LEAF GAS EXCHANGE CHARACTERISTICS OF FOUR PAPAYA GENOTYPES DURING DIFFERENT STAGES OF DEVELOPMENT

In this research, was used four papaya (Carica papaya L.) genotypes: three from the 'Solo ( Sunrise Solo TJ, Sunrise Solo 72/12 and Baixinho de Santa Amália) group and one from the 'Formosa' group (Know-You 01). They were grown in plastic pots containing a sandy-clay-loam soil subjected to pH correction and fertilization, under greenhouse conditions. Throughout the experimental period plants were subjected to periodic irrigation to maintain the soil humitidy around field capacity. The experiment was conducted 73 days after sowing. In all genotypes, leaf gas exchange characteristics were determined. The net photosynthetic rate (A, mumol m-2 s-1 ), stomatal conductance (g s mol m-2 s-1), leaf temperature (T I, 0C) and intercellular carbon dioxide concentration (ci, muL L-1) on the 4th, 5th, 6th, 7th, 8th and 9th leaves from the plant apex were determined. No significant differences were observed for A, g s, c i, or Tl either among the leaves sampled from any of the genotypes. A was positively correlated with g s and in the other hand T I and g s were negatively correlated. The results suggest that, for 73 DAP, all the sampled papaya leaves functioned as sources of organs.

Ochratoxin A at nanomolar concentration perturbs the homeostasis of neural stem cells in highly differentiated but not in immature three-dimensional brain cell cultures.

Ochratoxin A (OTA), a fungal contaminant of basic food commodities, is known to be highly cytotoxic, but the pathways underlying adverse effects at subcytotoxic concentrations remain to be elucidated. Recent reports indicate that OTA affects cell cycle regulation. Therefore, 3D brain cell cultures were used to study OTA effects on mitotically active neural stem/progenitor cells, comparing highly differentiated cultures with their immature counterparts. Changes in the rate of DNA synthesis were related to early changes in the mRNA expression of neural stem/progenitor cell markers. OTA at 10nM, a concentration below the cytotoxic level, was ineffective in immature cultures, whereas in mature cultures it significantly decreased the rate of DNA synthesis together with the mRNA expression of key transcriptional regulators such as Sox2, Mash1, Hes5, and Gli1; the cell cycle activator cyclin D2; the phenotypic markers nestin, doublecortin, and PDGFRα. These effects were largely prevented by Sonic hedgehog (Shh) peptide (500ngml(-1)) administration, indicating that OTA impaired the Shh pathway and the Sox2 regulatory transcription factor critical for stem cell self-renewal. Similar adverse effects of OTA in vivo might perturb the regulation of stem cell proliferation in the adult brain and in other organs exhibiting homeostatic and/or regenerative cell proliferation.

CO2-laserin soveltaminen WFU-paperin reunan leikkaamiseen

Tämän diplomityön tarkoitus oli selvittää CO2-laserin soveltuvuutta paperin reunan leikkaamiseen ennen liimapuristinta nopealle modernilleWFU-paperikoneelle. Merkittävimmät leikkauskokeet tehtiin leikkaamalla paperirataa todenmukaisissa olosuhteissa koekoneella. Koeleikkauksissa tutkittiin myös päällystettyjen paperilajien CO2-laserleikkausta. Paperin reunan koeleikkauksia suoritettiin leikkauspöytää vasten sekä telaa vasten. Leikkauspöytänä käytettiin korkeapainevesileikkaimelle suunniteltua leikkauspöytää, jota paranneltiin tämän työn yhteydessä paremmin laserleikkaukselle sopivaksi. Telaa vasten suoritetuilla leikkauksilla lasertehon tarve oli suurempi verrattuna pöytää vasten leikkaukseen samalla leikkausnopeudella ja samalla paperilajilla. Laserlaitteiston mitoittaminen oikein pelkkien arkkileikkauskokeiden perusteella ei ollut mahdollista. Myös rullilla tapahtuvia leikkauskokeita tarvittiin. Pöytää vasten tapahtuvaan leikkaamiseen tarvitaan 1000 W laserlaite paperin molemmille reunoille. Tämän tehoiset laserlaitteet riittävät kaikille Changshun PK 1:n paperilajeille niiden lajikohtaiseen maksimiajonopeuteen. Testatuista kolmesta polttovälistä antoi 5" polttoväli parhaat leikkaustulokset. Polttopisteen paikka voi vaihdella ± 0.75 mm paperin pinnasta vaikuttamatta silti merkittävästi lasertehon tarpeeseen. Laserleikatun paperin reuna oli hyvälaatuinen, eikä laserleikkaus aiheuttanut paperille epätoivottuja asioita kuten mustumista.

