Polymerization of tau into filaments in the presence of heparin: the minimal sequence required for tau-tau interaction

Paired helical filaments isolated from the brains of patients with Alzheimer's disease are composed of a major protein component, the microtubule-associated protein termed tau, together with other nonprotein components, including heparan, a glycosaminoglycan, the more extensively sulfated form of which is heparin. As some of these nonprotein components may modulate the assembly of tau into filamentous structures, we have analyzed the ability of the whole tau protein or some of its fragments to self-assemble in the presence of heparin. Different tau fragments, all of them containing some sequences of the tubulin-binding motif, can assemble in vitro into filaments. We have also found formation of polymers with the 18-residue-long peptide corresponding to the third tubulin-binding motif of tau. This suggests that the ability of tau for self-assembly could be localized in a short sequence of amino acids present in the tubulin-binding repeats of the tau molecule.

A novel GSK-3beta inhibitor reduces Alzheimer's pathology and rescues neuronal loss in vivo

Amyloid deposits, neurofibrillary tangles, and neuronal cell death in selectively vulnerable brain regions are the chief hallmarks in Alzheimer's (AD) brains. Glycogen synthase kinase-3 (GSK-3) is one of the key kinases required for AD-type abnormal hyperphosphorylation of tau, which is believed to be a critical event in neurofibrillary tangle formation. GSK-3 has also been recently implicated in amyloid precursor protein (APP) processing/Abeta production, apoptotic cell death, and learning and memory. Thus, GSK-3 inhibition represents a very attractive drug target in AD and other neurodegenerative disorders. To investigate whether GSK-3 inhibition can reduce amyloid and tau pathologies, neuronal cell death and memory deficits in vivo, double transgenic mice coexpressing human mutant APP and tau were treated with a novel non-ATP competitive GSK-3beta inhibitor, NP12. Treatment with this thiadiazolidinone compound resulted in lower levels of tau phosphorylation, decreased amyloid deposition and plaque-associated astrocytic proliferation, protection of neurons in the entorhinal cortex and CA1 hippocampal subfield against cell death, and prevention of memory deficits in this transgenic mouse model. These results show that this novel GSK-3 inhibitor has a dual impact on amyloid and tau alterations and, perhaps even more important, on neuronal survival in vivo further suggesting that GSK-3 is a relevant therapeutic target in AD.

Efficacy of the rhesus rotavirus-based quadrivalent vaccine in infants and young children in Venezuela

BACKGROUND

Rotaviruses are the principal known etiologic agents of severe diarrhea among infants and young children worldwide. Although a rhesus rotavirus-based quadrivalent vaccine is highly effective in preventing severe diarrhea in developed countries, in developing countries its efficacy has been less impressive. We thus conducted a catchment study in Venezuela to assess the efficacy of the vaccine against dehydrating diarrhea.

METHODS

In this randomized, double-blind, placebo-controlled trial, 2207 infants received three oral doses of the quadrivalent rotavirus vaccine (4x10(5) plaque-forming units per dose) or placebo at about two, three, and four months of age. During approximately 19 to 20 months of passive surveillance, episodes of gastroenteritis were evaluated at the hospital.

RESULTS

The vaccine was safe, although 15 percent of the vaccinated infants had febrile episodes (rectal temperature, > or =38.1 degrees C) during the six days after the first dose, as compared with 7 percent of the controls (P<0.001). However, the vaccine gave 88 percent protection against severe diarrhea caused by rotavirus and 75 percent protection against dehydration, and produced a 70 percent reduction in hospital admissions. Overall, the efficacy of the vaccine against a first episode of rotavirus diarrhea was 48 percent. Horizontal transmission of vaccine virus was demonstrated in 15 percent of the vaccine recipients and 13 percent of the placebo recipients with rotavirus-positive diarrhea.

CONCLUSIONS

In this study in a developing country, the quadrivalent rhesus rotavirus-based vaccine induced a high level of protection against severe diarrheal illness caused by rotavirus.

