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Biomedical subjects

C A Rossi

Publications and source records attributed to C A Rossi.

At least 19 recordsLinked to original sources
PubMed2005

The detection of protective antigen (PA) associated with spores of Bacillus anthracis and the effects of anti-PA antibodies on spore germination and macrophage interactions.

The protective antigen (PA) component of the anthrax toxins is an essential virulence factor of Bacillus anthracis and is the major protective immunogen. The kinetics of PA production during growth of B. anthracis, and the roles of anti-PA antibody in host immunity are not clearly defined. Production of PA by the vegetative organisms peaks during the shift from exponential to stationary phase of growth. Recently, PA was also found to be associated with spores. In our study, PA-specific mRNA was detected in spores by RT-PCR within 15-min of exposure to germinant. PA protein was detected by immunomagnetic electrochemiluminescence (ECL) on spores within 1 h of exposure to a germination medium and was rapidly released into the supernatant. PA was not demonstrated on ungerminated spores by RNA analysis, ECL, or spore-based anti-PA ELISA; however, it was detected on ungerminated spores by immunoelectron microscopy (immunoem). In rabbits, PA induces polyclonal antibodies (Abs) that, in addition to their anti-toxin neutralizing activities, exhibit anti-spore activities. In this study, the anti-spore effects of a human monoclonal Ab specific for PA (AVP-hPA mAb, Avanir Pharmaceuticals) were characterized. AVP-hPA mAb retarded germination in vitro, and enhanced the phagocytic and sporicidal activities of macrophages. The activities were comparable to those of the polyclonal rabbit anti-rPA Ab. Assays to detect germination inhibitory activity (GIA) in serum from vaccinated mice and guinea pigs suggested a possible role for anti-PA Abs in protection. Thus, anti-PA Ab-mediated, anti-spore activities may play a role in protection during the early stages of an anthrax infection.

Animals↗
PubMed2005

Isolation of viruses from mosquitoes (Diptera: Culicidae) collected in the Amazon Basin region of Peru.

As part of a comprehensive study on the ecology of arthropod-borne viruses in the Amazon Basin region of Peru, we assayed 539,694 mosquitoes captured in Loreto Department, Peru, for arboviruses. Mosquitoes were captured either by dry ice-baited miniature light traps or with aspirators while mosquitoes were landing on human collectors, identified to species, and later tested on Vero cells for virus. In total, 164 virus isolations were made and included members of the Alphavirus (eastern equine encephalomyelitis, Trocara, Una, Venezuelan equine encephalomyelitis, and western equine encephalomyelitis viruses), Flavivirus (Ilheus and St. Louis encephalitis), and Orthobunyavirus (Caraparu, Itaqui, Mirim, Murutucu, and Wyeomyia viruses) genera. In addition, several viruses distinct from the above-mentioned genera were identified to the serogroup level. Eastern equine encephalomyelitis virus was associated primarily with Culex pedroi Sirivanakarn & Belkin, whereas Venezuelan equine encephalomyelitis virus was associated primarily with Culex gnomatos Sallum, Huchings & Ferreira. Most isolations of Ilheus virus were made from Psorophora ferox (Von Humboldt). Although species of the Culex subgenus Melanoconion accounted for only 45% of the mosquitoes collected, 85% of the virus isolations were made from this subgenus. Knowledge of the viruses that are being transmitted in the Amazon Basin region of Peru will enable the development of more effective diagnostic assays, more efficient and rapid diagnoses of clinical illnesses caused by these pathogens, risk analysis for military/civilian operations, and development of potential disease control measures.

Animals↗
PubMed2001

Efficacy of a human anthrax vaccine in guinea pigs, rabbits, and rhesus macaques against challenge by Bacillus anthracis isolates of diverse geographical origin.

