Using biodosimetry to enhance the public health response to a nuclear incident.

Radiation Biodosimetry is a continually developing clinical diagnostic field, which focuses on biological markers that proportionally change in relationship to the amount of ionizing radiation absorbed. Examples of host marker response include changes in white cell count, specific proteins in circulation, RNAs in white blood cells, or chromosome fidelity in affected lymphocytes. Measurements of radiation biomarkers correlate with the approximate radiation dose absorbed and indirectly provide an assessment of the likelihood of developing acute radiation syndrome. The aim of this review is to summarize four biodosimetry programs that are in advanced development, later pipeline stages with funding from the Biomedical Advanced Research and Development Authority (BARDA), an agency under the Assistant Secretary for Preparedness and Response (ASPR) in the U.S. Department of Health and Human Services (HHS). With BARDA financial support, biodosimetry diagnostic assays in development will inform patient management, improve health and psychosocial outcomes, and save lives after a nuclear disaster. These tests include an SRI International developed rapid on-site screening test requiring only a finger stick of blood to triage those who have received little or no radiation from those who have received clinically significant levels of radiation and need further immediate patient management. In addition, multiple laboratory-based, high-throughput quantitative tests, currently under development by MRIGlobal, DxTerity, and ASELL, will more accurately define dose levels and possibly predict cellular and organ-damage and other longer-term effects of radiation. In the future, when clinical and analytical validation of these assays is complete, the data is reviewed by the FDA, and agency use status is obtained, rapid triage and laboratory-based biodosimetry test results will enable emergency medical teams to do the most good for the largest number of people after a nuclear blast.

A pharmacokinetic study of amphotericin B lipid complex injection (Abelcet) in patients with definite or probable systemic fungal infections.

This study describes a pharmacokinetic evaluation of amphotericin B (AMB) lipid complex injection (ABLC or Abelcet) in 17 patients with systemic fungal infection administered 5 mg/kg of body weight/day by infusion for 10 to 17 days. The results showed that AMB exhibited multiexponential disposition with high clearance, large volume of distribution at steady state, and long apparent elimination half-life but no evidence of accumulation in the blood after multiple daily doses. The results confirm previous observations and further reinforce the suggestion that ABLC may exist as a depot in the tissues from which free AMB is slowly released to limit exposure.

Efficacy of viral clearance methods used in the manufacture of activated prothrombin complex concentrates: focus on AUTOPLEX T.

Various methods are described for the elimination of infectious viruses from activated prothrombin complex concentrates (aPCCs) and for the analysis of the final products (AUTOPLEX T and FEIBA VH). Viruses of concern in human plasma-derived products are enveloped (hepatitis B and C, cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus [HIV]) and nonenveloped (hepatitis A and parvovirus B19). Donated blood used for AUTOPLEX T is screened for antihepatitis C, HBsAg, anti-HIV types 1 and 2, and p24 antigen. Plasma pools utilized for raw materials are also tested by PCR for HIV and hepatitis C virus. Partial virus inactivation and partitioning are achieved by purification of the aPCC. Further reduction of virus infectivity is accomplished by lyophilization and dry-heat treatment. Each step undergoes virus elimination validation studies in which a relevant sample is 'spiked' with the appropriate virus or model virus. The total reduction in virus from raw material to final product can then be calculated. For AUTOPLEX T the cumulative log10 reduction factors for several viruses vary from 4.2 to 14.3. This ensures an exceptionally high margin of safety. Definitive evidence for product safety was obtained by clinical observation of treated patients. The viral inactivation process of AUTOPLEX T involves a four-tier viral safety program, including Cohn alcohol fractionation and dry-heat treatment, in place of the two-stage vapour-heating process for FEIBA.

Amphotericin B lipid complex for invasive fungal infections: analysis of safety and efficacy in 556 cases.

The safety and antifungal efficacy of amphotericin B lipid complex (ABLC) were evaluated in 556 cases of invasive fungal infection treated through an open-label, single-patient, emergency-use study of patients who were refractory to or intolerant of conventional antifungal therapy. All 556 treatment episodes were evaluable for safety. During the course of ABLC therapy, serum creatinine levels significantly decreased from baseline (P < .02). Among 162 patients with serum creatinine values > or = 2.5 mg/dL at the start of ABLC therapy (baseline), the mean serum creatinine value decreased significantly from the first week through the sixth week (P < or = .0003). Among the 291 mycologically confirmed cases evaluable for therapeutic response, there was a complete or partial response to ABLC in 167 (57%), including 42% (55) of 130 cases of aspergillosis, 67% (28) of 42 cases of disseminated candidiasis, 71% (17) of 24 cases of zygomycosis, and 82% (9) of 11 cases of fusariosis. Response rates varied according to the pattern of invasive fungal infection, underlying condition, and reason for enrollment (intolerance versus progressive infection). These findings support the use of ABLC in the treatment of invasive fungal infections in patients who are intolerant of or refractory to conventional antifungal therapy.

