Aggregation features of partially unfolded bovine serum albumin modulated by hydrogenated and fluorinated surfactants: Molecular dynamics insights and experimental approaches.

Protein aggregation plays important roles in life science as, for instance, those associated to neurodegenerative diseases. Although extensive efforts have been done to elucidate all the possible variables related to the aggregation process, much has yet to be done to unveil the main pathways governing protein assembling. In the current work, we induce bovine serum albumin (BSA) association, at pH 3.7, by adding sodium dodecyl sulfate (SDS) and sodium perfluorooctanoate (SPFO) surfactants to BSA solution as promoters of protein aggregation. Firstly, we combine molecular dynamic simulations (MD) to obtain a partially unfolded state of BSA's monomer at the acid pH and small angle X-ray scattering (SAXS) to validate the model. Interestingly, we found by SAXS that at pH 3.7 BSA monomers coexist with dimers in surfactant-free solution. Upon SDS and SPFO addition, the partial unfolded BSA may evolve to large aggregates depending on surfactant concentration. The threshold occurs at 30:1 and 45:1 SDS:BSA and SPFO:BSA molar ratio, respectively, according to turbidity, Thioflavin (ThT) fluorescence, synchrotron radiation circular dichroism (SRCD), SAXS and scanning electron microscopy (SEM) experiments. BSA aggregates are larger in the presence of SDS and structurally more defined upon SPFO binding. Isothermal titration calorimetry (ITC) results give support to infer that both surfactants initially bind to the BSA macromolecule forming a complex. Then, these complexes self-associate towards supramolecular aggregates. Taking into account the physicochemical characteristics of both surfactants and also MD simulations we may suggest that the higher rigidity of the fluorinated chains in respect to hydrogenated ones is crucial to induce more ordered and smaller BSA's aggregates. Our results thus evidence that the ligand structural flexibility might be of a key importance in the pathway of protein aggregation and may pave the way to better understand the early steps of neurodegenerative disorders.

Pleasure: The missing link in the regulation of sleep.

Although largely unrecognized by sleep scholars, sleeping is a pleasure. This report aims first, to fill the gap: sleep, like food, water and sex, is a primary reinforcer. The levels of extracellular mesolimbic dopamine show circadian oscillations and mark the "wanting" for pro-homeostatic stimuli. Further, the dopamine levels decrease during waking and are replenished during sleep, in opposition to sleep propensity. The wanting of sleep, therefore, may explain the homeostatic and circadian regulation of sleep. Accordingly, sleep onset occurs when the displeasure of excessive waking is maximal, coinciding with the minimal levels of mesolimbic dopamine. Reciprocally, sleep ends after having replenished the limbic dopamine levels. Given the direct relation between waking and mesolimbic dopamine, sleep must serve primarily to gain an efficient waking. Pleasant sleep (i.e. emotional sleep), can only exist in animals capable of feeling emotions. Therefore, although sleep-like states have been described in invertebrates and primitive vertebrates, the association sleep-pleasure clearly marks a difference between the sleep of homeothermic vertebrates and cool blooded animals.

«Ateroembolismo» paradójico en paciente con síndrome de Paget-Schroetter / Paradoxical «atheromatous embolism» in a patient with Paget-Schroetter syndrome

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Polidocanol foam stability in terms of its association with glycerin.

