of CRC. We analyzed tumors of 40 Chilean CRC patients (Chp) using next-generation sequencing and compared them to data from mainly Caucasian cohorts (TCGA and MSK-IMPACT). We identified 388 mutations in 96 out of 135 genes, with TP53 (45%), KRAS (30%), PIK3CA (22.5%), ATM (20%), and POLE (20%) being the most frequently mutated. TSC2 mutations were associated with right colon cancer (44.44% in RCRC vs. 6.45% in LCRC, p-value = 0.016), and overall frequency was higher compared to TCGA (p-value = 1.847 × 10-5) and MSK-IMPACT cohorts (p-value = 3.062 × 10-2). Limited sample size restricts definitive conclusions, but our data suggest potential differences in driver mutations for Chilean patients, being that the RTK-RAS oncogenic pathway is less affected and the PI3K pathway is more altered in Chp compared to TCGA (45% vs. 25.56%, respectively). The prevalence of actionable pathways and driver mutations can guide therapeutic choices, but can also impact treatment effectiveness. Thus, these findings warrant further investigation in larger Chilean cohorts to confirm these initial observations. Understanding population-specific driver mutations can guide the development of precision medicine programs for CRC patients.

Increase in ADAR1p110 activates the canonical Wnt signaling pathway associated with aggressive phenotype in triple negative breast cancer cells

Triple-negative breast cancer (TNBC) represents a challenge in the search for new therapeutic targets. TNBCs are aggressive and generate resistance to chemotherapy. Tumors of TNBC patients with poor prognosis present a high level of adenosine deaminase acting on RNA1 (ADAR1). We explore the connection of ADAR1 with the canonical Wnt signaling pathway and the effect of modulation of its expression in TNBC. Expression data from cell line sequencing (DepMap) and TCGA samples were downloaded and analyzed. We lentivirally generated an MDA-MB-231 breast cancer cell line that overexpress (OE) ADAR1p110 or an ADAR knockdown. Abundance of different proteins related to Wnt/β-catenin pathway and activity of nuclear β-catenin were analyzed by Western blot and luciferase TOP/FOP reporter assay, respectively. Cell invasion was analyzed by matrigel assay. In mice, we study the behavior of tumors generated from ADAR1p110 (OE) cells and tumor vascularization immunostaining were analyzed. ADAR1 connects to the canonical Wnt pathway in TNBC. ADAR1p110 overexpression decreased GSK-3β, while increasing active β-catenin. It also increased the activity of nuclear β-catenin and increased its target levels. ADAR1 knockdown has the opposite effect. MDA-MB-231 ADAR1 (OE) cells showed increased capacity of invasion. Subsequently, we observed that tumors derived from ADAR1p110 (OE) cells showed increased invasion towards the epithelium, and increased levels of Survivin and CD-31 expressed in vascular endothelial cells. These results indicate that ADAR1 overexpression alters the expression of some key components of the canonical Wnt pathway, favoring invasion and neovascularization, possibly through activation of the β-catenin, which suggests an unknown role of ADAR1p110 in aggressiveness of TNBC tumors.

ADAR1-mediated RNA-editing of 3'UTRs in breast cancer

Background

Whole transcriptome RNA variant analyses have shown that adenosine deaminases acting on RNA (ADAR) enzymes modify a large proportion of cellular RNAs, contributing to transcriptome diversity and cancer evolution. Despite the advances in the understanding of ADAR function in breast cancer, ADAR RNA editing functional consequences are not fully addressed.

Results

We characterized A to G(I) mRNA editing in 81 breast cell lines, showing increased editing at 3′UTR and exonic regions in breast cancer cells compared to immortalized non-malignant cell lines. In addition, tumors from the BRCA TCGA cohort show a 24% increase in editing over normal breast samples when looking at 571 well-characterized UTRs targeted by ADAR1. Basal-like subtype breast cancer patients with high level of ADAR1 mRNA expression shows a worse clinical outcome and increased editing in their 3′UTRs. Interestingly, editing was particularly increased in the 3′UTRs of ATM, GINS4 and POLH transcripts in tumors, which correlated with their mRNA expression. We confirmed the role of ADAR1 in this regulation using a shRNA in a breast cancer cell line (ZR-75-1).

Conclusions

Altogether, these results revealed a significant association between the mRNA editing in genes related to cancer-relevant pathways and clinical outcomes, suggesting an important role of ADAR1 expression and function in breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s40659-018-0185-4) contains supplementary material, which is available to authorized users.

Two-Particle Interference of Electron Pairs on a Molecular Level

We investigate the photodouble ionization of H_{2} molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasiparticle consisting of both electrons (i.e., the "dielectron") does. The work highlights the fact that nonlocal effects are embedded everywhere in nature where many-particle processes are involved.

Growth hormone signaling in fibroblasts from newborn boys and prepubertal boys

BACKGROUND/AIM

Responsiveness to GH in target cells is mediated by its receptor, which activates the Janus kinase-2 (JAK2) and STAT5 (signal transducers and activators of transcription 5) leading to the expression of IGF-1 and IGFALS. The aim of this study was to compare the GH signaling pathway in newborns and prepubertal boys.

SUBJECTS AND METHODS

We determined the GHR protein content and the effect of stimulation with recombinant human GH (rhGH; 200ng/mL) on JAK2 and STAT5 phosphorylation in skin fibroblast cultures obtained from newborns and prepubertal boys. The transcript levels of IGFALS and IGF-I, were also studied and compared after 16h or 24h of stimulation with GH in both study groups.

