Computed tomographic diagnosis of intraventricular hemorrhage. Etiology and prognosis.

Sixty-eight patients with intraventricular hemorrhage (IVH) diagnosed by computed tomography (CT) were reviewed retrospectively to determine the etiology and prognosis, relationship to delayed hydrocephalus, and effect on neurological outcome. The most common causes were a ruptured aneurysm, trauma, and hypertensive hemorrhage. Ruptured aneurysms of the anterior communicating artery can often be predicted from the nonenhanced CT scan.

[Comparison of the kinetics of ionophore-induced ion transport in conventional and solventless membranes].

In contrast to conventional membranes prepared from a mixture of glyceryl-monooleate (GMO) and decane (GMO-D) which still contain decane in the final state, the membranes formed from a mixture of GMO and squalene (GMO-S) or triolein (GMO-T) contain finally only GMO and are said to be "solventless". The use of the electric current relaxation technique following a voltage jump has allowed us to characterize the effect of the absence of solvent on the various steps of ion transport induced by nonactin. We have measured the rates of formation (kri) of dissociation (kDi) and of translocation (kis) of the ion-ionophore complex as well as the rate of translocation of the ionophore (ks).

Effects of variation of ion and methylation of carrier on the rate constants of macrotetralide-mediated ion transport in lipid bilayers.

The effects of methylation on the rate constants of carrier-mediated ion transport have been studied on monooleindecane bilayers with K+, Rb+, NH4+, and Tl+ ions, using the series of homologue carriers, nonactin, monactin, dinactin, trinactin, and tetranactin, each member of the series differing from the previous one by only one methyl group. Measurements of the amplitude and time constant of the current relaxation after a voltage jump over a large domain of voltage and permeant ion concentration, together with a computer curve-fitting procedure, have allowed us, without the help of steady-state current-voltage data, to deduce and compare the values of the various rate constants for ion transport: formation (kRi) and dissociation (kDi) of the ion-carrier complex at the interface, translocation across the membrane interior of the carrier (ks) and the complex (kis). With the additional information from steady-state low-voltage conductance measurements, we have obtained the value of the aqueous phase-membrane and torus-membrane partition coefficient of the carrier (gammas and gammas).

Acute orbital pseudotumors: classification and CT features.

Acute orbital pseudotumors are inflammatory lesions of unknown etiology that may affect part or, less often, all of the tissue within the orbit. A retrospective computed tomographic (CT) study of 16 patients demonstrated that these lesions occur in one of five specific anatomic patterns: anterior, posterior, diffuse, lacrimal, or myositic. The most common location was lacrimal followed by anterior pseudotumors.

Skin-colour changes i the lizard, Anolis carolinensis, in response to localized electrical stimulation and lesions in the diencephalon.

A study was made of changes in skin colour in the lizard, Anolis carolinensis, in response to deep electrical stimulation at 0.2 mm intervals throughout the periventricular region of the diencephalon and the anterior brain stem. Double-barrelled glass microelectrodes with tip diameters of 3 microns were used.

The catalytic mechanism of glutamyl-tRNA synthetase of Escherichia coli. A steady-state kinetic investigation.

The sequence of substrate binding and of end-product dissociation at the steady state of the catalytic process of tRNAGlu aminoacylation by glutamyl-tRNA synthetase from Escherichia coli has been investigated using bisubstrate kinetics, dead-end and end-product inhibition studies. The nature of the kinetic patterns indicates that ATP and tRNAGlu bind randomly to the free enzyme, whereas glutamate binds only to the ternary enzyme . tRNAGlu .

Fibromatosis of dura presenting as infantile spasms.

A 6-month-old boy developed emprosthotonic infantile spasms and right hemiparesis. CT scan revealed a large mass related to a distended right temporal horn which on craniotomy proved to be a hard white tumour of the tentorium cerebelli which could be only incompletely resected. Microscopically and ultrastructurally, this lesion proved to be a typical fibromatosis containing myofibroblasts which invaded the brain.

Positioning of patients after metrizamide lumbar myelography.

This prospective study of 90 patients after lumbar metrizamide myelography indicates that the semiupright position at 45 degrees in bed or early ambulation reduces postprocedure vomiting but does not reduce the frequency of headache. Ambulatory patients have less frequent nausea than patients kept in bed.

Properties of the cytoplasmic glutamyl-tRNA synthetase in high molecular weight complexes from bovine brain.