pH Sensitive surfactants from lysine: assessment of their cytotoxicity and environmental behavior

The toxicity and environmental behavior of new pH-sensitive surfactants from lysine are presented. Three different chemical structures are studied: surfactants with one amino acid and one alkyl chain, surfactants with two amino acids on the polar head and one alkyl chain, and gemini surfactants. The pH sensitivity of these compounds can be tuned by modifying their chemical structures. Cytotoxicity has been evaluated using erythrocytes and fibroblast cells. The toxic effects against these cells depend on the hydrophobicity of the molecules as well as their cationic charge density. The effect of hydrophobicity and cationic charge density on toxicity is different for each type of cells. For erythrocytes, the toxicity increases as hydrophobicity and charge density increases. Nevertheless, for fibroblasts cationic charge density affects cytotoxicity in the opposite way: the higher charge density, the lower the toxicity. The effect of the pH on hemolysis has been evaluated in detail. The aquatic toxicity was established using Daphnia magna. All surfactants yielded EC50 values considerably higher than that reported for cationic surfactants based on quaternary ammonium groups. Finally, their biodegradability was evaluated using the CO2 headspace test (ISO 14593). These lysine derivatives showed high levels of biodegradation under aerobic conditions and can be classified as"readily biodegradable compounds".

Feasibility of Therapeutic Drug Monitoring (TDM) for Imatinib: Preliminary considerations on the dosage adjustment approach for CML patients enrolled in the Imatinib Concentration Monitoring (I-COME) study

Background: As imatinib pharmacokinetics are highly variable, plasma levels differ largely between patients under the same dosage. Retrospective studies in chronic myeloid leukemia (CML) patients showed significant correlations between low levels and suboptimal response, and between high levels and poor tolerability. Monitoring of plasma levels is thus increasingly advised, targeting trough concentrations of 1000 μg/L and above. Objectives: Our study was launched to assess the clinical usefulness of systematic imatinib TDM in CML patients. The present preliminary evaluation questions the appropriateness of dosage adjustment following plasma level measurement to reach the recommended trough level, while allowing an interval of 4-24 h after last drug intake for blood sampling. Methods: Initial blood samples from the first 9 patients in the intervention arm were obtained 4-25 h after last dose. Trough levels in 7 patients were predicted to be significantly away from the target (6 <750 μg/L, and 1 >1500 μg/L with poor tolerance), based on a Bayesian approach using a population pharmacokinetic model. Individual dosage adjustments were taken up in 5 patients, who had a control measurement 1-4 weeks after dosage change. Predicted trough levels were confronted to anterior model-based extrapolations. Results: Before dosage adjustment, observed concentrations extrapolated at trough ranged from 359 to 1832 μg/L (median 710; mean 804, CV 53%) in the 9 patients. After dosage adjustment they were expected to target between 720 and 1090 μg/L (median 878; mean 872, CV 13%). Observed levels of the 5 recheck measurements extrapolated at trough actually ranged from 710 to 1069 μg/L (median 1015; mean 950, CV 16%) and had absolute differences of 21 to 241 μg/L to the model-based predictions (median 175; mean 157, CV 52%). Differences between observed and predicted trough levels were larger when intervals between last drug intake and sampling were very short (~4 h). Conclusion: These preliminary results suggest that TDM of imatinib using a Bayesian interpretation is able to bring trough levels closer to 1000 μg/L (with CV decreasing from 53% to 16%). While this may simplify blood collection in daily practice, as samples do not have to be drawn exactly at trough, the largest possible interval to last drug intake yet remains preferable. This encourages the evaluation of the clinical benefit of a routine TDM intervention in CML patients, which the randomized Swiss I-COME study aims to.