RESULTS

Newborn infants showed less GHR protein than the prepubertal boys. After rhGH stimulation, JAK2 and STAT5 phosphorylation was absent in skin fibroblasts from newborns, but was clearly detectable in prepubertal boys. After 16h of treatment with rhGH, IGFALS and IGF-I transcript levels increased in the prepubertal boys when compared to baseline. In newborns, however, we did not observe a response after 16 and 24h of rhGH stimulation.

CONCLUSION

The significant attenuation of the GH signaling pathway observed in fibroblasts from newborn boys appears to be related to a reduction in GHR content and lack of phosphorylation of JAK2 and STAT5 in response to rhGH. This might impair STAT5 dimer formation, leading to a reduction in the transcript levels of IGFALS and IGF-I during the newborn period.

Climate change conditions (elevated CO2 and temperature) and UV-B radiation affect grapevine (Vitis vinifera cv. Tempranillo) leaf carbon assimilation, altering fruit ripening rates

The increase in grape berry ripening rates associated to climate change is a growing concern for wine makers as it rises the alcohol content of the wine. The present work studied the combined effects of elevated CO2, temperature and UV-B radiation on leaf physiology and berry ripening rates. Three doses of UV-B: 0, 5.98, 9.66 kJm(-2)d(-1), and two CO2-temperature regimes: ambient CO2-24/14 °C (day/night) (current situation) and 700 ppm CO2-28/18 °C (climate change) were imposed to grapevine fruit-bearing cuttings from fruit set to maturity under greenhouse-controlled conditions. Photosynthetic performance was always higher under climate change conditions. High levels of UV-B radiation down regulated carbon fixation rates. A transient recovery took place at veraison, through the accumulation of flavonols and the increase of antioxidant enzyme activities. Interacting effects between UV-B and CO2-temperature regimes were observed for the lipid peroxidation, which suggests that UV-B may contribute to palliate the signs of oxidative damage induced under elevated CO2-temperature. Photosynthetic and ripening rates were correlated. Thereby, the hastening effect of climate change conditions on ripening, associated to higher rates of carbon fixation, was attenuated by UV-B radiation.

Characterization of the adaptive response of grapevine (cv. Tempranillo) to UV-B radiation under water deficit conditions

This work aims to characterize the physiological response of grapevine (Vitis vinifera L.) cv. Tempranillo to UV-B radiation under water deficit conditions. Grapevine fruit-bearing cuttings were exposed to three levels of supplemental biologically effective UV-B radiation (0, 5.98 and 9.66kJm(-2)day(-1)) and two water regimes (well watered and water deficit), in a factorial design, from fruit-set to maturity under glasshouse-controlled conditions. UV-B induced a transient decrease in net photosynthesis (Anet), actual and maximum potential efficiency of photosystem II, particularly on well watered plants. Methanol extractable UV-B absorbing compounds (MEUVAC) concentration and superoxide dismutase activity increased with UV-B. Water deficit effected decrease in Anet and stomatal conductance, and did not change non-photochemical quenching and the de-epoxidation state of xanthophylls, dark respiration and photorespiration being alternative ways to dissipate the excess of energy. Little interactive effects between UV-B and drought were detected on photosynthesis performance, where the impact of UV-B was overshadowed by the effects of water deficit. Grape berry ripening was strongly delayed when UV-B and water deficit were applied in combination. In summary, deficit irrigation did not modify the adaptive response of grapevine to UV-B, through the accumulation of MEUVAC. However, combined treatments caused additive effects on berry ripening.

Study of the hidden-order of URu₂Si₂ by point contact tunnel junctions

URu2Si2 presents superconductivity at temperatures below 1.5 K and a hidden order (HO) at about 17.5 K. Both electronic phenomena are influenced by Fano and Kondo resonances. At 17.5 K the HO was related in the past to a Peierls distortion that produces an energy gap deformed by the resonances. This order has been studied for more than 20 years and still there is no clear understanding. In this work we studied the electronic characteristics of URu2Si2 in a single crystal, with tunneling and metallic point contact spectroscopies. In the superconducting state, we determined the energy gap, which shows the influence of the Fano and Kondo resonances. At temperatures where HO is observed, the tunnel junctions spectra show the influence of the two resonances. Tunnel junction characteristics show that the Fermi surface nesting depends on the crystallographic direction.

Chemical pressure in SmNiC(2-x)B(x) compounds: evidence of a quantum critical behavior

We studied the effect of carbon substituted by boron on polycrystalline samples of SmNiC(2) in the B content range 0 ⩽ x ⩽ 0.200. The structural parameters were determined from x-ray measurements by Rietveld analysis. The structural analysis shows that the cell volume increases as the B content increases indicating that the substitution produces an internal pressure. The samples were studied by resistance as a function of temperature from room temperature down to 2 K. The transition temperature of the charge density wave, TCDW = 148 K, decreases with an increment of B until the transition vanishes in the resistance measurements. At the same time, the ferromagnetic transition temperature changes showing a tiny dome with the B content, with a maximum transition temperature of ∼ 23.1 K. In addition, the resistance behaviour above the charge density wave is linear in temperature and this behaviour persists until the charge density wave disappears, suggesting that the system is a non-Fermi liquid. The resulting temperature--boron content phase--diagram indicates a quantum critical behaviour.