OBJECTIVES: Foam sclerotherapy effectiveness mainly depends on the concentration of the sclerosing agent and foam stability. The objective of this study was to determine if the addition of glycerol at different concentrations contributes to the stability of polidocanol foam. CONTROL GROUP: 3% polidocanol. Group 1: polidocanol 3% + glycerin 1.66%. Group 2: polidocanol 3% + glycerin 3.3%. Group 3: polidocanol 3% + Glycerin 5%. Tessari standard method. Five recordings were made for each mixture. Early visual liquefaction time and half liquid time decay were recorded in seconds. Microscopic measurement of the foams. Mixtures surface tension measurement (N/m). RESULTS: Early visual liquefaction: CONTROL GROUP: 27 (±3.11); Group 1: 67.8 (±6.49); Group 2: 48.6 (±8.2); and Group 3: 35.8 (±4.49). Half-liquid time: CONTROL: 129.2 (±11.00); Group 1: 260.4 (±18.99); Group 2: 224.6 (±13.03); and Group 3: 189.2 (±8.52). Bubbles/mm(2)-diameter-wall thickness: CONTROL: 68-98 µm-7 µm; Group 1: 189-60 µm-9 µm; Group 2: 76-92 µm-12 µm; and Group 3: 49-112 µm-20 µm. Surface tension: CONTROL = 5.54 N/m; Group 1 = 5.45 N/m; Group 2 = 5.35 N/m; and Group 3 = 5.21 N/m. CONCLUSIONS: Small amounts of glycerin highly increase the stability and quality of polidocanol foam. This simple chemical method is easily reproducible and applicable.

Effects of serotonergic drugs on locomotor activity and vigilance states in ring doves.

Serotonergic system is implicated on sleep-waking states in mammals. Since studies on serotonin regulation of sleep in birds are scarce, ring dove was chosen as experimental subject in the present work. The role of the neurotransmitter serotonin on vigilance states was studied in ring doves intraperitoneally treated with the 5-HT(1A) agonist 8-OH-DPAT, the 5-HT(1A) antagonist WAY100635 and the inhibitor of serotonin synthesis para-chlorophenylalanine (PCPA) by means of behavioural, electrophysiological and infrared actimetry criteria. 8-OH-DPAT (1 mg/kg) treatment increased locomotor activity, active waking and grooming states and reduced SWS and REM sleep. Pre-treatment with WAY100635 (0.5 mg/kg) prevented the effects induced by 8-OH-DPAT. Serotonin depletion induced by PCPA treatment (two consecutive injections of 300 mg/kg over two consecutive days) reduced locomotor activity, waking and grooming activity while increased both SWS and REM sleep. Moreover, 8-OH-DPAT (0.5 mg/kg) in PCPA treated ring doves produced a notable rise in the locomotor activity, active waking and grooming states, while it decreased sleep. Altogether, the results support the idea that serotonin plays an active role in wakefulness, probably through the activation of 5-HT(1A) receptors that increases wake activities and reduces sleep in ring doves.

Electroencephalogram functional connectivity between rat hippocampus and cortex after pilocarpine treatment.

The muscarinic agonist pilocarpine has been shown to increase the duration and total number of episodes presenting theta rhythm-simultaneously in hippocampus and cortex-in rats during the waking states. Theta waves are suggested to be involved in the flow of information between hippocampus and cortex during memory processes. This work investigates this functional interdependence using the spectral and phase synchronization analysis of the electroencephalogram (EEG) theta band recorded in these brain structures of rats after pilocarpine treatment. Pilocarpine was used at doses devoid of epilepticus-like seizures effects in conscious freely moving rats. The results showed that pilocarpine administration significantly increased the relative theta power during the waking states in the cortex, but not in the hippocampus of rats. Additionally, the EEG coherence between the hippocampal EEG theta band and that arising at the frontal cortex increased after pilocarpine treatment but only during the waking states. This result reveals an increase of the linear correlation between the theta waves of these two brain structures after pilocarpine treatment during the waking states. Moreover, phase synchronization results showed an effective phase locking with non-zero phase difference between hippocampus and frontal cortex theta waves that remained after pilocarpine treatment. Therefore, pilocarpine seems to reinforce the neural transmission waves from the hippocampus toward the cortex during waking. In conclusion, the present EEG study could suggest an effect of the muscarinic cholinergic agonist pilocarpine on the hippocampal-cortical functional connectivity.

Effects of pilocarpine on the cortical and hippocampal theta rhythm in different vigilance states in rats.