Intercellular communication in atherosclerosis.

Cell-to-cell communication is a process necessary for physiological tissue homeostasis and appears often altered during disease. Gap junction channels, formed by connexins, allow the direct intercellular communication between adjacent cells. After a brief review of the pathophysiology of atherosclerosis, we will discuss the role of connexins throughout the different stages of the disease.

The Effect of Adding CO2 to Hypoxic Inspired Gas on Cerebral Blood Flow Velocity and Breathing during Incremental Exercise

Hypoxia increases the ventilatory response to exercise, which leads to hyperventilation-induced hypocapnia and subsequent reduction in cerebral blood flow (CBF). We studied the effects of adding CO2 to a hypoxic inspired gas on CBF during heavy exercise in an altitude naïve population. We hypothesized that augmented inspired CO2 and hypoxia would exert synergistic effects on increasing CBF during exercise, which would improve exercise capacity compared to hypocapnic hypoxia. We also examined the responsiveness of CO2 and O2 chemoreception on the regulation ventilation (E) during incremental exercise. We measured middle cerebral artery velocity (MCAv; index of CBF), E, end-tidal PCO2, respiratory compensation threshold (RC) and ventilatory response to exercise (E slope) in ten healthy men during incremental cycling to exhaustion in normoxia and hypoxia (FIO2 = 0.10) with and without augmenting the fraction of inspired CO2 (FICO2). During exercise in normoxia, augmenting FICO2 elevated MCAv throughout exercise and lowered both RC onset andE slope below RC (P<0.05). In hypoxia, MCAv and E slope below RC during exercise were elevated, while the onset of RC occurred at lower exercise intensity (P<0.05). Augmenting FICO2 in hypoxia increased E at RC (P<0.05) but no difference was observed in RC onset, MCAv, or E slope below RC (P>0.05). The E slope above RC was unchanged with either hypoxia or augmented FICO2 (P>0.05). We found augmenting FICO2 increased CBF during sub-maximal exercise in normoxia, but not in hypoxia, indicating that the 'normal' cerebrovascular response to hypercapnia is blunted during exercise in hypoxia, possibly due to an exhaustion of cerebral vasodilatory reserve. This finding may explain the lack of improvement of exercise capacity in hypoxia with augmented CO2. Our data further indicate that, during exercise below RC, chemoreception is responsive, while above RC the ventilatory response to CO2 is blunted.

Emissão de etileno e de CO2 em mamão 'Sunrise Solo' e 'Golden'

Frutos de mamoeiro 'Sunrise Solo' e 'Golden' foram armazenados a 10º C e a 25º C e monitorados diariamente quanto às emissões de CO2 e de C2H4, observando-se a evolução do índice de cor de casca. A não-alteração do índice de cor de casca, ao longo dos 20 dias de conservação a 10º C, refletiu a influência da refrigeração na retenção do metabolismo dos mamões. Houve dois incrementos da respiração e da emissão de etileno, no quarto dia e entre o oitavo e o nono dia, nos frutos armazenados a 25º C. A temperatura de 10º C deteve a respiração climatérica do mamão e a emissão de etileno, comprovando que o seu metabolismo se reduz, permitindo que os frutos apresentem aspecto imaturo após 20 dias de armazenamento.

Correlations of glycogen synthase and phosphorylase activities with glycogen concentration in human muscle biopsies. Evidence for a double-feedback mechanism regulating glycogen synthesis and breakdown.

The purpose of this study was to verify in man the relationships of muscle glycogen synthase and phosphorylase activities with glycogen concentration that were reported in animal studies. The upper level of glycogen concentration in muscle is known to be tightly controlled, and glycogen concentration was reported to have an inhibitory effect on synthase activity and a stimulatory effect on phosphorylase activity. Glycogen synthase and phosphorylase activity and glycogen concentration were measured in muscle biopsies in a group of nine normal subjects after stimulating an increase of their muscle glycogen concentration through either an intravenous glucose-insulin infusion to stimulate glycogen synthesis, or an Intralipid (Vitrum, Stockholm, Sweden) infusion in the basal state to inhibit glycogen mobilization by favoring lipid oxidation at the expense of glucose oxidation. Phosphorylase activity increased from 71.3 +/- 21.0 to 152.8 +/- 20.0 nmol/min/mg protein (P < .005) after the glucose-insulin infusion. Phosphorylase activity was positively correlated with glycogen concentration (P = .005 and P = .0001) after the glucose-insulin and Intralipid infusions, respectively. Insulin-stimulated glycogen synthase activity was significantly negatively correlated with glycogen concentration at the end of the Intralipid infusion (P < .005). In conclusion, by demonstrating a negative correlation of glycogen concentration with glycogen synthase and a positive correlation with phosphorylase, this study might confirm in man the double-feedback mechanism by which changes in glycogen concentration regulate glycogen synthase and phosphorylase activities. It suggests that this mechanism might play an important role in the regulation of glucose storage.

