Photosynthetic responses of a dominant C4 grass to an experimental heat wave are mediated by soil moisture.

Extreme heat waves and drought are predicted to increase in frequency and magnitude with climate change. These extreme events often co-occur, making it difficult to separate their direct and indirect effects on important ecophysiological and carbon cycling processes such as photosynthesis. Here, we assessed the independent and interactive effects of experimental heat waves and drought on photosynthesis in Andropogon gerardii, a dominant C4 grass in a native mesic grassland. We experimentally imposed a two-week heat wave at four intensity levels under two contrasting soil moisture regimes: a well-watered control and an extreme drought. There were three main findings from this study. First, the soil moisture regimes had large effects on canopy temperature, leading to extremely high temperatures under drought and low temperatures under well-watered conditions. Second, soil moisture mediated the photosynthetic response to heat; heat reduced photosynthesis under the well-watered control, but not under the extreme drought treatment. Third, the effects of heat on photosynthesis appeared to be driven by a direct thermal effect, not indirectly through other environmental or ecophysiological variables. These results suggest that while photosynthesis in this dominant C4 grass is sensitive to heat stress, this sensitivity can be overwhelmed by extreme drought stress.

A study on the use of male animal models for developing a live vaccine for brucellosis.

To study the safety of Brucella melitensis WR201, a live vaccine candidate, we compared the course of infection of this strain with that of virulent 16M in male BALB/c mice. At various times after oral immunization with strains WR201 or 16M, lungs, liver, spleen, testis, epididymis, inguinal and cervical lymph nodes were removed. Tissues were divided for microbiologic culture and histopathological examination. WR201 infection in male BALB/c mice had lower intensity and shorter duration than infection caused by virulent 16M. Pathological examination of testis and epididymis revealed no inflammation following strain WR201 immunization. In contrast, animals given virulent 16M strain had substantial inflammation in infected tissues. These data confirm the marked attenuation of WR201 relative to 16M. In addition, these studies suggest that male mice may be useful to assess the safety of live, attenuated Brucella vaccine candidates.

T cell immunity to brucellosis.

Brucellosis is an ancient disease of animals and man that still threatens the health and prosperity of many, primarily in the third world, who depend on animal agriculture for their livelihood. Further, its pathogenicity and the facts that it is zoonotic is effectively eradicated from many Western nations make it a dangerous bioterrorism threat. Targeted human vaccination may reduce the various threats brucellosis poses. Significant effort has been expended toward this goal and many candidate vaccines exist. However, the ideal vaccine would be a subunit vaccine that specifically targets only the critical aspects of the immune response necessary to induce immunity. Much about the immune response, in particular the T cell response, remains to be discovered in order to accomplish that goal. In this review we focus on T cell responses to brucellosis with particular attention to the specific roles of T cell subtypes. We also point out areas of research on T cell responses that may allow exploitation of cutting edge vaccine technologies for the next generation vaccine for brucellosis.

Clinical recognition and management of patients exposed to biological warfare agents.

Concern regarding the use of biological agents (bacteria, viruses, or toxins) as tools of warfare or terrorism has led to measures to deter their use or, failing that, to deal with the consequences. Unlike chemical agents, which typically lead to severe disease syndromes within minutes at the site of exposure, diseases resulting from biological agents have incubation periods of days. Rather than a paramedic, it will likely be a physician who is first faced with evidence of the results of a biological attack. Provided here is an updated primer on 11 classic BW and potential terrorist agents to increase the likelihood of their being considered in a differential diagnosis. Although the resultant diseases are rarely seen in many countries today, accepted diagnostic and epidemiologic principles apply; if the cause is identified quickly, appropriate therapy can be initiated and the impact of a terrorist attack greatly reduced.

Deletion of wboA enhances activation of the lectin pathway of complement in Brucella abortus and Brucella melitensis.

