Pyrogenic Material Research Articles

Characterisation of black carbon-rich samples by 13C solid-state nuclear magnetic resonance

There are difficulties in quantifying and characterising the organic matter (OM) in soils that contain significant amounts of partially oxidised char or charcoal materials. The anthropogenic black carbon (BC), such as that found in the Terra Preta de Indio soils of the Amazon region, is a good example of the OM that is difficult to analyse in such soils. (13)C direct polarisation/magic angle spinning (DP/MAS) at high MAS frequency, (1)H-(13)C cross polarisation (CP)/MAS with total suppression of spinning sidebands (TOSS), and chemical shift anisotropy (CSA) filter nuclear magnetic resonance techniques have been applied successfully for quantifying the different components of OM. However, because pyrogenic materials present strong local magnetic susceptibility heterogeneities, the use of CSA-filter and TOSS make the pulse sequences very sensitive to imperfections in the pi pulses. In this study, the DP/MAS pulse sequence was replaced by a CP with a radio frequency ramp--variable amplitude CP (VACP)--VACP/MAS pulse sequence, and composite pi pulses were used in the CSA-filter and TOSS pulse sequences. In that way, the component functionalities in a humic acid from a BC soil were successfully determined. The spectrometer time needed was greatly decreased by employing this VACP/MAS technique. This development provides an accurate method for characterising BC-rich samples from different origins.

Environmental Stability of PAH Source Indices in Pyrogenic Tars

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants found in soil, sediments, and airborne particulates. The majority of PAHs found in modern soils and sediments arise from myriad anthropogenic petrogenic and pyrogenic sources. Tars and tar products such as creosote produced from the industrial pyrolysis of coal or oil at former manufactured gas plants (MGPs) or in coking retorts are viscous, oily substances that contain significant concentrations of PAH, usually in excess of 30% w/w. Pyrogenic tars and tar products have unique PAH patterns (source signatures) that are a function of their industrial production. Among pyrogenic materials, certain diagnostic ratios of environmentally recalcitrant 4-, 5- and 6-ring PAHs have been identified as useful environmental markers for tracking the signature of tars and petroleum in the environment. The use of selected PAH source ratios is based on the concept that PAHs with similar properties (i.e., molecular weight, partial pressure, solubility, partition coefficients, and biotic/abiotic degradation) will weather at similar rates in the environment thereby yielding stable ratios. The stability of more than 30 high molecular weight PAH ratios is evaluated during controlled studies of tar evaporation and aerobic biodegradation. The starting materials in these experiments consisted of relatively unweathered tars derivedmore » from coal and petroleum, respectively. The PAH ratios from these laboratory studies are compared to those measured in PAH residues found in tar-contaminated soils at a former MGP that operated with a carburetted water gas process.« less

Mesoporous ZSM-5 catalysts: Preparation, characterisation and catalytic properties. Part I: Comparison of different synthesis routes

In an attempt to improve mass-transport limitations, mesopores were created in a series of ZSM-5 catalysts by the carbon-templating procedure. A successful low-cost dry gel synthesis route was developed which almost entirely removed the need for the organic structure-directing agent (TPA/SiO 2 = 0.0033). Both an aqueous colloidal graphite sol and a pyrogenic (carbon black) material were investigated, at addition levels of 16.5–100 wt.%. No major differences were observed between the two carbon sources. The addition of carbon to the synthesis composition retarded the crystallisation rate and modified the crystal morphology. The products were characterised by a variety of physical techniques. Additional post-synthesis treatment (alkaline leaching) extended the mesopore system but also tended to reduce crystallinity and micropore volume.

Review

We compare the performance of three most accepted reagents for organic matter removal: hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl) and disodium peroxodisulfate (Na2S2O8). Removal of organic matter from soil is mostly incomplete with the efficiency of removal depending on reaction conditions and sample properties. Generally, NaOCl and Na2S2O8 are more effective in organic C removal than H2O2 Alkaline conditions and additives favoring dispersion and/or desorption of organic matter, such as sodium pyrophosphate, seem to be crucial for C removal. Pyrophosphate and additives for pH control (bicarbonate) may irreversibly adsorb to mineral surfaces. In soils with a large proportion of organic matter bound to the mineral matrix, for example subsoils, or rich in clay-sized minerals (Fe oxides, poorly crystalline Fe and Al phases, expandable phyllosilicates), C removal can be little irrespective of the reagents used. Residual organic C seems to seems to represent largely refractory organic matter, and comprises mainly pyrogenic materials and aliphatic compounds. If protected by close association with minerals, other organic constituents such as low-molecular weight carboxylic acids, lignin-derived and N-containing compounds may escape chemical destruction. For determination of mineral phase properties, treatment with H2O2 should be avoided since it may promote organic-assisted dissolution of poorly crystalline minerals at low pH, disintegration of expandable clay minerals, and transformation of vermiculite into mica-like products due to NH4+ fixation. Sodium hypochlorite and Na2S2O8 are less harmful for minerals than H2O2 While the NaOCl procedure (pH 9.5) may dissolve Al hydroxides, alkaline conditions favor the precipitation of metals released upon destruction of organic matter. Prolonged heating to >40°C during any treatment may transform poorly crystalline minerals into more crystalline ones. Sodium hypochlorite can be used at 25°C, thus preventing heat-induced mineral alteration.