Saliva composition and exercise

Little attention has been directed toward identifying the changes which occur in salivary composition in response to exercise. To address this, our article first refers to the main aspects of salivary gland physiology. A knowledge of the neural control of salivary secretion is especially important for the understanding of the effects of exertion on salivary secretion. Both salivary output and composition depend on the activity of the autonomic nervous system and any modification of this activity can be observed indirectly by alternations in the salivary excretion. The effects of physical activity (with reference to factors such as exercise intensity and duration, or type of exercise protocol) on salivary composition are then considered. Exercise might indeed induce changes in several salivary components such as immunoglobulins, hormones, lactate, proteins and electrolytes. Saliva composition might therefore be used as an alternative noninvasive indicator of the response of the different body tissues and systems to physical exertion. In this respect, the response of salivary amylase and salivary electrolytes to incremental levels of exercise is of particular interest. Beyond a certain intensity of exercise, and coinciding with the accumulation of blood lactate (anaerobic threshold or AT), a 'saliva threshold' (Tsa) does indeed exist. Tsa is the point during exercise at which the levels of salivary alpha-amylase and electrolytes (especially Na+) also begin to rise above baseline levels. The occurrence of the 2 thresholds (AT and Tsa) might, in turn, be attributable to the same underlying mechanism, that of increased adrenal sympathetic activity at high exercise intensities.

Synthesis of ecteinascidin ET-743 and phthalascidin Pt-650 from cyanosafracin B

An efficient new process is described for the synthesis of ecteinascidin ET-743 (1) and phthalascidin (2), starting from readily available cyanosafracin B (3).

Antibiotic susceptibility assay for Staphylococcus aureus in biofilms developed in vitro

Four slime-producing isolates of Staphylococcus aureus were used in an antibiotic susceptibility assay for biofilms developed on 96-well polystyrene tissue culture plates. The study involved 11 antibiotics, two biofilm ages (6 and 48 h), two biofilm growth media (tryptone soy broth (TSB) and delipidated milk) and three antibiotic concentrations (4 x MBC, 100 mg/L and 500 mg/L). ATP-bioluminescence was used for automated bacterial viability determination after a 24 h exposure to antibiotics, to avoid biofilm handling. Under the conditions applied, viability in untreated biofilms (controls) was lower when biofilm growth was attempted in milk rather than in TSB. Various antibiotics had a greater effect on viability when used at higher (> or =100 mg/L) antibiotic concentrations and on younger (6 h) biofilms. Increased antibiotic effect was observed in milk-grown rather than TSB-grown biofilms. Phosphomycin and cefuroxime, followed by rifampicin, cefazolin, novobiocin, vancomycin, penicillin, ciprofloxacin and tobramycin significantly affected biofilm cell viability at least under some of the conditions tested. Gentamicin and erythromycin had a non-significant effect on cell viability. Transmission electron microscopy revealed that cells at the inner biofilm layers tend to remain intact after antibiotic treatment and that TSB-grown biofilms favoured a uniformity of cell distribution and increased cell density in comparison with milk-grown biofilms. A reduced matrix distribution and enhanced cell density were observed as the biofilm aged. The S. aureus biofilm test discriminated antibiotics requiring shorter (3 h or 6 h) from those requiring longer (24 h) exposure and yielded results which may be complementary to those obtained by conventional tests.

Heart rate and performance parameters in elite cyclists: a longitudinal study

PURPOSE

This study was designed to evaluate the stability of target heart rate (HR) values corresponding to performance markers such as lactate threshold (LT) and the first and second ventilatory thresholds (VT1, VT2) in a group of 13 professional road cyclists (VO2max, approximately 75.0 mL x kg(-1) x min(-1)) during the course of a complete sports season.

METHODS

Each subject performed a progressive exercise test on a bicycle ergometer (ramp protocol with workload increases of 25 W x min(-1)) three times during the season corresponding to the "active" rest (fall: November), precompetition (winter: January), and competition periods (spring: May) to determine HR values at LT, VT1 and VT2.