Brucella spp. are gram-negative intracellular pathogens that survive and multiply within phagocytic cells of their hosts. Smooth organisms present O polysaccharides (OPS) on their surface. These OPS help the bacteria avoid the bactericidal action of serum. The wboA gene, coding for the enzyme glycosyltransferase, is essential for the synthesis of O chain in Brucella. In this study, the sensitivity to serum of smooth, virulent Brucella melitensis 16M and B. abortus 2308, rough wboA mutants VTRM1, RA1, and WRR51 derived from these two Brucella species, and the B. abortus vaccine strain RB51 was assayed using normal nonimmune human serum (NHS). The deposition of complement components and mannose-binding lectin (MBL) on the bacterial surface was detected by flow cytometry. Rough B. abortus mutants were more sensitive to the bactericidal action of NHS than were rough B. melitensis mutants. Complement components were deposited on smooth strains at a slower rate compared to rough strains. Deposition of iC3b and C5b-9 and bacterial killing occurred when bacteria were treated with C1q-depleted, but not with C2-depleted serum or NHS in the presence of Mg-EGTA. These results indicate that (i) OPS-deficient strains derived from B. melitensis 16M are more resistant to the bactericidal action of NHS than OPS-deficient strains derived from B. abortus 2308, (ii) both the classical and the MBL-mediated pathways are involved in complement deposition and complement-mediated killing of Brucella, and (iii) the alternative pathway is not activated by smooth or rough brucellae.

Urolithiasis in the low birth weight infant: the role and efficacy of extracorporeal shock wave lithotripsy.

PURPOSE: Nephrolithiasis in preterm infants rarely requires surgical management. When it persists despite conservative therapy, treatment options are not clearly defined. We report a single institutional experience with extracorporeal shock wave lithotripsy (ESWL)* for the treatment of these small infants. MATERIALS AND METHODS: We treated 8 infants (mean age 13 months) with a history of prematurity and 9 persistent stones with a Dornier HM3 lithotriptor between 1996 and 1999. Mean weight was 7,700 gm. Of the infants 7 had been treated with furosemide for bronchopulmonary dysplasia and 1 presented with multiple anatomical abnormalities. Gantry modification with a wooden platform and polystyrene foam positioning was used for lung and visceral protection. Ureteral stents were placed in 5 patients before ESWL. Renal ultrasonography was performed before, and 2 and a mean of 8 weeks after ESWL. Stone risk factors in our population were investigated through a multispecialty approach. RESULTS: Average stone burden was 47.9 mm.2. A total of 9 sessions of ESWL were required for complete fragmentation of the 9 renal stones. A mean total of 2,100 shocks at a mean 16.1 kV. were administered. One patient with bilateral stones was treated in 2 separate sessions after a 4-week interval. No repeat ESWL sessions or other surgical interventions were required in any patient. Renal ultrasonography demonstrated no post-ESWL morphological changes. Practices leading to a higher incidence of neonatal nephrolithiasis at our institution were also identified. CONCLUSIONS: ESWL is effective treatment for nephrolithiasis in small infants. Short-term safety has been established but continued long-term functional followup is essential. Multifactorial etiologies of nephrolithiasis must be identified and modified promptly in the care of preterm infants.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Over-expression of hsp-70 inhibits bacterial lipopolysaccharide-induced production of cytokines in human monocyte-derived macrophages.

Cytokines released from monocytes and macrophages are major mediators of inflammation. Heat shock significantly inhibits cytokine production from these cells. To investigate whether this inhibitory effect was mediated by heat-shock proteins (HSP), we transfected human peripheral blood monocyte-derived macrophages (MDM) with HSP-70 cDNA and examined Brucella melitensis lipopolysaccharide (LPS)-induced cytokine production in transfected cells. Over-expression of HSP-70 protein in the gene-transfected MDM had no effect on cytokine synthesis unless LPS was added. LPS-induced increases in production of tumour necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), IL-10 and IL-12 were significantly inhibited by the over-expression of HSP-70. However, over-expression of HSP-70 did not block LPS-induced increase in IL-6 synthesis. To further confirm these results, an antisense HSP-70 DNA oligomer was used to block HSP-70 synthesis. The inhibitory effect of HSP-70 on LPS-induced cytokine production in gene- transfected cells was completely reversed after treatment of cells with 5 microM antisense HSP-70. The same concentration of antisense HSP-70 also partially reversed heat-shock-induced inhibition of LPS-stimulated cytokine production. These results suggest that HSP-70 is involved in the regulation of LPS-induced cytokine production and that this family of proteins plays a role in mitigating adverse effects of endotoxin during infection or other pathological stresses.