Residual debris as a potential cause of postphacoemulsification endophthalmitis.

To examine residual debris within sterilised instruments prior to cataract surgery. (i) Flushings from 32 sets of phacoemulsification instruments, sterilised according to hospital routine protocols, were taken preoperatively and analysed by scanning electron microscopy (SEM). (ii) A total of 16 sets of flushings from a different institute were collected-with separation of samples collected from phacoemulsification and those from irrigation-aspiration (IA) instruments-and analysed in the same way. (iii) A total of 15 sets of flushings were collected from instruments where an automated flushing system was used prior to sterilisation. (i)In the first study, 62% were clean, 16% were moderately contaminated and 22% were severely contaminated. Various contaminants were identified including lens capsule and cells, man-made fibres, squamous cells, bacteria, fungal elements, diatoms, red blood cells and proteinaceous material. (ii) In the second study, the results were similar and contamination of both phacoemulsification and IA instruments was shown. (iii) The third study showed that although a decrease in contamination followed automated flushing, contamination was not completely eliminated. Although all equipment had been sterilised, pyrogenic material was still present. These findings emphasise the importance of meticulous cleaning of all surgical equipment in which biological debris can remain.

Interactive use of Electron Microscopy and Light Scattering as Diagnostics for Pyrogenic Aggregates

AbstractBoth electron microscopy and light scattering have played an important role in elucidating the processes of inception, growth, and oxidation of carbonaceous particles in flames. The techniques developed have application to the various pyrogenic materials including the metallic oxides, carbides, etc. Thermophoretic sampling has been developed to afford efficient extraction of particle samples from hot reaction zones. The sampling procedure preserves the particle morphology for subsequent analysis by transmission electron microscopy (TEM). Studies using this technique have shown aggregate structures with fractal dimensions of 1.6 to 1.8, a result that is consistent with the computer simulations of the cluster-cluster aggregation process. Diverse morphologies, including microparticles found in the particle inception zone, reveal the evolution of these aggregates. The optical cross sections for polydisperse aggregates which are used to interpret the laser scattering/extinction tests (LSE) are described. Population averaged properties - volume fraction, volume mean diameter, monomer and aggregate number concentrations, mean-square radius of gyration - are derived. The interactive use TEM and LSE data leads to a global description of the aggregate dynamic processes which are found to be regionally partitioned within the laminar hydrocarbon diffusion flame.

Interleukin 1 induces interleukin 1. I. Induction of circulating interleukin 1 in rabbits in vivo and in human mononuclear cells in vitro.

Interleukin 1 (IL-1) plays an important role in host defense mechanisms by increasing body temperature, inducing the synthesis of a variety of lymphokines and hepatic acute phase proteins and acting as a chemoattractant for lymphocytes. However, in some microenvironments such as injured tissue or joint spaces, elevated IL-1 levels may contribute to pathologic processes, for example, proliferation and fibrosis of tissue involved in pannus formation as well as degradation of matrix and abnormal tissue architecture. To investigate potential mechanisms that may lead to excessive production of IL-1, we have examined the ability of IL-1 to participate in an amplification event by inducing its own gene expression leading to synthesis of biologically active IL-1. When injected into rabbits, recombinant human IL-1-alpha induced biphasic fevers, and during the second temperature elevation 3 hr later, a circulating pyrogenic material was detected by passive transfer of plasma to other rabbits. Induction of the biphasic fever was not caused by endotoxin contamination of the recombinant IL-1. The 3-hr circulating pyrogen was heat-labile and was not residual injected IL-1-alpha. Chromatographic separation of this plasma and biologic assay suggested that it was new IL-1 of rabbit origin. We next incubated human blood mononuclear cells with recombinant IL-1-alpha and measured the intracellular and extracellular levels of IL-1 by bioassay using the D10.G4.1 murine T cell line. In order to control for the carryover of recombinant IL-1-alpha used to stimulate the mononuclear cells (MNC), we used neutralizing antibodies that were specific for IL-1-alpha or IL-1-beta. The results of these neutralizations showed that recombinant human IL-1-alpha induces the synthesis of IL-1-beta in human MNC in vitro. These results were verified with a radioimmunoassay specific for IL-1-beta. At concentrations of 100 ng/ml, IL-1-alpha induced prostaglandin E2 production in the MNC culture, and this was associated with decreased production of immunoreactive IL-1-beta. Adding indomethacin to the cultures prevented the decreased production of IL-1-beta induced by high concentrations of IL-1-alpha. Using nonadherent MNC, we observed an increase in IL-1-beta as well as IL-1-alpha mRNA after 4 hr of exposure to recombinant IL-1-alpha. These results demonstrate that IL-1-alpha induces biologically active and immunoreactive IL-1-beta from MNC in vitro and that the same concentrations of IL-1-alpha induce gene expression for both forms of IL-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Human leukocytic pyrogen test for detection of pyrogenic material in growth hormone produced by recombinant Escherichia coli.