The efficacy of a licensed human anthrax vaccine (Anthrax Vaccine Adsorbed (AVA)) was tested in guinea pigs, rabbits, and rhesus macaques against spore challenge by Bacillus anthracis isolates of diverse geographical origin. Initially, groups of Hartley guinea pigs were vaccinated at 0 and 4 weeks with AVA, then challenged intramuscularly at 10 weeks with spores from 33 isolates of B. anthracis. Survival among the vaccinated groups varied from 6 to 100%, although there were no differences in mean time to death among the groups. There was no correlation between isolate virulence and variable number tandem repeat category or protective antigen genotype identified. New Zealand white rabbits were then vaccinated with AVA at 0 and 4 weeks, and challenged at 10 weeks by aerosol with spores from six of the isolates that were highly virulent in vaccinated guinea pigs. AVA completely protected the rabbits from four of the isolates, and protected 90% of the animals from the other two isolates. Subsequently, two of these six isolates were then used to challenge rhesus macaques, previously vaccinated with AVA at 0 and 4 weeks, and challenged at 10 weeks by aerosol. AVA protected 80 and 100% of the animals from these two isolates. These studies demonstrated that, although AVA confers variable protection against different B. anthracis isolates in guinea pigs, it is highly protective against these same isolates in both rabbits and rhesus macaques.

Animals↗
PubMed2001

Comparison of dissociation-enhanced lanthanide fluorescent immunoassays to enzyme-linked immunosorbent assays for detection of staphylococcal enterotoxin B, Yersinia pestis-specific F1 antigen, and Venezuelan equine encephalitis virus.

The dissociation-enhanced lanthanide fluorescent immunoassays (DELFIA) were developed for the detection of staphylococcal enterotoxin B, Yersinia pestis-specific F1 antigen, and Venezuelan equine encephalitis virus. These assays were compared to previously developed enzyme-linked immunosorbent assays (ELISAs) by determining the sensitivity or limit of detection (LOD), the dynamic range, and the reproducibility of each assay in a number of different sample matrices. The sensitivity and specificity of each assay were then determined by using a small panel of blinded spiked and nonspiked samples. All three DELFIAs demonstrated at least 1 log greater sensitivity than corresponding ELISAs utilizing the same reagents and showed an increase in dynamic range of at least 2 log(10) concentrations. This increased LOD resulted in higher sensitivity rates for the DELFIA. The specificity of all of the assays evaluated was 100%, and no sample matrix effects were observed in either format. However, the reproducibility of the DELFIA was poor due to randomly distributed wells exhibiting excessive background signal (hot wells), which occurred throughout the evaluation. As this technology matures, the reproducibility of these assays should improve, as will the ability to identify hot wells. Despite its sensitivity, the logistical burden associated with the DELFIA and the technical expertise required to complete assays and interpret the data limit the application of this technology to reference or large clinical laboratories.

Animals↗
PubMed2000

Anthrax vaccine: increasing intervals between the first two doses enhances antibody response in humans.

The influence of dosing interval on the human antibody response to anthrax vaccine adsorbed (AVA) was evaluated in two retrospective serological studies. In both studies, the interval between the first two doses was 2, 3 or 4 weeks. In the first study, banked sera were selected from 89 at-risk individuals at a mean time of 13 days after the second dose of vaccine. In the second study, banked sera were selected from 51 at-risk individuals at a mean time of 48 days following the first dose of AVA. In both studies, the geometric mean anti-protective antigen IgG antibody titer increased significantly as the interval between the two doses increased from 2 to 4 weeks (p=0.0005-0.029). In the first study, the seroconversion rate also increased as the interval between the first two doses increased (p=0. 0034). A prospective, randomized study has been completed and is being analyzed to confirm these findings.

Antibodies, Bacterial↗
PubMed2000

Evaluation of a commercial enzyme-linked immunosorbent assay for detection of Borrelia burgdorferi exposure in dogs.

OBJECTIVE: To evaluate the effectiveness of a commercially available ELISA kit for detecting antibodies against Borrelia burgdorferi in dogs. SAMPLE POPULATION: Banked sera from 440 military working dogs were used for serologic analyses. PROCEDURE: Serum samples were analyzed for antibodies against B burgdorferi by use of a commercially available ELISA and subsequently by western blot analysis as a confirmatory test. RESULTS: Results from the ELISA indicated that 89 (20%) samples were positive for exposure to B burgdorferi or canine Lyme disease vaccine, and 351 (80%) were negative. Follow-up testing by western blot analysis indicated that results for 109 (25%) samples were positive and 331 (75%) were negative for exposure. All samples that had positive results on the ELISA also had positive results on western blot analysis (true positives). Of the 351 samples that had negative results on the ELISA, only 331 had negative results on western blot analysis (true negatives). The remaining 20 samples had positive results on western blot analysis. By use of a standard 2 x 2 table, it was determined that the ELISA had a sensitivity of 82%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 94%. CONCLUSIONS AND CLINICAL RELEVANCE: The commercial ELISA kit evaluated in this study appeared to lack adequate sensitivity for detecting all potential cases of borreliosis in dogs. The ELISA was also unable to discriminate natural exposure from exposure attributable to vaccination, which could complicate interpretation of positive results and treatment of dogs with clinical signs.

