Showing papers by "United States Department of the Army published in 1989"
TL;DR: T lymphocyte chemotactic factor was purified to homogeneity from the conditioned media of phytohemagglutinin-stimulated human blood mononuclear leukocytes and the amino-terminal amino acid sequence of the purified TCF showed identity with neutrophil-activating protein (NAP-1).
Abstract: T lymphocyte chemotactic factor (TCF) was purified to homogeneity from the conditioned media of phytohemagglutinin-stimulated human blood mononuclear leukocytes by a sequence of chromatography procedures. The amino-terminal amino acid sequence of the purified TCF showed identity with neutrophil-activating protein (NAP-1). Both TCF and recombinant NAP-1 (rNAP-1) were chemotactic for neutrophils and T lymphocytes in vitro supporting the identity of TCF with NAP-1. Injection of rNAP-1 into lymphatic drainage areas of lymph nodes in Fisher rats caused accelerated emigration of only lymphocytes in high endothelial venules. Intradermal injection of rNAP-1 caused dose-dependent accumulation of neutrophils and lymphocytes.
1,053 citations
TL;DR: Using the rationale described in this paper, the most evironmentally threatening PCB congeners were assigned to four groups, and weak inducers and noninducing congeners have the least potential for toxicity.
Abstract: Polychlorinated biphenyls (PCBs) as environmental contaminants often cannot be adequately described by reference to Aroclors or to total PCBs. Although there are 209 possible PCB configurations (congeners), perhaps half that number account for nearly all of the environmental contamination attributable to PCBs. Still fewer congeners are both prevalent and either demonstrably or potentially toxic. If potential toxicity, environmental prevalence, and relative abundance in animal tissues are used as criteria, the number of environmentally threatening PCB congeners reduces to about thirty-six. Twenty-five of these account for 50 to 75% of total PCBs in tissue samples of fish, invertebrates, birds, and mammals. A few PCB congeners that are sterically similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) are directly toxic. Other PCB congeners, as well as those that are directly toxic, may also be involved in toxicity indirectly by stimulating the production of (inducing) bioactivating enzyme systems. The most consequential of these have the ability to induce aryl hydrocarbon metabolizing mixed-function oxidases (MFOs). A result can be an increased capacity for bioactivation of otherwise nontoxic foreign compounds such as certain polynuclear aromatic hydrocarbons (PAH) to cytotoxic or genotoxic metabolites. The effectiveness of specific PCB congeners as inducers of different types of cytochrome P-450-dependent MFO systems is determined by their stereochemistry. Although MFO induction is not a proximate cause, it is a strong correlate of certain kinds of toxicities. Structural patterns can thus be used to discriminate among PCB congeners on the basis of toxic potential, if not entirely on toxicity per se. Congeners that demonstrate 3-methylcholanthrene-type (3-MC-type) and mixed-type MFO induction have the greatest toxic potential. These congeners most closely resemble 2,3,7,8-TCDD in their structures and in their toxic effects. The larger group of phenobarbital-type (PB-type) inducers have considerably less potential for contributing to toxic effects. Weak inducers and noninducing congeners have the least potential for toxicity. Using the rationale described in this paper, we assigned the most evironmentally threatening PCB congeners to four groups. Congeners assigned to Group 1 are considered most likely to contribute to adverse biological effects attributable to PCBs in an environmental sample. Group 1A contains the three most potent (pure 3-MC-type inducer) congeners, IUPAC numbers 77, 126, and 169. Six congeners, numbers 105, 118, 128, 138, 156, and 170, are assigned to Group 1B. These congeners are mixed-type inducers that have been reported frequently in environmental samples.(ABSTRACT TRUNCATED AT 400 WORDS)
712 citations
TL;DR: Ancona and Tiersten as mentioned in this paper presented a macroscopic description of conduction electrons in a semiconductor, in which the equation of state for the electron gas was generalized to include a dependence on the gradient of the density.
Abstract: In a recent paper [M. G. Ancona and H. F. Tiersten, Phys. Rev. B 35, 7959 (1987)] a macroscopic description of conduction electrons in a semiconductor was presented in which the equation of state for the electron gas was generalized to include a dependence on the gradient of the density. This generalization led to a new transport equation---often expressible as a generalized diffusion--drift-current equation---which has been shown to accurately describe some important quantum mechanical effects occurring in semiconductor structures. In the present paper sufficient microscopic conditions under which the density-gradient--dependent equation of state does represent lowest-order effects of quantum mechanics are established using methods of quantum statistical mechanics. A microscopic derivation of the transport equation is also given.