Pharmacokinetic profile of ABELCET (amphotericin B lipid complex injection): combined experience from phase I and phase II studies.

Amphotericin B (AmB) has been the most effective systemic antifungal agent, but its use is limited by the dose-limiting toxicity of the conventional micellar dispersion formulation (Fungizone). New formulations with better and improved safety profiles are being developed and include ABELCET (formerly ABLC), but their dispositions have not been well characterized; hence, the reason for their improved profiles remains unclear. This report details the pharmacokinetics of ABELCET examined in various pharmacokinetic and efficacy studies by using whole-blood measurements of AmB concentration performed by high-pressure liquid chromatography. The data indicated that the disposition of AmB after administration of ABELCET is different from that after administration of Fungizone, with a faster clearance and a larger volume of distribution. It exhibits complex and nonlinear pharmacokinetics with wide interindividual variability, extensive distribution, and low clearance. The pharmacokinetics were unusual. Clearance and volume of distribution were increased with dose, peak and trough concentrations after multiple dosings increased less than proportionately with dose, steady state appeared to have been attained in 2 to 3 days, despite an estimated half-life of up to 5 days, and there was no evidence of significant accumulation in the blood. The data are internally consistent, even though they were gathered under different conditions and circumstances. The pharmacokinetics of ABELCET suggest that lower concentrations in blood due to higher clearance and greater distribution may be responsible for its improved toxicity profile compared to those of conventional formulations.

Short-course, low-dose amphotericin B lipid complex therapy for visceral leishmaniasis unresponsive to antimony.

BACKGROUND: Visceral leishmaniasis (kala-azar) is a worldwide, disseminated intracellular protozoal infection for which prolonged, conventional therapy with pentavalent antimony has become increasingly less effective. OBJECTIVE: To determine the efficacy and minimal effective dose of short-course therapy with amphotericin B lipid complex in visceral leishmaniasis. DESIGN: A randomized, open-label study. SETTING: Inpatient kala-azar treatment unit in the state of Bihar in northeast India, where visceral leishmaniasis is endemic. PATIENTS: 60 patients with active infection who had not responded to or who had relapse after receiving conventional (> 30 days) treatment with pentavalent antimony. INTERVENTION: Intravenous amphotericin B lipid complex was given once daily for 5 consecutive days by 2-hour infusion. Patients were randomly assigned to receive 1, 2, or 3 mg/kg of body weight per day (total doses of 5, 10, or 15 mg/kg, respectively). MEASUREMENTS: Clinical and parasitologic responses (the latter were measured by parasite density score of the splenic aspirate) were determined 14 days after treatment. Definitive responses were assessed 6 months after treatment according to clinical outcomes and findings on examination of bone marrow aspirate. RESULTS: All 60 patients responded to 5 days of treatment. Fourteen days after therapy, all patients had parasite-free splenic aspirates and were considered to have an apparent clinical and parasitologic response. Six months after therapy, definitive responses were documented in 16 of 19 (84% [95% Cl, 60% to 97%]), 18 of 20 (90% [Cl, 68% to 99%]), and 21 of 21 (100% [Cl, 84% to 100%]) patients who received total doses of 5, 10, and 15 mg/kg, respectively. CONCLUSION: Short-course therapy with low-dose amphotericin B lipid complex is effective for visceral leishmaniasis and is an important therapeutic alternative in the management of this serious intracellular protozoal infection.

Initial safety and immunogenicity studies of an oral recombinant adenohepatitis B vaccine.

Orally administered adenovirus may be a useful vaccine carrier of cloned antigens of other pathogens. A recombinant adenohepatitis vaccine Wy-Ad7HZ6-1, which expressed hepatitis B surface antigen and contained a large deletion in early region 3 (E3), was constructed and studied in humans. Volunteers received Wy-Ad7HZ6-1 (n = 3), adenovirus type 7 vaccine (n = 3) or placebo (n = 3). Recipients of Wy-Ad7HZ6-1 shed less vaccine virus in the stool for a shorter period and had a lower titre of anti-adenovirus type 7 antibodies than recipients of the adenovirus 7 vaccine. None of the three Wy-Ad7HZ6-1 vaccinees developed antibody to hepatitis B surface antigen after this one dose primary immunization regimen. The E3 region may be required for optimal enteric growth of adenovirus-vectored vaccines.

Use and mechanism of action of AS101 in protecting bone marrow colony forming units-granulocyte-macrophage following purging with ASTA-Z 7557.