Impaired control of Brucella melitensis infection in Rag1-deficient mice.

After intranasal inoculation, Brucella melitensis chronically infects the mononuclear phagocyte system in BALB/c mice, but it causes no apparent illness. Adaptive immunity, which can be transferred by either T cells or antibody from immune to naive animals, confers resistance to challenge infection. The role of innate, non-B-, non-T-cell-mediated immunity in control of murine brucellosis, however, is unknown. In the present study, we documented that BALB/c and C57BL/6 mice had a similar course of infection after intranasal administration of 16M, validating the usefulness of the model in the latter mouse strain. We then compared the course of infection in Rag1 knockout mice (C57BL/6 background) (referred to here as RAG-1 mice) which have no B or T cells as a consequence of deletion of Rag1 (recombination-activating gene 1), with infection in normal C57BL/6 animals after intranasal administration of B. melitensis 16M. C57BL/6 mice cleared brucellae from their lungs by 8 to 12 weeks and controlled infection in the liver and spleen at a low level. In contrast, RAG-1 mice failed to reduce the number of bacteria in any of these organs. From 1 to 4 weeks after inoculation, the number of splenic bacteria increased from 2 to 4.5 logs and remained at that level. In contrast to the consistently high numbers of brucellae observed in the spleens, the number of bacteria rose in the livers sampled for up to 20 weeks. Immunohistologic examination at 8 weeks after infection disclosed foci of persistent pneumonia and large amounts of Brucella antigen in macrophages in lung, liver, and spleen in RAG-1, but not C57BL/6, mice. These studies indicate that T- and B-cell-independent immunity can control Brucella infection at a high level in the murine spleen, but not in the liver. Immunity mediated by T and/or B cells is required for clearance of bacteria from spleen and lung and for control of bacterial replication in the liver.

Shigella flexneri IpaH(7.8) facilitates escape of virulent bacteria from the endocytic vacuoles of mouse and human macrophages.

The behavior of Shigella flexneri ipaH mutants was studied in human monocyte-derived macrophages (HMDM), in 1-day-old human monocytes, and in J774 mouse macrophage cell line. In HMDM, strain pWR700, an ipaH(7.8) deletion mutant of S. flexneri 2a strain 2457T, behaved like the wild-type strain 2457T. This strain caused rapid host cell death by oncosis, and few bacterial CFU were recovered after incubation in the presence of gentamicin as previously described for 2457T-infected HMDM. However, analysis of bacterial compartmentalization within endocytic vacuoles with gentamicin and chloroquine indicated that more pWR700 than 2457T was present within the endocytic vacuoles of HMDM, suggesting that ipaH(7.8) deletion mutant transited more slowly from the vacuoles to the cytoplasm. In contrast to findings with HMDM, CFU recovered from pWR700-infected mouse J774 cells were 2 to 3 logs higher than CFU from 2457T-infected J774 cells. These values exceeded CFU recovered after infection of J774 cells with plasmid-cured avirulent strain M4243A1. Incubation with gentamicin and chloroquine clearly showed that pWR700 within J774 cells was mostly present within the endocytic vacuoles. This distribution pattern was similar to that seen with M4243A1 and contrasted with the pattern seen with 2457T. Complementation of pWR700 with a recombinant clone expressing ipaH(7. 8) restored the intracellular distribution of bacteria to that seen with the wild-type strain. Strains with deletions in ipaH(4.5) or ipaH(9.8), however, behaved like 2457T in both HMDM and J774 cells. The distribution profile of pWR700 in 1-day-old monocytes was similar to that seen in J774 cells. Like infected J774 cells, 1-day-old human monocytes demonstrated apoptosis upon infection with virulent Shigella. These results suggest that a role of the ipaH(7. 8) gene product is to facilitate the escape of the virulent bacteria from the phagocytic vacuole of monocytes and macrophages.

Kinetics of cellular and cytokine responses in a chimeric mouse model for the study of staphylococcal enterotoxin B pathogenesis.