478 citations
TL;DR: Ribavirin, a broad-spectrum antiviral drug, is active against hemorrhagic fever viruses (with the exception of Ebola virus) in cell culture systems and in therapeutic studies it has not prevented late-onset neurologic disease.
Abstract: Ribavirin, a broad-spectrum antiviral drug, is active against hemorrhagic fever viruses (with the exception of Ebola virus) in cell culture systems. In model infections with arenaviruses in guinea pigs and monkeys, ribavirin has demonstrated both prophylactic and therapeutic efficacy. In therapeutic studies it has not prevented late-onset neurologic disease. In human cases of Lassa fever, it significantly reduces mortality when administered before day 7 of illness to persons at high risk. In rodents and monkeys infected with Rift Valley fever virus, ribavirin therapy resulted in reduced mortality; prophylactic administration to volunteers infected with sandfly fever virus, Sicilian strain, prevented development of illness. Ribavirin increased the number of survivors and the mean time to death in suckling mice infected with Crimean-Congo hemorrhagic fever virus and in suckling mice infected with Hantaan virus. In the People's Republic of China, ribavirin significantly reduced mortality in patients with hemorrhagic fever with renal syndrome. Ribavirin has not been effective in animal models of filoviral and flaviviral infections. The only important adverse effect of ribavirin in humans is manageable, reversible anemia.
285 citations
TL;DR: A molecular clone of Venezuelan equine encephalitis virus (VEE) was constructed from four cDNAs that were synthesized using the viral RNA genome as template.
285 citations
TL;DR: The physiological and psychological stressors associated with sustained work, fatigue, and sleep loss affect worker performance as mentioned in this paper, resulting in reduced reaction time, decreased vigilance, perceptual and cognitive distortions, and changes in affect.
Abstract: The physiological and psychological stressors associated with sustained work, fatigue, and sleep loss affect worker performance. This review describes findings relating to sustained work stresses commonly found in our advancing technological world. Researchers report decrements in sustained performance as a function of fatigue, especially during and following one or more nights of complete sleep loss, or longer periods of reduced or fragmented sleep. Sleep loss appears to result in reduced reaction time, decreased vigilance, perceptual and cognitive distortions, and changes in affect. Sleep loss and workload interact with circadian rhythms in producing their effects. These interactions are a major source of stress in work situations requiring sustained work in continuous operations and have implications for theoretical models of sustained perceptual and cognitive functioning.
284 citations
TL;DR: Progress in producing pharmacologic defenses suggests that humans can be largely protected from the lethal and prolonged incapacitating effects of these compounds on a chemical battlefield.
Abstract: For nearly 50 years, nerve agents have constituted a serious threat that has stimulated extensive efforts to develop effective medical countermeasures. Recent progress in producing pharmacologic defenses suggests that humans can be largely protected from the lethal and prolonged incapacitating effects of these compounds on a chemical battlefield. Current research on new approaches to binding and inactivating nerve agents may further decrease their potential as a threat against protected persons. ( JAMA . 1989;262:649-652)
273 citations
TL;DR: In previously sedentary individuals, regularly performed aerobic exercise results in significant improvements in exercise capacity, and physiological adaptations associated with these improvements in both maximal exercise performance and submaximal exercise endurance include increases in both cardiovascular function and skeletal muscle oxidative capacity.
Abstract: In previously sedentary individuals, regularly performed aerobic exercise results in significant improvements in exercise capacity. The development of peak exercise performance, as typified by competitive endurance athletes, is dependent upon several months to years of aerobic training. The physiological adaptations associated with these improvements in both maximal exercise performance, as reflected by increases in maximal oxygen uptake (VO2max), and submaximal exercise endurance include increases in both cardiovascular function and skeletal muscle oxidative capacity.
170 citations
TL;DR: Deleted PA is expected to have normal immunogenicity, but would not combine with trace amounts of LF and EF to cause toxicity and be useful as a replacement for the PA that is the major active ingredient in the current human anthrax vaccine.
