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evidence for nonrandom distribution of GD1a ganglioside in rabbit brain microsomal membranes
No full textGD1a is the major ganglioside of rabbit brain microsomal membranes and occurs mainly with two molecular species, containing the C18:1 (62.3%) and C20:1 (37.7%) long-chain bases. The membranes were exposed to Vibrio cholerae (VC) sialidase under conditions where the enzyme hydrolyzed only GD1a (~9%), producing GM1 ganglioside, whereas the other gangliosides remained virtually unaffected. The long-chain-base analysis showed that newly-formed GM1 contained ~68% of the C20:1 molecular species. This indicates that VC sialidase did not randomly affect the two molecular species of GD1a but hydrolyzed preferentially the C20:1 one. In similar experiments, GD1a was inserted into the external layer of phosphatidylcholine vesicles and incubated with VC sialidase under conditions producing ~10% hydrolysis. Long-chain-base analysis showed that the proportion of C20:1 species in GM1 was 25.1% using vesicles composed of dipalmitoylphosphatidylcholine and 42.3% with egg phosphatidylcholine, whereas it was 39.2% in the starting GD1a. Therefore, in artificial membranes, VC sialidase acted preferentially on the C18:1 or C20:1 molecular species, depending on the length and unsaturation of the phospholipid fatty acids. Because VC sialidase is known to affect molecular dispersions more easily than packed aggregations of the gangliosidic substrate, the data suggest that in rabbit brain microsomal membranes the GD1a ganglioside molecular species carrying C20:1 long-chain base are more molecularly dispersed than those containing C18:1 long-chain base
PARTIAL CHARACTERIZATION OF A CHOLINERGIC-SPECIFIC GANGLIOSIDE (CHOL-1) AND ITS DEVELOPMENTAL EXPRESSION IN A CELL-CULTURE SYSTEM
No full textage-related changes in the ceramide composition of the major gangliosides present in rat brain subcellular fractions enriched in plasma membranes of neuronal and myelin origin
No full textAge-related changes of the ceramide composition of gangliosides were studied in the synaptosomal and myelin fractions from rat brain, carrying plasma membranes of neuronal and glial origin, respectively. The five major gangliosides (GM1, GD1a, GD1b, GT1b, and GQ1b) present in these fractions were separated and quantitated by normal-phase HPLC. Each ganglioside was then fractionated by reverse-phase HPLC into the molecular species carrying a single long-chain base (LCB). The largely preponderant LCBs in the synaptosomal and myelin fractions were the C18:1 and C20:1. The content of C20:1 LCB, generally low at 1 month, increased with age in all analyzed gangliosides and in all subcellular fractions and was greater in the 'b series' than in the 'a series' gangliosides. Remarkably, GM1 was the only ganglioside where the proportion of LCB 20:1 was higher in the synaptosomal fraction than in the myelin fraction. The fatty acid composition of the C18:1 or C20:1 LCB species of the different gangliosides in the synaptosomal and myelin fractions did not undergo appreciable changes with age. Stearic acid was largely predominant in all the gangliosides of the synaptosomal fraction, more in the C18:1 than in the C20:1 LCB species (80-90% vs 60-70%). The gangliosides of the myelin fraction were characterized by a lower content of 18:0 and a much higher content of 16:0 and 18:1 fatty acids than those of the synaptosomal fraction. Thus, the ceramide composition is different in the gangliosides of neuronal and myelin origin and appears to be subjected to an age-related control
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Red blood cell membrane composition following diet manipulation in the cow. II: phospholipid fatty acid distribution and physico-chemical characteristics of membrane and its constituents
No full textVariazioni della composizione della membrana di globulo rosso bovino in seguito a manipolazioni della dieta. II: distribuzione degli acidi grassi dei fosfolipidi e caratteristiche chimico-fisiche della membrana e dei suoi componenti. È stata analizzata la composizione in acidi grassi dei fosfolipidi estratti da membrane di globulo rosso di bovine da latte sottoposte per periodi di tempo variabili a regimi dietetici contenenti una supplementazione lipidica costituita da particolari saponi di calcio. Pertanto, la quantità e la qualità dei grassi presenti nelle diete sperimentali era differente come pure la loro utilizzazione e metabolizzazione a livello del rumine.
Per correlare i possibili cambiamenti nella porzione acilica dei fosfolipidi di membrana con le caratteristiche funzionali della membrana stessa sono state valutate mediante microcalorimetria e risonanza magnetica nucleare 31P, le caratteristiche fisiche sia della membrana sia delle miscele di lipidi totali e di fosfolipidi isolati dalla plasma membrana. I principali risultati ottenuti riguardano: 1) la mancata correlazione fra la distribuzione degli acidi grassi nella dieta e quelli presenti nei fosfolipidi; 2) le differenze osservate in questi ultimi in relazione al diverso contenuto in grassi nelle diete; 3) le differenze nelle temperature di transizione sia rispetto ai valori della letteratura per gli eritrociti normali sia fra le bovine trattate e i controlli; 4) il differente aspetto degli spettri 31P NMR fra lipidi totali, miscela di fosfolipidi e membrane intatte, indipendentemente dal tipo di trattamento dietetico.In the present research we analyzed in the cow: 1) the fatty acid distribution of phospholipids isolated from RBC membrane; 2) the thermotropic behaviour of membrane and of total lipids and phospholipids extracted from the membranes; 3) the physical configuration measured by 31P NMR.