Animals↗
PubMed2000

Rapid and sensitive immunomagnetic-electrochemiluminescent detection of staphyloccocal enterotoxin B.

Sensitive, rapid and reproducible detection of staphyloccocal enterotoxin B (SEB) in a range of different biological matrices was achieved using the ORIGEN((R)) Immunoassay System (Igen, Inc). The homologous immunoassay format consisted of a double antibody sandwich in which a biotinylated capture antibody, pre-bound to streptavidin-coated paramagnetic beads, was used to bind antigen from test samples. A detector antibody, labeled with ruthenium (II) tris-bipyridal chelate, was added and, when bound to the bead immunocomplex, generated light in the presence of an excess of tripropylamine. The light was detected and measured by the ORIGEN analyzer. The sensitivity of this assay was 1 pg of enterotoxin per ml of serum, urine, tissue, or buffer and was highly reproducible. Concentration curves generated from SEB standards produced consistently wide linear ranges (0.1-100 ng/ml), making quantitation possible with only two dilutions of sample (undiluted and 1:1000). The assay used 50 microl of sample per test and required a 30 min incubation period in addition to a 1 min per tube reading time (50 tubes maximum). This assay was significantly better in terms of sensitivity, linear range, and assay time than the standard microplate enzyme-linked immunosorbent assay and should permit early SEB detection in clinical samples, food, and environmental samples.

Animals↗
PubMed1999

Mayaro virus disease: an emerging mosquito-borne zoonosis in tropical South America.

This report describes the clinical, laboratory, and epidemiological findings on 27 cases of Mayaro virus (MV) disease, an emerging mosquito-borne viral illness that is endemic in rural areas of tropical South America. MV disease is a nonfatal, dengue-like illness characterized by fever, chills, headache, eye pain, generalized myalgia, arthralgia, diarrhea, vomiting, and rash of 3-5 days' duration. Severe joint pain is a prominent feature of this illness; the arthralgia sometimes persists for months and can be quite incapacitating. Cases of two visitors from the United States, who developed MV disease during visits to eastern Peru, are reported. MV disease and dengue are difficult to differentiate clinically.

Adult↗
PubMed1999

An accelerated schedule for tick-borne encephalitis vaccine: the American Military experience in Bosnia.

Tick-borne encephalitis (TBE) is a viral illness endemic to the Balkan region. United States military forces were deployed to Bosnia in early 1996 as part of Operation Joint Endeavor, a U.S.-led multinational peace-keeping operation. To counteract the TBE threat, an inactivated, parenteral vaccine (FSME-Immun Inject; Immuno AG, Vienna, Austria) was offered to soldiers at high risk on a volunteer basis in an accelerated, 3-dose schedule (0, 7, and 28 days). Passive adverse reaction surveillance was conducted on 3,981 vaccinated personnel. Paired sera from a randomly selected group of 1,913 deployed personnel (954 who received vaccine and 959 who were unvaccinated) were tested for antibodies to TBE by an ELISA. Three-dose recipients demonstrated an 80% seroconversion rate (4-fold or greater increase in anti-TBE titers). By comparison, the TBE infection rate in the unvaccinated cohort was found to be only 0.42% (4 of 959). Only 0.18% of vaccinees reported self-limited symptoms. An accelerated immunization schedule appears to be an acceptable option for military personnel or travelers on short-term notice to TBE-endemic areas.

Adult↗
PubMed1999

Dengue among United Nations mission in Haiti personnel, 1995: implications for preventive medicine.

