Mechanisms of growth inhibition of Phytomonas serpens by the alkaloids tomatine and tomatidine

Phytomonas serpens are flagellates in the family Trypanosomatidae that parasitise the tomato plant (Solanum lycopersicum L.), which results in fruits with low commercial value. The tomato glycoalkaloid tomatine and its aglycone tomatidine inhibit the growth of P. serpens in axenic cultures. Tomatine, like many other saponins, induces permeabilisation of the cell membrane and a loss of cell content, including the cytosolic enzyme pyruvate kinase. In contrast, tomatidine does not cause permeabilisation of membranes, but instead provokes morphological changes, including vacuolisation. Phytomonas treated with tomatidine show an increased accumulation of labelled neutral lipids (BODYPY-palmitic), a notable decrease in the amount of C24-alkylated sterols and an increase in zymosterol content. These results are consistent with the inhibition of 24-sterol methyltransferase (SMT), which is an important enzyme that is responsible for the methylation of sterols at the 24 position. We propose that the main target of tomatidine is the sterols biosynthetic pathway, specifically, inhibition of the 24-SMT. Altogether, the results obtained in the present paper suggest a more general effect of alkaloids in trypanosomatids, which opens potential therapeutic possibilities for the treatment of the diseases caused by these pathogens.

Mutational and acquired carbapenem resistance mechanisms in multidrug resistant Pseudomonas aeruginosa clinical isolates from Recife, Brazil

An investigation was carried out into the genetic mechanisms responsible for multidrug resistance in nine carbapenem-resistant Pseudomonas aeruginosaisolates from different hospitals in Recife, Brazil. Susceptibility to antimicrobial agents was determined by broth microdilution. Polymerase chain reaction (PCR) was employed to detect the presence of genes encoding β-lactamases, aminoglycoside-modifying enzymes (AMEs), 16S rRNA methylases, integron-related genes and OprD. Expression of genes coding for efflux pumps and AmpC cephalosporinase were assessed by quantitative PCR. The outer membrane proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The blaSPM-1, blaKPC-2 and blaGES-1 genes were detected in P. aeruginosaisolates in addition to different AME genes. The loss of OprD in nine isolates was mainly due to frameshift mutations, premature stop codons and point mutations. An association of loss of OprD with the overexpression of MexAB-OprM and MexXY-OprM was observed in most isolates. Hyper-production of AmpC was also observed in three isolates. Clonal relationship of the isolates was determined by repetitive element palindromic-PCR and multilocus sequence typing. Our results show that the loss of OprD along with overexpression of efflux pumps and β-lactamase production were responsible for the multidrug resistance in the isolates analysed.

Differential gene expression, induced by salicylic acid and Fusarium oxysporum f. sp. lycopersici infection, in tomato

The objective of this work was to determine the transcript profile of tomato plants (Lycopersicon esculentum Mill.), during Fusarium oxysporum f. sp. lycopersici infection and after foliar application of salicylic acid. The suppression subtractive hybridization (SSH) technique was used to generate a cDNA library enriched for transcripts differentially expressed. A total of 307 clones was identified in two subtractive libraries, which allowed the isolation of several defense-related genes that play roles in different mechanisms of plant resistance to phytopathogens. Genes with unknown roles were also isolated from the two libraries, which indicates the possibility of identifying new genes not yet reported in studies of stress/defense response. The SSH technique is effective for identification of resistance genes activated by salicylic acid and F. oxysporum f. sp. lycopersici infection. Not only the application of this technique enables a cost effective isolation of differentially expressed sequences, but also it allows the identification of novel sequences in tomato from a relative small number of sequences.

Low-P tolerance mechanisms and differential gene expression in contrasting wheat genotypes

The objectives of this study were to determine low-P tolerance mechanisms in contrasting wheat genotypes and to evaluate the association of these mechanisms to differential gene expression. Wheat seedlings of cultivars Toropi (tolerant to low-P availability) and Anahuac (sensitive) were evaluated. Seedlings were hydroponically grown in the absence or presence of P (1.0 mmol L-1) during three different time periods: 24, 120 and 240 hours. Free phosphate (Pi) and total P contents were measured in shoots and roots. The experiment's design was in randomized blocks with three replicates, each formed by ten plants. The relative expression of genes encoding the malate transporter TaALMT1 and the transcription factor PTF1 was evaluated. Phosphorus starvation beyond ten days increased the expression of TaALMT1 only in 'Toropi'. PTF1's expression was early induced in both genotypes under P starvation, but remained significant after ten days only in 'Toropi'. Shoot Pi concentration in 'Toropi' was independent from P availability; under starvation, 'Toropi' favored the maintenance of shoot Pi concentration. The low-P tolerance of Toropi cultivar at initial growth stages is mainly due to its ability to maintain constant the Pi shoot level.

