A neutral beam sciopticon

A sciopticon based on the pinhole-camera effect is being used to determine individual beamlet contributions to the quality of neutral beams extracted from multiaperture ion sources. The technique outlined in this note can be used to study the effects on beam optics of nonhomogeneous source plasma density or acceleration gap nonuniformities, grid nonparallelism or aperture misplacement, and space-charge blowup or scattering in the neutralizer cell.

Extraction and partial characterization of a leukotoxin from a plaque-derived Gram-negative microorganism

The plaque-derived gram-negative microorganism Y4 identified as a member of the genus Actinobacillus, was tested for a soluble cytotoxic factor(s). Sonication or incubation of viable Y4 microorganisms in distilled water or normal human serum resulted in liberation of a soluble material which was cytotoxic in vitro for human polymorphonuclear leukocytes (PMNs). The Y4 soluble sonic extract was also cytotoxic to human peripheral blood monocytes. However, human lymphocytes, platelets, and fibroblasts, as well as rabbit, rat, and mouse leukocytes and chicken embryo fibroblasts, were not killed by exposure to the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. Consequently, the factor(s) in the Y4 sonic extract was referred to as Y4 leukotoxin. The Y4 leukotoxin was inactive at 4 degrees C, heat sensitive (56 degrees C, 30 min), and inactivated by proteases. The cytotoxic effect of Y4 leukotoxin on PMNs was dose, time, and temperature dependent. The leukotoxin did not bind to viable PMNs at 4 degrees C but did bind to dead PMN membrane components at both 4 and 37 degrees C. The addition of bovine serum albumin (51 mg/ml) to PMN-Y4 leukotoxin cultures inhibited the release of lactate dehydrogenase from the PMNs, but did not prevent the death of the cells as indicated by electron microscopy. Lysosomal markers were released in parallel to the cytoplasmic enzyme lactate dehydrogenase from Y4 leukotoxin-treated PMNs. The addition of 0.02 M ethylenedinitrilotetraacetic acid to these cultures inhibited release of lysosomal markers but enhanced the release of lactate dehydrogenase. These results suggested that a soluble leukotoxin with specificity for only human PMNs and monocytes can be liberated from viable Y4. What role this leukotoxin plays in the pathogenicity of the Y4 microorganism is not yet known. However, this leukotoxin is one of the first materials from a plaque-derived microorganism with a potential role in the pathogenesis of juvenile periodontitis.

Properties of an intense 40-kV neutral beam injector

The properties of an intense neutral beam injector, the modified duoPIGatron ion source, are discussed and compared with other injectors. For this source (a) beam composition for hydrogen is approximately (85+/-5) % monatomic, (b) nucleon gas efficiency is 50%, (c) the electrical efficiency of ion generation is 1.1 A/kW, and (d) up to 52% of the input power is delivered in the ion and neutral beam to a target subtending a half angle of 1.8 degrees x1.4 degrees .

Interaction of inflammatory cells and oral microorganisms. VIII. Detection of leukotoxic activity of a plaque-derived gram-negative microorganism

In the present study we identified a gram-negative anaerobic rod referred to as Y4 which was cytotoxic for human polymorphonuclear leukocytes. Y4 was isolated from dental plaque of a patient with juvenile periodontitis and presented most of the taxonomic characteristics of Actinobacillus species. Under experimental conditions, viable Y4 were cytotoxic for human peripheral blood polymorphonuclear leukocytes in serum-free cultures. Cytotoxicity was dependent on bacterial concentrations and was enhanced in the presence of a fresh or heat-inactivated (56 degrees C, 30 min) autologous serum. Leukotoxicity was independent of phagocytosis. Y4 leukotoxic effect was abolished when bacteria were heat treated (56 degrees C, 30 min) or when incubations were carried out at 4 degrees C instead of at 37 degrees C. The leukotoxicity was monitored by electron microscopy and biochemically by measuring lactate dehydrogenase indicator of cell viability. No cytotoxic effects of Y4 on human mononuclear cells, chicken fibroblasts, or mouse macrophages were detected under the conditions studied. Polymorphonuclear leukocytes may play an important role in the host defense against bacteria in periodontal disease. The cytotoxic effect of Y4 for polymorphonuclear leukocytes presented in this study is the first report of a direct offensive microbial vector in a plaque-derived microorganism and may prove to be relevant in the pathogenesis of juvenile periodontitis.

