Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

BACKGROUND: Ultrasonography (US) by acknowledged experts enhances the diagnostic performance and reduces the rate of negative laparotomies in patients with suspected acute appendicitis (AA). METHODS: The diagnostic accuracy and clinical impact of routine US performed by surgical residents was prospectively studied in 504 unselected patients admitted for AA. Clinical and US findings were correlated with laparotomy findings and pathological outcome in 135 patients (113 cases with proven AA, prevalence 22.4%) and clinical as well as follow-up data were compared in the remainder. RESULTS: The overall accuracy, sensitivity, and specificity of the clinical diagnosis of AA were 84.9%, 51.3%, and 94.6% and those of US were 93. 6%, 83.1%, and 96.6%. Joint evaluation of the results from clinical evaluation and US further improved diagnostic performance (accuracy 93.4%, sensitivity 84.1%, specificity 96.2) and significantly reduced the rate of diagnostic errors to 3.4% (p < 0.001) and unnecessary laparotomies to 9.6% (p < 0.01) in patients with suspected AA. CONCLUSIONS: Ultrasonographic evaluation of the patient with suspected AA is considered to be of value in surgical practice.     

Complement C6 and C2 biosynthesis in syngeneic PVG/c- and PVG/c+ rat strains

A PVG rat with total deficiency of C6 and partial deficiency of C2 (PVG/c-), and a syngeneic control strain (PVG/c+), were used to study the production of extrahepatically synthesized complement. Livers of complement deficient rats were transplanted in sufficient rats (Tx-L). The C6 and C2 levels in Tx-L rats declined within 2 days to 25% and 30%, respectively, and remained stable for more than 6 weeks. To investigate the contribution of C6 synthesis by the liver, C6 sufficient livers were grafted in deficient rats (Tx + 1). After an initial increase, with maximum C6 levels of 119% at 10 days following transplantation, the C6 levels decreased gradually and C6 was no longer detectable 28 days after transplantation. This decline in C6 levels was dependent on antibody production against C6. No significant change in the C3, C4, factor H and factor B levels was observed. Expression of C6 mRNA in the grafted PVG/c+ sufficient liver was comparable to the expression of C6 mRNA in control PVG/c+ livers while C6 mRNA expression in the transplanted PVG/ c- liver and the control PVG/c- liver was lower. In conclusion, it was demonstrated in vivo that not only C6 but also C2 is synthesized extrahepatically in PVG/c rats.     

Prostaglandins suppress an outward potassium current in embryonic rat sensory neurons

One of the challenges in understanding ciliary and flagellar motility is determining the mechanisms that locally regulate dynein-driven microtubule sliding. Our recent studies demonstrated that microtubule sliding, in Chlamydomonas flagella, is regulated by phosphorylation. However, the regulatory proteins remain unknown. Here we identify the 138-kD intermediate chain of inner arm dynein I1 as the critical phosphoprotein required for regulation of motility. This conclusion is founded on the results of three different experimental approaches. First, genetic analysis and functional assays revealed that regulation of microtubule sliding, by phosphorylation, requires inner arm dynein I1. Second, in vitro phosphorylation indicated the 138-kD intermediate chain of I1 is the only phosphorylated subunit. Third, in vitro reconstitution demonstrated that phosphorylation and dephosphorylation of the 138-kD intermediate chain inhibits and restores wild-type microtubule sliding, respectively. We conclude that change in phosphorylation of the 138-kD intermediate chain of I1 regulates dynein-driven microtubule sliding. Moreover, based on these and other data, we predict that regulation of I1 activity is involved in modulation of flagellar waveform.     