Growth, photosynthetic acclimation and yield quality in legumes under climate change simulations: an updated survey

Continued emissions of CO2, derived from human activities, increase atmospheric CO2 concentration. The CO2 rise stimulates plant growth and affects yield quality. Effects of elevated CO2 on legume quality depend on interactions with N2-fixing bacteria and mycorrhizal fungi. Growth at elevated CO2 increases photosynthesis under short-term exposures in C3 species. Under long-term exposures, however, plants generally acclimate to elevated CO2 decreasing their photosynthetic capacity. An updated survey of the literature indicates that a key factor, perhaps the most important, that characteristically influences this phenomenon, its occurrence and extent, is the plant source-sink balance. In legumes, the ability of exchanging C for N at nodule level with the N2-fixing symbionts creates an extra C sink that avoids the occurrence of photosynthetic acclimation. Arbuscular mycorrhizal fungi colonizing roots may also result in increased C sink, preventing photosynthetic acclimation. Defoliation (Anthyllis vulneraria, simulated grazing) or shoot cutting (alfalfa, usual management as forage) largely increases root/shoot ratio. During re-growth at elevated CO2, new shoots growth and nodule respiration function as strong C sinks that counteracts photosynthetic acclimation. In the presence of some limiting factor, the legumes response to elevated CO2 is weakened showing photosynthetic acclimation. This survey has identified limiting factors that include an insufficient N supply from bacterial strains, nutrient-poor soils, low P supply, excess temperature affecting photosynthesis and/or nodule activity, a genetically determined low nodulation capacity, an inability of species or varieties to increase growth (and therefore C sink) at elevated CO2 and a plant phenological state or season when plant growth is stopped.

Methodological advances: using greenhouses to simulate climate change scenarios

Human activities are increasing atmospheric CO2 concentration and temperature. Related to this global warming, periods of low water availability are also expected to increase. Thus, CO2 concentration, temperature and water availability are three of the main factors related to climate change that potentially may influence crops and ecosystems. In this report, we describe the use of growth chamber - greenhouses (GCG) and temperature gradient greenhouses (TGG) to simulate climate change scenarios and to investigate possible plant responses. In the GCG, CO2 concentration, temperature and water availability are set to act simultaneously, enabling comparison of a current situation with a future one. Other characteristics of the GCG are a relative large space of work, fine control of the relative humidity, plant fertirrigation and the possibility of light supplementation, within the photosynthetic active radiation (PAR) region and/or with ultraviolet-B (UV-B) light. In the TGG, the three above-mentioned factors can act independently or in interaction, enabling more mechanistic studies aimed to elucidate the limiting factor(s) responsible for a given plant response. Examples of experiments, including some aimed to study photosynthetic acclimation, a phenomenon that leads to decreased photosynthetic capacity under long-term exposures to elevated CO2, using GCG and TGG are reported.

Short- and long-term physiological responses of grapevine leaves to UV-B radiation

The present study aimed at evaluating the short- and long-term effects of UV-B radiation on leaves of grapevine Vitis vinifera (cv. Tempranillo). Grapevine fruit-bearing cuttings were exposed to two doses of supplemental biologically effective UV-B radiation (UV-BBE) under glasshouse-controlled conditions: 5.98 and 9.66kJm(-2)d(-1). The treatments were applied either for 20d (from mid-veraison to ripeness) or 75d (from fruit set to ripeness). A 0kJm(-2)d(-1) UV-B treatment was included as control. The main effects of UV-B were observed after the short-term exposure (20d) to 9.66kJm(-2)d(-1). Significant decreases in net photosynthesis, stomatal conductance, sub-stomatal CO2 concentration, the actual photosystem II (PSII) efficiency, total soluble proteins and de-epoxidation state of the VAZ cycle were observed, whereas the activities of several antioxidant enzymes increased significantly. UV-B did not markedly affect dark respiration, photorespiration, the maximum potential PSII efficiency (Fv/Fm), non-photochemical quenching (NPQ), as well as the intrinsic PSII efficiency. However, after 75d of exposure to 5.98and 9.66kJm(-2)d(-1) UV-B most photosynthetic and biochemical variables were unaffected and there were no sign of oxidative damage in leaves. The results suggest a high long-term acclimation capacity of grapevine to high UV-B levels, associated with a high accumulation of UV-B absorbing compounds in leaves, whereas plants seemed to be tolerant to moderate doses of UV-B.

KCNH1 potassium channels are expressed in cervical cytologies from pregnant patients and are regulated by progesterone

Potassium voltage-gated channel, subfamily H (eag-related), member 1 (KCNH1) potassium channels are potential tumour markers and cancer therapeutic targets and are up-regulated by oestrogens and human papilloma virus (HPV) oncogenes. However, the role of KCNH1 in normal tissues is poorly understood, and its expression in pregnancy is unknown. We wondered whether KCNH1 channels are expressed in cervical cells from pregnant patients and whether progesterone (P4) regulates KCNH1. The association with HPV was also investigated. KCNH1 protein expression was studied by immunocytochemistry in liquid-based cervical cytologies; 93 samples were obtained from pregnant patients at different trimesters, and 15 samples were obtained from non-pregnant women (controls). The presence ofHPVwas studied by PCR with direct sequencing and nested multiplex PCR. HeLa cervical cancer cells were transfected with human progesterone receptor-B (PR-B) and treated with P4.KCNH1mRNA expression in these cultures was studied by real-time PCR. KCNH1 protein was detected in 100% of the pregnancy samples and in 26% of the controls. We found 18 pregnant patients infected with HPV and detected 14 types ofHPV. There was no association between the percentage of cells expressing KCNH1 and either the presence or type of HPV. P4induced KCNH1 mRNA and protein expression in cells transfected with human PR-B. No regulation of KCNH1 by P4was observed in non-transfected cells. We show for the first time the expression of an ion channel during human pregnancy at different trimesters and KCNH1 regulation by P4in human cells. These data raise a new research field for KCNH1 channels in human tissues.

