Evaluation of the onset time and intubation conditions of rocuronium bromide in children

Publisher's copy made available with the permission of the publisher © 1997 Australian Society of AnaesthetistsWe have assessed, in children aged three to eight years, the intubating conditions after administration of rocuronium 0.6 mg/kg at 50 or 60 seconds, in groups of 15 patients. Intubating conditions were excellent in 11, good in 3 and fair in 1 patient at 50 seconds and excellent in 12 and good in 3 patients at 60 seconds. The mean onset time, for all patients, to when the first twitch of the train of four (T1), measured at the adductor pollicis, was depressed to less than 30% and 5% of control was 50 (SD 11.4) seconds and 94 (SD 31.7) seconds respectively. Depression of T1 to less than 30% of control, measured at the adductor pollicis in children, appears to indicate that intubating conditions will be clinically acceptable when using rocuronium.P.F. McDonald, D.A. Sainsbury, R.J. Lain

Study of vascular enzymes in experimental hypertension

1. The acute fibrinoid necrosis of visceral arterioles which occurs in the malignant phase of hypertension is generally attributed to the critical rise in blood pressure which takes place in this condition. Experimental evidence, obtained in the rat with deoxycortone hypertension, led to the hypothesis that early in the development of the hypertension a change occurred in the internal environment of the smooth muscle cell which might predispose the cell to necrosis. 2. It was suggested that this alteration might be, or could be attributable to, a disturbance of the energy production by metabolism in the cell. A study of selected enzymes in the arterioles of rats in the early phase of deoxycortone hypertension was therefore undertaken. As energy production in cardiac muscle may also be disturbed when raised blood pressure is maintained, enzymes in this muscle were also studied. 3. The techniques chosen for enzyme assays were those which could subsequently be adapted to the study of isolated arteriolar smooth muscle cells. Methods were developed for the preparation of freeze-dried vascular tissue and for the assay of alkaline phosphatase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase and malate dehydrogenase in microgram quantities of this material. The localisation of the enzymes was also studied by qualitative histochemical methods. 4. Hypertension was initiated in male, albino, Wistar rats by implanting deoxycortone acetate subcutaneously in uninephrectomised,salt-loaded animals. Control groups of uninephrectomised rats, salt-loaded rats and normal animals were maintained under identical conditions. 5. A significant decrease in alkaline phosphatase activity and a significant increase in glucose-6-phosphate dehydrogenase activity were found in the cardiac tissue of deoxycortonetreated rats after one week: the systolic blood pressure had risen significantly in these animals. Changes of a similar size were found in the activity of these two enzymes in the cardiac tissue of control uninephrectomised and salt-loaded animals: a slight but statistically significant increase in blood pressure occurred in these groups. No differences were found in the mean values of the activities of lactate dehydrogenase or malate dehydrogenase in heart tissue from the four groups.of rats. 6. The different relationships observed between cardiac alkaline phosphatase activity and the blood pressure in the individual animals of the treated groups suggested that the enzyme value showed a trend of returning to normal in these animals in which raised blood pressure was accompanied by compensatory renal hyperplasia. 7. In the second experiment the enzymes were studied in mesenteric arterioles. A significant increase in blood pressure occurred only in the deoxycortone-treated rats. A significant increase in alkaline phosphatase and in glucose-6- phosphate dehydrogenase activity in mesenteric arterioles occurred only in this group. There was a trend for arteriolar alkaline phosphatase activity to decrease with increasing weight of the animals. This was not significant in normal-19V animals but was so in uninephrectomised rats. The trend for the increase in arteriolar glucose-6-phosphate dehydrogenase activity to be greater in animals with the greater increase in blood pressure failed to reach conventional levels of signi¬ ficance. No differences were observed in the mean values of the activities of lactate dehydrogenase or malate dehydrogenase in the arterioles of the four groups of rats. 8. A comparison of the enzyme activities measured suggested that whereas cardiac muscle has a greater capacity for metabolism by glycolysis and the citric acid cycle the pentose phosphate pathway is more important in arteriolar tissue. 9. Neither in cardiac tissue nor in arteriolar tissue of hypertensive animals were there alterations in the enzymes of the glycolytic pathway or the citric acid cycle, the main energy-supplying routes of metabolism. The activities of the enzymes altered are known to be under hormonal control. The small amount of evidence there is on vascular tissue enzymes suggests that the variation in the enzyme activities in the early stage of experimental hypertension is possibly determined by a pituitary or adrenal dysfunction initiated by the sodium load. 10. The enzyme changes which occurred in the different groups of animals in arteriolar tissue showed a closer relationship to the capacity of the given treatment for increasing blood pressure and producing arteriolar damage than those which occurred in cardiac tissue. 11. Further studies are necessary to determine if the observed changes in the vascular enzymes are also found at an-195- early stage in other forms of experimental hypertension. A study of the enzymes in arterioles from human biopsy material from hypertensive patients would establish the relationship of these observations in experimental disease to the human condition uninephrectomised rats, salt-loaded rats and normal animals were maintained under identical conditions

