Controlo mecânico de infestantes

As infestantes são plantas indesejáveis que crescem juntamente com as plantas cultivadas e que interferem no seu desenvolvimento normal. As infestantes podem ser uma das principais causas da diminuição do rendimento das culturas, porque competem com elas para o espaço, para a água, luz solar, nutrientes e dióxido de carbono, podem segregar substâncias alelopáticas, ser o meio no qual temporariamente se instalam alguns organismos responsáveis por inúmeras pragas e doenças que atacam as culturas dificultando assim o combate às mesmas, dificultam a colheita quer esta seja manual ou mecanizada, podem contaminar o produto final, depreciando-o e, asseguram a reinfestação para as culturas seguintes. O controlo de infestantes ter-se-á iniciado quando o homem deixou a de ser nómada e de assegurar as suas necessidades através da colheita de frutos e da caça e passou após a “domesticação“ das espécies animais e vegetais a fazer agricultura, tornando-se sedentário. Portanto, desde o início da agricultura, que o homem tem feito grandes esforços para controlar as plantas infestantes, primeiro à mão, depois com o uso de alguns artefactos, ferramentas e equipamentos para melhorar a eficiência no seu controlo. Hoje existem equipamentos mecânicos sofisticados tal como, substâncias químicas ou biológicas que permitem o seu controlo prevenindo ou retardando a sua germinação ou crescimento. Interferência das plantas infestantes com a cultura pode gerar perdas significativas, na qualidade e quantidade de alimentos produzidos, desperdiçando enormes quantidades de energia, especialmente não renováveis. Os custos no controlo e os efeitos sobre os rendimentos são muito variáveis, dependendo do agricultor, das espécies de plantas infestantes e da estratégia ou estratégias adoptadas para garantir a eficácia no controlo. Nas últimas cinco décadas têm vindo a fazer-se significativos avanços científicos e tecnológicos na criação de estratégias para o aumento da eficácia no controlo de infestantes seja mecanicamente, seja através da utilização de substâncias químicas ou biológicas menos tóxicas para o homem, menos agressivas ao meio ambiente, com menores custos de produção e ao mesmo tempo, mais selectivas para as culturas onde são aplicadas. A alternativa ao controlo químico de infestantes através da aplicação de herbicidas é o controlo mecânico pela utilização de diversas alfaias agrícolas, tais como a charrua de aivecas, a charrua de discos, o escarificador de braços rígidos, o escarificador de braços flexíveis (vibrocultor) e a fresa. O controlo mecânico de infestantes poderá ser levado a cabo também por máquinas de corte, como por exemplo, as gadanheiras. Cortar as infestantes numa fase de desenvolvimento antes da produção de semente evita a sua propagação. Se o agricultor optar pela sementeira directa como técnica de instalação das culturas, a única alternativa que tem para o controlo de infestantes é a química, mas se optar pelo sistema de mobilização tradicional ou pela mobilização reduzida poderá controlar as infestantes, química e/ou mecanicamente. A eficácia das diferentes alfaias no controlo de infestantes depende da própria alfaia, da época do ano em que se realiza esse controlo, do estado do solo, das espécies de infestantes presentes e seu estádio de desenvolvimento. Iremos no presente trabalho, referir os aspectos mais importantes do controlo mecânico de infestantes

Type II Diabetes Patients under Sildenafil Citrate: Case Series Showing Benefits and a Side Effect

Background. Diabetes mellitus is a highly prevalent disease with rapid universal growth. In 2013, there were already 382 million people with diabetes, and it is expected that by 2035, this number will double. Chronic hyperglycemia causes a series of biochemical and structural changes, especially in the eyes, kidneys, heart, arteries, and peripheral nerves, which usually leads to the progression of microvascular disease. Several literature reports showed that the chronic use of phosphodiesterase-5 inhibitors enhances the insulin sensitivity, improves the markers of endothelial function, and helps in the treatment of severe extremity ischemia and pulmonary hypertension. We aim to test the effect of sildenafil citrate (SC) as a glucose and microcirculation regulator in diabetic patients, paying special attention to the consequences of its use in the regulation of blood glucose level. Case Presentation. Two male patients, aged 53 and 73 years, with type II diabetes, using oral hypoglycemic agents and presenting pathology associated with microcirculation alterations and ischemia, were medicated daily with SC. Both patients presented a reduction in the glycemic level, requiring lower doses or no other oral diabetes medications. Patient 1, who presented diabetic foot, was treated in the ambulatory, and patient 2, with chronic obstructive pulmonary disease and consequent mild pulmonary hypertension, was treated in the office. In addition to the clinical improvement of foot wounds and dyspnea due to the increase in microcirculatory perfusion, hypoglycemic episodes were observed in both patients under SC. The patient with pulmonary hypertension experienced one severe hypoglycemia episode and had to be taken to an emergency room. Conclusion. Type 2 diabetic patients may benefit from the use of a phosphodiesterase-5 inhibitor in order to improve the microcirculatory perfusion as well as glycemic control. However, adverse side effects may involve hypoglycemia. Since off-label use of SC in patients suffering from microcirculatory alterations has increased recently, our results showed that more studies are needed to verify the prevalence of hypoglycemia episodes as well as it's possible physiologic mechanism