Phosphotyrosine phosphatases in GH-stimulated skin fibroblasts from children with idiopathic short stature

AIM

Some cases of idiopathic short stature (ISS) may be caused by defects in the modulation of the negative feedback regulation of the growth hormone receptor (GHR)/ Janus kinase (JAK)2/signal transducers and activators of transcription (STAT)5 signaling pathway. The cytosolic tyrosine phosphatases, protein tyrosine phosphatase 1B (PTP1B) and Src homology 2 (SH2) domain-containing protein-tyrosine phosphatase-1 (SHP-1), the later which translocates to the nucleus after activation, interact with JAK2 in a GH-dependent manner. The possible contribution of PTP1B and SHP-1 to GH signaling in fibroblasts from ISS patients has not been studied.

METHODS

We determined the basal protein content of PTP1B and SHP-1 in the presence of recombinant human GH (rhGH) for 24 h in skin fibroblast cultures, obtained from patients with ISS, and were compared with a normal height control children group. JAK2 activation was determined in both groups.

RESULTS

JAK2 activation was delayed in fibroblasts from ISS patients compared to controls. Under basal conditions, the protein content of SHP-1 was lower in ISS, and after incubation with rhGH, it decreased in the non-nuclear and nuclear fraction of controls, but not in ISS patients. The protein content of PTP1B, however, increased in a similar fashion in fibroblasts from both ISS and control children.

CONCLUSION

The delayed activation of JAK2 and the lack of response of SHP-1 after incubation with GH in fibroblasts from ISS patients, suggests that the growth retardation observed in some of these children may be mediated in part by this phosphotyrosine phosphatase.

Expression of SOCS1, SOCS2, and SOCS3 in growth hormone-stimulated skin fibroblasts from children with idiopathic short stature

BACKGROUND/AIM

Possible etiologies of idiopathic short stature (ISS) include a range of conditions, some of which may be caused by defects in the modulation of the growth hormone (GH)-signaling pathway. The Janus kinase/signal transducer and activator of transcription pathway is regulated by several mechanisms, including negative feedback regulation by the suppressors of cytokine signaling (SOCS). However, the specific induction of SOCS transcript levels in fibroblasts from ISS patients has not been studied.

METHODS

We determined the transcript levels of the SOCS1-3 genes under basal conditions, and in the presence or absence of stimulation with rhGH for 24 h in skin fibroblast cultures obtained from patients with ISS and children with normal height.

RESULTS

Under basal conditions, ISS patients express higher SOCS2-3 transcript levels than control children. After incubation with recombinant human GH (rhGH), the transcript levels of SOCS2 increased significantly in ISS patients compared to controls (0.79 +/- 0.06 vs. 0.55 +/- 0.07; p = 0.03), a pattern which did not achieve statistical significance for SOCS3 transcript levels (0.55 +/- 0.08 vs. 0.40 +/- 0.07).

CONCLUSION

The higher baseline transcript levels of the SOCS genes, and the increase observed for SOCS2 after rhGH treatment in ISS patients, suggest that growth retardation in some of these children may be mediated, at least in part, by intracellular overexpression of the SOCS genes.

Attosecond control in photoionization of hydrogen molecules

We report experiments where hydrogen molecules were dissociatively ionized by an attosecond pulse train in the presence of a near-infrared field. Fragment ion yields from distinguishable ionization channels oscillate with a period that is half the optical cycle of the IR field. For molecules aligned parallel to the laser polarization axis, the oscillations are reproduced in two-electron quantum simulations, and can be explained in terms of an interference between ionization pathways that involve different harmonic orders and a laser-induced coupling between the 1sσ(g) and 2pσ(u) states of the molecular ion. This leads to a situation where the ionization probability is sensitive to the instantaneous polarization of the molecule by the IR electric field and demonstrates that we have probed the IR-induced electron dynamics with attosecond pulses.

Novel substituted quinazolines for potent EGFR tyrosine kinase inhibitors

The type I receptor tyrosine kinases (RTKs) are involved in various aspects of cell growth, survival, and differentiation. Among the known RTKs, the epidermal growth factor receptor (EGFR) and ErbB-2 (HER-2) are two widely studied proteins that are prototypic members of the ErbB family which also includes ErbB-3 (Her-3) and ErbB-4 (Her-4). Overexpression of ErbB-2 and EGFR has been associated with aggressive disease and poor patient prognosis in a range of human tumour types (e.g. breast, lung, ovarian, prostate, and squamous carcinoma of head and neck). Disruption of signal transduction of these kinases has been shown to have an antiproliferative effect. Various approaches have been developed to target the ErbB signalling pathways including monoclonal antibodies (trastuzumab/Herceptin™ and cetuximab/Erbitux™) directed against the receptor, and synthetic tyrosine kinase inhibitors (gefitinib/Iressa™ and erlotinib/Tarceva™). Since many tumours overexpress ErbB receptors, simultaneous targeting of multiple ErbB receptors therefore becomes a promising approach to cancer treatment. Lapatinib (Tykerb™), a potent dual EGFR/ErbB-2 inhibitor, was approved for the treatment of ErbB-2-positive breast cancer. Despite years of intensive research on EGFR inhibitors, there is a surprising dearth of chemically distinct small inhibitors with a high degree of selectivity. There is also a need for new scaffolds due to the recent finding of EGFR mutations which render the kinase resistant to gefinitib and erlotinib. The structures under study will be quinazolines with different substituents. The structure-activity relationships and biological evaluation of compounds published during the last four years will be reviewed herein.

