Solidification structures in rapidly quenched Cu-Ti-Zr alloys

The melt-spinning and pulsed laser-quenching techniques were used to generate fast cooling rates necessary to form metallic glass in ternary Cu-Ti-Zr alloys. Even though the cooling rates generated during melt-spinning were much lower than those generated during pulse laser-quenching, the amount of glass obtained in the melt spun alloys was much larger than in the laser-quenched alloys. The microstructure of the laser-quenched alloys consisted of metallic glass and a fine microcrystalline fcc phase, whereas the melt-spun ribbons of the same compositions were completely amorphous. Glass transition temperature trends in the ternary system were determined from alloys of composition traversing linearly from the binary Cu-Ti side to the Cu-Zr side. These trends showed a nearly linear change of T_g with composition.     

Antimyeloperoxidase-associated proliferative glomerulonephritis: an animal model

To develop an animal model for antimyeloperoxidase (MPO)-associated necrotizing crescentic glomerulonephritis (NCGN), we immunized Brown Norway rats with MPO and localized a neutrophil lysosomal enzyme extract, primarily consisting of MPO and elastinolytic enzymes, plus H2O2, the substrate of MPO, to the glomerular basement membrane (GBM). Upon immunization rats developed antibodies and positive skin tests to MPO. After unilateral perfusion of the left kidney with the lysosomal enzyme extract and H2O2, MPO and immunoglobulin (Ig)G localized transiently along the GMB. At the time of maximal inflammation, at 4 and 10 d after perfusion, MPO, IgG, and C3 could not be detected anymore. MPO-immunized rats perfused with the lysosomal enzyme extract and H2O2, in contrast to control-immunized and/or control-perfused rats, developed a proliferative GN characterized by intra- and extracapillary cell proliferation, ruptured Bowman's capsule, periglomerular granulomatous inflammation, and formation of giant cells. Monocytes, polymorphonuclear leukocytes (PMN), and to a far lesser extent T cells were found in the glomeruli. Interstitial infiltrates consisted of monocytes, PMN, and T cells. Granulomatous vasculitis of small vessels was found at 10 d after perfusion. The proliferative NCGN in this rat model closely resembles human anti-MPO-associated pauci-immune NCGN, and enables the study of the pathophysiology of anti-MPO-associated NCGN.     

Randomized double-blinded trial of rifampin with either novobiocin or trimethoprim-sulfamethoxazole against methicillin-resistant Staphylococcus aureus colonization: prevention of antimicrobial resistance and effect of host factors on outcome

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen in hospitals. Current antimicrobial regimens for eradicating colonizing strains are not well defined and are often complicated by the emergence of resistance. The combination of novobiocin plus rifampin in vitro and in vivo was found to prevent the emergence of resistant populations of initially susceptible strains of MRSA, particularly resistance to rifampin. We therefore studied, in a randomized, double-blind, multicenter comparative trial, the combination of novobiocin plus rifampin versus trimethoprim-sulfamethoxazole (T/S) plus rifampin in order to determine the efficacy of each regimen in eradicating MRSA colonization and to further characterize the host factors involved in the response to this antimicrobial therapy. Among the 126 individuals enrolled in the study, 94 (80 patients; 14 hospital personnel) were evaluable. Among the 94 evaluable subjects, no significant demographic or medical differences existed between the two treatment groups. Successful clearance of the colonizing MRSA strains was achieved in 30 of 45 (67%) subjects receiving novobiocin plus rifampin, whereas successful clearance was achieved in 26 of 49 (53%) subjects treated with T/S plus rifampin (P = 0.18). The emergence of resistance to rifampin developed more frequently in 14% (7 of 49) of subjects treated with T/S plus rifampin than in 2% (1 of 45) of subjects treated with novobiocin plus rifampin (P = 0.04). Restriction endonuclease studies of large plasmid DNA demonstrated that the same strain was present at pretherapy and posttherapy in most refractory cases (24 of 29 [83%] subjects). Among the 56 successfully treated subjects, clearance of MRSA was age dependent: 29 of 36 (80%) subjects in the 18- to 49-year-old age group, 19 of 35 (54%) subjects in the 50- to 69-year-old age group, and 8 of 23 (35%) in the 70- to 94-year-old age group (P < 0.01). Clearance was also site dependent; culture-positive samples from wounds were related to a successful outcome in only 22 (48%) of 46 subjects, whereas culture-positive samples from sites other than wounds (e.g., nares, rectum, and sputum) were associated with a success rate of 34 of 48 (71%) subjects (P = 0.02). Foreign bodies in wounds did not prevent the eradication of MRSA by either regimen. T/S plus rifampin was less effective in clearing both pressure and other wounds, whereas novobiocin plus rifampin was equally effective in clearing both pressure and other wounds. There were no significant differences in toxicity between the two regimens. Thus, the combination of novobiocin plus rifampin, in comparison with T/S plus rifampin, was more effective in preventing the emergence of resistance to rifampin and demonstrated a trend toward greater activity in clearing the MRSA carrier state. The response to either combination depended on host factors, particularly age and the site of MRSA colonization.     