Magnetic multipole line-cusp plasma generator for neutral beam injectors

The magnetic multipole line-cusp device developed by MacKenzie and associates has been adapted for use as a neutral beam ion source. It has produced high-density, large volume, quiescent, uniform hydrogen plasmas, which makes it a potential candidate for use as a plasma generator for neutral beam injectors. The device is a water-cooled cylindrical copper discharge chamber (25 cm in diameter by 36 cm long) with one end enclosed by a set of extraction grids with a 15-cm-diam multi-aperture pattern. The chamber wall serves as an anode and is surrounded by an external system of rare-earth cobalt magnets arranged in a line-cusp geometry of 12 cusps; plasma is produced by electron emission from a hot cathode assembly. This source has achieved extracted beam currents of 12 A at 18.5 kV, radial plasma density uniformities of +/-5% over a 15-cm diameter, noise levels of less than +/-0.5%, and arc efficiencies (beam current/arc power) of 0.6 A/kW.

Interaction of inflammatory cells and oral microorganisms. VII. In vitro polymorphonuclear responses to viable bacteria and to subcellular components of avirulent and virulent strains of Actinomyces viscosus

Both virulent (V) and avirulent (AV) strains of Actinomyces viscosus T14 are capable of colonizing the oral cavity of gnotobiotic rats, but only T14-V causes destructive periodontal disease. The basis for this difference in in vivo pathogenicity has not been adequately defined. In the present study we compared the capacities of T14-AV and T14-V to provoke in vitro extracellular release of lysosomal constituents from human polymorphonuclear leukocytes (PMNs). In serum-free cultures, viable T14-V but not T14-AV stimulated discharge of PMN lysosomes. The release response was correlated with PMN phagocytic activity; thus, PMNs readily ingested T14-V but not T14-AV. To explain these differences in PMN-bacteria interactions, subcellular fractions of T14-AV or T14-V were incubated with PMNs. A crude, insoluble sonic extract derived from T14-V caused PMN lysosome release, but a similar fraction from T14-AV was inactive. However, following extensive washing and treatment with deoxyribonuclease or sodium dodecyl sulfate, cell wall fractions of T14-AV stimulated lysosome release. These procedures apparently removed an extracellular polysaccharide slime which is synthesized by T14-AV but not by T14-V. There was a significant reduction in the capacities of viable T14-V or cell wall fractions of T14-V or T14-AV to provoke PMN lysosome release when these agents were preincubated with a slime material isolated from T14-AV. This inhibitory influence of slime was overcome by the addition of fresh or heated (56 degrees C, 30 min) serum to the PMN-bacteria cultures. The data suggest a relationship between the abilities of the avirulent and virulent strains of A. viscosus T14 to act as periodontal pathogens in vivo and to serve as stimuli for PMN lysosome release in vitro.

Conformational flexibility in DNA structure and its implications in understanding the organization of DNA in chromatin

X-ray crystallographic studies of drug-nucleic acid crystalline complexes have suggested that DNA first bends or 'kinks' before accepting an intercalative drug or dye. This flexibility in DNA structure is made possible by altering the normal C2' endo deoxyribose sugar puckering in B DNA to a mixed sugar puckering pattern of the type C3' endo (3'-5') C2' endo and partially unstacking base pairs. A kinking scheme such as this would require minimal sterochemical rearrangement and would also involve small energies. This has prompted us to ask more generally if a conformational change such as this could be used by proteins in their interactions with DNA. Here we describe an interesting superhelical DNA structure formed by kinking DNA every ten base pairs. This structure may be used in the organization of DNA within the nucleosome structure in chromatin.

Influence of chromatic aberrations on space charge ion optics

By solution to the Poisson-Vlasov equation the influence of fluctuations (chromatic aberrations) on ion optics is shown for various accelerator designs : (1) cylindrical bore triode with various aspect ratios, (2) pseudo-Pierce shaped electrode triode at various aspect ratios, (3) insulated coating emission electrode triode for various preacceleration potentials, and (4) cylindrical bore tetrodes for various field distributions. Fluctuation levels of 20% can be very important in limiting the ion optics in certain cases.

Skin lesions in viral hepatitis: histologic and immunofluorescent findings

A variety of skin rashes are knowned to occur as a part of the serum sickness-like prodrome of acute viral hepatitis which is thought to be due to immune complex deposition. We report the histologic and immunofluorescent findings in the skin and the seroloigc abnormalities in a patient with both erythematous maculopapular and purpuric rashes. We found circulating hepatitis B surface antigen (HBsAg), hypocomplementemia and cultaneous vasculitis associated with deposition of immunoglobulin and complement in the skin. We could not demonstrate intradermal deposition of HBsAg, but the findings are consistent with the immune complex hypothesis.