Carboxylate metabolism in sugar beet plants grown with excess Zn

The effects of Zn excess on carboxylate metabolism were investigated in sugar beet (Beta vulgaris L.) plants grown hydroponically in a growth chamber. Root extracts of plants grown with 50 or 100μM Zn in the nutrient solution showed increases in several enzymatic activities related to organic acid metabolism, including citrate synthase and phosphoenolpyruvate carboxylase, when compared to activities in control root extracts. Root citric and malic acid concentrations increased in plants grown with 100μM Zn, but not in plants grown with 50μM Zn. In the xylem sap, plants grown with 50 and 100μM Zn showed increases in the concentrations of citrate and malate compared to the controls. Leaves of plants grown with 50 or 100μM Zn showed increases in the concentrations of citric and malic acid and in the activities of citrate synthase and fumarase. Leaf isocitrate dehydrogenase increased only in plants grown with 50μM Zn when compared to the controls. In plants grown with 300μM Zn, the only enzyme showing activity increases in root extracts was citrate synthase, whereas the activities of other enzymes decreased compared to the controls, and root citrate concentrations increased. In the 300μM Zn-grown plants, the xylem concentrations of citric and malic acids were higher than those of controls, whereas in leaf extracts the activity of fumarase increased markedly, and the leaf citric acid concentration was higher than in the controls. Based on our data, a metabolic model of the carboxylate metabolism in sugar beet plants grown under Zn excess is proposed.

Patient preferences and treatment safety for uncomplicated vulvovaginal candidiasis in primary health care

Background

Vaginitis is a common complaint in primary care. In uncomplicated candidal vaginitis, there are no differences in effectiveness between oral or vaginal treatment. Some studies describe that the preferred treatment is the oral one, but a Cochrane's review points out inconsistencies associated with the report of the preferred way that limit the use of such data. Risk factors associated with recurrent vulvovaginal candidiasis still remain controversial.

Methods/Design

This work describes a protocol of a multicentric prospective observational study with one year follow up, to describe the women's reasons and preferences to choose the way of administration (oral vs topical) in the treatment of not complicated candidal vaginitis. The number of women required is 765, they are chosen by consecutive sampling. All of whom are aged 16 and over with vaginal discharge and/or vaginal pruritus, diagnosed with not complicated vulvovaginitis in Primary Care in Madrid.

The main outcome variable is the preferences of the patients in treatment choice; secondary outcome variables are time to symptoms relief and adverse reactions and the frequency of recurrent vulvovaginitis and the risk factors. In the statistical analysis, for the main objective will be descriptive for each of the variables, bivariant analysis and multivariate analysis (logistic regression).. The dependent variable being the type of treatment chosen (oral or topical) and the independent, the variables that after bivariant analysis, have been associated to the treatment preference.

Discussion

Clinical decisions, recommendations, and practice guidelines must not only attend to the best available evidence, but also to the values and preferences of the informed patient.

Stomatal and mesophyll conductances to CO2 are the main limitations to photosynthesis in sugar beet (Beta vulgaris) plants grown with excess zinc

*The effects of zinc (Zn) toxicity on photosynthesis and respiration were investigated in sugar beet (Beta vulgaris) plants grown hydroponically with 1.2, 100 and 300 microM Zn. *A photosynthesis limitation analysis was used to assess the stomatal, mesophyll, photochemical and biochemical contributions to the reduced photosynthesis observed under Zn toxicity. *The main limitation to photosynthesis was attributable to stomata, with stomatal conductances decreasing by 76% under Zn excess and stomata being unable to respond to physiological and chemical stimuli. The effects of excess Zn on photochemistry were minor. Scanning electron microscopy showed morphological changes in stomata and mesophyll tissue. Stomatal size and density were smaller, and stomatal slits were sealed in plants grown under high Zn. Moreover, the mesophyll conductance to CO(2) decreased by 48% under Zn excess, despite a marked increase in carbonic anhydrase activity. Respiration, including that through both cytochrome and alternative pathways, was doubled by high Zn. *It can be concluded that, in sugar beet plants grown in the presence of excess Zn, photosynthesis is impaired due to a depletion of CO(2) at the Rubisco carboxylation site, as a consequence of major decreases in stomatal and mesophyll conductances to CO(2).

Photosynthetic response of pepper plants to wilt induced by Verticillium dahliae and soil water deficit

Greenhouse experiments were conducted to compare stress effects caused by Verticillium dahliae and drought on gas exchange, chlorophyll (Chl) fluorescence and photosynthetic pigments of pepper plants. Three treatments were compared: Verticillium inoculated plants (+V), non-inoculated well-watered plants (-V) and non-inoculated plants subjected to progressive drought (D). Gas exchange, fluorescence and photosynthetic pigments were measured and represented along a gradient of relative water content (RWC) and stomatal conductance (g(s)). Net photosynthesis (A) and electron transport rate (ETR) decreased, as RWC and g(s) declined, similarly in both +V and D plants. However, dark respiration (R(D)) and photorespiration (R(L)) tended to increase in inoculated plants compared to those subjected to soil drought, as g(s) decreased. Photoinhibitory damage was not observed in infected or in droughted plants. Soil drought decreased intrinsic PSII efficiency (Phi(exc.)), which seemed to result in part from enhanced xanthophyll cycle- and/or lutein-related thermal energy dissipation. Nevertheless, the fact that 1-Phi(exc.) increased in D only at high values of the de-epoxidation state of the xanthophyll cycle (DPS) suggests that DeltapH could be the major factor controlling thermal energy dissipation in this treatment. By contrast, antheraxanthin, zeaxanthin and lutein, as well as Phi(exc.), were not markedly affected in +V. Water stress appeared to be the main limitation to photosynthesis in Verticillium infected plants, probably through stomatal closure, together with impaired mesophyll conductance (g(m)). However, our results indicate differential effects of V. dahliae on dark respiration, photorespiration, g(m) and on the capability of thermal energy dissipation under low g(s) values.

