Synthesis of charged phenyl radicals and biradicals by laser photolysis in a Fourier-transform ion cyclotron resonance mass spectrometer

The feasibility of generating substituted phenyl radicals and biradicals (with a charged substituent) in the gas phase by laser photolysis was examined by using a Fourier-transform ion cyclotron resonance mass spectrometer. The precursors were generated by ipso-substitution of a halogen atom in the radical cation of a di- or trihalobenzene by various nucleophiles. Photolytic cleavage of the remaining carbon-halogen bond(s) with 266-nm radiation was found to produce many substituted phenyl radicals in greater yields than the earlier employed method, sustained off-resonance irradiated collision-activated dissociation (SORI-CAD). Furthermore, ion generation by photolysis leads to isomerization less often than collisional activation. Finally, not only phenyl-bromine and phenyl-iodine but also certain phenyl-chlorine bonds can be cleaved by photolysis, whereas the synthetic utility of SORI-CAD appears to be largely limited to the cleavage of phenyl-iodine bonds. Hence, laser photolysis greatly expands the variety of substituted phenyl radicals and biradicals that can be synthesized inside a mass spectrometer.     

An evaluation of the effect of an alpha hydroxy acid-blend skin cream in the cosmetic improvement of symptoms of moderate to severe xerosis, epidermolytic hyperkeratosis, and ichthyosis

It has been observed that the occurrence of respiratory complications and diarrhoea among measles cases has changed over time but this change has not been quantified. A study was carried out in the city of Gweru, Zimbabwe, to quantify these changes. Rates of respiratory complications and diarrhoea among measles cases were determined in each year for the period 1968-89. It was found that mean rates of respiratory complications and diarrhoea during 1968-78 were 17.2 per cent (95 per cent CI = 11.6-22.8) and 5.2 per cent (95 per cent CI = 0-11) respectively while during 1979-89, mean rates of respiratory complications and diarrhoea were 6.5 per cent (95 per cent CI = 1-12.1) and 16.4 per cent (95 per cent CI = 10.1-22.0) respectively. Analysis of variance (ANOVA) to determine the main effects and the interaction showed that the main effects were not statistically significant (F = 0.01, d.f.1,2 = 1,40, p = 0.935; and F = 0.13, d.f.1,2 = 1,40, p = 0.725 respectively) Meanwhile the interaction term of complications and period was statistically significant (F = 15.7, d.f.1,2 = 1,40, p < 0.001). It was concluded that a change in rates of respiratory complications and diarrhoea had occurred among measles cases. It is suggested that the increase in vaccination coverage in 1979-89 and the shift in age at infection to older age groups in the same period may have brought about this change through selective suppression of respiratory complications among measles cases.     

Charakterisierung von Plasma‐ Polymerfilmen mittels Flugzeit‐ Sekundärionen‐Massenspektrometrie (ToF‐SIMS). Characterisation Plasma‐Polymerfilms by Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS)

Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) is a surface sensitive analytical method which is utilised in many scientific and industrial branches. The area of application is the identification and localisation of all elements as well as organic and inorganic chemical compounds on arbitrary solid surfaces. The information on the surface is obtained from mass spectra. Due to the high mass resolution (m/Δm > 5.000) different chemical species of the same nominal mass can be clearly separated from each other. Furthermore, the lateral distribution of elemental and molecular species on the surface can be displayed with a lateral resolution < 1 μm. By multivariate modeling the complete information from the mass spectra can be correlated with physical surface properties such as wetting behaviour, elemental concentrations, tribological parameters etc. The outcome of this are decisive information about the functionality of the analysed surface structure. For this reason Time‐of‐Flight Secondary Ion Mass Spectrometry becomes an essential analysis tool in the development of functional surfaces which are the basis of novel and innovative products.     

