Variation in neurosurgical management of traumatic brain injury

Background: Neurosurgical management of traumatic brain injury (TBI) is challenging, with only low-quality evidence. We aimed to explore differences in neurosurgical strategies for TBI across Europe. Methods: A survey was sent to 68 centers participating in the Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. The questionnaire contained 21 questions, including the decision when to operate (or not) on traumatic acute subdural hematoma (ASDH) and intracerebral hematoma (ICH), and when to perform a decompressive craniectomy (DC) in raised intracranial pressure (ICP). Results: The survey was completed by 68 centers (100%). On average, 10 neurosurgeons work in each trauma center. In all centers, a neurosurgeon was available within 30 min. Forty percent of responders reported a thickness or volume threshold for evacuation of an ASDH. Most responders (78%) decide on a primary DC in evacuating an ASDH during the operation, when swelling is present. For ICH, 3% would perform an evacuation directly to prevent secondary deterioration and 66% only in case of clinical deterioration. Most respondents (91%) reported to consider a DC for refractory high ICP. The reported cut-off ICP for DC in refractory high ICP, however, differed: 60% uses 25 mmHg, 18% 30 mmHg, and 17% 20 mmHg. Treatment strategies varied substantially between regions, specifically for the threshold for ASDH surgery and DC for refractory raised ICP. Also within center variation was present: 31% reported variation within the hospital for inserting an ICP monitor and 43% for evacuating mass lesions. Conclusion: Despite a homogeneous organization, considerable practice variation exists of neurosurgical strategies for TBI in Europe. These results provide an incentive for comparative effectiveness research to determine elements of effective neurosurgical care

Purification of beta-(1-4)-N-acetylhexosaminidase secreted by Streptomyces albus G and active on the cell walls of Micrococcus lysodeikticus.

The N-acetylhexosaminidase (referred as Str) secreted by Streptomyces albus G. has been purified by zone electrophoresis. It is slightly less basic than egg-white lysozyme. Its isoelectric point is close to pH 10.3. It has no action on the [alpha]- and [beta]-phenylglycosides of N-acetylglucosamine and on the disaccharides [beta]-(1-4)-di-N-acetylglucosamine (di-N-acetylchitobiose) and [beta]-(1-6)-N-acetylglucosaminyl-N-acetylmuramic acid but it splits the tetrasaccharide [beta]-(1-4)-tetra-N-acetylglucosamine(tetra-N-acetylchitotetraose) in di-N-acetylchitobiose. Contrary to lysozyme, it does not split the tetrasaccharide O-[beta]-N-acetylglucosaminyl-(1-6)-O-[beta]-N-acetylmuraminyl-(1-4)-O-[beta]-N-acetylglucosaminyl-(1-6)-[beta]-N-acetylmuramic acid in disaccharide by hydrolyzing the [beta](1-4) linkage. In those conditions the disaccharide liberated, as well as the tetrasaccharide, from Microccus lysodeikticus cell walls after incubation with the N-acetylhexosaminidase Str, can not be put down to a further digestion of some tetrasaccharidic fragments. A chitobiase only active on the [beta]-phenyl-glycoside of N-acetylglucosamine and on the di-N-acetylchitobiose is also present in contentrated culture filtrates. It is a protein acid at pH 6.6

Structure of the cell walls of Bacillus megaterium KM I. Isolation of amidase and of a newly found enzyme of Streptomyces albus G, working on the cell walls of Bacillus megaterium KM and Micrococcus lysodeikticus

La préparation F2B obtenue par fractionnement sur Amberlite du filtrat de culture de Streptomyces albus G a été examinée par électrophorèse de zone en gradient de sucrose. Cinq enzymes ont été mis en évidence dont trois ont été isolés, les deux derniers restant associés. Trois enzymes distincts rendent la caséine non-précipitable par l'acide trichloracétique. Ils semblent dépourvus d'action sur les parois cellulaires de Bacillus megaterium KM et de Micrococcus lysodeikticus. Le quatrième enzyme est l'amidase, dont la présence dans F2B avait été précédemment démontrée. Cet enzyme hydrolyse les liaisons muraminyle-alanine présentes dans les parois cellulaires bactériennes. L'amidase isolée ne clarifie pas les suspensions des deux types de parois bactériennes étudiés mais exalte l'activité lytique du cinquième enzyme avec lequel elle est associée dans la préparation F2B. Ce cinquième enzyme semble agir comme le lysozyme et la N-ac e thylexosaminidase de Streptomyces au niveau des fragments polysaccharidiques du mucopeptide de base des parois bactériennes. Il s'en distingue par le fait que son action dissolvante sur les parois de Micrococcus lysodeikticus ne s'accompagne pas d'une libération d'oligosaccharides. Il est dénommé: Enzyme "32".The Streptomyces albus G enzymic complex of the F2B preparation has been fractionated by zone electrophoresis in sucrose gradient. Five enzymes have been shown to be present and three of them have been fully separated. Three distinct enzymes make the casein no further precipitable by the trichloroacetic acid. They are likely not to have any action on Bacillus megaterium KM and on Micrococcus lysodeikticus cell walls. A fourth enzyme is the amidase previously studied which splits the muraminyl-alanine linkages present in the bacterial walls. The amidase does not clarify by itself the wall suspensions so far examined but enhances the lytic activity of a fifth enzyme also present in the F2B preparation. As lysozyme and Streptomyces N-acetylhexosaminidase, this fifth enzyme seems to act at the level of the polysaccharide residues of the walls basal mucopeptide but, contrary to those enzymes, its hydrolyzing action does not induce the liberation of free oligosaccharides from Micrococcus lysodeikticus walls. This enzyme will be referred to as Enzyme “32”

Structure of the walls of Bacillus megaterium KM. II Study of the mucopeptide and phosphomuco-polysaccharide complexes

Bacillus megaterium KM cell walls are composed of two distinct heteropolymers. The first, referred as to X-teichoic acid, presents a molecular weight of about 11000. It consists of about 10 subunits containing P, glucose and GlcNHAc in the molar ratio 1/2/1.3 as well as a polyol compound. It does not play any role in maintaining the rigidity of the wall. The second can be visualized as a three-dimensional network of structural subunits consisting of four mucopeptide residues with an average composition GlcNHAc1- (N-acetylmuramic acid)1-Ala2.20-Glu1- ([alpha],[epsilon]-diaminopimelic acid)1. They also contain glucose. This mucopeptide is the basal structure of the wall. The two heteropolymers are present in equimolar proportions. They are covalently bound through glucosido-muraminyl bridges branched on some of the alanine residues of the basal mucopeptide thanks to amidic linkages

Energy hypersurface local properties of the O2HF-1 rearrangement

This work analyses a case where Murrell's proposal, stating that a second-order point must lie above a first-order one, is apparently violated. Study at the SCF-UMP2 level within the D95 + + basis set, of one critical point of the O2HF- anion, previously proposed to be of order two by Lopez, shows the importance of the electronic correlation. The critical point associated with the (2)PI first-order ones. The present analysis reveals that this contradistinction can be explained by three unconsidered elements: the local symmetry, the electronic correlation and the internal variables description