It has been suggested that theta rhythm gates the flow of information between the hippocampus and cortex during memory processes. The cholinergic system plays an important role in regulating vigilance states and in generating theta rhythm. This study aims to analyse the effects of the muscarinic agonist pilocarpine (120 and 360 microg, i.c.v.) on hippocampal and frontal cortical theta rhythm during several vigilance states in rats. Pilocarpine injection increased the duration and number of episodes with theta activity, particularly when theta rhythm appeared during waking states in the cortex and hippocampus simultaneously. It seems that the effects of pilocarpine are related to the appearance of cortical theta activity in waking states, and suggest that pilocarpine could modify the transference rate of information from the hippocampus to cortex in rats during wakefulness states, in relation to the postulated effect of cholinergic system modulating memory consolidation.

Comments on evolution of sleep and the palliopallial connectivity in mammals and birds.

This commentary is referred to the review signed by Rattemborg [N.C. Rattenborg, Evolution of slow wave sleep and palliopallial connectivity in mammals and birds. A hypothesis. Brain Res. Bull. 69 (2006) 20-29]. We propose that the review missed important aspects in relation to the characteristics of sleep in poikilotherm vertebrates and in the evolution of sleep. Poikilotherms continuously show an EEG dominated by slow waves, but its highest amplitude appears not during sleep, but during active waking. In addition, they show an arousal reaction which consists in an increase in EEG amplitude and synchrony, opposite to mammals and birds. As a consequence, most of the conclusions proposed in the review should be rejected.

Improved circadian sleep-wake cycle in infants fed a day/night dissociated formula milk.

On the basis of the circadian nutritional variations present in breast milk, and of the implications for the sleep/wake cycle of the nutrients present in infant formula milks, we designed a formula milk nutritionally dissociated into a Day/Night composition. The goal was to improve the bottle-fed infant's sleep/wake circadian rhythm. A total of 21 infants aged 4-20 weeks with sleeping difficulties were enrolled in the three-week duration study. The sleep analysis was performed using an actimeter (Actiwatch) placed on an ankle of each infant to uninterruptedly record movements during the three weeks. The dissociated Day milk, designed to be administered from 06:00 to 18:00, contained low levels of tryptophan (1.5g/100g protein) and carbohydrates, high levels of proteins, and the nucleotides Cytidine 5 monophosphate, Guanosine 5 monophosphate and Inosine 5 monophosphate. The dissociated Night milk, designed to be administered from 18.00 to 06.00, contained high levels of tryptophan (3.4g/100g protein) and carbohydrates, low levels of protein, and the nucleotides Adenosine 5 monophosphate and Uridine 5 monophosphate. Three different milk-feeding experiments were performed in a double-blind procedure covering three weeks. In week 1 (control), the infants received both by day and by night a standard formula milk; in week 2 (inverse control), they received the dissociated milk inversely (Night/Day instead of Day/Night); and in week 3, they received the Day/Night dissociated formula concordant with the formula design. When the infants were receiving the Day/Night dissociated milk in concordance with their environment, they showed improvement in all the nocturnal sleep parameters analyzed: total hours of sleep, sleep efficiency, minutes of nocturnal immobility, nocturnal awakenings, and sleep latency. In conclusion, the use of a chronobiologically adjusted infant formula milk seems to be effective in improving the consolidation of the circadian sleep/wake cycle in bottle-fed infants.

Antioxidant response analysis in the brain after pilocarpine treatments.