Biallelic mutations in the ATM gene in T-prolymphocytic leukemia

Ataxia-telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar ataxia, oculocutaneous telangiectasia, immune deficiency, genome instability and predisposition to malignancies, particularly T-cell neoplasms. The responsible gene, designated ataxia-telangiectasia mutated (ATM), was recently identified by positional cloning in the chromosomal region 11q22.3-23.1 (ref. 4, 5) ATM is 150 kb in length, consists of 66 exons and encodes a nuclear phosphoprotein of approximately 350 kDa (ref. 4-9). Although ATM is considered to be a tumorigenic factor in several human cancers, it has not yet been found mutated in tumors of non-AT patients. Given the marked predisposition of AT patients to develop neoplasms of the T-cell lineage, we analyzed a series of T-cell leukemias (T-prolymphocytic leukemia, or T-PLL) in non-AT patients in search of genomic changes associated with the development of this disease. Among the recurrent aberrations identified, deletion of the chromosome arm 11q was very frequent. Subsequent molecular cytogenetic analyses allowed us to define a small commonly deleted segment at 11q22.3-23.1 in 15 of 24 T-PLLs studied. Since this critical region contained ATM, we further analyzed the remaining copy of the gene in six cases showing deletions affecting one ATM allele. In all six cases, mutations of the second ATM allele were identified, leading to the absence, premature truncation or alteration of the ATM gene product. Thus, our study demonstrates disruption of both ATM alleles by deletion or point mutation in T-PLL, suggesting that ATM functions as a tumor-suppressor gene in tumors of non-AT individuals.     

Study of the vertical transport in <Emphasis Type="Italic">p</Emphasis>-doped superlattices based on group III-V semiconductors

The electrical conductivity σ has been calculated for p-doped GaAs/Al_0.3Ga_0.7As and cubic GaN/Al_0.3Ga_0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.     

Synthesis of High Coercivity Core–Shell Nanorods Based on Nickel and Cobalt and Their Magnetic Properties

Hybrid magnetic nanostructures with high coercivity have immense application potential in various fields. Nickel (Ni) electrodeposited inside Cobalt (Co) nanotubes (a new system named Ni @ Co nanorods) were fabricated using a two-step potentiostatic electrodeposition method. Ni @ Co nanorods were crystalline, and they have an average diameter of 150 nm and length of ~15 μm. The X-ray diffraction studies revealed the existence of two separate phases corresponding to Ni and Co. Ni @ Co nanorods exhibited a very high longitudinal coercivity. The general mobility-assisted growth mechanism proposed for the growth of one-dimensional nanostructures inside nano porous alumina during potentiostatic electrodeposition is found to be valid in this case too.     

Effect of dry‐salt processing on the textural properties and cell wall polysaccharides of cv. Thasos black olives

BACKGROUND: Thasos is an olive variety cultivated mainly in Greece used to produce ‘naturally black dry‐salted olives’. This process consists in placing the olives in disposed layers with coarse sodium chloride. The loss of water and other solutes gradually debitters and wrinkles the fruits. In this study, the effect of dry‐salt processing on the texture and cell wall polysaccharide composition was investigated. RESULTS: This type of processing affected primarily the mechanical properties of the olive flesh. In processed olives, this tissue was approximately 4.5 times stronger and also more deformable up to failure and stiffer than that from the raw olives. The dry‐salt processing had its strongest effect on pectic polysaccharides. This included the increment of solubilization of arabinose‐rich polymers in aqueous solutions, and thus their partial loss to the soak medium during dry‐salting. Contrarily, galacturonic acid‐rich polymers were further retained in the processed olives, probably by their stabilization within the cell walls by reduction of the electrostatic repulsion between the acidic groups of these polysaccharides due to sodium ions. CONCLUSION: The texture improvement of olive flesh by dry‐salt processing seems to be correlated with the reorganization of the galacturonic acid‐rich pectic polysaccharides into the cell wall of the fruit. Copyright © 2008 Society of Chemical Industry     

