Substitution of Copper by Magnesium in Malachite: Insights into the Synthesis and Structural Effects

The phase width of the copper hydroxycarbonate malachite, Cu₂CO₃(OH)₂, upon substitution with magnesium has been studied in detail. In extension of a previous study on amorphous precursors, the introduction of a hydrothermal aging step allowed the retrieval of crystalline hydroxycarbonate samples with up to 37 atom % Mg (metal content) that are suitable candidates as precursors to Cu/MgO catalysts for CO hydrogenation. Simultaneous refinements of X-ray powder diffraction and pair distribution function (PDF) data as well as complementary spectroscopic insight (X-ray absorption and infrared spectroscopy) revealed that samples with up to 18 atom % Mg are phase-pure magnesian malachites but the magnesium content can be increased beyond this threshold when mcguinnessite (CuMgCO₃(OH)₂) is accepted as a side phase. In a complementary study, a continuous increase of the magnesium fraction was found during aging and the corresponding structural evolution was studied by means of PDF. These findings add significant insight into the aging chemistry of crystalline Cu,Mg hydroxycarbonates. Furthermore, both phase-pure magnesian malachite and mcguinnessite-containing samples with up to 37 atom % Mg have been examined by thermogravimetry, X-ray powder diffraction, and N₂ physisorption and were found to be promising candidates for use as precursors for the preparation of Cu/MgO catalysts.

Zinc selenide nano- and microspheres via microwave-assisted ionothermal synthesis

Zinc selenide nanospheres were prepared from a diphenyl diselenide precursor and halozincate(ii) ionic liquids via a microwave-assisted ionothermal route.

Cluster of pulmonary infections caused by Cunninghamella bertholletiae in immunocompromised patients

Cunninghamella bertholletiae is a rare cause of pulmonary mucormycosis. We describe a cluster of invasive pulmonary infections caused by C. bertholletiae in 4 immunocompromised patients that occurred during a 2-year period at 1 center. Three of the patients were receiving antifungal prophylaxis with itraconazole. Presenting symptoms were fever unresponsive to antibacterial chemotherapy, hemoptysis, and infiltrates on chest radiograms. Three patients were treated with liposomal amphotericin B. Only 1 patient survived.

Influence of antimicrobial treatment on mortality in septicemia

OBJECTIVE

To determine the influence of antimicrobial therapy and of predisposing illness on the septicemia mortality rate.

METHOD

All blood-culture-positive episodes of septicemia in the Department of Medicine at the University Hospital in Frankfurt between 1989 and 1993 were entered on a database. Underlying illnesses were classified as immunocompromising diseases (hematological malignancies, AIDS and others), severe chronic and chronic illnesses and no predisposing illnesses. Therapy was judged on the basis of the in-vitro-susceptibility of the organism ('appropriate') and the interval (no. of days) between the onset of septicemia and start of appropriate treatment noted. For mortality all deaths within 28 days after the onset of septicemia were counted.

RESULTS

Overall mortality due to septicemia was 18.1%, ranging from 9.4% (organ transplantation) to 50% (liver cirrhosis) according to the underlying illness. Mortality in patients receiving appropriate treatment (83.1%) was 16% as opposed to 28%, if no appropriate treatment was given (p<0.001). Comparison of appropriate treatment started within and after 48 hours revealed a reduction in mortality from 30.9% to 15.4% for early appropriate therapy in patients with hematological malignancies (p<0.002). For septicemia in patients with AIDS and chronic illnesses mortality was significantly higher (p<0.05) if treatment remained inappropriate (AIDS 28.6%, chronic illness 33.3%), but was similar when early and delayed appropriate therapy were compared (AIDS: 13% vs. 12.8%, chronic illness 11.8% vs. 11.1%).

CONCLUSION

First-line treatment regimens for septicemia in patients with hematological malignancies should include the greatest possible part of the spectrum of causative organisms. In contrast to that it may be acceptable to rely to some extent on a change of treatment, when treating septicemia in patients with chronic illnesses or AIDS. These considerations are of value in the debate on rising health care costs. Several other facts, such as the stable mortality rate of 8 - 12% in previously healthy patients and the range of mortality from 9.4 - 50%, if predisposing illnesses are present, indicate the existence of adverse factors influencing the outcome of septicemia in spite of appropriate therapy. These pathophysiological factors will have to be studied in detail in order to improve the prognosis of septicemia further.

Ultrasensitive enzymatic radioimmunoassay using a fusion protein of protein A and neomycin phosphotransferase II in two-chamber-well microtiter plates

A new sensitive method for antigen detection employing a phosphorylation reaction is described using human serum albumin as a model. The antigen is initially bound to the surface of polystyrene microtiter plates and reacted with an antibody (rabbit). A microbiologically produced bifunctional fusion protein of protein A and neomycin phosphotransferase II (NPT II) serves as a second immunological reagent by virtue of its protein A component. The detection is based on the phosphorylation of an aminoglycoside antibiotic by the NPT II moiety of the fusion protein using [gamma-32P]ATP as a cosubstrate. This reaction is performed in solution and the evaluation is accomplished by dotting aliquots of the reaction mixture onto phosphocellulose paper, washing with water, and autoradiography. Microtiter plates with a specially designed 10 microliter-volume reaction chamber are particularly advantageous for this procedure. The sensitivity of detection is currently 10 fg (1 pg/ml) of antigen.