RESULTS

Despite a significant improvement in performance throughout the training season (i.e., increases in the power output eliciting LT, VT1, or VT2), target HR values were overall stable (HR at LT: 154 +/- 3, 152 +/- 3, and 154 +/- 2 beats x min(-1); HR at VT1: 155 +/- 3, 156 +/- 3, and 159 +/- 3 beats x min(-1); and at VT2: 178 +/- 2, 173 +/- 3, and 176 +/- 2 beats x min(-1) during rest, precompetition, and competition periods, respectively).

CONCLUSION

A single laboratory testing session at the beginning of the season might be sufficient to adequately prescribe training loads based on HR data in elite endurance athletes such as professional cyclists. This would simplify the testing schedule generally used for this type of athlete.

Synthesis of enantiopure trans-3,4-disubstituted piperidines. An enantiodivergent synthesis of (+)- and (-)-paroxetine

Reaction of (R)-phenylglycinol with methyl 5-oxopentanoate gave either bicyclic lactam cis-1 (the kinetic product) or its isomer trans-1 (under equilibrating conditions) as the major products, which were converted to the corresponding (cis or trans) unsaturated lactams 4 and 5. On treatment with lithium alkyl (or aryl) cyanocuprates, these chiral building blocks undergo conjugate addition to give enantiopure trans-3,4-substituted 2-piperidone derivatives in high yield and stereoselectivity. The synthetic potential of this transformation is illustrated by the synthesis of (+)-femoxetine and the two enantiomers of the known antidepressant paroxetine.

Combined aerobic and resistance training in breast cancer survivors: A randomized, controlled pilot trial

The purpose of this pilot study was to examine the effects of a combined cardiorespiratory and resistance exercise training program of short duration on the cardiorespiratory fitness, strength endurance, task specific functional muscle capacity, body composition and quality of life (QOL) in women breast cancer survivors. Sixteen subjects were randomly assigned to either a training (n = 8; age: 50 +/- 5 yrs) or control non-exercising group (n = 8; age: 51 +/- 10 yrs). The training group followed an 8-week exercise program consisting of 3 weekly sessions of 90-min duration, supervised by an experienced investigator and divided into resistance exercises and aerobic training. Before and after the intervention period, all of the subjects performed a cardiorespiratory test to measure peak oxygen uptake (VO2peak), a dynamic strength endurance test (maximum number of repetitions for chest and leg press exercise at 30 - 35 % and 100 - 110 % of body mass, respectively) and a sit-stand test. Quality of life was assessed using the European Organization for Research and Treatment of Cancer QLQ-C30 (EORTC-C30) questionnaire. In response to training, QOL, VO2peak (mean 3.9 ml/kg/min; 95 % CI, 0.93, 6.90) performance in leg press (17.9 kg; 95 % CI, 12.8, 22.4) and sit-stand test (- 0.67 s; 95 % CI, - 0.52, - 1.2) improved (p < or = 0.05). We observed no significant changes in the control group. Combined cardiorespiratory and resistance training, even of very brief duration, improves the QOL and the overall physical fitness of women breast cancer survivors.

In situtime-resolved characterization of Au–CeO2 and AuOx–CeO2 catalysts during the water-gas shift reaction: Presence of Au and O vacancies in the active phase

Synchrotron-based in situ time-resolved x-ray diffraction and x-ray absorption spectroscopies were used to study the behavior of nanostructured {Au+AuO(x)}-CeO(2) catalysts under the water-gas shift (WGS) reaction. At temperatures above 250 degrees C, a complete AuO(x)-->Au transformation was observed with high catalytic activity. Photoemission results for the oxidation and reduction of Au nanoparticles supported on rough ceria films or a CeO(2)(111) single crystal corroborate that cationic Au(delta+) species cannot be the key sites responsible for the WGS activity at high temperatures. The rate determining steps for the WGS seem to occur at the gold-ceria interface, with the active sites involving small gold clusters (<2 nm) and O vacancies.