Temperature-dependent benzoic acid elimination mechanisms in pyrolysis of (-)-cocaine

The thermal elimination of benzoic acid from (-)-cocaine is shown to be temperature-dependent. In the temperature range of 200-500 °C only a trans-elimination is observed leading to methylecgonidine. Above ca. 500 °C a second mechanism, the cis-elimination, comes up yielding a novel alkaloid methylisoecgonidine which has been characterized by means of mass spectrometry. At 600 °C the cis-elimination predominates. The trans-elimination is postulated a two-step process consisting of a 1,7- and a 1,5-hydrogen shift. The chemistry of cocaine base smoking is explained using the theory of chemical activation.

Induction of plant defense responses by Ocimum gratissimum L. (Lamiaceae) leaf extracts

Aqueous extracts of the leaves of Ocimum gratissimum at 10, 25, 40 and 50% (w/v) concentrations induced the production of phytoalexins in soybean cotyledons and sorghum mesocotyls. The aqueous extracts also induced systemic resistance in cucumber to Colletotrichum lagenarium, reflected by reduction in disease incidence and an increase in chitinase production. Modes of action and the existence of possible elicitors of defense response in O. gratissimum leaf extracts are discussed.

Comparison of metering mechanisms of corn seed

It was compared the performance of the metering mechanism of corn seeds (Zea mays) in direct seeding in an area of ​​200 ha, a property in Piraí do Sul, State of Paraná - PR, in Brazil. It was seeded 4 maize hybrids, 50 ha of each, with seeds of different sieves. The experiment was conducted in a randomized block design (RBD), with 3 treatments and 9 repetitions for each corn hybrid. The treatments were the pneumatic seed of metering mechanisms, horizontal perforated disc with and without ramp®. The plots were 40 m² and were distributed at the early, middle and late sowing. The variables analyzed in each corn hybrid were initial population, faulty spacing, multiple spacing, acceptable spacing, and yield components. As there were no significant differences in the variables, it was concluded that the quality of seeding with different systems of distribution was similar in the different sieves of distributed corn seeds.

Coverage mobilization by different no-tillage in-line handling mechanisms

Vegetation cover on soil acts positively in maintaining temperature and soil moisture, yet, it has been imposing specific operational conditions on seeders. The objective of this study was to evaluate performance of different mechanisms regarding straw mobilization, employed in a no-till seeder. The experimental area was conducted on clayey soil under no-tillage with a large quantity of sorghum residue. The experiment was established in a randomized block design, as the treatments consisted of a combination of two mechanisms at front of the furrow opener composed of cutting disc and row cleaners, and three mechanisms behind the seed furrower, covering discs prototype model M1, Spider and commercial model, with the combination of cutting disc and Spider model not being evaluated. We assessed the coverage permanence on soil index, vegetation mass on surface and inside the line. The treatment containing the row cleaner mechanism efficiently removed straw from the surface of sowing line as well as the return one acted on straw replacement. It was identified that use of the cutting disc at the front of seeder contributed to the increase of straw installation inside the line, three times more than in the row cleaner system when operating individually. Covering mechanism with row cleaners reduced straw inside the line and kept line covering similar to treatment of cutting disc operating alone.

Comparative analysis between identified injuries of victims of fall from height and other mechanisms of closed trauma