Transport of UDP-galactose into the Golgi lumen regulates the biosynthesis of proteoglycans

The lumen of the Golgi apparatus is the subcellular site where galactose is transferred, from UDP-galactose, to the oligosaccharide chains of glycoproteins, glycolipids, and proteoglycans. The nucleotide sugar, which is synthesized in the cytosol, must first be transported into the Golgi lumen by a specific UDP-galactose transporter. Previously, a mutant polarized epithelial cell (MDCKII-RCAr) with a 2% residual rate of transport of UDP-galactose into the lumen of Golgi vesicles was described (Brandli, A. W., Hansson, G. C., Rodriguez-Boulan, E., and Simons, K. (1988) J. Biol. Chem. 263, 16283-16290). The mutant has an enrichment in glucosyl ceramide and cell surface glycoconjugates bearing terminal N-acetylglucosamine, as well as a 75% reduction in sialylation of cell surface glycoproteins and glycosphingolipids. We have now studied the biosynthesis of galactose containing proteoglycans in this mutant and the corresponding parental cell line. Wild-type Madin-Darby canine kidney cells synthesize significant amounts of chondroitin sulfate, heparan sulfate, and keratan sulfate, while the above mutant synthesizes chondroitin sulfate and heparan sulfate but not keratan sulfate, the only proteoglycan containing galactose in its glycosaminoglycan polymer. The mutant also synthesizes chondroitin 6-sulfate rather than only chondroitin 4-sulfate as wild-type cells. Together, the above results demonstrate that the Golgi membrane UDP-galactose transporter is rate-limiting in the supply of UDP-galactose into the Golgi lumen; this in turn results in selective galactosylation of macromolecules. Apparently, the Km for galactosyltransferases involved in the synthesis of linkage regions of heparan sulfate and chondroitin sulfate are significantly lower than those participating in the synthesis of keratan sulfate polymer, glycoproteins, and glycolipids. The results also suggest that the 6-O-sulfotransferases, in the absence of their natural substrates (keratan sulfate) may catalyze the sulfation of chondroitin 4-sulfate as alternative substrate

Minimum Fragments of the Heparin Molecule Able to Produce the Accumulation and Change of the Sulfation Pattern of an Antithrombotic Heparan Sulfate from Endothelial Cells

Heparin and low molecular weight heparins stimulate two to three fold the accumulation of an antithrombotic heparan sulfate secreted by endothelial cells in culture. This led us to search for the minimum structural requirements of the heparin molecule able to elicit the enhancement of the heparan sulfate. Fragments were prepared from heparin by degradation with bacterial heparinase and heparitinases. A heparin pentasulfated tetrasaccharide was shown to be the minimum structural sequence able to enhance two to three fold the secretion of heparan sulfate by endothelial cells. The stimulation is specific for the endothelial cell, is concentration dependent and the effect is already noticed after one hour of exposure of the cells to heparin and the tetrasaccharide. Degradation of the [S-35]-heparan sulfate synthesized in the presence of heparin or the tetrasaccharide has shown a higher degree of sulfation of its iduronic acid residues.ESCOLA PAULISTA MED,DEPT BIOQUIM,BR-04044 SAO PAULO,BRAZILESCOLA PAULISTA MED,DEPT BIOQUIM,BR-04044 SAO PAULO,BRAZILWeb of Scienc

Genotoxicity in peripheral blood leukocytes and reticulocytes of e-waste management workers