Small ruminant lentivirus infections and diseases

Small ruminant lentiviruses include viruses with diverse genotypes that frequently cross the species barrier between sheep and goats and that display a great genetic variability. These characteristics stress the need to consider the whole host range and to perform local surveillance of the viruses to opt for optimum diagnostic tests, in order to establish control programmes. In the absence of effective vaccines, a comprehensive knowledge of the epidemiology of these infections is of major importance to limit their spread. This article intends to cover these aspects and to summarise information related to characteristics of the viruses, pathogenesis of the infection and description of the various syndromes produced, as well as the diagnostic tools available, the mechanisms involved in transmission of the pathogens and, finally, the control strategies that have been designed until now, with remarks on the drawbacks and the advantages of each one. We conclude that there are many variables influencing the expected cost and benefits of control programs that must be evaluated, in order to put into practice measures that might lead to control of these infections.

Tau dephosphorylation at tau-1 site correlates with its association to cell membrane

It has been considered that tau protein is mainly a cytoplasmic protein since it is a microtubule associated protein. However, it has also been suggested that tau could be located in the cell nucleus and membrane. In our work, the cellular distribution of tau has been studied by immunofluorescence and western blot analysis, after subcellular fractionation in neuroblastoma cells and in tau-transfected non neural cells using, mainly, two types of tau antibodies; antibody 7.51 (that recognizes tau independent of its phosphorylation level); and antibody Tau-1 (that recognizes tau only in its dephosphorylated form). Also, tau was expressed in COS-1 cells to test for the features involved in the sorting of tau to different cell localizations. Our results show that tau associated to cell membrane has a lower phosphorylation level in its proline-rich region. Additionally, in differentiated neuroblastoma cells, tau phosphorylation, at that region, decreases and the amount of tau associated to cell membrane increases.

Polar targeting of Shigella virulence factor IcsA in Enterobacteriacae and Vibrio

Asymmetric localization is key to the proper function of certain prokaryotic proteins important to virulence, chemotaxis, cell division, development, motility, and adhesion. Shigella IcsA is localized to the old pole of the bacterium, where it mediates assembly of an actin tail inside infected mammalian cells. IcsA (VirG) is essential to Shigella intracellular motility and virulence. We used translational fusions between portions of IcsA and the green fluorescent protein (GFP) to determine the regions of IcsA that are necessary and sufficient for its targeting to the bacterial old pole. An IcsA-GFP fusion that lacks a signal peptide localized to the old pole, indicating that signal peptide-mediated secretion is not required for polar localization. Two regions within IcsA were required for localization of an IcsA-GFP fusion to the old pole. Further characterization of these regions indicated that amino acids 1-104 and 507-620 were each independently sufficient for polar localization. Finally, when expressed in Escherichia coli, Salmonella typhimurium, Yersinia pseudotuberculosis, and Vibrio cholerae, each of the two targeting regions localized to the pole, indicating that the mechanism of polar targeting used by IcsA is present generally among Enterobacteriacae and Vibrio.

Polymerization of tau peptides into fibrillar structures. The effect of FTDP-17 mutations

The peptides corresponding to the four repeats found in the microtubule binding region of tau protein were synthesized and their ability for self-aggregation in presence of heparin or chondroitin sulfate was measured. Mainly, only the peptide containing the third tau repeat is able to form polymers in a high proportion. Additionally, the peptide containing the second repeat aggregates with a very low efficiency. However, when this peptide contains the mutation (P301L), described in a fronto temporal dementia, it is able to form polymers at a higher extent. Finally, it is suggested to have a role for the first and fourth tau repeats. It could be to decrease the ability of the third tau repeat for self-aggregation in the presence of heparin.

Prospective randomized comparison of cefepime and cefotaxime for treatment of bacterial meningitis in infants and children

Ninety infants and children were prospectively randomized to receive cefepime (n = 43) or cefotaxime (n = 47) for therapy of bacterial meningitis. The two treatment groups were comparable in terms of age, duration of illness before enrollment, history of seizures, clinical status on admission, and etiology. Six (7%) patients died--two treated with cefepime and four treated with cefotaxime. Clinical response, cerebrospinal fluid sterilization, development of complications, antibiotic toxicity, and hospital stay were similar for the two treatment regimens. Concentrations of cefepime in cerebrospinal fluid varied from 55 to 95 times greater than the maximal MIC required by the causative pathogens. Audiologic and/or neurologic sequelae were found in 16% of the cefepime-treated patients and 15% of the cefotaxime-treated patients examined 2 to 6 months after discharge. We conclude that cefepime is safe and therapeutically equivalent to cefotaxime for management of bacterial meningitis in infants and children.