The animals were fed on with different types and amount of fats; moreover some of the fatty material was administered as calcium soaps.
The aim of the work was to investigate in this particular animal model, the cow, some possible correlations such as: 1) the type and amount of dietary fatty acids with the acyl composition of RBC phospholipids; 2) the influence of dietary fats on the physical characteristics of the membrane which in turn might be correlated with RBC functions.
The main results we found are: 1) the distribution of fatty acids in the diet is not correlated in our model, with the acyl composition of RBC membrane phospholipids; 2) in these membrane components there are however differences in relation to the fat content of the diets; 3) such differences influence the thermotropic behaviour of the membranes and of the lipid mixtures (total lipids and phospholipids) examined; 4) regardless the diets the 31P NMR spectra showed differences between the membranes and the lipid mixtures extracted from the same membranes
Clinical evaluation and long-term follow-up in 16 patients with pseudotumour cerebri
No full textMedical treatment must be promptly established in patients with pseudotumour cerebri. In fact, even though a spontaneous remission of the symptoms is recognized in the literature, we have not any predictive criteria of future visual impairment
Inaccurate early assessment of neurological severity in head injury
No full textIntubation, which requires sedation and myorelaxants, may lead to inaccurate neurological evaluation of severely head-injured patients. Aims of this study were to describe the early clinical evolution of traumatic brain injured (TBI) patients admitted to intensive care unit (ICU), to identify cases of over-estimated neurological severity, and to quantify the risk factors for this over-estimation. A total of 753 TBI patients consecutively admitted to ICU of three academic neurosurgical hospitals (NSH) were assessed. Cases whose severity was potentially over-estimated were identified by four criteria and indicated as "mistakenly severe" (MS): (1) no surgical intracranial masses; (2) could not follow commands at neurological assessment; (3) were dismissed from the ICU in < or =3 days to a regular ward; and (4) had regained the ability to obey commands. A total of 675 patients were intubated and/or sedated-paralyzed at the post-stabilization evaluation. In all, 304 patients had surgically treated intracranial masses. Among the 449 non-surgical cases, 58 patients fulfilling the criteria for MS were identified. The main features distinguishing MS from truly severe cases were younger age, higher Glasgow Coma Scale (GCS) score at all time points, Marshall classification of Computerized Tomographic (CT) scan mostly Diffuse Injury I and II, fewer pupillary abnormalities, and a lower frequency of hypoxia, hypotension, and extra-cranial injuries. In a certain proportion of non-surgical TBI patients, mostly intubated and sedated, neurological examination is difficult and severity can be over-estimated. Risk factors for this inaccurate evaluation can be identified, and clinical decisions should be based on further examination
Prone positioning improves pulmonary function in obese patients during general anesthesia
No full textWe investigated the effects of prone position on functional residual capacity (FRC), the mechanical properties (compliance and resistance) of the total respiratory system, lung and chest wall, and the gas exchange in 10 anesthetized and paralyzed obese (body mass index more than 30 kg/m2) patients, undergoing elective surgery. We used the esophageal balloon technique together with rapid airway occlusions during constant inspiratory flow to partition the mechanics of the respiratory system into its pulmonary and chest wall components. FRC was measured by the helium dilution technique. Measurements were taken in the supine position and after 15-30 min of prone position maintaining the same respiratory pattern (tidal volume 12 mL/kg ideal body weight, respiratory rate 14 breaths/ min, fraction of inspired oxygen [FIO2]0.4). We found that FRC and lung compliance significantly (P < 0.01) increased from the supine to prone position (0.894 +/- 0.327 L vs 1.980 +/- 0.856 L and 91.4 +/- 55.2 mL/cm H2O vs 109.6 +/- 52.4 mL/cm H2O, respectively). On the contrary, the prone position reduced chest wall compliance (199.5 +/- 58.7 mL/cm H2O vs 160.5 +/- 45.4 mL/cm H2O, P < 0.01), thus total respiratory system compliance did not change. Resistance of the total respiratory system, lung, and chest wall were not modified on turning the patients prone. The increase in FRC and lung compliance was paralleled by a significant (P < 0.01) improvement of PaO2 from supine to prone position (130 +/- 31 vs 181 +/- 28 mm Hg, P < 0.01), while PaCO2 was unchanged. We conclude that, in anesthetized and paralyzed obese subjects, the prone position improves pulmonary function, increasing FRC, lung compliance, and oxygenation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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