Human growth hormone is biosynthetically produced in recombinant strains of Escherichia coli as methionyl human growth hormone (met-hGH). When purified from the bacterial culture, met-hGH is biologically active in established assays for growth hormone. Therefore, a phase I trial of met-hGH was carried out in healthy human adults; during the first trial, however, signs, symptoms, and clinical laboratory tests characteristic of an acute-phase response to pyrogenic agents was observed. Prior testing of the met-hGH preparation used in the phase I trial did not reveal evidence of toxicity, and the U.S. Pharmacopeial Convention rabbit pyrogen test, as well as the Limulus amoebocyte lysate (LAL) test, had not detected significant levels of exogenous pyrogens or endotoxin. In addition, standard inhibition studies with added endotoxin showed no inhibition by the LAL test. When this preparation of met-hGH was incubated with human blood mononuclear cells, leukocytic pyrogen (LP) was released into the supernatant medium, suggesting that the preparation contained pyrogenic material. Various lots of met-hGH based on different purification and formulating methods were tested by the human LP assay for contaminating pyrogens. The results of these tests aided in the identification of procedures for met-hGH preparations which did not induce LP in vitro. Thus, subsequent lots of met-hGH which had passed the LP test were used in repeat clinical studies, and no inflammatory or pyrogenic reactions were observed. When the LP test was used, experiments revealed that the original lot of met-hGH was contaminated with endotoxin which had not been detected in the LAL or rabbit pyrogen tests. Lyophilization in glycine-phosphate buffer had resulted in a 10- to 20-fold reduction of endotoxin reactivity in the LAL test and the U.S. Pharmacopeial Convention rabbit pyrogen test. These data provide a probable explanation for the negative result from the LAL and rabbit pyrogen test in the initial lot of met-hGH which induced acute-phase reactions. In addition, these studies demonstrate that the release of LP from human cells is a reliable indicator of the presence of materials that are pyrogenic for humans.

A procedure for pyrogen decontamination of Sephacryl S-300

A procedure is described for eliminating pyrogens and pyrogen-producing organisms from a carbohydrate-based chromatographic support. Pyrogen contamination in a sample of enzyme prepared for replacement therapy trials was traced to an apparent bacterial colonization of a Sephacryl S-300 gel filtration column employed in the final steps of purification. Sequential washing of the column with 70% ethanol to eliminate pyrogen-producing organisms and 4 m urea to remove matrix-bound pyrogenic materials reduced pyrogen levels in column eluates from 2.2 ng/ml to 0.1 ng/ml. This decontamination approach should be applicable to various polysaccharide-based chromatographic matrices which are often avoided in the preparation of materials for parenteral administration because of their propensity for colonization.

Measurement of hypozincaemia in mice: a sensitive test for detection of pyrogens.

1. The effect of bacterial pyrogens on plasma zinc concentration in mice was studied as a method of bioassay for these substances. 2. A dose-related depression of plasma zinc concentrations was observed 4 h after intravenous injection of doses of 0.05-500 ng of purified endotoxins of Salmonella abortus equi, Shigella dysenteriae and Escherichia coli. Responses were dose-dependent and reproducible for each endotoxin in five strains of mice. 3. Tolerance to endotoxin could be induced in mice by injection of doses of 500 ng but was not seen with doses of less than 5 ng, even after repeated treatment. 4. Dinitrophenol, a metabolic inhibitor, and amphetamine, a metabolic enhancer, did not affect plasma zinc levels, indicating that changes in basal metabolic rate do not affect the outcome of this assay. The effects of pyrogenic materials other than endotoxin on plasma zinc levels were also tested and the results suggest that measurement of hypozincaemia in mice provides the basis for a simple, practical and inexpensive test for endotoxins and other pyrogens.

