Mevalonate dependency of the early cell cycle mitogenic response to epidermal growth factor and prostaglandin F2α in Swiss mouse 3T3 cells

Lovastatin (LOV), a hydroxy-methylglutaryl-coenzyme A (HMGCoA) reductase competitive inhibitor, blocks epidermal growth factor (EGF)— or prostaglandin F_2α (PGF_2α)—induced mitogenesis in confluent resting Swiss 3T3 cells. This inhibition occurs even in the presence of insulin, which potentiates the action of these mitogens in such cells. LOV exerts its effect in a 2–80 μM concentration range, with both mitogens attaining 50% inhibition at 7.5 μM. LOV exerted its effect within 0–8 h following mitogenic induction. Mevanolactone (10–80 μM) in the presence of LOV could reverse LOV inhibition within a similar time period. LOV-induced blockage of PGF_2α response is reflected in a decrease in the rate of cell entry into S phase. Neither cholesterol, ubiquinone, nor dolichols of various lengths could revert LOV blockage. In EGF- or PGF_2α-stimulated cells, LOV did not inhibit [³H]leucine or [³H]mannose incorporation into proteins, while tunicamycin, an inhibitor of N′ glycosylation, prevented this last phenomenon. Thus, it appears that LOV exerts its action neither by inhibiting unspecific protein synthesis nor by impairing the N′ glycosylation process. These findings strongly suggest that either EGF or PGF_2α stimulations generate early cell cycle signals which induce mevalonate formation, N′ glycoprotein synthesis, and proliferation. The causal relationship of these events to various mechanisms controlling the onset of DNA synthesis is also discussed. © 1995 Wiley-Liss, Inc.     

Partial characterization of the cohemolytic factor produced by Streptococcus uberis and comparison with the CAMP-factor

Abstract Exosubstances (cohemolysins) produced by Streptococcus agalactiae (CAMP-factor) and Streptococcus uberis (Uberis-factor) showing hemolytic synergism with β-lysin produced by Staphylococcus aureus were compared. Cohemolytic activity was evaluated in the supernatants of bacterial cultures, before and after ammonium sulfate precipitation. Sheep erythrocytes sensitized with β-lysin were used as substrate. The assays were performed in microtiter plates and results were expressed as cohemolytic units/ml. Maximum cohemolytic activity was detected, respectively, after 8 h and 14 h of growth in Columbia broth in S. uberis and S. agalactiae cultures. Cohemolytic activities of both microorganisms showed similarities when submitted to various physical and chemical treatments. They were significantly decreased by heating at 60°C and 100°C, or in presence of trypsin, and were abolished in the presence of Tween 20. Activities were found to be stable in crude supernatants and concentrated preparations maintained at −20°C for 3 months. Differences were related to levels of activity and kinetics of detection during the growth cycle. The results indicate the proteic nature, at least in part, of the Uberis factor. Analysis by PAGE in the presence or absence of SDS allowed us to correlate Uberis activity with a protein band with apparent molecular mass of 42 kDa, while CAMP activity was associated with a protein band of 27 kDa.     

Role of angiotensin II and oxidative stress on renal aquaporins expression in hypernatremic rats

The aim of this study was to assess whether endogenous Ang II and oxidative stress produced by acute hypertonic sodium overload may regulate the expression of aquaporin-1 (AQP-1) and aquaporin-2 (AQP-2) in the kidney. Groups of anesthetized male Sprague–Dawley rats were infused with isotonic saline solution (control) or with hypertonic saline solution (Na group, 1 M NaCl), either alone or with losartan (10 mg kg^?1) or tempol (0.5 mg min^?1 kg^?1) during 2 h. Renal function parameters were measured. Groups of unanesthetized animals were injected intraperitoneally with hypertonic saline solution, with or without free access to water intake, Na+W, and Na?W, respectively. The expression of AQP-1, AQP-2, Ang II, eNOS, and NF-kB were evaluated in the kidney by Western blot and immunohistochemistry. AQP-2 distribution was assessed by immunofluorescence. Na group showed increased natriuresis and diuresis, and Ang II and NF-kB expression, but decreased eNOS expression. Losartan or tempol enhanced further the diuresis, and AQP-2 and eNOS expression, as well as decreased Ang II and NF-kB expression. Confocal immunofluorescence imaging revealed labeling of AQP-2 in the apical plasma membrane with less labeling in the intracellular vesicles than the apical membrane in kidney medullary collecting duct principal cells both in C and Na groups. Importantly, our data also show that losartan and tempol induces a predominantly accumulation of AQP-2 in intracellular vesicles. In unanesthetized rats, Na+W group presented increased diuresis, natriuresis, and AQP-2 expression (112?±?25 vs 64?±?16; *p?<?0.05). Water deprivation increased plasma sodium and diuresis but decreased AQP-2 (46?±?22 vs 112?±?25; §p?<?0.05) and eNOS expression in the kidney. This study is a novel demonstration that renal endogenous Ang II–oxidative stress, induced in vivo in hypernatremic rats by an acute sodium overload, regulates AQP-2 expression.     