Hemostatic disorder of uremia: the platelet defect, main determinant of the prolonged bleeding time, is correlated with indices of activation of coagulation and fibrinolysis

Several parameters of primary hemostasis and markers of activation of coagulation and fibrinolysis were measured in 48 patients with severe (creatinine clearance < 20 ml/min) chronic renal failure (CRF) without dialysis and disease or drugs affecting hemostasis. Bleeding time (BT) was prolonged in 25/48 patients, and was correlated with age of patients, severity of renal failure, hematocrit, impairment in platelet aggregation-secretion and decrease in platelet ATP content. Defects in von Willebrand factor played no role in the prolongation of the BT. Multivariate analysis showed that only platelet dysfunction and severity of renal disease were independent predictors of the BT in uremia. The platelet functional disorder was significantly correlated with a reduction in platelet ATP and ADP. High levels of plasma thrombin-antithrombin complexes (TAT), prothrombin fragment F1 + 2, fibrinogen and factor VIIc were observed in patients with CRF, as described in prethrombotic states. Plasmin-antiplasmin complexes (PAP), fibrinogen and fibrin degradation products (FgDP, FnDP) were significantly increased, and the activity of plasminogen activator inhibitor (PAI-1) was slightly reduced, denoting an activation of fibrinolysis. A negative correlation was found between platelet levels of ATP and ADP with plasma TAT, F1 + 2 and PAP. Furthermore, plasma PAI-1 activity was negatively correlated with the BT and was lower in patients with prolonged BT as compared with controls and patients with normal BT. These links between primary hemostasis and activation of coagulation and fibrinolysis suggest that increased intravascular generation of thrombin and/or plasmin is an important mediator of the defects in primary hemostasis, prolongation of the BT and, probably, bleeding in CRF.

Expression of the human glucocorticoid receptor alpha and beta isoforms in human respiratory epithelial cells and their regulation by dexamethasone

Two isoforms of the human glucocorticoid receptor (hGR) have been described, hGRalpha and hGRbeta. We analyzed the expression and regulation of both hGR isoforms in human respiratory epithelial cells (BEAS-2B, A549, and primary nasal epithelial cells). In BEAS-2B cells, the expression of hGRalpha messenger RNA (mRNA) was much higher than that of hGRbeta mRNA. Dexamethasone (DEX) (10(-6) M) downregulated hGRalpha mRNA at 6 and 24 h (55 +/- 8 and 58 +/- 5% of control, respectively; P < 0.01), whereas it decreased hGRbeta mRNA only at 6 h (55 +/- 7% of control; P < 0.01). Downregulation of hGRalpha and hGRbeta mRNAs occurred even in the presence of cycloheximide. Actinomycin-D studies revealed that DEX enhanced the stabilization of hGRalpha and hGRbeta messages. hGRalpha but not hGRbeta protein was detected in BEAS-2B, A549, and nasal epithelial cells. After 24 h of incubation, 10(-6) M DEX decreased the expression of hGRalpha protein in BEAS-2B, A549, and nasal epithelial cells (16 +/- 4, 14 +/- 4, and 28 +/- 7% of control, respectively; P < 0.01). These results suggest that in respiratory epithelial cells: (1) hGRalpha is much more expressed than hGRbeta at both the mRNA and protein levels; (2) hGRalpha is downregulated by corticosteroids both in cell lines (BEAS-2B, A549) and in nasal primary cells; and (3) transcriptional, post-transcriptional, and post-translational mechanisms appear to be involved in the regulation of hGR expression by corticosteroids.