164 citations
Patent•
31 Aug 1989TL;DR: The Reactive Bed Plasma (RBP) as mentioned in this paper is a novel air purification and material processing device which may efficiently treat both toxic chemicals and hazardous aerosols, which can achieve high power efficiency by eliminating dielectric barriers and selectively increased residence time of contaminants in active plasma zones through interaction with the packing material.
Abstract: The Reactive Bed Plasma is a novel air purification and material processingevice which may efficiently treat both toxic chemicals and hazardous aerosols. The Reactive Bed Plasma device embodies an active alternating current discharge plasma permeating a dielectric packed bed. Advantages of this device include an increased power efficiency by the elimination of dielectric barriers (characteristic of ozonizer devices); a selectively increased residence time of contaminants in the active plasma zones through interaction with the packing material (analogous to chromotographic separations); also a reduced size and power consumption while maintaining high processing efficiency. Further advantages include greatly increased operating lifetime without failure due to electrical arcing (problematic with ozonizers) or poisoning of the packing surfaces (problematic with adsorbents and catalysts); an achievement of a high processing efficiency at low temperature; a control over plasma air by-product formation; and the promotion of chemical and physical reactions simultaneously in a single device heretofore requiring several vastly different devices (promoting photoionoization, catalytic oxidation, plasma-induced decomposition, combustion, electrostatic precipitation, or plasma etching processes).
150 citations
TL;DR: Combined use of chemical degradation, derivatization, and tandem mass spectrometry for rapid structural characterization of toxic cyclic peptides from blue-green algae at the nanomole level is described.
Abstract: Combined use of chemical degradation, derivatization, and tandem mass spectrometry for rapid structural characterization of toxic cyclic peptides from blue-green algae at the nanomole level is described. Previously, all blue-green algal toxins were thought to belong to a family of seven-residue cyclic peptides, having the general structure cyclo-D-Ala-L-Xaa-erythro-beta-methyl-D-isoaspartic acid-L-Yaa-Adda-D-isoglutamic acid-N-methyldehydroalanine, where Xaa and Yaa represent variable amino acids of the L configuration and Adda is 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid. Structural characterization of two additional toxins indicates that further variability can exist within this family of naturally occurring toxic cyclic peptides. Isoaspartic acid and dehydroalanine can substitute for beta-methylisoaspartic acid and N-methyldehydroalanine, respectively.
TL;DR: In this paper, the authors focus on radiation-induced interface traps, describing first how they fit into the overall radiation response of metal-oxide-semiconductor structures, and discuss several models which fall into three classes, corresponding roughly to the three processes observed experimentally.
Abstract: The authors focus on radiation-induced interface traps, describing first how they fit into the overall radiation response of metal-oxide-semiconductor structures. Detailed measurements of the time, field and temperature dependences of the build-up of radiation-induced interface traps indicate three processes by which the build-up occurs. The largest of these is the slow two-stage process described by McLean and co-workers (1989) which is rate-limited by the hopping transport of hydrogen ions. Two other faster processes also contribute small interface trap build-ups in gate oxides. The processes seem to be controlled by hole transport to the Si/SiO2 interface and by neutral hydrogen diffusion respectively. They also discuss several models which fall into three classes, corresponding roughly to the three processes observed experimentally. Other topics discussed briefly are dose dependence, field oxide effects, chemical and processing dependences and scaling effects.
TL;DR: It is demonstrated that diazepam or high doses of atropine can antagonize the development of brain lesions that result from soman exposure and no single drug or drug combination was effective in protecting all animals in a group from some brain pathology.
TL;DR: In this article, the authors demonstrate the existence of a family of gravitational water waves that propagate practically without change of form on the surface of shallow water of uniform depth, i.e., they are periodic in two spatial directions and in time.
Abstract: Experimental data are presented that demonstrate the existence of a family of gravitational water waves that propagate practically without change of form on the surface of shallow water of uniform depth. The surface patterns of these waves are genuinely two-dimensional and fully periodic, i.e. they are periodic in two spatial directions and in time. The amplitudes of these waves need not be small; their form persists even up to breaking. The waves are easy to generate experimentally, and they are observed to propagate in a stable manner, even when perturbed significantly. The measured waves are described with reasonable accuracy by a family of exact solutions of the Kadomtsev-Petviashvili equation (KP solutions of genus 2) over the entire parameter range of the experiments, including waves well outside the putative range of validity of the KP equation. These genus-2 solutions of the KP equation may be viewed as two-dimensional generalizations of cnoidal waves.