The magnetized medium around the radio galaxy B2 0755+37: an interaction with the intra-group gas

We explore the magneto-ionic environment of the isolated radio galaxy B2 0755+37 using detailed imaging of the distributions of Faraday rotation and depolarization over the radio source from Very Large Array observations at 1385,1465 and 4860 MHz and new X-ray data from XMM-Newton. The Rotation Measure (RM) distribution is complex, with evidence for anisotropic fluctuations in two regions. The approaching lobe shows low and uniform RM in an unusual `stripe' along an extension of the jet axis and a linear gradient transverse to this axis over its Northern half. The leading edge of the receding lobe shows arc-like RM structures with sign reversals. Elsewhere, the RM structures are reasonably isotropic. The RM power spectra are well described by cut-off power laws with slopes ranging from 2.1 to 3.2 in different sub-regions. The corresponding magnetic-field autocorrelation lengths, where well-determined, range from 0.25 to 1.4 kpc. It is likely that the fluctuations are mostly produced by compressed gas and field around the leading edges of the lobes. We identify areas of high depolarization around the jets and inner lobes. These could be produced by dense gas immediately surrounding the radio emission containing a magnetic field which is tangled on small scales. We also identify four ways in which the well known depolarization (Faraday depth) asymmetry between jetted and counter-jetted lobes of extended radio sources can be modified by interactions with the surrounding medium.Comment: 16 pages, 13 figures, accepted for publication in MNRAS. Full resolution paper available at: ftp://ftp.ira.inaf.it/pub/outgoing/guidetti/ Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO

Structures of the magnetoionic media around the FR I radio galaxies 3C 31 and Hydra A

We use high-quality VLA images of the Fanaroff & Riley Class I radio galaxy 3C 31 at six frequencies in the range 1365 to 8440MHz to explore the spatial scale and origin of the rotation measure (RM) fluctuations on the line of sight to the radio source. We analyse the distribution of the degree of polarization to show that the large depolarization asymmetry between the North and South sides of the source seen in earlier work largely disappears as the resolution is increased. We show that the depolarization seen at low resolution results primarily from unresolved gradients in a Faraday screen in front of the synchrotron-emitting plasma. We establish that the residual degree of polarization in the short-wavelength limit should follow a Burn law and we fit such a law to our data to estimate the residual depolarization at high resolution. We show that the observed RM variations over selected areas of 3C 31 are consistent with a power spectrum of magnetic fluctuations in front of 3C 31 whose power-law slope changes significantly on the scales sampled by our data. The power spectrum can only have the form expected for Kolmogorov turbulence on scales <5 kpc. On larger scales we find a flatter slope. We also compare the global variations of RM across 3C 31 with the results of three-dimensional simulations of the magnetic-field fluctuations in the surrounding magnetoionic medium. We show that our data are consistent with a field distribution that favours the plane perpendicular to the jet axis - probably because the radio source has evacuated a large cavity in the surrounding medium. We also apply our analysis techniques to the case of Hydra A, where the shape and the size of the cavities produced by the source in the surrounding medium are known from X-ray data. (Abridged)Comment: 33 pages, 25 figures, accepted for publication in MNRA