CREATING AND EVALUATING DIGITAL ELEVATION MODEL‐BASED STREAM‐POWER MAP AS A STREAM ASSESSMENT TOOL

As urban development increases, a need is emerging to understand and predict river behaviour in order to focus rehabilitation efforts and protect the natural river system while preserving urban infrastructure. Stream assessment methods are reviewed to demonstrate the need for a physically based and objective method that is also accessible in terms of time, data requirements and expertise. The case of Highland Creek near Toronto, Canada, is used to demonstrate a new type of initial stream assessment method that is based on the concept of stream power and performed entirely in a geographic information system using information from a digital elevation model (DEM). The results from this analysis are tested against existing information for Highland Creek. This includes a hydraulic model (Hydraulic Engineering Center's ‘River Analysis System’), field‐measured slopes, air photos and the geomorphic effects of an extreme flood. In addition, the results are presented in map form to demonstrate the effectiveness of visualizing the stream‐power distribution over the entire basin and also the usefulness of overlaying stream power onto other available information. The slopes extracted from the DEM are found to be statistically similar to those from a one‐dimensional hydraulic model and field‐measured slopes. Individual peaks in slope as well as locations of stream‐power maxima and minima are found to correlate to actual channel features as seen in air photos. The extreme flood event of August 2005 caused a dramatic change in channel form at the exact location of maximum energy predicted by the DEM‐based stream‐power analysis. The case of Highland Creek illustrates how this approach yields a useful outcome for understanding stream dynamics and stability as part of a stream assessment process. Copyright © 2011 John Wiley & Sons, Ltd.     

Bed morphology, flow structure, and sediment transport at the outlet of Lake Huron and in the upper St. Clair River

An integrated multibeam echo sounder and acoustic Doppler current profiler field survey was conducted in July 2008 to investigate the morphodynamics of the St. Clair River at the outlet of Lake Huron. The principal morphological features of the upper St. Clair River included flow-transverse bedforms that appear weakly mobile, erosive bedforms in cohesive muds, thin non-cohesive veneers of weakly mobile sediment that cover an underlying cohesive (till or glacio-lacustrine) surface, and vegetation that covers the bed. The flow was characterized by acceleration as the banks constrict from Lake Huron into the St. Clair River, an approximately 1500-m long region of flow separation downstream from the Blue Water Bridge, and secondary flow connected to: i) channel curvature; ii) forcing of the flow by local bed topography, and iii) flow wakes in the lee side of ship wrecks. Nearshore, sand-sized, sediment from Lake Huron was capable of being transported into, and principally along, the banks of the upper St. Clair River by the measured flow. A comparison of bathymetric surveys conducted in 2007 and 2008 identifies that the gravel bed does undergo slow downstream movement, but that this movement does not appear to be generated by the mean flow, and could possibly be caused by ship-propeller-induced turbulence. The study results suggest that the measured mean flow and dredging within the channel have not produced major scour of the upper St. Clair River and that the recent fall in the level of Lake Huron is unlikely to have been caused by these mechanisms.     

EPR kinetic studies of oxygen release in thylakoids and PSII membranes: a kinetic intermediate in the S3 to S0 transition

Time-resolved EPR oximetry has been used to determine the oxygen release kinetics in spinach thylakoids and PSII membranes. We observe release kinetics with half-times of approximately 0.85 and approximately 1.45 ms for thylakoids and PSII membranes, respectively, which are in close agreement with the EPR determined Yz decay kinetics for the S3 --> --> S0 transition in these systems. The results show conclusively that water-oxygen chemistry is not a rate-limiting step in the donor side of PSII under normal turnover conditions. By analyzing the oxygen release kinetics in thylakoids under nonphysiological, but still functionally competent conditions (low pH or high salt), we observed an initial delay in the O2 release of up to 200 microseconds following flash turnover from the S3 state. This is the first direct indication of a probable quasi-stable intermediate in the S3 --> --> S0 turnover of PSII, possibly representing the putative S4 state. Under conditions more closely approaching physiological, no such delay was resolved, indicating that the S4 --> O2 transition occurs within 50 microseconds under such circumstances. Two possible reaction sequences for O2 formation consistent with these and other data are discussed. It is suggested that the more probable form of "S4" is in fact the S3 + Yz* combination, which must undergo some molecular rearrangement on the tens to hundreds of microseconds time scale before O2 formation chemistry occurs.