Cholinergic and gabaergic systems play an important role generating electroencephalographic activity and regulating vigilance states. Pilocarpine is a cholinergic agonist commonly used to induce seizures and an epilepticus-like state in rodents. A relationship between status epilepticus and reactive oxygen species has been also suggested which could result in seizure-induced neurodegeneration. The aim of this study was to evaluate the existence of oxidative damage as well as the antioxidant enzyme response in cortex and hippocampus after the administration of an intraperitoneal (350 mg/kg) and an intracerebroventricular (360 microg, 1 microl) pilocarpine injection in rats. The GABA agonist muscimol (1 mg/kg, i.p.), with described neuroprotective properties, was used as a negative control. Only systemic pilocarpine induced oxidative damage. Malondialdehyde levels, as a marker of lipid peroxidation (LP), increased in both regions (55-56%). Catalase (52-80%) and superoxide dismutase (53-60%) activities also rose in both regions but glutathione peroxidase activity only increased in cortex (45%). Glutathione reductase and caspase-3 activity did not change. In conclusion, systemic pilocarpine produced oxidative brain damage, whereas local pilocarpine brain injection had no effects. Moreover, the enzymatic determinations performed in this study are a good tool to study brain injury in pharmacological manipulations such as the ones used in short recording EEG studies.

[The work of Santiago Ramón y Cajal in the Revista Trimestral Micrográfica (Trabajos del Laboratorio de Investigaciones Biológicas)]. / La obra de Santiago Ramón y Cajal en Revista Trimestral Micrográfica (Trabajos del Laboratorio de Investigaciones Biológicas).

AIM: This paper is based on a study of Revista Trimestral Micrografica (Trabajos del Laboratorio de Investigaciones Biologicas) between its creation by Santiago Ramon y Cajal in 1896 and his death in 1934. DEVELOPMENT: The journal Revista Trimestral Micrografica was the main way in which Santiago Ramon y Cajal and his school published their work since its creation. Ramon y Cajal created the journal for two main reasons: first, he needed a rapid system to publish his own work; second, the journal could serve to encourage his pupils. The journal published many important reports defending the neuronal theory which expanded the cellular one to include the nervous system.

[Interrelations between sleep and the immune status]. / Interrelaciones entre el sueño y el estado inmune.

INTRODUCTION: The idea of the healing effects of the sleep over the disease is quite extended. Besides, the sleep and the circadian rhythms cause deep changes on the immune function. Reciprocally, the sleep also suffers deep changes when the immune system is challenged during an external aggression. DEVELOPMENT: This review shows some of the data supporting both observations. From the relationships between the sleep and the immune system, it has been proposed that one function of sleep is just to support the immune defense. However, an important fraction of the relationships between sleep and immune function might be a response to the stress produced both during the sleep disorders and when the organism activates the immune defense. Moreover, the epidemiological evidence only shows negligible results when contrasting the amount of sleep and the life expectancy. CONCLUSION: It seems thus probable that the relationships between sleep and immune function are only a reflect of additional factors, such as stress, which cause deep changes in sleep and immunity.

Interrelaciones entre el sueño y el estado inmune / Interrelations between sleep and the immune status

Introducción. Se cree que el sueño ejerce efectos beneficiosos sobre el sistema inmune. También hay evidencias firmes de que el sueño y los ritmos circadianos determinan cambios en el estado del sistema inmune. Recíprocamente, cuando el sistema inmune está afectado por una agresión externa, el sueño sufre importantes modificaciones. Desarrollo. Se presentan algunos de los datos que soportan las observaciones anteriores. De estas interrelaciones algunos autores consideran que una de las funciones del sueño es mantener las defensas inmunes. Sin embargo, una gran parte de las interacciones entre sueño y sistema inmune puede estar determinada por el estrés que se produce, tanto cuando el sueño está perturbado, como cuando el organismo sufre una agresión que determina una activación de las defensas inmunitarias. Además, la evidencia epidemiológica muestra que la esperanza de vida sufre muy pocos cambios en las personas que duermen más o menos que la mayoría de la población. Conclusión. Parece probable que las interacciones entre el sueño y el estado inmune no sean más que reflejos de otros factores que, como el estrés, ejercen profundos efectos sobre ambos