TL;DR: Experimental data obtained from 420 noise-exposed animals (chinchilla) show consistent outer hair cell losses with less than 5 dB permanent threshold shifts (PTS) across all the test frequencies, and hearing thresholds are least sensitive to IHC loss in the octave band centered at 4 kHz.
TL;DR: Viral yields for strains of CCHF virus from Europe, Asia, and Africa in African green monkey kidney cells were markedly reduced by this drug, and a dose of ribavirin at least 9 times greater was required to induce a comparable inhibitory effect on the yields of Rift Valley fever virus.
Abstract: : Ribavirin was evaluated as a potential therapeutic for Crimean-Congo hemorrhagic fever (CCHF). Viral yields for strains of CCHF virus from Europe, Asia, and African in African green monkey kidney (Vero) cells were markedly reduced by this drug. Some CCHF viral strains appeared more sensitive than others, but in general, ribavirin doses as low as 5 ug/ml caused a transient reduction of viral yields. A further reduction in viral yields was induced by a dose of 25 ug/ml, and evidence of viral replication was not demonstrated in cells treated with 50 or 250 ug/ml. In contrast, a dose of ribavirin at least 9 times greater was required to induce a comparable inhibitory effect on the yields of Rift Valley fever virus, for which the drug has been shown to inhibit replication in monkeys and rodents. Keywords: Reprints; Therapy.
TL;DR: The distribution and abundance of fishes in submersed aquatic plants of three relative densities (no plants, intermediate plant density, high plant density) were estimated in the tidal Potomac River near Alexandria, Virginia.
Abstract: The distribution and abundance of fishes in submersed aquatic plants of three relative densities (no plants, intermediate plant density, high plant density) were estimated in the tidal Potomac River near Alexandria, Virginia. Fish were sampled with a boat-mounted electroshocker at night in May (when plants were emerging), August (peak plant densities), and November (plant senescence) of 1986. Mean densities of all plants ranged from 9 to 33 g/m2 (dry-weight basis) in May, and 400 to greater than 1,000 g/m2 in August and November. Hydrilla verticillata was usually the dominant aquatic plant. In May, overall mean fish abundance was highest in areas of high plant density (36 fish/5 min shocking), whereas in August and November fish abundance was highest in areas of intermediate plant densities (100 and 62 fish/5 min electroshocking, respectively). Areas without plants contained a relatively high number of filter-feeding fishes, including Atlantic menhaden Brevoortia tyrannus and blueback herring Alo...
TL;DR: In this paper, a study of the performance parameters for a journal bearing of finite length lubricated with micropolar fluids is undertaken. And it is shown that a significantly higher load carrying capacity than the Newtonian fluids may result depending on the size of material characteristic length and the coupling number.
Abstract: A study of the performance parameters for a journal bearing of finite length lubricated with micropolar fluids is undertaken. Results indicate that a significantly higher load carrying capacity than the Newtonian fluids may result depending on the size of material characteristic length and the coupling number. It is also shown that although the frictional force associated with micropolar fluid is in general higher than that of a Newtonian fluid, the friction coefficient of micropolar fluids tends to be lower than that of the Newtonian.
TL;DR: In this article, thin films of PbTiO3 were deposited on fused silica, resistor-grade alumina, and single-crystal (100) MgO by a sol-gel processing method.
Abstract: Thin films of PbTiO3 were deposited on fused silica, resistor-grade alumina, and single-crystal (100) MgO by a sol–gel processing method. Whereas the films deposited on silica and alumina substrates were randomly oriented and polycrystalline, highly {100} oriented PbTiO3 films were grown on the MgO single crystals. The perovskite-type structure was observed with films deposited on the single-crystal MgO and annealed at temperatures as low as 470°C, whereas a pyrochlore-type strcuture was observed with films on fused silica and alumina processed in a similar manner. All films heat-treated at temperatures in excess of 570°C showed significant formation of a second PbTi3O7 phase. The films were characterized by electron microscopy and glancing-incidence-angle X-ray diffraction.
TL;DR: There is no evidence that Lewisite is either carcinogenic, mutagenic or teratogenic, and the lack of such evidence eminating from epidemiological sources or from animal studies is resounding.