OBJECTIVE: To analyze the lesions diagnosed in victims of falls, comparing them with those diagnosed in other mechanisms of blunt trauma.METHODS: We conducted a retrospective study of trauma protocol charts (prospectively collected) from 2008 to 2010, including victims of trauma over 13 years of age admitted to the emergency room. The severity of injuries was stratified by the Abbreviated Injury Scale (AIS) and Injury Severity Score (ISS). Variables were compared between the group of victims of falls from height (Group 1) and the other victims of blunt trauma (Group 2). We used the Student t, chi-square and Fisher tests for comparison between groups, considering the value of p <0.05 as significant.RESULTS: The series comprised 4,532 cases of blunt trauma, of which 555 (12.2%) were victims of falls from height. Severe lesions (AISe"3) were observed in the extremities (17.5%), in the cephalic segment (8.4%), chest (5.5%) and the abdomen (2.9%). Victims of Group 1 had significantly higher mean age, AIS in extremities / pelvis, AIS in the thoracic segment and ISS (p <0.05). The group 1 had significantly (p <0.05) higher incidence of tracheal intubation on admission, pneumothorax, hemothorax, rib fractures, chest drainage, spinal trauma, pelvic fractures, complex pelvic fractures and fractures to the upper limbs.CONCLUSION: Victims of fall from height had greater anatomic injury severity, greater frequency and severity of lesions in the thoracic segment and extremities.

Comparative analysis between identified injuries of victims of fall from height and other mechanisms of closed trauma

OBJECTIVE:to identify predictors of death in blunt trauma patients sustaining pelvic fractures and, posteriorly, compare them to a previously reported series from the same center.METHOD: Retrospective analysis of trauma registry data, including blunt trauma patients older than 14 y.o. sustaining pelvic fractures admitted from 2008 to 2010. Patients were assigned into group 1 (dead) or 2 (survivors). We used Student's t, qui square and Fisher's tests for statistical analysis, considering p<0.05 as significant. Posteriorly, we compared predictors of death between both periods.RESULTS: Seventy-nine cases were included. Mean RTS, ISS and TRISS were, respectively, 6.44 + 2.22, 28.0 + 15.2 e 0.74 + 0.33. Nineteen patients died (24,0%). Main cause of death was hemorrhage (42,1%). Group 1 was characterized by (p<0.05) lower systolic blood pressure and Glasgow coma scale means on admission, higher heart rate, head AIS, extremity AIS and ISS means, as well as, higher frequency of severe head injuries and complex pelvic fractures. Comparing both periods, we notice that the anatomic and physiologic severity of injury increased (RTS and ISS means). Furthermore, there was a decrease in the impact of associated thoracic and abdominal injuries on the prognosis and an association of lethality with the presence of complex pelvic fractures.CONCLUSION: There were significant changes in the predictors of death between these two periods. The impact of thoracic and abdominal associated injures decreased while the importance of severe retroperitoneal hemorrhage increased. There was also an increase in trauma severity, which accounted for high lethality.

Comparative analysis of the frequency and the severity of diagnosed lesions between pedestrians struck by motor vehicles and other blunt trauma mechanisms victims

ABSTRACTObjective:to compare the frequency and the severity of diagnosed injuries between pedestrians struck by motor vehicles and victims of other blunt trauma mechanisms.Methods:retrospective analysis of data from the Trauma Registry, including adult blunt trauma patients admitted from 2008 to 2010. We reviewed the mechanism of trauma, vital signs on admission and the injuries identified. Severity stratification was carried using RTS, AIS-90, ISS e TRISS. Patients were assigned into group A (pedestrians struck by motor vehicle) or B (victims of other mechanisms of blunt trauma). Variables were compared between groups. We considered p<0.05 as significant.Results:a total of 5785 cases were included, and 1217 (21,0%) of which were in group A. Pedestrians struck by vehicles presented (p<0.05) higher mean age, mean heart rate upon admission, mean ISS and mean AIS in head, thorax, abdomen and extremities, as well as lower mean Glasgow coma scale, arterial blood pressure upon admission, RTS and TRISS. They also had a higher frequency of epidural hematomas, subdural hematomas, subarachnoid hemorrhage, brain swelling, cerebral contusions, costal fractures, pneumothorax, flail chest, pulmonary contusions, as well as pelvic, superior limbs and inferior limbs fractures.Conclusion:pedestrian struck by vehicles sustained intracranial, thoracic, abdominal and extremity injuries more frequently than victims of other blunt trauma mechanism as a group. They also presented worse physiologic and anatomic severity of the trauma.