Iron and vitamin status biomarkers and its association with physical fitness in adolescents: the HELENA study

There is a lack of studies that analyze the association between micronutrient-related biomarker status and physical fitness in adolescents. In the present study, biochemical parameters for iron and vitamin status were studied, along with objective measures of physical fitness in healthy male and female European adolescents. One thousand eighty-nine adolescents (580 girls, 12.5-17.5 yr) from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) cross-sectional study were included. Hierarchical linear models were performed to determine the associations between micronutrient biomarkers and physical fitness. Age, seasonality, latitude, body mass index, menarche (in girls), and physical activity were used as covariates. For cardiorespiratory fitness, concentrations of hemoglobin, retinol, and vitamin C in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with maximal oxygen consumption. For muscular fitness, concentrations of hemoglobin, β-carotene, retinol, and α-tocopherol in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with better performance of the standing long jump test. In summary, concentrations of hemoglobin and most antioxidant vitamins in male adolescents and β-carotene and 25(OH)D in female adolescents were positively associated with cardiorespiratory and muscular fitness, after controlling for relevant confounders. The associations between physical fitness and iron or vitamin status observed in this cross-sectional study in adolescents should be followed up by a study specifically designed to evaluate causal relationships.     

Lack of adequate seed supply is a major bottleneck for effective ecosystem restoration in Chile: friendly amendment to Bannister et al. (2018)

We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration.     

Role of melatonin in the oxidative damage prevention at different times of hepatic regeneration

The process of regenerating liver is the result of a balance between stimulating factors and inhibitors of hepatocyte proliferation. Melatonin and its metabolites have been found to protect tissues against oxidative damage generated by a variety of toxic agents and metabolic processes. Furthermore, studies in liver of rats showed a decrease in the liver mitochondrial hydroxylation of drugs returning to the normal state after the administration of antioxidants. This study was designed to determine, in experimental animals, whether the administration of an antioxidant agent such as melatonin could prevent cells events leading to tissue injury and hepatic dysfunction after partial hepatectomy (PH). Biliary flow (BF), oxidative stress in hepatic tissue and Na⁺/K⁺ATPase activities in whole plasma membrane were determined. PH decreased the Na⁺/K⁺ATPase activity. PH significantly reduced the BF (36%) and promoted oxidative stress with an increase of lipoperoxidation and decrease of glutathione peroxidase and catalase activities. Treatment with melatonin prevented the decrease of BF in rats with hepatectomy and normalized the Na⁺/K⁺ATPase activity. Moreover, melatonin markedly attenuated oxidative stress produced by PH. This may be the results of the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes. We suggest that oxidative stress before and during liver regeneration has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage and the impairment in liver transport function induced by PH and that melatonin could modulate the degree of oxidative stress and through it prevent the alterations in liver function carrier. Copyright © 2012 John Wiley & Sons, Ltd.     

The Construction of Turrets for Nest Ventilation in the Grass-Cutting Ant Atta vollenweideri: Import and Assembly of Building Materials