High-sensitivity protein detection by a new "contact-copy" method using a protein A-neomycin phosphotransferase II fusion protein

A new system for high-sensitivity protein detection by an immunoenzymatic "contact-copy" procedure is described. It is based on two components: (i) a microbiologically produced bifunctional fusion protein of protein A and neomycin phosphotransferase II (protein A-NPT II) in which the protein A moiety acts as a second immunological reagent while NPT II catalyzes the detection reaction and (ii) a novel kanamycin-loaded substrate matrix (kanamycin-cyanuric chloride-activated and sulfanilic acid-derivatized paper) brought into direct contact with a protein-carrying matrix after blot or dot application and initial immunoreaction--the NPT II enzyme reaction with [gamma-32P]ATP as cosubstrate leads to phosphorylation of the substrate kanamycin on the substrate matrix, which is used for further analysis. The contact-copy method has at least the same detection sensitivity as procedures employing 125I-protein A, but allows extremely short exposure times and avoids probe prelabeling. Twenty-five picograms of specific protein blotted from sodium dodecyl sulfate-polyacrylamide gels onto nitrocellulose is detected after 15 min of autoradiography. The limit of detection in dot tests was found to be 10 pg per dot (3 mm2). The method is suitable for quantitative determination of antigens in the range down to 100 pg. Several contact copies of the same original protein-carrying matrix can be produced and used for detection or quantitative analysis without destroying the original matrix.

A new neomycin phosphotransferase II solid phase assay in combination with polyacrylamide sodium dodecylsulphate gel electrophoresis

A new general method for the determination of neomycin phosphotransferase (NPT) II (EC 2.7.1.95) activity in cell extracts after separation in SDS-polyacrylamide gels is described. The enzymatic activity of NPT II is restored after SDS-polyacrylamide gel electrophoresis by incubating the gel for 3 h (20 mM Tris-HCl buffer, pH 7.4). The enzymatic activity is determined by in situ phosphorylation of aminoglycoside antibiotics bound to solid supports and brought into direct contact with the gel surface. A novel, mechanically stable, negatively charged matrix was synthesized for use in this solid phase enzyme assay and compared to phosphocellulose and carboxymethylcellulose paper. This new method allows the easy and exact determination of the molecular weight of any fusion protein with NPT II by assaying the position of the enzymatic activity in the gel and a consecutive immunological reaction following protein transfer onto nitrocellulose membranes.

A protein-free blocking system for the covalently binding matrix cyanuric chloride-activated paper in immunological procedures

A new protein-free blocking system containing 10% (w/v) sulfanilic acid/10% (v/v) triethanolamine/0.05% (v/v) Tween 20 has been used to block free binding sites of the covalently binding matrix cyanuric chloride-activated paper (CCA-paper). This method allows a reversible staining of protein blots with Coomassie brilliant blue after each step of the immunological procedure and reuse of the blots for a repeated antibody probing. Non-radioactive and radioactive detection procedures have been compared with blots on CCA-paper and nitrocellulose. The best combination is a Coomassie brilliant blue staining and immunological detection with 125I-protein A.

Use of cyanuric chloride-activated paper for detection of subpicogram quantities of specific DNA sequences and its application to linked restriction fragment length polymorphism analysis in a Duchenne muscular dystrophy affected family

Conditions for the optimal use of cyanuric chloride-activated (CCA) paper in Southern transfer hybridization experiments of genomic DNA were investigated. They depend critically on pH and ionic strength during transfer and on the composition of the hybridization solution. Simplified hybridization conditions using a SSC/dextran sulfate system at 65 degrees C without sodium dodecyl sulfate and the complex Denhardt's solution are applied. CCA paper allows repeated use in hybridization experiments. Under optimized conditions CCA paper allows a more sensitive detection of single-copy gene sequences in the subpicogram range than do nylon membranes. Application of these transfer and hybridization conditions with our newly developed CCA paper to carrier determination and prediction of the healthy male haplotype demonstrates its usefulness for prenatal counseling of a Duchenne muscular dystrophy family.

CCA paper: a new two-dimensional cyanuric chloride-activated matrix for universal application in molecular biology

A novel two-dimensional cyanuric chloride-activated (CCA) paper has been developed. It is composed of a cellulosic base, covalently bound cyanuric chloride, and microprecipitated complex cyanuric chloride-sodium chloride crystals on its surface. CCA paper covalently binds nucleic acids and proteins. Its binding capacity for nucleic acids is about 400 micrograms/cm2. Sealed into nitrogen-filled bags and stored at -20 degrees C, it retains its binding activity for at least a year and is always ready for use. CCA paper has been successfully used for capillary and electroblotting of DNA, RNA, and proteins (Southern, Northern, and Western blotting) as well as for dot tests. Furthermore, it was applied to colony and plaque hybridization. A unique property of it is that it permits the staining of proteins after blotting and subsequent performance of radioimmunological detection of specific protein components. This has proven advantageous in two-dimensional Western blotting experiments. Of further importance is its ability to bind DNA fragments from one up to several hundred bp from polyacrylamide sequencing gels.