Specific heat studies of pure Nb(3)Sn single crystals at low temperature

Specific heat measurements performed on high purity vapor-grown Nb(3)Sn crystals show clear features related to both the martensitic and superconducting transitions. Our measurements indicate that the martensitic anomaly does not display hysteresis, meaning that the martensitic transition could be a weak first-order or a second-order thermodynamic transition. Careful measurements of the two transition temperatures display an inverse correlation between them. At low temperature, specific heat measurements show the existence of a single superconducting energy gap feature.

Effects of zinc toxicity on sugar beet (Beta vulgaris L.) plants grown in hydroponics

The effects of high Zn concentration were investigated in sugar beet (Beta vulgaris L.) plants grown in a controlled environment in hydroponics. High concentrations of Zn sulphate in the nutrient solution (50, 100 and 300 microm) decreased root and shoot fresh and dry mass, and increased root/shoot ratios, when compared to control conditions (1.2 microm Zn). Plants grown with excess Zn had inward-rolled leaf edges and a damaged and brownish root system, with short lateral roots. High Zn decreased N, Mg, K and Mn concentrations in all plant parts, whereas P and Ca concentrations increased, but only in shoots. Leaves of plants treated with 50 and 100 microm Zn developed symptoms of Fe deficiency, including decreases in Fe, chlorophyll and carotenoid concentrations, increases in carotenoid/chlorophyll and chlorophyll a/b ratios and de-epoxidation of violaxanthin cycle pigments. Plants grown with 300 microm Zn had decreased photosystem II efficiency and further growth decreases but did not have leaf Fe deficiency symptoms. Leaf Zn concentrations of plants grown with excess Zn were high but fairly constant (230-260 microg.g(-1) dry weight), whereas total Zn uptake per plant decreased markedly with high Zn supply. These data indicate that sugar beet could be a good model to investigate Zn homeostasis mechanisms in plants, but is not an efficient species for Zn phytoremediation.

Effects of zinc toxicity on sugar beet (Beta vulgaris L.) plants grown in hydroponics

The effects of high Zn concentration were investigated in sugar beet (Beta vulgaris L.) plants grown in a controlled environment in hydroponics. High concentrations of Zn sulphate in the nutrient solution (50, 100 and 300 microm) decreased root and shoot fresh and dry mass, and increased root/shoot ratios, when compared to control conditions (1.2 microm Zn). Plants grown with excess Zn had inward-rolled leaf edges and a damaged and brownish root system, with short lateral roots. High Zn decreased N, Mg, K and Mn concentrations in all plant parts, whereas P and Ca concentrations increased, but only in shoots. Leaves of plants treated with 50 and 100 microm Zn developed symptoms of Fe deficiency, including decreases in Fe, chlorophyll and carotenoid concentrations, increases in carotenoid/chlorophyll and chlorophyll a/b ratios and de-epoxidation of violaxanthin cycle pigments. Plants grown with 300 microm Zn had decreased photosystem II efficiency and further growth decreases but did not have leaf Fe deficiency symptoms. Leaf Zn concentrations of plants grown with excess Zn were high but fairly constant (230-260 microg.g(-1) dry weight), whereas total Zn uptake per plant decreased markedly with high Zn supply. These data indicate that sugar beet could be a good model to investigate Zn homeostasis mechanisms in plants, but is not an efficient species for Zn phytoremediation.

Classical two-slit interference effects in double photoionization of molecular hydrogen at high energies

Recent experiments on double photoionization of H2 with photon energies between 160 and 240 eV have revealed body-frame angular distributions that suggest classical two-slit interference effects may be present when one electron carries most of the available energy and the second electron is not observed. We report precise quantum mechanical calculations that reproduce the experimental findings. They reveal that the interpretation in terms of classical diffraction is only appropriate at substantially higher photon energies. At the energies considered in the experiment we offer an alternative explanation based on the mixing of two nondiffractive contributions by circularly polarized light.

Effects of 2 concentrations of sodium citrate on coagulation test results, von Willebrand factor concentration, and platelet function in dogs

BACKGROUND

Blood collection tubes containing 3.2% (0.109 M) sodium citrate, instead of 3.8% (0.129 M) sodium citrate, have recently become available in the United States. These tubes are visually indistinguishable from the traditional 3.8% sodium citrate tubes, except for wording on the label. Consequently, samples for hemostatic evaluation are frequently collected in tubes containing the lower concentration of sodium citrate.

HYPOTHESIS

Results of hemostasis assays are different in samples collected in 3.2% versus 3.8% sodium citrate.

ANIMALS

Twenty healthy dogs.

METHODS

This study aimed at determining whether results of standard coagulation tests, von Willebrand factor concentration (vWF:Ag), and platelet function with the platelet function analyzer PFA-100a were affected by the different concentrations of sodium citrate. Blood samples were collected in tubes containing either 3.2% or 3.8% sodium citrate concentrations and processed routinely for coagulation assays (one-stage prothrombin time [OSPT], activated partial thromboplastin time [aPTT], fibrinogen concentration, and platelet count), vWF:Ag, and platelet function assays with a PFA-100.