Introduction. The idea of the healing effects of the sleep over the disease is quite extended. Besides, the sleep and the circadian rhythms cause deep changes on the immune function. Reciprocally, the sleep also suffers deep changes when the immune system is challenged during an external aggression. Development. This review shows some of the data supporting both observations. From the relationships between the sleep and the immune system, it has been proposed that one function of sleep is just to support the immune defense. However, an important fraction of the relationships between sleep and immune function might be a response to the stress produced both during the sleep disorders and when the organism activates the immune defense. Moreover, the epidemiological evidence only shows negligible results when contrasting the amount of sleep and the life expectancy. Conclusion. It seems thus probable that the relationships between sleep and immune function are only a reflect of additional factors, such as stress, which cause deep changes in sleep and immunity

[The evolution of sleep: birds at the crossroads between mammals and reptiles]. / La evolución del sueño: las aves en la encrucijada entre mamíferos y reptiles.

INTRODUCTION: The evolution of sleep is one of the mysteries surrounding the sleep. Since the discovery of the two phases in the mammalian sleep, NREM and REM, the sleep researchers have unsuccessfully tried to understand their origin and the causes of the sleep duality. Looking for an answer to these questions, the sleep of reptiles (the parental group of mammals) and birds (also descending from reptiles) has been studied. As a result, NREM and REM were found in birds but not in reptiles, and the question remains thus unresolved. DEVELOPMENT AND CONCLUSIONS: This review presents a critical analysis of the published sleep studies developed in birds and points to a possible cause of the conflict: considerable doubts can be cast on the existence of the two sleep phases in birds. If birds turn to have only one sleep phase, they would have a very similar sleep to that of reptiles. As a consequence, the two phases, REM and NREM, would be exclusive of mammals, and both would have appeared as a consequence of the evolutionary changes in the development of the brain from reptiles to mammals.

La evolución del sueño: las aves en la encrucijada entre mamíferos y reptiles / The evolution of sleep: birds at the crossroads between mammals and reptiles

Introducción. La evolución del sueño es uno más de los misterios que envuelven el sueño. Desde el descubrimiento de las dos fases del sueño de mamíferos, REM y no REM, se intentó –con pocos resultados– comprender el origen de las dos fases y las razones por las cuales se mantiene la dualidad del sueño. Buscando la respuesta a estas preguntas se estudió el sueño de los reptiles, el grupo antecesor de los mamíferos, y de las aves, otro grupo que también desciende de los reptiles. El resultado es que las dos fases se han hallado en las aves, pero no han podido demostrarse en los reptiles, por lo que el misterio sigue sin resolverse. Desarrollo y conclusiones. En la presente revisión se analizan de forma crítica los resultados más conocidos del sueño de las aves y se apunta una solución para el conflicto: es posible que las dos fases de sueño tampoco existan en este grupo y, en consecuencia, su sueño sería similar al de los reptiles. Con esto, las dos fases, REM y no REM, serían exclusivas de los mamíferos y se habrían desarrollado como consecuencia de los cambios evolutivos en la estructura del cerebro

Introduction. The evolution of sleep is one of the mysteries surrounding the sleep. Since the discovery of the two phases in the mammalian sleep, NREM and REM, the sleep researchers have unsuccessfully tried to understand their origin and the causes of the sleep duality. Looking for an answer to these questions, the sleep of reptiles (the parental group of mammals) and birds (also descending from reptiles) has been studied. As a result, NREM and REM were found in birds but not in reptiles, and the question remains thus unresolved. Development and conclusions. This review presents a critical analysis of the published sleep studies developed in birds and points to a possible cause of the conflict: considerable doubts can be cast on the existence of the two sleep phases in birds. If birds turn to have only one sleep phase, they would have a very similar sleep to that of reptiles. As a consequence, the two phases, REM and NREM, would be exclusive of mammals, and both would have appeared as a consequence of the evolutionary changes in the development of the brain from reptiles to mammals

Treatment of type II endoleaks after endovascular repair of abdominal aortic aneurysms: translumbar puncture and injection of thrombin into the aneurysm sac.