The mechanisms by which superantigens, such as staphylococcal enterotoxin B (SEB), contribute to microbial pathogenicity have been poorly defined. The study of such pathogenic processes has been hampered by the lack of an adequate animal model. We utilized a previously described murine chimeric model to determine the cytokines and cell populations that might be involved in SEB toxicity. In the absence of bone marrow transplantation (BMT), all total body irradiated (TBI) mice died, while all transplanted mice survived up to 6 months. Compared with non-TBI and non-BMT mice, chimeric mice had an increased percentage of CD11b (Mac-1)-positive splenocytes (17 vs. 59%, P < 0.05) and decreased CD45R-positive (B) cells (33 vs. 6%, P < 0.05) at 6 weeks after BMT. The relative numbers of splenocyte CD4 and CD8 cells were similar in chimeric and normal mice. Susceptibility of chimeric animals to 10 or 100 microg SEB was time-dependent: no mice challenged at 2 weeks post-BMT died, but 15% of mice challenged at 4 weeks and 50% of those challenged at 6-8 weeks died. Compared with TBI and non-BMT C3H/HeJ mice, SEB-challenged chimeric mice at 6-8 weeks had (1) increased splenocyte mRNA expression for: IFN-gamma (3.5 x optimally at 1 h), TNF-alpha (6.5 x at 2 h), IL-6 (4.8 x at 4 h), IL-1beta (8.4 x at 4 h), IL-2 (4.7 x at 4 h), and IL-10 (3 x at 16 h), and (2) increased and earlier peak serum levels of IFN-gamma, IL-6, IL-1beta and IL-2, but no increase in serum TNF-alpha or IL-4. These data support the hypothesis that the decreased percentage of B cells and increased macrophages in chimeric mice lead to enhanced T cell-macrophage interactions after SEB administration and a lethal burst of T cell and macrophage cytokine release. This model will provide insight into cell populations and mechanisms that mediate superantigen-induced toxicity.

Effects of opsonization and gamma interferon on growth of Brucella melitensis 16M in mouse peritoneal macrophages in vitro.

Entry of opsonized pathogens into phagocytes may benefit or, paradoxically, harm the host. Opsonization may trigger antimicrobial mechanisms such as reactive oxygen or nitric oxide (NO) production but may also provide a safe haven for intracellular replication. Brucellae are natural intramacrophage pathogens of rodents, ruminants, dogs, marine mammals, and humans. We evaluated the role of opsonins in Brucella-macrophage interactions by challenging cultured murine peritoneal macrophages with Brucella melitensis 16M treated with complement- and/or antibody-rich serum. Mouse serum rich in antibody against Brucella lipopolysaccharide (LPS) (aLPS) and human complement-rich serum (HCS) each enhanced the macrophage uptake of brucellae. Combinations of suboptimal levels of aLPS (0. 01%) and HCS (2%) synergistically enhanced uptake. The intracellular fate of ingested bacteria was evaluated with an optimal concentration of gentamicin (2 microg/ml) to control extracellular growth but not kill intracellular bacteria. Bacteria opsonized with aLPS and/or HCS grew equally well inside macrophages in the absence of gamma interferon (IFN-gamma). Macrophage activation with IFN-gamma inhibited replication of both opsonized and nonopsonized brucellae but was less effective in inhibiting replication of nonopsonized bacteria. IFN-gamma treatment of macrophages with opsonized or nonopsonized bacteria enhanced NO production, which was blocked by N(G)-monomethyl L-arginine (MMLA), an NO synthesis inhibitor. MMLA also partially blocked IFN-gamma-mediated bacterial growth inhibition. These studies suggest that primary murine macrophages have limited ability to control infection with B. melitensis, even when activated by IFN-gamma in the presence of highly opsonic concentrations of antibody and complement. Additional cellular immune responses, e.g., those mediated by cytotoxic T cells, may play more important roles in the control of murine brucellosis.

Protection of mice against brucellosis by vaccination with Brucella melitensis WR201(16MDeltapurEK).