RESULTS

There was no significant difference between samples collected in 3.2% versus those collected in 3.8% sodium citrate for OSPT, aPTT, fibrinogen concentration, platelet count, or vWF:Ag. The closure times with collagen/adenosine diphosphate were significantly shorter (66 +/- 8.1 versus 74.8 +/- 9.7 seconds; P < .0001) with the 3.2% than with 3.8% sodium citrate concentration, and the hematocrit was significantly higher (47.9 +/- 5.6 versus 46.0 +/- 4.7 seconds; P = .03) in samples collected in 3.2% than in those collected in 3.8% sodium citrate.

CONCLUSIONS AND CLINICAL IMPORTANCE

There is no clinically relevant effect of collection of blood into 3.2% or 3.8% sodium citrate.

Assessment of pathological complete response (pCR) to neoadjuvant dose-dense chemotherapy in HER2+ patients with locally advanced breast cancer (LABC) treated with trastuzumab (T) compared with HER2+ and HER2- patients treated without T

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Purpose: To identify Her2+expression as predictive factor for pCR to T in pts with LABC treated with neoadjuvant chemotherapy. Methods: A total of 127 newly diagnosed stage II-III, including inflammatory tumors, breast cancer pts were reviewed. Median age was 47,7 (r 26,4 - 73,6). Median tumor size was 5 cm (1–10). 57 (44,8%) were T2, 33 (26%) T3 and 37 (29,2%) T4 (25 of them inflammatory). 59 (46,5%) pts were clinically lymph node positive before treatment. 50 pts (39,4%) were hormonal receptor negative, and 38 (30,4%) Her2+. The pts received one of the 2 chemotherapy regimens every 2 weeks with prophylactic growth factors support: A) epirubicin 90 mg/m2-cyclophophamide 600 mg/m2 d1 for 3 cycles, followed by a second sequence with paclitaxel (P) 150 mg/m2- gemcitabine (G) 2500 mg/m2 d1 ± T 2mg/kg/wk according to status Her2 (n= 73); B) adriamicin 40mg/m2 d1 plus P 150mg/m2-G 2000 mg/m2 d2 for 6 cycles (n=54). Subsequently pats underwent surgery and radiotherapy and/or adjuvant hormonal therapy according to institutional practice. Results: 43 (33,9 %) pts achieved a pCR (absence of invasive tumor in the breast). The pts were classified in two groups to analyze the influence of the treatment with T on pCR: (1) Her2+ pats treated with T (20 pts): pCR 50%; (2) The rest of the pts, treated only with chemotherapy (107 pts: 18 Her2+ and 89 Her2- ): pCR 32% (p=0.068). Breast-conserving surgery was performed in 77 pts (60,6%). Conclusions: Both dose dense chemotherapy regimens were highly effective in terms of pCR. Although there were not a significative correlation of Her2+ status and trastuzumab therapy with pCR, probably due to the small number of pts, a favorable tendency was seen in the group of Her2+ tumors treated with T. At the meeting, analysis of the correlation of pCR with progression free survival will be presented.

No significant financial relationships to disclose.

Organ Donation in Latin America

Recently in Latin America, there has been a strong influence of the "Spanish model" of organ procurement. In 2001, The "Punta Cana Group" was created by Latin American transplantation coordinators with the objective of registering and improving the system of donation and procurement. In many countries there is no universal financial support from the government for medical treatment, including dialysis and transplantation. In other countries there is complete financial support for all of the population, including immunosuppressive drugs. Practically all countries have transplantation laws that follow ethical concepts, such as brain death diagnosis criteria, forms of consent, criteria of allocation, and inhibition of commerce. The rate of potential donors notified in countries that perform transplantations with deceased donors varied from 6 to 47 per million population yearly (pmp/y); The rate of effective donors varied from 1 to 20 pmp. In 2004, the mean rate of effective donors in Latin America was 5.4 pmp. The family refusal rate for the donation of organs varied from 28% in Uruguay to 70% in Peru. In some countries, such as Puerto Rico, Uruguay, and Cuba, it was more than 15 pmp, whereas in others countries deceased donors were practically not used. The number of patients on the waiting list for solid organ transplants in 12 Latin American countries is 55,000. Although the donation rate has increased by 100% during the last 10 years, it is lower than that in Europe (15 pmm/y) or the United States (20 pmp/y).

A novel approach to speed up peptide sequencing via MS/MS spectra analysis

In proteomics, tandem mass spectrometry is the key technology for peptide sequencing from the cells. Different methods have been proposed to sequence peptides through tandem mass spectra. While the methods are capable of providing more robust and accurate results, they are also computationally expensive, and create a bottleneck in high throughput peptide identification. In this work, we introduce a novel approach to speedup peptide sequencing. In contrast to the traditional approaches, we conduct coarse comparison of spectral profiles to drastically shrink the size of candidate peptides. A fast algorithm has been developed for this goal. It is shown in our experiments that such an approach can significantly improve the speed for peptide sequencing.

Determination of the systematic and random measurement error in an LC-FTICR mass spectrometry analysis of a partially characterized complex peptide mixture

In high-throughput proteomics, a promising approach presently being explored is the use of liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS) to provide measurements of the masses of tryptic peptides in complex mixtures, which can then be used to identify the proteins which gave rise to those peptides. In order to apply this method, it is necessary to account for any systematic measurement error, and it is useful to have an estimate of the random error in measured masses. In this investigation, a complex mixture of peptides derived from a partially characterized sample was analyzed by LC-FTICR-MS. Through the application of a Bayesian probability model of the data, partial knowledge of the composition of the sample is sufficient both to determine any systematic error and to estimate the random error in measured masses.

