Spontaneous pneumothorax complicating lung metastasis from lingual carcinoma

Cervical cancer is the fourth cancer in women. It is the first malignancy for which mass population screening has been demonstrated to significantly reduce the mortality due to this disease. In Belgium, the mortality associated to cervical cancer decreased from 6 to 4 per 100,000 women-years from 1955-1959 to 1985-1989. European recommendations regarding cervical cancer screening are to perform a cervical smear each three years in women aged 25 to 65 years. In Belgium, while the Flemish region has decided to organize the cervical cancer screening according to the European recommendations, the screening in the French part of the country is essentially opportunistic. In this short review, the cost/benefit of the organized screening versus the opportunistic screening is discussed.     

Catalytic graphitization of a phenolic resin carbon by nickel (~100 μm): Selective gasification of three resultant components as studied by SEM

A phenolic resin carbon containing nickel particles, ~100 μm diam., was graphitized to 2773K for 1 h. This treatment created within the specimen three structural components known as graphitic (G), turbostratic (T_s) and matrix (A). The graphitized carbon was oxidized by carbon dioxide, HNO₃-H₂SO₄ mixed acid and Simon's reagent and topographical changes were monitored by SEM. The CO₂ gasified preferentially the T_s-component to produce fissures mainly at the interface with the A- andG-component. The mixed acid reacted preferentially with the G- andT_s-components, the Simon's reagent reacting significantly only with the G-component. The mineral matter of metallurgical coke can act as a graphitization catalyst similar to nickel particles. Hence, the development of structural components within the metallurgical coke followed by gasification by carbon dioxide may cause weakening of the coke at the interfaces of components.     

Vacancy generation in deformed thin metal

Kiritani found that vacancy clusters of large number density form in f.c.c. thin metal of 100 nm thickness deformed to their fracture. In the present work, a computer simulation of deformation of thin metal is carried out to investigate how vacancies of high concentration generate during a deformation of thin specimens of Al and Cu. A crystal of 4000 atoms whose size is (10a₀ × 10a₀ × 10a₀) is elongated to z-axes. Two modes of simulation are carried out. In the mode 1, surface which are normal to x-axes and y-axes are kept free. In the mode 2, the periodic boundary condition is applied for all surfaces. The mode 2 is equivalent to the deformation of bulk metal. In the simulation of mode 1, the tilting of 1 1 0 atom row initiates on the surface. A tilting of rows to the same direction expands on a (1 1 1) plane and arrives to other side of surface. Dislocations do not form during the tilting. The tilting of atom rows occurs due to easy movement of atoms on surface responding to stress. In highly deformed thin metal, the tilting of atom rows occurs on multi-layers of parallel planes. Subsequently a tilted row split into two rows. A new row initiates by moving an atom on surface to the interstitial position. A transportation of atoms from the normal row to the new row occurs during deformation, which contributes to the reduction of thickness. Vacancies of high concentration are not generated in the case of the mode 1 deformation. In the simulation of the mode 2, the formation of domain in which atom rows tilt to the same direction occurs. At the domain boundary ordered array of atom rows becomes disordered in an instant and grows to a small crack of vacancy cluster. The formation process of vacancy clusters which were observed in deformed thin metal is due to the combination of the processes of the modes 1 and 2.     

Existence of an iron-oxidizing bacterium Acidithiobacillus ferrooxidans resistant to organomercurial compounds

Acidithiobacillus ferrooxidans MON-1 which is highly resistant to Hg2+ could grow in a ferrous sulfate medium (pH 2.5) with 0.1 microM p-chloromercuribenzoic acid (PCMB) with a lag time of 2 d. In contrast, A. ferrooxidans AP19-3 which is sensitive to Hg2+ did not grow in the medium. Nine strains of A. ferrooxidans, including seven strains of the American Type Culture Collection grew in the medium with a lag time ranging from 5 to 12 d. The resting cells of MON-1, which has NADPH-dependent mercuric reductase activity, could volatilize Hg0 when incubated in acidic water (pH 3.0) containing 0.1 microM PCMB. However, the resting cells of AP19-3, which has a similar level of NADPH-dependent mercuric reductase activity compared with MON-1, did not volatilize Hg0 from the reaction mixture with 0.1 microM PCMB. The activity level of the 11 strains of A. ferrooxidans to volatilize Hg0 from PCMB corresponded well with the level of growth inhibition by PCMB observed in the growth experiments. The resting cells of MON-1 volatilized Hg0 from phenylmercury acetate (PMA) and methylmercury chloride (MMC) as well as PCMB. The cytosol prepared from MON-1 could volatilize Hg0 from PCMB (0.015 nmol mg(-1) h(-1)), PMA (0.33 nmol mg(-1) h(-1)) and MMC (0.005 nmol mg(-1) h(-1)) in the presence of NADPH and beta-mercaptoethanol.     