Microbial and pyrogenic contamination of molybdenum 99/Technetium 99m radionuclide generators

Radionuclide generators employed for the production of short-lived radionuclides may be contaminated with microorganisms during use, although this may not result in significant microbial contamination of the eluate. The mechanism by which this reduction was achieved was examined, using technetium 99m generators deliberately contaminated with known numbers of Escherichia coli. Results indicated that a small proportion of the inoculum was eluted from loaded (‘active’) or unloaded columns suggesting that organisms were entrapped in the alumina bed. Cell death occurred and could be caused by significant exposure to radiation, and the toxicity of aluminium and molybdate ions. Loss of viability led to an increased release of pyrogenic material into the eluate.

The antigen of Bordetella pertussis that induces bactericidal antibody and its relationship to protection of mice.

SUMMARY The ability to protect mice against intracerebral infection and to elicit, after one dose, complement-mediated bactericidal antibody capable of killing a mouse-virulent phase I strain in vitro, was tested in seven cultures of Bordetella pertussis: three typical phase I strains; two strains grown in the presence of 0·5 mg nicotinic acid/ml; one phase IV strain; and the atypical strain 134. The typical strains showed both activities; the nicotinic acid-grown and phase IV strains elicited high antibody titres, but did not confer protection, whereas strain 134 protected, but did not elicit bactericidal antibody. Pyrogenic material extracted from dried organisms by hot phenol and water (lipopolysaccharide) was not antigenic in mice; however, with all strains, except 134, multiple doses of this material coupled to stromata or Escherichia coli conjugated protein elicited bactericidal and precipitating antisera in mice, although the mice were not protected. Strain 134 contained approximately one quarter of the normal amount of endotoxin, as assayed in actinomycin d-sensitized mice, but was as effective as normal strains as an adjuvant for haemolysin production.

Separation of contaminating pyrogenic material from commercial bovine serum albumin.

SummaryA pyrogenic material in commercial supplies of bovine serum albumin (BSA) has been identified as bacterial endo-toxin by its hyporeactivity in endotoxin-tolerant rabbits. Non-pyrogenic BSA was prepared from sterile calf serum. Using Sephadex G-100 column chromatography, the pyrogen could be separated from the protein in commercial BSA samples. Because of the widespread use of commercial BSA in immunologic and other types of biologic research, the contaminating endotoxin could modify results or lead to misinterpretation of experimental observations.The authors would like to thank Mrs. Elizabeth Desmond and Miss Dorothy Maloney for their technical work. Dr. Elisha Atkins helped with the studies of pyrogenicity and provided much helpful advice.

THE PRESENCE OF ENDOGENOUS PYROGEN IN NORMAL RABBIT TISSUES.

Saline extracts of homogenized, uninfected, rabbit tissues produced febrile responses when injected intravenously into rabbits. Extracts of muscle, lung, and heart evoked fevers that were similar to those induced by leucocyte pyrogen; extracts of spleen, liver, and kidney caused more sustained fevers. The minimal pyrogenic dose appeared to be between 1.5 and 3 gm wet weight of tissue. Evidence is presented that neither Gram-negative bacterial endotoxin nor polymorphonuclear leucocytes (circulating or sequestered in the tissues) can be implicated as the source of pyrogen in tissue extracts. It seems likely, therefore, that a pyrogenic material of truly endogenous origin is widely distributed in tissues. Tissue pyrogen appears to be a large molecule which is relatively resistant to treatment with acid but not with alkali. Possible pathological roles for this endogenous agent (or agents) are briefly indicated.

A Potent Pyrogenic Extract Derived from a Strain of Aerobacter Aerogenes

Utilizing a simple technic, a good yield of pyrogenic material has been obtained from a strain of Aerobacter aerogenes. This dried product consistently elicits pyrogenic response in rabbits in dilutions of approximately 1:100,000,000 (0.01 μg./ml.) and is relatively stable to dry heat when exposed to 120° for forty minutes.

Studies on the pathogenesis of fever. II. Characterization of fever-producing substances from polymorphonuclear leukocytes and from the fluid of sterile exudates.