Abstract: Arsenic is a metalloid member of group V elements in the periodic table, which combines chemically with most nonmetals to form a variety of both inorganic and organic compounds, and is pervasively distributed in nature. Several pertinent reviews are extant that attest to its ubiquitous presence in the earth’s crust, air, and aquatic environments. It is likewise present in industrial emission (Pinto and Nelson 1976; Landrigan 1981), is used in agricultural production, and appears in food and in food chains (Gates et al. 1946; NAS 1977; Pershagen 1983; Squibb and Fowler 1983; Fielder et al. 1986; Hindmarsh and McCurdy 1986; Irgolic 1986a, 1986b; Pershagen 1986).
31 May 1989
TL;DR: In this article, the authors proposed a method using a harmonically related pair of c-modes of an SC-cut that is simultaneously excited in a dual-mode oscillator, and then combined to produce a thermometric frequency having a monotonic and nearly linear dependence on temperature.
Abstract: A thermometry method using resonator self-temperature-sensing is described. The method uses a harmonically related pair of c-modes of an SC-cut that is simultaneously excited in a dual-mode oscillator, and then combined to produce a thermometric frequency having a monotonic and nearly linear dependence on temperature. It avoids the activity dip problems of the b-mode and overcomes limitations of using external sensors that are subject to thermal lab and temperature gradients. This method provides a means of measuring resonator temperature with high accuracy, limited only by the stability difference between the c-mode frequencies. The concept for this dual c-mode thermometry method is presented and its implementation in a microcomputer-compensated crystal oscillator discussed. >
TL;DR: Etude du taux de mortalite des mecanismes de contagion and relation avec l'ethnologie des sujets a risque.
TL;DR: In this article, effective medium theory was applied to the problem of four-wave mixing in composites consisting of conducting particles embedded in a linear dielectric medium, where spheroidal conducting particles were considered.
Abstract: We apply effective-medium theory, generalized for nonlinear media, to the problem of four-wave mixing in composites consisting of conducting particles embedded in a linear dielectric medium. For spheroidal conducting particles two cases are considered: (i) the particles are oriented and (ii) the particles have a random orientation. An experiment on gold particle suspensions in glass (Schott RG6) examines the frequency dependence of the conjugate signal intensity in a four-wave mixing geometry. Analysis of these results indicates that the particles with spheroidal shapes are mixed in the glass. We find that frequency and optical depth dependence of the conjugate intensity can be used to gain insight into the shape of the particles, since a large enhancement of the conjugate reflectivity is expected at the surface plasmon resonances, which are highly sensitive to small shape distortions.
TL;DR: The presence of a nicotine metabolite in the saliva and gingival crevicular fluid reflects the extent of the systemic distribution of nicotine in smokers and may possibly affect the pathogenesis of periodontal disease.
Abstract: A study was undertaken to determine the presence of cotinine, a metabolite of nicotine, in the saliva and gingival crevicular fluid of smokers with periodontal disease. Saliva and crevicular fluid samples were obtained from 16 habitual cigarette smokers and analyzed by High Performance Liquid Chromatography (HPLC) for the presence of cotinine. Thirteen non-smokers with periodontal disease served as controls. There was no evidence of cotinine (within our detection levels) in either the saliva or crevicular fluid of any of the nonsmokers. Cotinine, in a wide range of concentrations, was detected in the saliva and crevicular fluid in all of the 16 cigarette smokers. The presence of a nicotine metabolite in the saliva and gingival crevicular fluid reflects the extent of the systemic distribution of nicotine in smokers. The vasoactive properties of nicotine are well known and may possibly affect the pathogenesis of periodontal disease.
TL;DR: The QBC tube is not a substitute for the blood smear, but its speed and ease of use make it an important new tool for the diagnosis of malaria.
Patent•
14 Nov 1989TL;DR: In this paper, the magnetically rigid material is cylindrically configured and magnetized to provide individual magnetic fields between sets of north and south poles on only one cylindrical surface thereof.
Abstract: Magnetically rigid materials are utilized to enhance the field magnitudes oduced by permanent magnet structures that are utilized in electric machinery. Magnetic circuit losses due to unnecessary magnetic fields are eliminated without employing a conventional shunt. The magnetically rigid material is cylindrically configured and magnetized to provide individual magnetic fields between sets of north and south poles on only one cylindrical surface thereof. At least one coaxial cylinder of the magnetically rigid material is included in each permanent magnet structure of the invention and each of the cylinders is constructed from a plurality of segments in one preferred embodiment thereof. Segments having a substantially triangular cross-sectional configuration are utilized in other preferred embodiments, while flux contributions from at least three segments combine to sustain each set of north and south poles in still other preferred embodiments.