Human brucellosis can be acquired from infected animal tissues by ingestion, inhalation, or contamination of the conjunctiva or traumatized skin by infected animal products. A vaccine to protect humans from occupational exposure or from zoonotic infection in areas where the disease is endemic would reduce an important cause of morbidity worldwide. Vaccines currently used in animals are unsuitable for human use. We tested a live, attenuated, purine-auxotrophic mutant strain of Brucella melitensis, WR201, for its ability to elicit cellular and humoral immune responses and to protect mice against intranasal challenge with B. melitensis 16M. Mice inoculated intraperitoneally with WR201 made serum antibody to lipopolysaccharide and non-O-polysaccharide antigens. Splenocytes from immunized animals released interleukin-2 (IL-2), gamma interferon, and IL-10 when cultured with Brucella antigens. Immunization led to protection from disseminated infection but had only a slight effect on clearance of the challenge inoculum from the lungs. These studies suggest that WR201 should be further investigated as a vaccine to prevent human brucellosis.

Penile neurofibromas.

Unless omitted and underreported, penile neurofibromas are rare. Between January 2, 1982 and December 31, 1997 through the USF Regional Genetics Program we evaluated 566 propositi with suspected or clinically diagnosed neurofibromatosis (NF1, NF2, segmental NF=NF5, NF/Noonan syndrome, familial café-au-lait macules, and solitary neurofibroma, NF). These index cases were part of 32,715 families evaluated during the period. NF1 was the diagnosis in 361; 2 of them had penile NFs. A toddler presented with congenital plexiform NF of the penile shaft and another propositus developed two small subcutaneous NFs, on the penile shaft and on the left scrotal wall, respectively. A review documented 26 additional patients with penile NF. As to the pathogenesis of the NF1 lesions, a paracrine growth model including the multiple levels of regulation of expression of the NF1 gene appeared more plausible than the loss of heterozygosity (LOH) model, which ignores the complexity of the paracrine growth mechanism.

Hemolysin-positive enteroaggregative and cell-detaching Escherichia coli strains cause oncosis of human monocyte-derived macrophages and apoptosis of murine J774 cells.

Infection of human monocyte-derived macrophages (HMDM) and J774 cells (murine macrophage cell line) with several enteroaggregative and cytodetaching Escherichia coli (EAggEC and CDEC, respectively) strains demonstrated that some strains could induce macrophage cell death accompanied by release of lactate dehydrogenase activity and interleukin 1beta (IL-1beta) into culture supernatants. The mode of cell death differed in the two types of macrophages. Damage to macrophage plasma membrane integrity without changes in nuclear morphology resulted in cytolysis of HMDM. This mechanism of cell death has been previously described for virulent Shigella infection of HMDM and is termed oncosis. In contrast, infection of J774 cells by EAggEC and CDEC strains resulted in apoptosis. The presence of alpha-hemolysin (Hly) in EAggEC and CDEC strains appears to be critical for both oncosis in HMDM and apoptosis in J774 cells. Bacteria lacking Hly, including Hly- EAggEC strains as well as enterotoxigenic, enteropathogenic, and enterohemorrhagic E. coli strains, behaved like avirulent Shigella flexneri in that the macrophage monolayers were intact, with no release of lactate dehydrogenase activity or IL-1beta into the culture supernatants.

Covalent polymyxin B conjugate with human immunoglobulin G as an antiendotoxin reagent.

Polymyxin B (PMB) is a cyclic decapeptide antibiotic which also binds and neutralizes endotoxin. Unfortunately, PMB can be considerably nephrotoxic at clinically utilized doses, thereby limiting its utility as a therapeutic antiendotoxin reagent. We sought to change the pharmacokinetics and toxicity profile of PMB by covalently linking it to a human immunoglobulin G (IgG) carrier. Conjugates of PMB with IgG were prepared by EDAC [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide]-mediated amide formation. Analysis by dot enzyme-linked immunosorbent assay with an anti-PMB monoclonal antibody showed that the purified conjugate contained bound PMB. The IgG-PMB conjugate reacted with lipid A and J5 lipopolysaccharide in Western blot assays in a manner comparable to that of whole antiserum with anti-lipid A reactivity; unconjugated IgG had no reactivity. The PMB bound in the conjugate retained its endotoxin-neutralizing activity compared to that of unbound PMB as evidenced by its dose-dependent inhibition of tumor necrosis factor release by endotoxin-stimulated human monocytes in vitro; unconjugated IgG had no activity. By this assay, the PMB-IgG conjugate was determined to have approximately 3.0 microg of bound functional PMB per 100 microg of total protein of conjugate (five molecules of PMB per IgG molecule). The PMB-IgG conjugate was also bactericidal against clinical strains of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae relative to unconjugated IgG with MBCs of <4 microg of conjugate per ml for each of the tested strains. The conjugate appeared to be nontoxic at the highest doses deliverable and provided statistically significant protection from death to galactosamine-sensitized, lipopolysaccharide-challenged mice in a dose-dependent fashion when administered prophylactically 2 h before challenge. However, neither free PMB nor the PMB-IgG conjugate could protect mice challenged with endotoxin 2 h after administration. This suggests that these reagents can play a role in prophylaxis but not in therapy of sepsis. These experiments demonstrated that the PMB-IgG conjugate retains bound yet functional PMB as evidenced by its endotoxin-neutralizing activity both in vitro and in vivo. Further work is required to define the role that this or related conjugate compounds may play in the prophylaxis of endotoxin-mediated disease.