Purification, gene cloning, targeted knockout, overexpression, and biochemical characterization of the major pyrazinamidase from Mycobacterium smegmatis

The pyrazinamidase from Mycobacterium smegmatis was purified to homogeneity to yield a product of approximately 50 kDa. The deduced amino-terminal amino acid sequence of this polypeptide was used to design an oligonucleotide probe for screening a DNA library of M. smegmatis. An open reading frame, designated pzaA, which encodes a polypeptide of 49.3 kDa containing motifs conserved in several amidases was identified. Targeted knockout of the pzaA gene by homologous recombination yielded a mutant, pzaA::aph, with a more-than-threefold-reduced level of pyrazinamidase activity, suggesting that this gene encodes the major pyrazinamidase of M. smegmatis. Recombinant forms of the M. smegmatis PzaA and the Mycobacterium tuberculosis pyrazinamidase/nicotinamidase (PncA) were produced in Escherichia coli and were partially purified and compared in terms of their kinetics of nicotinamidase and pyrazinamidase activity. The comparable Km values obtained from this study suggested that the unique specificity of pyrazinamide (PZA) for M. tuberculosis was not based on an unusually high PZA-specific activity of the PncA protein. Overexpression of pzaA conferred PZA susceptibility on M. smegmatis by reducing the MIC of this drug to 150 micrograms/ml.     

Spontaneous thrombosis of a basilar artery traumatic aneurysm in a child

Traumatic aneurysms are rare and occur most commonly in young adults; however, the relative frequency in the pediatric population is high, owing to the low prevalence of congenital saccular aneurysms in children. Traumatic aneurysms typically involve the anterior circulation, and spontaneous thrombosis is uncommon; hence, surgery is usually necessary. We present a case of a posttraumatic aneurysm in a child that occurred after a fall from a large height and that spontaneously thrombosed.     

Characterisation of amorphous carbon coatings for magnetic storage devices via AFM‐Nanoscratching devices. AFM‐Nanoscratching an amorphen Kohlenstoffschichten für die Speichertechnologie

The mechanical properties of ultra‐thin amorphous carbon films used as protective coatings for magnetic storage devices were investigated by means of atomic force microscopy (AFM). Diamond‐tipped cantilevers were used in order to generate scratches with residual scratch depths of only a few Angstroms and even below. The presented method simulates mechanical strains at the head‐disk interface. A driftcompensating image subtracting technique allows the visualisation of these ultra‐shallow scratches and enables the mechanical characterisation of only few Nanometer films widely independent from the hardness of the substrate. The scratch resistance as it is defined here correlates well with the mass density and the sp³ content of the investigated films.     

Possible functions of peptide antibiotics during growth of producer organisms: bacitracin and metal (II) ion transport

The inhibitory effect of bacitracin upon growth of the producer strain Bacillus licheniformis ATCC 10716 was dependent upon the presence of several different metal (II) ions, particularly Mn (II), Co (II), or Zn (II) ions. This supports our previous suggestion that the normal function of bacitracin during growth of the producer organism may be to promote the uptake of several divalent metal ions. Due to the striking similarity between the antimicrobial effect of bacitracin towards susceptible organisms and the effect of bacitracin towards the producer organisms B. licheniformis ATCC 10716, the possibility that the antimicrobial effect of bacitracin may be an induction of uptake of toxic amounts of metal ions is discussed. The possibility that peptide antibiotics may normally participate in ion transport during growth of producer organisms is also discussed.     

Regional differences in stratum corneum reactivity to surfactants. Quantitative assessment using the corneosurfametry bioassay

A highly sensitive and specific chemiluminescent immunoassay (CLIA) was developed for quantification of growth hormone (GH) in salmonid species. The CLIA for salmon GH was performed using the sandwich method with anti-GH IgG as the first antibody and chemiluminescent acridinium ester-labelled specific anti-GH F(ab')2 as the second antibody. The measurable range of salmon GH in the CLIA was 39-1250 pg/mL using a short assay (1 day) protocol and 3.9-125 pg/mL in a longer (2-day) assay. The dilution curve in the CLIA of serum from masu salmon (Oncorhynchus masou) was parallel to the standard curve of recombinant chum salmon (Oncorhynchus keta) GH. Seasonal changes of serum GH levels were measured in 1 year-old masu salmon cultivated in a pond from March to November. Their serum GH levels increased during smoltification from March to April, achieved a maximum level of 21 ng/mL in August, and then declined gradually to 11 ng/mL in October.