Further studies on fever production by injection of leukocyte extracts or cell-free supernatant fluids from peritoneal exudates in rabbits are reported. Granulocytes collected from peripheral blood or from pleural exudates contain a heat-labile pyrogenic substance. The material in extracts of leukocytes and in peritoneal fluids, which causes fever, is destroyed by heating for 30 minutes at 90 degrees C. at pH 7.2 and at 70 degrees C. at pH 4.5. It is active in producing fever over a pH range of 2.0 to 10.5 and maintains potency for as long as 6 months at 4 degrees C. The fever-producing substance in leukocyte extracts is not dialyzable. Its activity is not destroyed by trypsin, chymotrypsin, or ribonuclease. No evidence of plasma activator or inhibitor was detected. Significant temperature elevation in the rabbit was effected by a quantity of leukocyte extract containing 0.76 mg. protein and 0.054 mg. polysaccharide. The febrile response produced by the material under study was compared with that of Menkin's pyrexin as well as with that of bacterial pyrogens. Several significant differences were noted. The properties of pyrexin are similar to those of bacterial pyrogens. Amidopyrine suppressed the febrile response to injection of leukocyte extracts, whereas neither amidopyrine nor cortisone influenced the appearance of pyrogenic material in induced peritoneal exudates. Peritoneal fluids collected from rabbits made leukopenic by HN(2) were found to contain a fever-promoting substance. Its character has yet to be determined. It is concluded that there is present in polymorphonuclear leukocytes of rabbits a heat-labile factor capable of producing fever in rabbits and that the leukocyte is probably not the only source of such a factor.

Influence of Nitrogen Mustard upon Reactions to Bacterial Endotoxins: Shwartzman Phenomenon and Fever.

Discussion and SummaryThe finding of Stetson and Good that the period of inhibition of the Shwartzman phenomenon which follows injection of HN2 in the rabbit coincides with the time of maximum depression of circulating leukocytes was confirmed. In addition, the prevention of severe leukopenia by cysteine resulted in retention of Shwartzman activity, further evidence for the role of the leukocyte in the Shwartzman reaction. Although injection of colloidal materials abolishes natural or acquired resistance to the Shwartzman phenomenon, thorotrast did not influence the Shwartzman non-reactivity produced by HN2. The failure of HN2-induced leukopenia to influence the febrile response of rabbits to pyrogenic bacterial materials indicates that pyrogen fever is not dependent upon the presence of normal numbers of circulating leukocytes.

Splanchnic removal of bacteria from blood stream of pyrogen-tolerant rabbits.

Discussion and ConclusionsBeeson(2) has shown that in animals made tolerant to the pyrogenic effect of typhoid vaccine, there is an increased disappearance of the pyrogenic material from the blood stream. The increase in disappearance rate is blocked by the administration of thorotrast. He interpreted this as an indication that the reticuloendothelial system removes the pyrogenic material from the blood stream and that it does so with increased efficiency on repeated contact with the pyrogen, thus leaving less and less pyrogen in the blood stream to damage other susceptible tissues. More recent studies by Bennett and Cluff(l) have shown that rabbits made tolerant to pyrogens become non-reactive also to the Shwartzman phenomenon. Both of these effects are blocked by the injection of thorotrast(2,3); as is the removal of bacteria from the blood stream(4). However, although there seem to be some similarities between the characteristics of resistance to the Shwartzman phenomenon and resistance to pyrogen effe...

Some current problems in the field of parenteral nutrition.

ALTHOUGH recent developments in the field of parenteral nutrition have done a great deal to improve the care of surgical patients, both before and after operation, they have also created additional problems which must be solved if further progress is to follow. Thus in a variety of surgical situations the parenteral use of protein hydrolysates has helped materially to reduce or to minimize the catabolic loss of tissue nitrogen. This advance has been facilitated by manufacturing improvements, such as the elimination of antigenic and pyrogenic materials from the hydrolysates and the development of disposable plastic tubing. But, despite these signal advances, a number of problems remain which continue to limit the wider acceptance of these therapeutic agents. The solution of these problems must await further clinical and laboratory investigation. Probably the greatest deterrent to the more general acceptance of the protein hydrolysates is the current necessity of administering them under

Influence of Adrenergic Blocking Drug [N-Ethyl-N-(2-bromoethyl)-l-naphthylenemethylamine {middle dot} HBr] On Pyrogenic Reaction.

SummaryA potent adrenergic blocking drug, N-Ethyl-N- (2-bromoethy1)-1-naphthyl-enemethylamine · HBr, has been shown to reduce and alter the febrile response of normal and curarized dogs to the intravenous injection of a purified pyrogenic material obtained from pseudomonas aeruginosa. This evidence is interpreted as supporting the hypothesis that the pyrogenic reaction is due, at least in part, to a reduction in heat loss caused by adrenergic nerve mediated vasoconstriction in the skin.