Results of a combined adjustable recession and posterior fixation suture of the same vertical rectus muscle for incomitant vertical strabismus.

PURPOSE: The posterior fixation suture (fadenoperation) is an effective treatment for complicated incomitant vertical strabismus. Traditional operative methods do not permit the simultaneous use of an adjustable recession of the same muscle. METHODS: Seven patients with incomitant vertical strabismus and diplopia were treated with a combined adjustable recession and posterior fixation suture of the same vertical rectus muscle. Preoperative vertical misalignments in the primary position ranged from 4 to 10 prism diopters. Vertical incomitance from the primary position into the field of action of the recessed vertical rectus muscle ranged from 6 to 30 prism diopters (mean, 17 prism diopters). This was the sole operation in five patients and was combined with other vertical muscle surgery in two others. RESULTS: All seven patients experienced improvement in their diplopia. Five of 7 patients (71%) required postoperative adjustments to achieve orthophoria in the primary position. This combined procedure reduced large deviations in the field of action of the recessed vertical muscle in all cases. Six of 7 patients (86%) did not require prismatic correction after this operation. One patient required prism only in his reading glasses. CONCLUSIONS: A combined adjustable recession and posterior fixation suture of the same vertical rectus muscle was effective in reducing or eliminating vertical incomitant strabismus.

Survival of a bacterioferritin deletion mutant of Brucella melitensis 16M in human monocyte-derived macrophages.

A bacterioferritin (BFR) deletion mutant of Brucella melitensis 16M was generated by gene replacement. The deletion was complemented with a broad-host-range vector carrying the wild-type bfr gene, pBBR-bfr. The survival and growth of the mutant, B. melitensis PAD 2-78, were similar to those of its parental strain in human monocyte-derived macrophages (MDM). These results suggest that BFR is not essential for the intracellular survival of B. melitensis in human MDM.

Clinical recognition and management of patients exposed to biological warfare agents.

Concern regarding the use of biological agents--bacteria, viruses, or toxins--as tools of warfare or terrorism has led to measures to deter their use or, failing that, to deal with the consequences. Unlike chemical agents, which typically lead to violent disease syndromes within minutes at the site of exposure, diseases resulting from biological agents have incubation periods of days. Therefore, rather than a paramedic, it will likely be a physician who is first faced with evidence of the results of a biological attack. We provide here a primer on 10 classic biological warfare agents to increase the likelihood of their being considered in a differential diagnosis. Although the resultant diseases are rarely seen in many countries today, accepted diagnostic and epidemiologic principles apply; if the cause is identified quickly, appropriate therapy can be initiated and the impact of a terrorist attack greatly reduced.

Lymphocyte proliferative responses of goats vaccinated with Brucella melitensis 16M or a delta purE201 strain.

The response to a Brucella melitensis purEK deletion mutant, delta purE201 (referred to as strain 201), was compared with the response to its parental strain, 16M, in juvenile goats. Proliferative responses to gamma-irradiated bacteria were detected earlier in strain 201-infected goats. Lymphocytes from strain 16M- or 201-infected goats proliferated in response to one-dimensional polyacrylamide gel electrophoresis-separated proteins of similar mass isolated from strain 16M or Brucella abortus RB51. Data from this study suggest that some antigens stimulating cell-mediated responses are conserved among Brucella species, as 201- and 16M-infected goats recognized similar proteins expressed by RB51 and 16M.