The glutamyl-tRNA synthetase purified 300-fold from calf brain is associated with other aminoacyl-tRNA synthetases in a complex whose molecular weight is about 2,000,000. However, in a less purified state, the enzyme is present in a complex larger than 5,000,000. The properties of the enzyme are the same in both complexes except for the pH optimum of the aminoacylation reaction.

The glutaminyl-transfer RNA synthetase of Escherichia coli. Purification, structure and function relationship.

Glutaminyl-tRNA synthetase from Escherichia coli has been purified to homogeneity with a yield of about 50%. It is a monomer of about 69 000 daltons. Arginyl and glutamyl-tRNA synthetases are also monomeric synthetases of molecular weight significantly lower than 100 000.

The catalytic mechanism of the glutamyl-tRNA synthetase from Escherichia coli. Detection of an intermediate complex in which glutamate is activated.

Up to now it was not possible to isolate an enzyme . adenylate complex after mixing the glutamyl-tRNA synthetase from Escherichia coli with ATP, MgCl2, and glutamate. This enzyme catalyzes an AMP-dependent and PPi-independent deacylation of Glu-tRNAGlu.

[Regulation of transcription by elements of the translation system in Escherichia coli].

The study of the structure of the operons tryptophan, phenylalanine and histidine has indicated that the transcription of these operons is controlled by the level of aminoacylation of the corresponding tRNAs which modulates the termination of transcription at an attenuator site. The derepression of the level of two enzymes responsible for the biosynthesis of glutamate and glutamine in Escherichia coli, following a decrease of the level of aminoacylation of tRNAglutamate in vivo, suggests that attenuator sites are involved in the control of the transcription of the two operons coding for these enzymes. The fact that tRNAglutamate is involved in this regulation whereas tRNAglutamine is not, supports the model of an evolution of the gene for the glutaminyl-tRNA synthetase of E.

Glutamyl transfer ribonucleic acid synthetase of Escherichia coli. Study of the interactions with its substrates.

The binding of the various substrates to Escherichia coli glutamyl-tRNA synthetase has been investigated by using as experimental approaches the binding study under equilibrium conditions and the substrate-induced protection of the enzyme against its thermal inactivation. The results show that ATP and tRNAGlu bind to the free enzyme, whereas glutamate binds only to an enzyme form to which glutamate-accepting tRNAGlu is associated. By use of modified E.

The glutamyl-tRNA synthetase of Escherichia coli: substrate-induced protection against its thermal inactivation.

The substrates-induced protection against the heat-inactivation of the glutamyl-tRNA synthetase has been investigated. tRNAGlu and ATP protect efficiently the enzyme, whereas glutamate does not. In the presence of tRNAGlu, glutamate induces an additional protection to that given by the tRNAGlu alone.

The monomeric glutamyl-tRNA synthetase of Escherichia coli. Purification and relation between its structural and catalytic properties.

The glutamyl-tRNA synthetase has been purified to homogeneity from Escherichia coli with a yield of about 50%. It is a monomer with a molecular weight of 56,000 and has the same kinetic properties as those of the alpha chain of the dimeric alphabeta-glutamyl-tRNA synthetase described previously (Lapointe, J., and Söll, D.

The twenty aminoacyl-tRNA synthetases from Escherichia coli. General separation procedure, and comparison of the influence of pH and divalent cations on their catalytic activities.

A general separation procedure of the twenty E. coli aminoacyl-tRNA synthetases including either a 105 000 g centrifugation or a poly-ethyleneglycol-dextran two-phases partition fractionation, and chromatographies on DEAE-cellulose, phosphocellulose and hydroxyapatite is described. The specific activities of the synthetases have been determined after each chromatographic step and compared to their respective activities in the 105 000 g supernatant.

Growth retardation and prevention of Ehrlich solid tumor by Clostridium perfringens type A spores and culture supernatant.

When given by direct s.c. injection into the Ehrlich solid carcinoma 1 week after s.

Derepressed levels of glutamate synthase and glutamine synthetase in Escherichia coli mutants altered in glutamyl-transfer ribonucleic acid synthetase.

The levels of glutamate synthase and of glutamine synthetase are both derepressed 10-fold in strain JP1449 of Escherichia coli carrying a thermosensitive mutation in the glutamyl-transfer ribonucleic acid (tRNA) synthetase and growing exponentially but at a reduced rate at a partially restrictive temperature, compared with the levels in strain AB347 isogenic with strain JP1449 except for this thermosensitive mutation and the marker aro. These two enzymes catalyze one of the two pathways for glutamate biosynthesis in E. coli, the other being defined by the glutamate dehydrogenase.