Purification and some properties of sulfur reductase from the iron-oxidizing bacterium Thiobacillus ferrooxidans NASF-1

Thiobacillus ferrooxidans strain NASF-1 grown aerobically in an Fe2+ (3%)-medium produces hydrogen sulfide (H2S) from elemental sulfur under anaerobic conditions with argon gas at pH 7.5. Sulfur reductase, which catalyzes the reduction of elemental sulfur (S0) with NAD(P)H as an electron donor to produce hydrogen sulfide (H2S) under anaerobic conditions, was purified 69-fold after 35-65% ammonium sulfate precipitation and Q-Sepharose FF, Phenyl-Toyopearl 650 ML, and Blue Sepharose FF column chromatography, with a specific activity of 57.6 U (mg protein)(-1). The purified enzyme was quite labile under aerobic conditions, but comparatively stable in the presence of sodium hydrosulfite and under anaerobic conditions, especially under hydrogen gas conditions. The purified enzyme showed both sulfur reductase and hydrogenase activities. Both activities had an optimum pH of 9.0. Sulfur reductase has an apparent molecular weight of 120,000 Da, and is composed of three different subunits (M(r) 54,000 Da (alpha), 36,000 Da (beta), and 35,000 Da (gamma)), as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is the first report on the purification of sulfur reductase from a mesophilic and obligate chemolithotrophic iron-oxidizing bacterium.     

The effects of aluminum on structural development of a carbon derived from phenolic resin

The catalytic graphitization of a phenolic resin carbon by aluminum powder was carried out under an N₂ atmosphere. The following catalytic mechanism is proposed: In the heating process up to 2000°C, AlN is formed at first by the reaction of the aluminum with the N₂ gas. At approximately 2000°C, the AlN begins to react with the carbon matrix to form an intermediate, A₁₄C₃. The Al₄C₃ penetrates into the surrounding carbon matrix through an Al₄C₃ formation-decomposition sequence, leaving a graphite crystal behind. As the penetration proceeds, smaller graphite crystals are formed because of the division of the Al₄C₃ particles. When a most finely divided Al₄C₃ is produced by the further penetration, instead of the graphite, only turbostratic carbon is formed by this catalytic process.     

Cytochrome c oxidase purified from a mercury-resistant strain of Acidithiobacillus ferrooxidans volatilizes mercury

We suggested in our previous study that the plasma membrane cytochrome c oxidase of the mercury-resistant iron-oxidizing bacterial strain Acidithiobacillus ferrooxidans, SUG 202, is involved in Fe2+-dependent mercury volatilization. To study the involvement of A. ferrooxidans cytochrome c oxidase in mercury reduction, the cytochrome c oxidase was extracted from mercury-resistant and mercury-sensitive strains and purified. The Fe2+-dependent mercury volatilization activities of the oxidases from these strains were compared. The cytochrome c oxidase from strain SUG 2-2 volatilized 39% of the total Hg2+ (7 nmol) that had been added to a 10-ml reaction mixture (pH 3.8) in the presence of 10 micromol of Fe2+ after a 7-d incubation period at 30 degrees C. In contrast, the enzyme purified from the mercury-sensitive strain AP19-3 volatilized 3.5% of the total mercury under the same conditions. The boiled SUG 2-2 oxidase did not exhibit activity to volatilize mercury. Fe2+ reduced the oxidase from SUG 2-2 and Hg2+ oxidized the reduced enzyme. The purified SUG 2-2 oxidase is composed of three protein subunits with apparent molecular weights of 56,000 Da (alpha), 24,000 Da (beta), and 19,000 Da (gamma). The amount of mercury bound to the purified SUG 2-2 oxidase was 6.2 microg/mg protein and those bound to alpha-, beta- and gamma-subunits of the cytochrome c oxidase were 3.5, 2.6 and 0.7 microg/mg protein, respectively.