Benefits of intrahospital exercise training after pediatric bone marrow transplantation

The purpose of this study was to determine if an eight-week intrahospital supervised, conditioning program improves functional capacity and quality of life (QOL) in children (4 boys, 4 girls) (mean [SD] age: 10.9 [2.8] years [range: 8-16]) who have undergone bone marrow transplantation (BMT) for leukemia treatment within the last 12 months. A group of 8 age and gender-matched healthy children served as controls. The experimental group performed 3 weekly sessions of resistance and aerobic training inside an intra-hospital gymnasium. A significant combined effect of group and time (p < 0.05) was observed for muscle functional capacity (Timed Up and Down Stairs [TUDS] test) and peak oxygen uptake (V.O(2peak)), i.e., with BMT children showing greater improvements than controls (V.O(2peak) at pre- and post-training of 25.9 (8.2) and 31.1 (7.6) mL/kg/min in diseased children). Muscle strength (6 RM test for bench and leg press and seated row) also improved after training (p < 0.05) in the BMT group. Concerning QOL, a significant combined effect of group and time (p < 0.05) was also observed for children's self-report of comfort and resilience and for parents' report of their children's satisfaction and achievement. In summary, children who have received BMT experience physical and overall health benefits after a relatively short-term (8 weeks) supervised exercise training program.

Reproductive function in male endurance athletes: sperm analysis and hormonal profile

The purpose of this investigation was to study the effects of endurance exercise on male reproductive function (sex hormones and seminograms). Professional cyclists [n = 12; mean age 24 +/- 2 (SD) yr], elite triathletes (n = 9; 26 +/- 3 yr), recreational marathon runners (n = 10; 32 +/- 6 yr), and sedentary subjects (control group; n = 9; 30 +/- 4 yr) were selected as subjects. for each group, the following parameters were measured three times during the sports season (training period: winter; competition period: spring; resting period: fall): percentage of body fat, hormonal profile (resting levels of follicle-stimulating hormone, luteinizing hormone, total and free testosterone, and cortisol), and seminograms (quantitative parameters sperm volume and sperm count; qualitative parameters: sperm motality and morphology). The following comparisons were made in the measured parameters: 1) within groups (longitudinal design) and 2) between groups in each of the three periods (cross-sectional design) and over time (mixed design). In addition, both the volume and the intensity of training of each subject during the season (except for the control group) were quantified. Despite significant differences in training characteristics and in body fat percent, in general no significant differences (P > 0.05) were found in hormonal profiles or in semen characteristics between or within groups. A lower sperm motility (46.2 +/- 19.5%), however, was observed in the cyclists during the competition period when compared either with the other groups during this same period (P < 0.05) or with themselves during the other two periods of study (P < 0.01). In any case, the later phenomenon was attributed to physical factors associated with cycling, such as mechanical trauma to the testis and/or increased gonadal temperature. In conclusion, our findings suggest that endurance exercise does not adversely affect the hypothalamic-pituitary-testis axis.

Applications of artificial intelligence in dentistry: A comprehensive review

OBJECTIVE

To perform a comprehensive review of the use of artificial intelligence (AI) and machine learning (ML) in dentistry, providing the community with a broad insight on the different advances that these technologies and tools have produced, paying special attention to the area of esthetic dentistry and color research.

MATERIALS AND METHODS

The comprehensive review was conducted in MEDLINE/PubMed, Web of Science, and Scopus databases, for papers published in English language in the last 20 years.

RESULTS

Out of 3871 eligible papers, 120 were included for final appraisal. Study methodologies included deep learning (DL; n = 76), fuzzy logic (FL; n = 12), and other ML techniques (n = 32), which were mainly applied to disease identification, image segmentation, image correction, and biomimetic color analysis and modeling.

CONCLUSIONS

The insight provided by the present work has reported outstanding results in the design of high-performance decision support systems for the aforementioned areas. The future of digital dentistry goes through the design of integrated approaches providing personalized treatments to patients. In addition, esthetic dentistry can benefit from those advances by developing models allowing a complete characterization of tooth color, enhancing the accuracy of dental restorations.