Besides the excavation of underground nest chambers, Atta vollenweideri grass-cutting ants build ventilation turrets on the topmost openings of their huge nests. Turret construction was studied in a laboratory colony, addressing the question whether turrets are simply heaps of disposed soil, or result from the import and a particular spatial arrangement of materials. The colony was daily offered different building materials, i.e., clay, coarse and fine sands, which workers collected and deposited around a nest opening to construct a turret. After 10 days, the spatial arrangement of the different building materials, offered either simultaneously or consecutively in independent experiments, was characterized via thin sections and micromorphological analysis of the turret’s walls. Workers did not select particular materials to be imported for turret building, but were selective in their spatial distribution and assembly into the turret structure. Particular types of microstructures were observed depending on the available materials, such as simple piles of sands, porous fabrics only composed of clay pellets, or fabrics with clay and sands combined. Turrets were very dynamic structures: while most imported materials were initially piled up at the shortest distance from the source, a marked subsequent material redistribution occurred as the turret grew, resulting in a new, mixed structure. Material re-assembly was particular evident when clay and sands were offered consecutively: a remarkable tendency to construct microstructures combining both materials was observed, i.e., clays were mobilized and included in sandy walls, and sands were intercalated in much compact clay walls. Irrespective of the materials used, walls showed a marked regular porosity in the range 50–60%, with the exception of secondary galleries that occasionally permeated the turret structure, which evinced lower porosity and therefore a more compact microstructure. Ants appeared to respond to local variations in the structural stability of the construction, since clay coatings smoothed and reinforced the surface of unstable sandy gallery walls. The observed building responses appear to be aimed at the maintenance of a porous yet mechanically-stable structure. The attained turret porosity may represent a compromise between high structural stability and low construction costs because of savings in material import.     

Hospital costs associated with delirium in older medical patients

Introduction

Delirium is a common and serious complication in older patients, associated with increased, potentially preventable, morbidity and mortality. The aim of this study was to evaluate the associated costs of delirium during hospitalization in a university affiliated hospital in Chile.

Materials and methods

Prospective cohort study of consecutive patients 65 years and older, admitted to a medical ward. A psychogeriatric team assessed patients during the first and every 48 h until discharge using the Confusion Assessment Method (CAM-S), length of hospital stay, pharmacy and total hospitalization costs were analyzed. Statistical analysis was performed using bivariate and multivariate analysis according to delirium diagnosis.

Results

Data from 454 patients was analyzed, 160 of them in a delirium cohort (35.2%) and 294 in a non-delirium cohort (64.8%). The delirium cohort had a longer hospital stay (DATA) and higher mortality (7.0% versus 1.7%). The median of total costs of delirium during hospital stay was 38.7% higher than the non-delirium cohort (P < .001). Total costs were significantly higher in the delirium cohort after adjustment of covariables (P = .01).

Conclusions

This study confirms that delirium is associated with significantly greater costs. Considering that effective delirium prevention is possible, the knowledge of associated costs can help health care providers to justify prevention strategies and finally give better care for older patients.     

Toll-like receptor 4 gene polymorphism influences dendritic cell in vitro function and clinical outcomes in vaccinated melanoma patients

Toll-like receptor 4 (TLR4) is expressed on dendritic cells (DCs), sensing environmental danger molecules that induce their activation and maturation. Recently, we reported a method for the production of therapeutic DCs against melanoma, called tumor antigen-presenting cells (TAPCells), using a heat-shocked allogeneic melanoma cell lysate (TRIMEL) as an activation factor and antigen provider. Since TRIMEL contains endogenous TLR4 ligands, we evaluated the role of TLR4 in TAPCells differentiation by antibody neutralization and the association of a Tlr4 polymorphism (896A/G) (Asp299Gly), determined by PCR–RFLP, with the in vitro activation capacity and the clinical outcome of TAPCells-vaccinated patients. Antibody blocking of monocyte TLR4 inhibited surface expression, determined by flow cytometry, of the major histocompatibility complex class I, CCR7, CD80, CD83 and CD86 on TAPCells, reduced interleukin (IL)-6 and tumor necrosis factor -α gene expression evaluated by qRT-PCR, and also inhibited the TAPCells-mediated interferon-γ (IFN-γ) secretion of melanoma-specific CD8⁺ T cells determined by ELISpot (p?<?0.01). Moreover, CD8⁺ T-cell activation capacity was significantly reduced in TAPCells bearing the TLR4 Asp299Gly receptor (p?<?0.05). Finally, TAPCells-vaccinated stage-IV melanoma patients bearing the Tlr4 896G allele showed a shortened post-therapy median survival rate compared with those carrying the Tlr4 896A allele (p?<?0.05; log-rank test). Our results indicate that TLR4 is a key receptor for the tumor lysate-mediated in vitro generation of clinically efficient antigen-presenting cells. Further analysis of patients included in different vaccine protocols is necessary for definitively establishing a role for TLR4 polymorphism in clinical responses.