TL;DR: A two-level hierarchical model is proposed in which each subsystem is modeling as a Markov chain and the system reliability is then modeled as a series system of independent Markov components, to compute the instantaneous availability of the system with imperfect coverage and online repair.
Abstract: Based on the nature of the upper- and lower-bound block diagram models of multistage interconnection networks (MINs), a series system consisting of independent subsystems is considered To model the reliability of such a system with online repair and imperfect coverage, the usual approach is to construct and solve a large, overall Markov model A two-level hierarchical model is instead proposed in which each subsystem is modeled as a Markov chain and the system reliability is then modeled as a series system of independent Markov components This technique is extended to compute the instantaneous availability of the system with imperfect coverage and online repair Extensions to allow for transient faults and phase-type repair time distributions are straightforward It should be possible to apply this approach to other fault-tolerant MINs and to any system that can be modeled as a series system where each subsystem has a parallel-redundant structure >
TL;DR: VO2max was lower after altitude exposure compared with initial sea level values, indicating that exposure had not improved sea level exercise capacity and was crucial to exercise performance during chronic, severe hypoxemia.
Abstract: Chronic exposure to high altitude reduces maximal O2 uptake (VO2max). At extreme altitudes approaching the summit of Mt. Everest [inspiratory PO2(PIO2) = 43 Torr], mean VO2max have been determined ...
TL;DR: High-frequency ventilation is suggested to be effective in the treatment of patients with severe inhalation injury because of the low incidence of pulmonary infection and the high incidence of iatrogenic barotrauma caused by conventional ventilation.
Abstract: Inhalation injury complicated by bacterial pneumonia is now one of the primary causes of morbidity and mortality in patients with thermal injury. We have investigated the use of high-frequency percussive ventilation (HFPV) as a means of ventilatory support for these patients. We propose that high-frequency ventilation may decrease the incidence of pulmonary infection following inhalation injury and decrease the incidence of iatrogenic barotrauma caused by conventional ventilation. High-frequency ventilation was instituted initially as salvage therapy in a group of five patients. In each case, normocapnia or arterial pO2 saturation of greater than 90% on a FIO2 of 60% or less was achieved with high-frequency ventilation but not with conventional ventilation. A second group of ten patients was prospectively entered into a study on the use of HFPV in patients with inhalation injury. One patient was removed from the study, and one patient was unable to be ventilated because of severely noncompliant lungs. Eight patients with a mean age of 29 years and a mean burn size of 38% of the total body surface completed the protocol. All patients survived, two developed pneumonia, and one developed subcutaneous emphysema. These results suggest that HFPV is effective in the treatment of patients with severe inhalation injury.
TL;DR: The large toxin plasmid, pXO1, found in virulent strains of B. anthracis, was required for stimulation of transcription of pag by bicarbonate, suggesting the existence of a trans-acting factor that is involved in the activation of pag transcription.
Abstract: Bicarbonate is required for production of the major virulence factors, the toxins and capsule, of Bacillus anthracis. In this study we examined the basis for stimulation of production of protective antigen (PA), a central component of the two anthrax toxins encoded by plasmid pXO1. RNA prepared from B. anthracis grown in media with and without added bicarbonate was probed for PA mRNA. Data showed that bicarbonate was required for increased transcription of the PA gene (pag) in minimal medium. Transcription of pag was low in rich medium and could not be stimulated by the addition of bicarbonate. To characterize further the factors required for transcriptional regulation of pag, the promoter region of pag was fused to the chloramphenicol acetyltransferase gene (cat-86) of vector pPL703 and transformed by electroporation into pXO1+ (Tox+) and pXO1- (Tox-) strains of B. anthracis. Analysis of chloramphenicol acetyltransferase produced by the pag-cat-86 fusion in each of these backgrounds confirmed the results obtained by hybridization. Data obtained with this fusion also revealed that the large toxin plasmid, pXO1, found in virulent strains of B. anthracis, was required for stimulation of transcription of pag by bicarbonate. This result suggests the existence of a trans-acting factor that is involved in the activation of pag transcription.