CLINICAL SIGNIFICANCE

The use of AI and ML has an increasing impact on the dental profession and is complementing the development of digital technologies and tools, with a wide application in treatment planning and esthetic dentistry procedures.

A prospective study of unplanned endotracheal extubation in intensive care unit patients

OBJECTIVE

To evaluate incidence, factors associated with unplanned endotracheal extubation (UEE), and prognostic factors for reintubation.

DESIGN

A prospective study over a 32-mo period.

SETTING

A 16-bed general intensive care unit of a tertiary university hospital.

PATIENTS

Adult subjects undergoing endotracheal intubation for >48 hrs.

INTERVENTIONS

Observation of patients who presented unplanned extubation.

MEASUREMENTS AND MAIN RESULTS

Over the 32-mo period, there were 59 episodes of UEE in 55 patients (frequency 7.3%). Deliberate self-extubation occurred in 46 episodes (77.9%), while there were 13 episodes (22.1%) of accidental extubation. Twenty-seven (45.8%) episodes occurred in patients who were receiving full mechanical ventilatory support and 32 (54.2%) episodes occurred during the weaning period from mechanical ventilation. Reintubation was required in 27 (45.8%) episodes of UEE. The need for reintubation after UEE was 36.9% in deliberate self-extubation patients and 76.9% in accidental extubation patients (p = .01). Only 15.6% (5/32) of patients who presented UEE during weaning required reintubation, while reintubation was mandatory in 81.5% (22/27) of patients who presented UEE during full mechanical ventilatory support (p < .001). A multiple logistic regression analysis was performed to determine the variables independently associated with the need for reintubation: days of mechanical ventilation were significantly associated with the need for reintubation, and weaning was associated with no need for reintubation. The model correctly classified the need for reintubation in 84.7% (50/59) of cases.

CONCLUSIONS

Reintubation in UEE patients strongly depends on the type of mechanical ventilatory support. The probability of requiring reintubation if UEE occurs during full ventilatory support is higher than if UEE occurs during weaning. These data suggest that some patients are under mechanical ventilation longer than necessary.

Role of Angiotensin II type 1 receptor on renal NAD(P)H oxidase, oxidative stress and inflammation in nitric oxide inhibition induced-hypertension

AIMS

Activation of the renin-angiotensin system (RAS), renal oxidative stress and inflammation are constantly present in experimental hypertension. Nitric oxide (NO) inhibition with N(w)-nitro-L-arginine methyl ester (L-NAME) has previously been reported to produce hypertension, increased expression of Angiotensin II (Ang II) and renal dysfunction. The use of Losartan, an Ang II type 1 receptor (AT1R) antagonist has proven to be effective reducing hypertension and renal damage; however, the mechanism by which AT1R blockade reduced kidney injury and normalizes blood pressure in this experimental model is still complete unknown. The current study was designed to test the hypothesis that AT1R activation promotes renal NAD(P)H oxidase up-regulation, oxidative stress and cytokine production during L-NAME induced-hypertension.

MAIN METHODS

Male Sprague-Dawley rats were distributed in three groups: L-NAME, receiving 70 mg/100ml of L-NAME, L-NAME+Los, receiving 70 mg/100ml of L-NAME and 40 mg/kg/day of Losartan; and Controls, receiving water instead of L-NAME or L-NAME and Losartan.

KEY FINDINGS

After two weeks, L-NAME induced high blood pressure, renal overexpression of AT1R, NAD(P)H oxidase sub-units gp91, p22 and p47, increased levels of oxidative stress, interleukin-6 (IL-6) and interleukin-17 (IL-17). Also, we found increased renal accumulation of lymphocytes and macrophages. Losartan treatment abolished the renal expression of gp91, p22, p47, oxidative stress and reduced NF-κB activation and IL-6 expression.

SIGNIFICANCE

These findings indicate that NO induced-hypertension is associated with up-regulation of NADPH oxidase, oxidative stress production and overexpression of key inflammatory mediators. These events are associated with up-regulation of AT1R, as evidenced by their reversal with AT1R blocker treatment.