Structure of the magnetoionic medium around the FR Class I radio galaxy 3C 449

The goal of this work is to constrain the strength and structure of the magnetic field associated with the environment of the radio source 3C 449, using observations of Faraday rotation, which we model with a structure function technique and by comparison with numerical simulations. We assume that the magnetic field is a Gaussian, isotropic random variable and that it is embedded in the hot intra-group plasma surrounding the radio source. For this purpose, we present detailed rotation measure images for the polarized radio source 3C 449, previously observed with the Very Large Array at seven frequencies between 1.365 and 8.385 GHz. We quantify the statistics of the magnetic-field fluctuations by deriving rotation measure structure functions, which we fit using models derived from theoretical power spectra. We quantify the errors due to sampling by making multiple two-dimensional realizations of the best-fitting power spectrum.We also use depolarization measurements to estimate the minimum scale of the field variations. We then make three-dimensional models with a gas density distribution derived from X-ray observations and a random magnetic field with this power spectrum. Under these assumptions we find that both rotation measure and depolarization data are consistent with a broken power-law magnetic-field power spectrum, with a break at about 11 kpc and slopes of 2.98 and 2.07 at smaller and larger scales respectively. The maximum and minimum scales of the fluctuations are around 65 and 0.2 kpc, respectively. The average magnetic field strength at the cluster centre is 3.5 +/-1.2 micro-G, decreasing linearly with the gas density within about 16 kpc of the nucleus.Comment: 19 pages; 14 figures; accepted for publication on A&A. For a high quality version use ftp://ftp.eso.org/pub/general/guidetti

Asymmetry of jets, lobe size and spectral index in radio galaxies and quasars

We investigate the correlations between spectral index, jet side and extent of the radio lobes for a sample of nearby FRII radio galaxies. In Dennett-Thorpe et al. (1997) we studied a sample of quasars and found that the high surface brightness regions had flatter spectra on the jet side (explicable as a result of Doppler beaming) whilst the extended regions had spectral asymmetries dependent on lobe length. Unified schemes predict that asymmetries due to beaming will be much smaller in narrow-line radio galaxies than in quasars: we therefore investigate in a similar manner, a sample of radio galaxies with detected jets. We find that spectral asymmetries in these objects are uncorrelated with jet sidedness at all brightness levels, but depend on relative lobe volume. Our results are not in conflict with unified schemes, but suggest that the differences between the two samples are due primarily to power or redshift, rather than to orientation. We also show directly that hotspot spectra steepen as a function of radio power or redshift. Whilst a shift in observed frequency due to the redshift may account for some of the steepening, it cannot account for all of it, and a dependence on radio power is required.Comment: accepted for publication in MNRAS, 10 pages; typos/minor correctio

Multifrequency VLA observations of the FR I radio galaxy 3C 31: morphology, spectrum and magnetic field

We present high-quality VLA images of the FR I radio galaxy 3C 31 in the frequency range 1365 to 8440 MHz with angular resolutions from 0.25 to 40 arcsec. Our new images reveal complex, well resolved filamentary substructure in the radio jets and tails. We also use these images to explore the spectral structure of 3C 31 on large and small scales. We infer the apparent magnetic field structure by correcting for Faraday rotation. Some of the intensity substructure in the jets is clearly related to structure in their apparent magnetic field: there are arcs of emission where the degree of linear polarization increases, with the apparent magnetic field parallel to the ridges of the arcs. The spectral indices are significantly steeper (0.62) within 7 arcsec of the nucleus than between 7 and 50 arcsec (0.52 - 0.57). The spectra of the jet edges are also slightly flatter than the average for their surroundings. At larger distances, the jets are clearly delimited from surrounding larger-scale emission both by their flatter radio spectra and by sharp brightness gradients. The spectral index of 0.62 in the first 7 arcsec of 3C 31's jets is very close to that found in other FR I galaxies where their jets first brighten in the radio and where X-ray synchrotron emission is most prominent. Farther from the nucleus, where the spectra flatten, X-ray emission is fainter relative to the radio. The brightest X-ray emission from FR I jets is therefore not associated with the flattest radio spectra, but with a particle-acceleration process whose characteristic energy index is 2.24. The spectral flattening with distance from the nucleus occurs where our relativistic jet models require deceleration, and the flatter-spectra at the jet edges may be associated with transverse velocity shear. (Slightly abridged)Comment: 17 pages, 13 figures, accepted for publication in MNRA