The incidence of dengue infections has been increasing in the Caribbean, and cases have been identified among successive deployments of multinational peacekeepers to Haiti (1994-1997). In the absence of an effective vaccine or chemoprophylaxis to prevent dengue fever, vector-control operations and use of personal protection measures to prevent arthropod bites are the most effective means of limiting disease transmission. During our 5-month deployment as part of the United Nations Mission in Haiti, 79 cases of recent dengue fever were identified among 249 patients (32%) presenting with febrile illness to the 86th Combat Support Hospital. Further investigation revealed low unit readiness to perform standard vector-control activities and poor individual adherence to measures to prevent arthropod bites. Command enforcement of existing field preventive medicine doctrine is essential to prevent casualties caused by dengue, other arthropod-borne infections, and nuisance arthropod bites during military deployments.

Dengue↗
PubMed1999

Comparison of noninvasive sampling sites for early detection of Bacillus anthracis spores from rhesus monkeys after aerosol exposure.

Bacillus anthracis, a spore-forming bacterium, is the etiologic agent of anthrax. B. anthracis spores can be aerosolized, are relatively easy to produce, and are capable of producing high mortality when inhaled. The prompt use of postexposure antibiotics combined with vaccination greatly increases the survival rate. Rapid detection of exposure is critical to effective case management. Using common collection swabs, culture medium, and culturing equipment, we compared six different noninvasive sampling sites to determine which might best be used to rapidly detect the presence of B. anthracis spores on rhesus monkeys after aerosolization. The results indicate that the greatest number of spores were deposited in the nares, on the face, and on the haired portions of the head, suggesting that these locations are the most effective sampling sites when attempting to detect B. anthracis aerosol exposure.

Aerosols↗
PubMed1998

Immunologic interference from sequential administration of live attenuated alphavirus vaccines.

Two different human vaccine trials examined interference arising from sequential administration of vaccines against heterologous alphaviruses. The first trial indicated that persons previously vaccinated against Venezuelan equine encephalitis virus (VEEV) exhibited poor neutralizing antibody responses to a live attenuated chikungunya virus (CHIKV) vaccine (46% response rate). The second trial prospectively examined neutralizing antibody responses to live attenuated VEEV vaccine in persons previously inoculated with either CHIKV vaccine or placebo. Following seroconversion to CHIKV, CHIKV vaccine recipients' geometric mean titers (GMTs) to VEEV by 80% plaque-reduction neutralization titration never exceeded 10, compared with a peak GMT of 95 after VEEV vaccination for alphavirus-naive volunteers who initially received placebo (P < .003). ELISA antibody responses demonstrated cross-reactive IgG to VEEV after primary CHIKV immunization and then an anamnestic response upon subsequent VEEV vaccination. These data indicate that preexisting alphavirus immunity in humans interferes with subsequent neutralizing antibody response to a live attenuated, heterologous vaccine.

Adolescent↗
PubMed1998

Laboratory diagnosis of acute dengue fever during the United Nations Mission in Haiti, 1995-1996.

We evaluated laboratory methods to confirm a clinical diagnosis of dengue. Acute sera were collected from personnel (n = 414) supporting the United Nations Mission in Haiti and presenting with febrile illness consistent with dengue fever or no apparent underlying cause. Dengue virus was recovered from 161 of 379 acute sera by inoculation into C6/36 cell culture. While 93 of 414 acute sera had detectable IgM antibodies, the IgM capture ELISA (MAC ELISA) had a sensitivity of only 13% compared with the virus isolation gold standard. If presumptive dengue fever cases were identified by both virus isolation and the presence of IgM, virus isolation and the MAC ELISA had clinical sensitivities of 69% and 40%, respectively. This study suggests that a combination of laboratory methods that target virus or subviral components as well as anti-viral IgM antibodies may be necessary for sensitive laboratory diagnosis with acute sera.

Acute Disease↗
PubMed1997

Linoleic acid metabolism in primary cultures of adult rat cardiomyocytes is impaired by aging.