Phosphorylated, but not native, tau protein assembles following reaction with the lipid peroxidation product, 4-hydroxy-2-nonenal

A correlation between hyperphosphorylation of tau protein and its aberrant assembly into paired helical filaments has lead to suggestions that phosphorylation controls assembly, but lacked a mechanistic basic. In this work, we have found that phosphorylated, but not native, tau protein is able to form polymers after the reaction with 4-hydroxy-2-nonenal, a highly toxic product of lipid peroxidation. Phosphorylation of tau by both proline or non-proline directed kinases, was able to assemble it into polymers.

GSK3beta-mediated phosphorylation of the microtubule-associated protein 2C (MAP2C) prevents microtubule bundling

A major determinant of neuronal morphology is the cytoskeleton. And one of the main regulatory mechanisms of cytoskeletal proteins is the modification of their phosphorylation state via changes in the relative activities of protein kinases and phosphatases in neurons. In particular, the microtubule-associated protein 2 (MAP2) family of proteins are abundant cytoskeletal components predominantly expressed in neurons and have been found to be substrates for most of protein kinases and phosphatases present in neurons, including glycogen-synthase kinase 3 (GSK3). It has been suggested that changes in GSK3-mediated MAP phosphorylation may modify MT stability and could control neuronal development. We have previously shown that MAP2 is phosphorylated in vitro and in situ by GSK3 at Thr1620 and Thr1623, located in the proline-rich region of MAP2 and recognized by antibody 305. However, the function of the phosphorylation of this site of MAP2 is still unknown. In this study, non-neuronal COS-1 cells have been co-transfected with cDNAs encoding MAP2C and either wild type or mutated GSK3beta to analyze possible effects on microtubule stability and on the association of MAP2 with microtubules. We have found that GSK3beta phosphorylates MAP2C in co-transfected cells. Moreover, this phosphorylation is inhibited by the specific GSK3 inhibitor lithium chloride. Additionally, the formation of microtubule bundles, which is observed after transfection with MAP2C, was decreased when MAP2C was co-transfected with GSK3beta wild type. Microtubule bundles were not observed in cells expressing MAP2C phosphorylated at the site recognized by antibody 305. The absence of microtubule bundles was reverted after treatment of MAP2C/GSK3beta wild type transfected cells with lithium chloride. Highly phosphorylated MAP2C species, which were phosphorylated at the site recognized by antibody 305, appeared in cells co-transfected with MAP2C and GSK3beta wild type. Interestingly, these MAP2C species were enriched in cytoskeleton-unbound protein preparations. These data suggests that GSK3-mediated phosphorylation of MAP2 may modify its binding to microtubules and regulate microtubule stability.

Modulation of the allergic reactivity of slum children by helminthic infection

Infection by helminthic parasites can cause the polyclonal stimulation of IgE synthesis, possibly via an enhanced production of interleukin-4 (IL-4), and this has been suggested to influence the allergic reactivity of tropical populations where these parasites are endemic. We evaluated a group of urban slum children in Caracas, Venezuela, with a high prevalence of helminthic infection (70.8%), to establish the relationship between the elevated IgE levels (3696 IU/ml) induced by these parasites and various aspects of the allergic response. Although the absolute levels of IL-4 detected in the sera of these children were low (0.65 +/- 0.20 ng/ml), a strong positive correlation (r = 0.78) was found between these and serum IgE. The cutaneous immediate hypersensitivity reactivity to extracts of common environmental allergens was relatively low (17.5% to house dust), although that to Ascaris extract was moderately high (49.4%). Significant inverse correlations were found between total IgE levels and the different skin test reaction diameters, including Ascaris. The positivity of Prausnitz-Kustner passive transfer tests was low in this group (34%), with a strong inverse correlation (r = -0.75) being found between this and total IgE levels. Significant inverse correlations were also found between total IgE levels and specific IgE antibody to environmental allergens, and to Ascaris antigen. We suggest that the polyclonal production of IgE stimulated by helminthic infection can suppress the allergic response to environmental and parasite allergens via both mast cell saturation and inhibition of specific IgE production.