OBJECTIVES: The aim of this article is to report our experience in the use of a new technique for the treatment of type II endoleaks which appear after the endovascular treatment of abdominal aortic aneurysms. MATERIALS AND METHODS: In three patients with secondary type II endoleaks, we performed a translumbar puncture, introducing a 22-Gauge needle into the aneurysm sac under CT guidance. Once intrasac pressure had been registered, 1000U (2 ml) of human thrombin were slowly injected into the sac. RESULTS: Complete sealing of the endoleak was achieved in all three patients, confirmed by the lack of contrast filling of the sac in the CT scans performed 5 min and 24 h after the procedure. Initial intrasac pressure was equal to systolic arterial pressure in the three patients. After the procedure, the pressure decreased by 30-40 mmHg. There were no complications during the procedure, which lasted 45-90 min. No endoleak recurrence has been observed in any of the three cases 6 months later. CONCLUSIONS: We present an alternative method of treating type II endoleaks, which could become the treatment of choice if and when a wider experience confirms our initial good results.

Operative repair of popliteal aneurysms: effect of factors related to the bypass procedure on outcome.

The objective of this study was to compare patency rates following the repair of popliteal aneurysms according to the site of inflow, material of bypass graft and quality of distal runoff. Seventy bypasses were performed over an 11-year period. Autogenous saphenous vein was used in 53 procedures (75.7%) and prosthetic material was used in 17 (24.3%). Early mortality was 2.8%. Early primary and secondary patency rates were 95.7% and 97.1%, respectively. Autogenous vein showed better 10-year patency than prosthetic material (86% vs. 57%; p = 0.02). No significant differences in patency were observed according to the inflow site (87.8% groin vs. 74.7% supragenicular). Bypasses that originated in the groin showed improved patency when a saphenous vein was used (84.8% vs. 43.7%; p = 0.01). However, no influence of the graft material was noted in supragenicular bypasses (90.4% vs. 84.8%; p = 0.6). Bypasses in extremities with good runoff showed better patency than those in limbs showing poor runoff (86% vs. 55%; p = 0.003). The use of saphenous vein for the repair of popliteal aneurysms showed better results than those with prosthetic material, although in bypasses originating from the distal superficial femoral or above-knee popliteal artery, no significant differences in patency were observed. Good distal runoff was associated with improved overall outcome.

Why we sleep: the evolutionary pathway to the mammalian sleep.

The cause of sleep is a complex question, which needs first, a clear distinction amongst the different meanings of a causal relationship in the study of a given behavior, second, the requisites to be met by a suggested cause, and third, a precise definition of sleep to distinguish behavioral from polygraphic sleep. This review aims at clarifying the meaning of the question and at showing the phylogenetic origin of the mammalian and avian sleep. The phylogenetic appearance of sleep can be approached through a study of the evolution of the vertebrate brain. This began as an undifferentiated dorsal nerve, which was followed by the development of an anterior simplified brain and ended with the formation of the multilayered mammalian neocortex or the avian neostriate. The successive stages in the differentiation of the vertebrate brain produced, at least, two different waking types. The oldest one is the diurnal activity, bound to the light phase of the circadian cycle. Poikilotherms control the waking from the whole brainstem, where their main sensorymotor areas lie. Mammals developed the thalamocortical lines, which displaced the waking up to the cortex after acquiring homeothermy and nocturnal lifestyle. In order to avoid competence between duplicate systems, the early waking type, controlled from the brainstem, was suppressed, and by necessity was turned into inactivity, probably slow wave sleep. On the other hand, the nocturnal rest of poikilotherms most probably resulted in rapid eye movement sleep. The complex structure of the mammalian sleep should thus be considered an evolutionary remnant; the true acquisition of mammals is the cortical waking and not the sleep.