Abstract publicado em: Toxicology Letters 2023 Sep;384(Suppl 1):S64. https://doi.org/10.1016/S0378-4274(23)00425-3The European Commission has recently adopted a new Circular Economy Action Plan, which recognizes the critical role of material circulation in achieving sustainable development. The waste management sector will play a pivotal role in this, and an increase in the number of workers involved in waste recycling is expected. However, a recent multi-centric study conducted as part of the European Human Biomonitoring Initiative (HBM4EU) highlights potential occupational health risks associated with e-waste management. This study reports the exposure of e-waste workers from six European countries to metals and the early genotoxic effects from exposure to a wide array of toxic chemicals (and their mixtures) in the occupational environment. The results showed that e-waste workers are exposed to higher levels of hazardous metals such as lead (Pb), cadmium (Cd), mercury (Hg), and chromium (Cr) than controls. Significantly higher levels were detected in the post-shift urine and blood samples of different subcategories of e-waste workers. Especially the level of Pb was elevated in urine and blood samples among all worker categories, and the highest values were detected in battery recycling workers. Genotoxic effects were assessed by the micronucleus frequencies in peripheral blood lymphocytes (MNPBL) and reticulocytes (MNRET). MNPBL were analyzed in 95 workers and 50 controls, and MNRET in 82 workers and 41 controls. While there were no statistically significant differences between all workers and controls, the subgroup of battery recycling workers showed significantly higher frequency of MNPBL than controls or other exposed subgroups such as workers handling white goods, metals and plastics or miscellaneous e-waste. The highest MNPBL and MNRET frequencies were observed in workers handling brown goods, but the difference to controls, or to the other worker categories, was not statistically significant. Post-shift urinary levels of studied metals did not show positive correlation with the micronucleus frequencies, which might be partially explained by the heterogeneity of activities considered and related exposure levels found. In addition to metals, the study also measured exposure to flame retardants, phthalates, and polychlorinated biphenyls (PCBs) and, thereby, correlations between exposure to those compounds and effect biomarkers will be further explored. Overall, the study highlights the need to raise awareness of potential hazards and improve risk management measures in the e-waste management sector. The micronucleus results provide valuable new information on early biological effects from occupational exposures during e-waste management that also contribute to identifying worker groups that are at higher risk of adverse health effects.Funding was received from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 733032 (HBM4EU, European Human Biomonitoring Initiative), from the European Union’s Horizon Europe research and innovation programme under Grant Agreement No 101057014 (PARC, European Partnership for the Assessment of Risks from Chemicals) and received co-funding from the author’s organizations and/or Ministries and other national funding sources such as the Finnish Work Environment Fund (grant agreement no 200345) .N/

Effect biomarkers in e-waste management workers

During e-waste handling/processing, a broad range of toxic chemicals (metals and persistent organic compounds), are released and may affect workers’ health. This work intended to identify genotoxic effects in workers from European e-waste management companies. Micronuclei were analysed in peripheral blood lymphocytes (MNPBL) from 95 workers and 50 controls and in reticulocytes (MNRET) from 82 workers and 41 controls. No statistically significant differences were detected between the total exposed and control groups, for both MNPBL and MNRET frequencies. Stratification of workers in subgroups according to the main activities performed revealed that the subgroup involved in batteries recycling (n=23) presented a frequency of MNPBL significantly higher than that of controls. Significant differences in MNPBL frequencies were also found between battery workers and the subgroups handling/processing white goods, metals and plastics, and miscellaneous E-waste; no differences in MNRET frequencies among subgroups were detected. Worth to note, the subgroup dealing with brown goods (n=12) displayed the highest MNPBL and MNRET frequencies, although statistical significances were not observed when comparing with the other subgroups or controls. These preliminary results highlight the value of adding effect biomarkers to biomonitoring campaigns, to uncover groups of workers at enhanced risk and to prioritize risk management measures’ implementation.This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 733032, from the European Union’s Horizon Europe research and innovation programme under Grant Agreement No 101057014 (European Partnership for the Assessment of Risks from Chemicals) and received co-funding from the author’s organizations and/or Ministries.info:eu-repo/semantics/publishedVersio

Endocytosis and the Participation of Glycosaminoglycans Are Important to the Mechanism of Cell Death Induced by β-Hairpin Antimicrobial Peptides

The cytotoxic mode of action of four antimicrobial peptides (AMPs) (gomesin, tachyplesin, protegrin, and polyphemusin) against a HeLa cell tumor model is discussed. A study of cell death by AMP stimulation revealed some similarities, including annexin-V externalization, reduction of mitochondrial potential, insensitivity against inhibitors of cell death, and membrane permeabilization. Evaluation of signaling proteins and gene expression that control cell death revealed wide variation in the responses to AMPs. However, the ability to cross cell membranes emerged as an important characteristic of AMP-dependent cell death, where endocytosis mediated by dynamin is a common mechanism. Furthermore, the affinity between AMPs and glycosaminoglycans (GAGs) and GAG participation in the cytotoxicity of AMPs were verified. The results show that, despite their primary and secondary structure homology, these peptides present different modes of action, but endocytosis and GAG participation are an important and common mechanism of cytotoxicity for β-hairpin peptides

Proliferation and cell cycle of EC-derived cell lines.

<p>(<b>A</b>) Growth curves of EC, EJ-<i>ras</i> transfected cells (EJ-ras EC), and EC anoikis resistant (Adh1⁻EC and Adh2⁻EC). (B) BrdU incorporation for 20 h. Serum-starved EC, EJ-ras-transfected cells (EJ-ras EC) and EC anoikis resistant (Adh1⁻EC and Adh2⁻EC) were serum-starved, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116001#s2" target="_blank">Methods</a>, and stimulated to proliferate by the addition of 10% FCS. (C) Cell cycle distribution of EC, EJ-<i>ras</i> transfected cells (EJ-ras EC), and EC anoikis resistant (Adh1⁻EC and Adh2⁻EC). Histograms show the proportion of cells at different stages in the cell cycle (DNA content of propidium iodide–stained nuclei) analyzed by flow cytometry. ABS: absorbance. All experiments were repeated three times. The bars represent the standard error. * P≤0.05.</p