PCR for the detection of pathogens in neonatal early onset sepsis.

BACKGROUND: A large proportion of neonates are treated for presumed bacterial sepsis with broad spectrum antibiotics even though their blood cultures subsequently show no growth. This study aimed to investigate PCR-based methods to identify pathogens not detected by conventional culture. METHODS: Whole blood samples of 208 neonates with suspected early onset sepsis were tested using a panel of multiplexed bacterial PCRs targeting Streptococcus pneumoniae, Streptococcus agalactiae (GBS), Staphylococcus aureus, Streptococcus pyogenes (GAS), Enterobacteriaceae, Enterococcus faecalis, Enterococcus faecium, Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis and Mycoplasma genitalium, a 16S rRNA gene broad-range PCR and a multiplexed PCR for Candida spp. RESULTS: Two-hundred and eight samples were processed. In five of those samples, organisms were detected by conventional culture; all of those were also identified by PCR. PCR detected bacteria in 91 (45%) of the 203 samples that did not show bacterial growth in culture. S. aureus, Enterobacteriaceae and S. pneumoniae were the most frequently detected pathogens. A higher bacterial load detected by PCR was correlated positively with the number of clinical signs at presentation. CONCLUSION: Real-time PCR has the potential to be a valuable additional tool for the diagnosis of neonatal sepsis

Boson Sampling from Gaussian States

We pose a generalized Boson Sampling problem. Strong evidence exists that such a problem becomes intractable on a classical computer as a function of the number of Bosons. We describe a quantum optical processor that can solve this problem efficiently based on Gaussian input states, a linear optical network and non-adaptive photon counting measurements. All the elements required to build such a processor currently exist. The demonstration of such a device would provide the first empirical evidence that quantum computers can indeed outperform classical computers and could lead to applications

Ordered magnetic fields around radio galaxies: evidence for interaction with the environment

We present detailed imaging of Faraday rotation and depolarization for the radio galaxies 0206+35, 3C 270, 3C 353 and M 84, based on Very Large Array observations at multiple frequencies in the range 1365 to 8440 MHz. This work suggests a more complex picture of the magneto-ionic environments of radio galaxies than was apparent from earlier work. All of the sources show spectacular banded rotation measure (RM) structures with contours of constant RM perpendicular to the major axes of their radio lobes. We give a comprehensive description of the banded RM phenomenon and present an initial attempt to interpret it as a consequence of interactions between the sources and their surroundings. We show that the material responsible for the Faraday rotation is in front of the radio emission and that the bands are likely to be caused by magnetized plasma which has been compressed by the expanding radio lobes. A two-dimensional magnetic structure in which the field lines are a family of ellipses draped around the leading edge of the lobe can produce RM bands in the correct orientation for any source orientation. We also report the first detections of rims of high depolarization at the edges of the inner radio lobes of M 84 and 3C 270. These are spatially coincident with shells of enhanced X-ray surface brightness, in which both the field strength and the thermal gas density are likely to be increased by compression.Comment: 21 pages, 15 figures, accepted for publication in MNRAS. Full resolution paper available at http://www.ira.inaf.it/~guidetti/bands/ Subjects: Astrophysics (astro-ph