When cholesterol is not cholesterol: a note on the enzymatic determination of its concentration in model systems containing vegetable extracts

Background: Experimental evidences demonstrate that vegetable derived extracts inhibit cholesterol absorption in the gastrointestinal tract. To further explore the mechanisms behind, we modeled duodenal contents with several vegetable extracts. Results: By employing a widely used cholesterol quantification method based on a cholesterol oxidase-peroxidase coupled reaction we analyzed the effects on cholesterol partition. Evidenced interferences were analyzed by studying specific and unspecific inhibitors of cholesterol oxidase-peroxidase coupled reaction. Cholesterol was also quantified by LC/MS. We found a significant interference of diverse (cocoa and tea-derived) extracts over this method. The interference was strongly dependent on model matrix: while as in phosphate buffered saline, the development of unspecific fluorescence was inhibitable by catalase (but not by heat denaturation), suggesting vegetable extract derived H2O2 production, in bile-containing model systems, this interference also comprised cholesterol-oxidase inhibition. Several strategies, such as cholesterol standard addition and use of suitable blanks containing vegetable extracts were tested. When those failed, the use of a mass-spectrometry based chromatographic assay allowed quantification of cholesterol in models of duodenal contents in the presence of vegetable extracts. Conclusions: We propose that the use of cholesterol-oxidase and/or peroxidase based systems for cholesterol analyses in foodstuffs should be accurately monitored, as important interferences in all the components of the enzymatic chain were evident. The use of adequate controls, standard addition and finally, chromatographic analyses solve these issues.

Short communication. Potential to mitigate anthropogenic CO2 emissions by tillage reduction in dryland soils of Spain

Spain is one of the countries with the highest greenhouse gas (GHG) emissions within the EU-27. Consequently, mitigation strategies need to be reported and quantified to accomplish the goals and requirements of the Kyoto Protocol. In this study, a first estimation of the carbon (C) mitigation potential of tillage reduction in Mediterranean rainfed Spain is presented. Results from eight studies carried out in Spain under rainfed agriculture to investigate the effects of no-tillage (NT) and reduced tillage (RT) compared with conventional tillage (CT) on soil organic carbon (SOC) were used. For current land surface under conservation tillage, NT and RT are sequestering 0.14 and 0.08 Tg C yr-1, respectively. Those rates represent 1.1% and 0.6% of the total CO2 emissions generated from agricultural activities in Spain during 2006. Alternatively, in a hypothetical scenario where all the arable dryland was under either NT or RT management, SOC sequestration would be 2.18 and 0.72 Tg C yr-1 representing 17.4% and 5.8% of the total 2006 CO2 equivalent emissions generated from the agricultural sector in Spain. This is a significant estimate that would help to achieve GHG emissions targets for the current commitment period of the Kyoto Protocol.

Esterification of oleic acid catalayzed by an Aspergillus niger strain. Influence of water activity and alcohol concentration

Effects of water activity and 1-propanol concentration on synthesis of propyl oleate from oleic acid using Aspergillus niger cell-bound lipases in isooctane are described. A. niger produces lipases (EC 3.1.1.3) which partly bind to the mycelium during growth. Ester production was monitored for 72 hours at different 1-propanol concentrations and water activities. Aliquots were sequentially withdrawn and propyl esters were quantified using GC and methyl palmitate as an internal standard. In all assayed conditions A. niger cell-bound lipases catalysed propyl oleate synthesis, but at different degrees.