Many of the changes that occur in the rat cardiac muscle with advancing age are related to modifications in membrane fatty acid composition, polyunsaturated fatty acids decreasing and saturated increasing as the animal develops. In the present study, using cultured adult cardiomyocytes isolated from the hearts of rats of a broad (1-24 months) age range, we demonstrated that the modifications in the fatty acid pattern of cardiomyocytes have to be related to alterations in the mechanism of desaturation/elongation of essential fatty acids. In fact, independent of the age of the animal, heart cells in culture were capable of rapidly metabolizing radiolabeled linoleic acid taken up from the surrounding medium, but to a different extent. The ability of heart cells to metabolize linoleic acid to higher and more unsaturated metabolites decreased with the animal's age. As the age of the animal increased, the pattern of fatty acids of the cultured cardiomyocytes showed a gradual but significant shift, similar to those reported in the whole heart. Data here reported confirm that the basic aging-related process in the cellular model system may also be relevant to aging in the whole animal.

Aging↗
PubMed1997

Bladder and urethral anaesthesia with electromotive drug administration (EMDA): a technique for invasive endoscopic procedures.

OBJECTIVE: To assess the efficacy of the electromotive administration of lignocaine and adrenalin as local anaesthesia (EMDA/LA) for invasive lower urinary tract procedures. PATIENTS AND METHODS: Electric current generators, catheters and electrodes were designed and fabricated, using defined electrochemical principles, to carry out EMDA/LA of the bladder and prostatic urethra of 91 patients who underwent 27 bladder-mapping biopsies, 62 transurethral resections (TURs) of bladder tumours, 21 transurethral incisions on the prostate or bladder neck incisions, 12 TURs of the prostate (122 operations in total) and nine miscellaneous interventions, all using rigid instruments. Resections were performed using electrocautery. Most patients, while minimally sedated and fully conscious, completed an assessment of EMDA/LA using a simple pain scale. RESULTS: In five of the 122 procedures, the pain was described as intolerable, six were recorded as painful but tolerable and the remaining 111 procedures were recorded as having minimal to no discomfort only. Side-effects were few, there was no clinical evidence of lignocaine toxicity and serial serum lignocaine levels measured in four patients were innocuous. CONCLUSIONS: EMDA/LA provides safe, effective anaesthesia for most invasive endoscopic procedures in the lower urinary tract.

Adult↗
PubMed1996

gamma-Linolenic acid supplementation can affect cancer cell proliferation via modification of fatty acid composition.

We examined the effect of gamma-linolenic acid (GLA) supplementation on the growth and fatty acid composition of three human tumor cell lines (the neuroblastoma CHP-212, the tubal carcinoma TG, and the colon carcinoma SW-620), in order to evaluate the relationship between GLA-induced tumor cell death and the distribution of fatty acids in tumor cells. At the highest GLA concentrations (10 and 20 micrograms/ml), the DNA synthesis was completely abolished; at 5 micrograms/ml GLA only SW-620 cells did not proliferate, while CHP-212 and TG cells showed a residual [3H]-thymidine incorporation. GLA levels were very low in cells grown in control medium; GLA supplementation caused a significant incorporation of GLA itself in all the cell lines at each concentration. In TG and CHP-212 cells, GLA was metabolized, although to a different extent, to dihomo-gamma linolenic acid and arachidonic acid. SW-620 cells neither elongated nor desaturated the incorporated GLA. The highest cytostatic effect was reached when GLA was not transformed into its metabolites, suggesting that the GLA toxicity to tumor cells is not dependent on metabolites but is due to GLA itself.

Cell Division↗
PubMed1996

Hantavirus serologies in patients hospitalized with community-acquired pneumonia.

In many patients, the etiology of community-acquired pneumonia is not known but may be caused by previously undescribed pathogens in some cases. The recently identified hantavirus Sin Nombre (SN) causes hantavirus pulmonary syndrome. Because sporadic cases have occurred outside the range of its reservoir (the deer mouse Peromyscus maniculatus), an investigation sought to determine whether hantaviruses contributed to cases of community-acquired pneumonia in a large Baltimore hospital. Acute-phase sera from 385 hospitalized patients with pneumonia were examined using an IgG ELISA technique with antigens prepared from several hantaviruses: prototype Hantaan (HTN), Seoul (SEO), Puumala (PUU), Convict Creek (HN107), and SN. Of 385 sera, 8 (2.1%) showed some reactivity with one or more HTN, SEO, or PUU antigens but none had detectable specific IgM antibodies. No sera were reactive with SN or HN107 antigens. Thus, hantaviruses are an uncommon cause of community-acquired pneumonia in the Baltimore area.

Adult↗