An Investigation into Mechanisms of Loss of Safe Basins in a 2 D.O.F. Nonlinear Oscillator

In this work we consider the transient stability of coupled motions of a 2 D.O.F. nonlinear oscillator that can represent, for example, the motions of a sea vessel under the action of trains of regular lateral waves. Instability is studied as the escape of the system from a safe potential well. The set of initial conditions in phase space that lead to acceptable motions constitutes its safe basin. We investigate the evolution of these safe basins under variation of parameters such as frequency and amplitude of waves, and an internal tuning parameter. Complex nonlinear phenomena are known to play an important role in determining the loss of safe basins as, say, wave amplitude is increased. We therefore investigate those processes, and attempt to classify them in terms of their speed relative to changes in parameter values. "Mechanism basins" are produced depicting regions of parameter space in which rapid or slow losses of safe basin are observed. We propose that a comprehensive understanding of mechanisms of loss of safe basins can be a valuable tool in assessing stability properties of these systems, and we give a conceptual view of how such information could be used.

Vasopressor mechanisms in acute aortic coarctation hypertension

Angiotensin II (ANG II) and vasopressin (AVP) act together with the mechanical effect of aortic constriction in the onset of acute aortic coarctation hypertension. Blockade of ANG II and AVP V1 receptors demonstrated that ANG II acts on the prompt (5 min) rise in pressure whereas AVP is responsible for the maintenance (30-45 min) of the arterial pressure elevation during aortic coarctation. Hormone assays carried out on blood collected from conscious rats submitted to aortic constriction supported a role for ANG II in the early stage and a combined role for both ANG II and AVP in the maintenance of proximal hypertension. As expected, a role for catecholamines was ruled out in this model of hypertension, presumably due to the inhibitory effect of the sinoaortic baroreceptors. The lack of afferent feedback from the kidneys for AVP release from the central nervous system in rats with previous renal denervation allowed ANG II to play the major role in the onset of the hypertensive response. Median eminence-lesioned rats exhibited a prompt increase in proximal pressure followed by a progressive decline to lower hypertensive levels, revealing a significant role for the integrity of the neuroaxis in the maintenance of the aortic coarctation hypertension through the release of AVP. In conclusion, the important issue raised by this model of hypertension is the likelihood of a link between some vascular territory - probably renal - below the coarctation triggering the release of AVP, with this vasoconstrictor hormone participating with Ang II and the mechanical effect of aortic constriction in the acute aortic coarctation hypertension

The interaction of meal-related, rhythmic and homeostatic mechanisms and the generation of thirst and drinking

One of the primary goals of the study of thirst is to understand why drinking occurs under ad libitum or natural conditions. An appreciation of the experimental strategies applied by physiologists studying thirst from different perspectives can facilitate progress toward understanding the natural history of drinking behavior. Drinking research carried out using three separate perspectives - homeostatic, circadian rhythms, and food-associated - generates types of information about the mechanisms underlying drinking behavior. By combining research strategies and methods derived from each of these approaches, it has been possible to gain new information that increases our appreciation of the interactions between homeostatic mechanisms and circadian rhythms in the modulation of water intake and how these might be related to drinking associated with food intake under near natural conditions

Photochemistry and photobiology of actinic erythema: defensive and reparative cutaneous mechanisms

Sunlight is part of our everyday life and most people accept it as beneficial to our health. With the advance of our knowledge in cutaneous photochemistry, photobiology and photomedicine over the past four decades, the terrestrial solar radiation has become a concern of dermatologists and is considered to be a major damaging environmental factor for our skin. Most photobiological effects (e.g., sunburn, suntanning, local and systemic immunosuppression, photoaging or dermatoheliosis, skin cancer and precancer, etc.) are attributed to ultraviolet radiation (UVR) and more particularly to UVB radiation (290-320 nm). UVA radiation (320-400 nm) also plays an important role in the induction of erythema by the photosensitized generation of reactive oxygen species (singlet oxygen (1O2), superoxide (O2.-) and hydroxyl radicals (.OH)) that damage DNA and cellular membranes, and promote carcinogenesis and the changes associated with photoaging. Therefore, research efforts have been directed at a better photochemical and photobiological understanding of the so-called sunburn reaction, actinic or solar erythema. To survive the insults of actinic damage, the skin appears to have different intrinsic defensive mechanisms, among which antioxidants (enzymatic and non-enzymatic systems) play a pivotal role. In this paper, we will review the basic aspects of the action of UVR on the skin: a) photochemical reactions resulting from photon absorption by endogenous chromophores; b) the lipid peroxidation phenomenon, and c) intrinsic defensive cutaneous mechanisms (antioxidant systems). The last section will cover the inflammatory response including mediator release after cutaneous UVR exposure and adhesion molecule expression