Ammonium trichloro(dioxoethylene-O,O')tellurate (AS101) has been shown previously to provide radioprotective effects when given to mice 24 h prior to irradiation and to protect mice from lethal and sublethal doses of cyclophosphamide (CTX). In this study we examined the ability of AS101 to protect mice bone marrow colony forming units-granulocyte-macrophage treated in vitro with various doses of ASTA-Z 7557, a potent derivative of cyclophosphamide. We demonstrate that prior incubation with AS101 protects colony forming units-granulocyte-macrophage from toxic effects of ASTA-Z. This protection can also be conferred by injection of mice with AS101 prior to incubation of their bone marrow in vitro with ASTA-Z. Prior incubation with AS101 was shown not to protect K562 leukemic cells or HL-60 cells from the toxic effects of ASTA-Z. We show that AS101 protection from the toxic effects of ASTA-Z in vitro and CTX in vivo can be partially ascribed to increased aldehyde dehydrogenase (ALDH) activity induced by AS101. This was shown directly by measuring cellular ALDH activity and indirectly by measuring the toxicity of ASTA-Z and CTX in the presence of cyanamide, an inhibitor of ALDH. AS101 is also demonstrated in this study to protect spleen cells from the toxic effects of 5-fluorouracil, probably through a different mechanism. These properties of AS101 make it a useful candidate for increasing the qualitative potential of bone marrow used for autologous transplantation after purging with ASTA-Z. In addition, the results suggest an increase in ALDH activity by AS101 as one of the mechanisms of protection from the toxic effects of ASTA-Z and CTX. However, the chemoprotectiveness of AS101 was found not to be restricted to cyclophosphamide, since as shown in this study, AS101 helped by other mechanisms to reconstitute the number of spleen cells after 5-fluorouracil treatment.

Protective and restorative role of AS101 in combination with chemotherapy.

The immunomodulator AS101 has been found previously by us to stimulate the secretion of high levels of interleukin 1 and colony stimulating factor (CSF) in vitro, as well as the production of CSF in vivo in mice models. These cytokines are known to induce proliferation and differentiation of hematopoietic progenitor cells from the spleen and bone marrow (BM) and to protect mice from DNA-damaging agents. The present studies were designed to evaluate the effects of prolonged treatment with AS101 on myelopoiesis, BM cellularity, and CSF secretion in mice treated with a sublethal dose of cyclophosphamide (CYP) and on the survival of mice undergoing treatment with lethal doses of this compound. In this model, the hematopoietic progenitors were suppressed during the overbound phase of myelopoiesis resulting from the cytotoxic effects of CYP. This allowed the detection of a significant proliferative effect of AS101 in vivo on BM colony-forming units granulocyte-macrophage progenitor cells, BM cellularity, and the secretion of CSF. Moreover, AS101 protected these animals from the lethal effects of high doses of CYP. These protective effects were demonstrable only when AS101 was administered to mice prior to CYP treatment. The only exception was CSF secretion by spleen cells that had been reconstituted when AS101 was administered both prior to and following CYP treatment. AS101 was found to have a synergistic effect with CYP in the treatment of tumor-bearing mice, suggesting that the combination of these two modalities provides a more effective treatment of their tumors. These results strongly suggest an immunoregulatory role for AS101 in counteracting the chemotherapy-induced hematopoietic suppression as well as usefulness as adjunct treatment of cancer when used in combination with CYP.

Current use and future directions of adenovirus vaccine.

Adenoviruses are a major cause of respiratory illnesses in military recruits and also are common causes of respiratory and gastrointestinal infections during childhood. Forty-one serotypes of human respiratory and enteric adenoviruses have been identified. Live, oral adenovirus vaccines developed for the military and tested in large clinical trials have proved to be safe and highly effective in decreasing hospitalizations related to adenoviral acute respiratory diseases. Studies have demonstrated little horizontal transmission among military personnel but substantial transmission among family members. Use of recombinant techniques have opened new opportunities for the development of recombinant adenovirus vector vaccines against a number of viral pathogens such as hepatitis B, human immunodeficiency, herpes simplex and respiratory syncytial virus.

A rapid immunofluorescent procedure for serodiagnosis of Q fever in mice, guinea pigs, sheep, and humans.

The ability to diagnose Q fever has been hampered by the fact that diagnosis depends upon difficult serologic tests such as complement fixation (CF) or slide immunofluorescence performed only at reference laboratories. A new quantitative solid phase fluorescent antibody test (FIAX) has recently been developed and applied to measure antibodies in several microbial systems. The test takes less than 2 hr to perform and employs stable reagents. We have utilized this technique and developed a rapid immunofluorescent assay for detection of antibodies to Coxiella burnetii in man and animals. Sera from guinea pigs and mice immunized with phase I vaccine and from naturally infected sheep show high levels of fluorescence against both phase I and phase II antigens by this technique. We have tested over 100 CF positive humans from a recent laboratory outbreak of Q fever and find an excellent correlation between FIAX and CF results.