A systems biology analysis of the Drosophila phagosome

Phagocytes have a critical function in remodelling tissues during embryogenesis and thereafter are central effectors of immune defence. During phagocytosis, particles are internalized into 'phagosomes', organelles from which immune processes such as microbial destruction and antigen presentation are initiated. Certain pathogens have evolved mechanisms to evade the immune system and persist undetected within phagocytes, and it is therefore evident that a detailed knowledge of this process is essential to an understanding of many aspects of innate and adaptive immunity. However, despite the crucial role of phagosomes in immunity, their components and organization are not fully defined. Here we present a systems biology analysis of phagosomes isolated from cells derived from the genetically tractable model organism Drosophila melanogaster and address the complex dynamic interactions between proteins within this organelle and their involvement in particle engulfment. Proteomic analysis identified 617 proteins potentially associated with Drosophila phagosomes; these were organized by protein-protein interactions to generate the 'phagosome interactome', a detailed protein-protein interaction network of this subcellular compartment. These networks predicted both the architecture of the phagosome and putative biomodules. The contribution of each protein and complex to bacterial internalization was tested by RNA-mediated interference and identified known components of the phagocytic machinery. In addition, the prediction and validation of regulators of phagocytosis such as the 'exocyst', a macromolecular complex required for exocytosis but not previously implicated in phagocytosis, validates this strategy. In generating this 'systems-based model', we show the power of applying this approach to the study of complex cellular processes and organelles and expect that this detailed model of the phagosome will provide a new framework for studying host-pathogen interactions and innate immunity.

[Skull base meningiomas: a predictive system to know the extent of their surgical resection and patient outcome]

OBJECTIVE

The aim of this study was to build a preoperative predictive system which could provide reliable information about: 1 degrees which skull base meningiomas can be total or partially removed, and 2 degrees their surgical outcome.

METHOD

Patient histories and imaging data were reviewed retrospectively from 85 consecutive skull base meningiomas patients who underwent surgery from 1990 and 2002. From the preoperative data, nine variables were selected for conventional statistical analysis as regards their relationship with: 1 degrees total vs partial tumor resection and 2 degrees with patients outcome according to the degree of tumour removal.

RESULTS

From the nine variables analysed only two had a statistical association with the type of tumour resection performed (total vs partial) and the patient outcome: 1) arteries encasement and 2) cranial nerves involvement. Upon correlating these two variables with the type of tumour resection performed (total vs partial) and with the Karnofsky'scale to evaluate patients surgical outcome, the following grading groups were identified: Grade I: skull base meningiomas which did not involve cranial nerves or artery or only encased one artery or one cranial nerve. In these cases the incidence of gross tumour resection was 98.3% (p< 0.0001) and the perspective to reach 70 points in the Karnofsky'scale was of 96.5% ( p=0.001). Grade II: skull base meningiomas which involved one cranial nerve and encased, at least, two main cerebral arteries. In these cases, the frequency of total resection, decreased to 83.3% (p<0.0001) and the probability to reach 70 points in the Karnofsky'scale was 70.6% (p=0.001). Grade III: skull base meningiomas which involved two or more cranial nerves and encased several arteries In this group, the frequency of a total resection was of 42.9% (p<0.0001) and the probability of reaching 70 points in the Karnofsky'scale was only 60% (p=0.001).

CONCLUSIONS

We propose a preoperative grading system for skull base meningiomas that helps predicting both whether total or partial tumor removal will be achieved during surgery and the immediate postsurgical outcome of the patient. In applying this predictive system we will be able to reduce surgical morbidity, to advance the possibility of a radiosurgical treatment and give a more precise information to the patients and their families about our surgical decision-making process.

Effects of two iron sources on iron and cadmium allocation in poplar (Populus alba) plants exposed to cadmium

Effects of 10 microM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar (Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic) Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in long-distance transport of Fe rather than in acquisition of Fe by roots.

Seasonal changes in photosynthesis and photoprotection in a Quercus ilex subsp. ballota woodland located in its upper altitudinal extreme in the Iberian Peninsula

Quercus ilex L. subsp. ballota (Desf.) Samp., a Mediterranean evergreen species growing in a continental Mediterranean climate, did not experience water stress and showed greater sensitivity to winter stress than to summer stress over a 12-month period. Net CO2 assimilation rates and photosystem II (PSII) efficiency decreased markedly during the cold months and recovered completely in spring. Lutein, neoxanthin and beta-carotene to chlorophyll (Chl) molar ratios all showed the same trend throughout the year, increasing from September to March. This increase was a result of increases in carotenoid concentrations, because Chl concentration per unit leaf area remained stable, and was higher at the end than at the beginning of the first growing season. Lutein-epoxide was a minor component of the total lutein pool. Thermal energy dissipation and non-photochemical quenching (NPQ) were associated with the de-epoxidated forms of the xanthophyll cycle pigments in the warm months. Photosynthetic rates decreased slightly at midday in summer. These changes were accompanied by decreases in maximum potential PSII efficiency (which recovered during the night), actual and intrinsic PSII efficiencies, photochemical quenching and increases in NPQ. Overall, our data indicate down-regulation of photosynthesis during the summer. The diurnal de-epoxidation of violaxanthin to antheraxanthin and zeaxanthin occurred throughout the year, except in January. Antioxidant enzymatic activity increased in the winter months, especially during the coldest months, highlighting its key role in photoprotection against photo-oxidation. Structural and functional modifications protected PSII from permanent damage and allowed 1-year-old leaves to photosynthesize at high rates when temperatures increased in spring.