Complications of indwelling, silastic central venous access catheters in dogs and cats

RATIONALE AND OBJECTIVES: We investigated the effects of various metallic stents on the aortic wall. METHODS: The wires of Gianturco-type expandable metallic stents were plated with gold, silver, or copper or coated with Teflon or silicone. Stents were inserted into the aortas of 15 adult mongrel dogs. The time course of radiologic, macroscopic, and histologic changes in the aorta at the site of the stent was investigated at 1, 2, and 4 weeks after implantation. RESULTS: The gold-plated stent appeared to produce fewer macroscopic and histopathologic changes in the aorta than the other types of stents. The neointima was thinnest with gold (83.9 +/- 40.3 microns), followed by stainless steel (103.6 +/- 57.0 microns), Teflon (115.0 +/- 30.2 microns), silicone (209.6 +/- 25.9 microns), silver (228.6 +/- 33.8 microns), and copper (unmeasurable). With the copper-plated stent, the aorta suffered severe erosion of the vessel wall, marked thrombus formation, and aortic rupture. CONCLUSION: Gold is a useful intravascular material because it reacts only minimally with the vessel wall.     

Optical properties of transparent and infra-red-reflecting ITO films in the 0.2–50 μm range

High quality ITO films were produced by reactive e-beam deposition onto heated glass. The complex dielectric function was evaluated from spectrophotometric measurements in the full 0.2–50 μm range. These data are interpreted within an effective-mass-model for heavily n-doped semiconductors. For infra-red and visible wavelengths, the properties are governed mainly by free electrons damped by scattering against ions. In the ultra-violet, the semiconductor bandgap is widened by the Burstein-Moss effect partially compensated by electron-electron and electron-ion scattering.     

The relationship of structure and function in human Hageman factor. The association of enzymatic and binding activities with separate regions of the molecule

Three regions of the human Hageman factor molecule termed the c, d, and e regions have been defined. Division of the molecule into these three regions is based on the analysis of fragments obtained by enzymatic cleavage during fluid-phase activation. The three regions have the following properties: (a) the c region has a mol wt of 40,000, has the capacity to bind to negatively charged surfaces, and does not have detectable enzymatic activity; (b) the e region possess a mol wt of 28,000 has enzymatic activity, and does not bind to negatively charged surfaces; (c) the d region has a mol wt of 12,000, is located between the c and e fragments but has not been detected as a freely existing polypeptide, and can bind firmly to negatively charged surfaces. The preparation of antibodies specific for the c and e regions is described as well as their use in defining the electrophoretic characteristics of the cde, cd, de, c, and e polypeptide fragments of Hageman factor. Evidence is given showing that the e region, but not the c or d, is released from a negatively charged surface when bound Hageman factor is exposed to proteolytic enzymes or whole plasma and that when this occurs in the presence of normal plasma, the e fragment becomes bound to C1 esterase inhibitor.     

Baldcypress allelochemics and the inhibition of silkworm enteric microorganisms Some Ecological Considerations

Exposure ofBombyx mori larvae to 2-furaldehyde, a major volatile component of baldcypress heartwood,Taxodium distichum, resulted in in vivo inhibition of enteric microorganisms at concentrations (1–47 ppm) that were released naturally from heartwood. The 7 bacterial and 2 fungal enteric isolates were also inhibited in vitro at the same concentrations. It is suggested that inhibition of leaf surface micro-organisms or in vivo inhibition of silkworm enteric microflora, as a result of indirect or direct action of 2-furaldehyde, exacerbates the growth-inhibitory effects of this compound on larvae by reducing the microbial nutritional contribution. The ecological significance of insect enteric microbial inhibition by plant allelochemics is discussed.     

Mitoxantrone and cytosine arabinoside as treatment for acute myelogenous leukemia (AML) at first recurrence

A total of 107 patients with newly diagnosed acute myeloblastic leukemia (AML) were referred to the ICRF Department of Medical Oncology at St Bartholomew's Hospital between August 1986 and July 1989. Of those referred, 92 (87%) were treated with remission induction chemotherapy comprising: Adriamycin, cytosine arabinoside (ara-C) and 6-thioguanine if aged < 60 years (57 patients) or mitoxantrone (MTN) and ara-C if aged > 60 years (35 patients). Of those treated, 54 (58%) entered complete remission (CR). Recurrent AML developed in 38 out of these 54 patients (70%) of whom 25 aged 19-73 years (median 50 years) subsequently received MTN and ara-C as reinduction therapy. The 19 younger patients (under 60 years old) received MTN at 12 mg/m2, intravenously, daily for 5 days and ara-C at 100 mg/m2, intravenously, twice daily for 7 days. The six older patients received the same ara-C schedule but the dose of MTN was reduced to 10 mg/m2 for 5 days. Second CR was achieved in 16 out of 25 patients (64%) [12/19 (63%) and 4/6 (67%) for patients aged under or over 60 years, respectively]. Eight of the patients in whom second CR was achieved were aged under 50 years and were thus eligible for additional consolidation comprising myeloablative therapy with autologous bone marrow transplantation (ABMT). Four patients actually received the latter treatment: two remain in second CR at 21 and 46 months. Three of the remaining eight patients aged > 50 years in whom second CR was achieved remain in second CR 8 to 43 months later. Censored for myeloablative therapy + ABMT, the overall median duration of second CR was 5 months. Although remissions tended to be short, in younger patients the possibility of proceeding to myeloablative therapy with autologous bone marrow support makes the regimen worthwhile and, even in older patients, it was sometimes possible to achieve prolonged second remissions.