A primate model of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABA) in man is featured by the presence of IgE skin sensitizing and IgG precipitating antibodies against Aspergillus fumigatus (AF). An animal model of this disease was created. 2 monkeys immunized with AF produced IgG-precipitating antibody. Normal human serum was infused into both immunized and unimmunized monkeys and allergic human serum containing a high titer of IgE against AF was infused into another pair of immunized and unimmunized monkeys. All monkeys then received an aerosol of AF. Lung biopsies were obtained and light microscopic, immunofluorescent and electron microscopic studies were performed. Only the monkey with precipitating antibody to AF who received human allergic serum showed changes which included an interstitial cellular infiltrate containing large numbers of eosinophils, edema of the intra-alveolar spaces, thickening of the alveolar septa, intracellular and interstitial deposits of IgG and IgM and proliferation of collagen fibrils. No evidence of vasculitis was observed. This primate model of ABA should enhance our understanding of the inflammatory response and the immunologic processes in this disease.

Dermal and glomerular deposition of IgA in anaphylactoid purpura

During the period of acute anaphylactoid purpura, skin biopsies were performed on 14 patients with purpuric and nonpurpuric skin. In addition, four patients had renal biopsies. Examination of the tissue by immunofluorescence to anti-human immunoglobulins IgG, IgA, IgM, and IgE, fibrin/fibrinogen, complement Clq, C4, and C3 demonstrated predominant IgA, C3, fibrin/fibrinogen in the purpuric skin and glomerulus, without Clq and C4. These immunohistochemical findings are characteristic of anaphylactoid purpura and suggest that IgA is involved in the pathogenesis of anaphylactoid purpura and may operate through the alternate pathway of the complement system.

Interaction of inflammatory cells and oral microorganisms. IV. In vitro release of lysosomal constituents from polymorphonuclear leukocytes exposed to supragingival and subgingival bacterial plaque

The deposition of bacterial plaques on tooth surfaces appears to be responsible for the initiation and progression of periodontal disease. In this study, human peripheral blood polymorphonuclear leukocytes (PMNs) actively released lysosomal constituents upon in vitro exposure to either viable or irradiated, supragingival or subgingival dental plaque. Plaques were obtained from the PMN donors (autologous plaque) or from pooled samples (homologous plaque) secured from patients with periodontal lesions. Fresh sera from PMN donors amplified the release reactions to supragingival and subgingival plaques. Heated (56 degrees C, 30 min) sera also enhanced release reactions, but not as consistently as fresh serum. It was postulated that modulation of PMN release by serum is mediated by complement components and/or antibodies to plaque bacteria. Electron microscopic observations indicated that degranulation and discharge of PMN lysosomal enzymes may be associated with phagocytosis of gram-positive and gram-negative plaque bacteria and with reverse endocytosis of lysosomes from cells contacting relatively large masses of aggregated plaque bacteria. These data suggest that PMN lysosome release in response to plaque may serve as a potential mechanism of tissue injury in the pathogenesis of gingival and periodontal inflammation.

Experimental toxemia in the pregnant primate

In order to develop a model for the study of eclamptogenic toxemia, a series of experiments were carried out on 31 female baboons. In Group 1, consisting of 10 animals, metal clips were placed around the uterine arteries in order to partially occlude them, and the ovarian vessels were transected. The animals were subsequently mated. Nine developed hypertension and proteinuria, and one aborted. The renal lesions in these animals were indistinguishable from those described in human toxemia. Group 2 consisted of three of the 10 baboons from Group 1, which became pregnant a second time. They again developed hypertension and proteinuria. In Group 3, three baboons at 100 days of gestation were treated as in Group 1 with similar results. Groups 4 and 5 served as pregnant (3) and nonpregnant (15) controls. It is concluded that a toxemia model has been developed in a subhuman primate. This model will prove useful in the further study of eclamptogenic toxemia.

Mutagen-nucleic acid intercalative binding: structure of a 9-aminoacridine: 5-iodocytidylyl(3'-5')guanosine crystalline complex

9-Aminoacridine forms a crystalline complex with the dinucleoside monophosphate, 5-iodocytidylyl(3'-5')guanosine. We have solved the three-dimensional structure of this complex by x-ray crystallography and have observed two distinct intercalative binding modes by this drug to miniature Watson-Crick double helical structures. The first of these involves a pseudosymmetric stacking interaction between 9-aminoacridine molecules and guanine-cytosine base-pairs. This configuration may be used by 9-aminoacridine when intercalating into DNA. The second configuration is an asymmetric interaction, largely governed by stacking forces between acridine and guanine rings. This type of association may play an important role in the mechanism of frameshift mutagenesis.