Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography.

The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

A phylogenetic approach to following West Nile virus in Connecticut.

The 1999 outbreak of West Nile (WN) virus in the northeastern United States was the first known natural occurrence of this flavivirus in the Western Hemisphere. In 1999 and 2000, 82 independent Connecticut WN virus isolates were cultured from nine species of birds, five species of mosquitoes, and one striped skunk. Nucleotide sequences obtained from these isolates identified 30 genetic changes, compared with WN-NY99, in a 921-nt region of the viral genome beginning at nucleotide position 205 and ending at 1125. This region encodes portions of the nucleocapsid and envelope proteins and includes the entire coding regions for the premembrane and membrane proteins. Amino acid changes occurred at seven loci in six isolates relative to the WN-NY99 strain. Although 34 of the isolates showed sequences identical to the WN-NY99 isolate, we were able to show geographical-based clusters of mutations. In particular, 26 isolates were characterized by mutation of C to T at position 858. This group apparently originated in Stamford, CT and disseminated to sites located as far as 54 miles from Stamford. Sequences of WN virus isolated from both brain and heart tissues from the same avian host were identical in all 14 tested individual birds, suggesting that the mutations we have documented are real and not caused by culture, RNA extraction, or PCR procedures. We conclude that this portion of the viral genome will enable us to follow the geographical and temporal movement of variant WN virus strains as they adapt to North America.

Virus serology in familial Crohn disease.

BACKGROUND: Recent findings that early-in-life virus infections represent a risk factor for Crohn disease, that exacerbations of disease sometimes appear associated with common viral infections, and, in particular, suggestions that Crohn disease may be the result of persistent infection with measles virus prompted serologic studies for antibody to 19 common viruses, Chlamydia psittaci, and Mycoplasma pneumoniae. METHODS: Sera from 14 affected members of 2 French families with a high frequency of Crohn disease and from age- and sex-matched controls, taken in 1990 and 1992, and from unaffected family members were tested. Complement fixation, enzyme immunoassay, and indirect immunofluorescent tests were used. RESULTS: There were no significant differences between patients and controls or between affected and unaffected family members of family 2, with the exception that affected siblings carried higher antibody titers for mycoplasma one year and for varicella another year. There were no differences in measles IgM and IgG or mumps IgG antibody levels between patients and controls, or between patients and unaffected family members. CONCLUSIONS: Serology failed to find evidence of participation by 19 common viruses, C. psittaci, and M. pneumoniae in Crohn disease. The data do not support the hypothesis that persistent measles virus infection causes Crohn disease.

Evaluation of Enterolert for enumeration of enterococci in recreational waters.

Enterolert (IDEXX Laboratories Inc., Westbrook, Maine), a semiautomated, most probable number method for enumeration of enterococci, was compared with the standard membrane filter method by parallel testing of 138 marine and freshwater recreational bathing water samples. No statistically significant difference and a strong linear correlation were found between methods. Culturing of 501 Enterolert test wells resulted in false-positive and false-negative rates of 5.1 and 0.4%, respectively. Less time for setup, incubation (24 versus 48 h), and reading of Enterolert permits more efficient monitoring of recreational bathing areas.

Evaluation of a commercial measles virus immunoglobulin M enzyme immunoassay.

Paired serum samples from 93 patients suspected of having measles were assayed for measles virus-specific immunoglobulin M (IgM) antibodies by an enzyme immunoassay (EIA), and the results were compared with results from a complement fixation assay and an EIA for measles virus IgG. By using significant serologic rises as the standard for comparison, the IgM EIA assay had a sensitivity of 85.7%, a specificity of 81.3%, a positive predictive value of 95.7%, and a negative predictive value of 54.2%. This assay can be expected to perform well in outbreak situations.

Absent specific viral antibodies in patients with transient hypogammaglobulinemia of infancy.

Of 247 patients referred to the Pediatric Immunology Clinic, University of Connecticut Health Center, Farmington, Conn., for recurrent infections, 13 patients were found to have an abnormal delay in the onset of IgG synthesis and prolongation of the physiologic hypogammaglobulinemia of infancy. At first observation, their mean age was 10.6 months. All patients had abnormally low serum IgG levels (less than or equal to 2 SD for their age). The mean serum IgG level for our patient population was 270 +/- 81 mg/dl; the mean serum IgG level of the control group was 749 +/- 440 mg/dl. Clinically, these patients were first observed with recurrent otitis media, respiratory infections, bronchitis and/or asthma, and formula intolerance. Despite recurrent respiratory tract infections, specific antibodies to the respiratory viruses were absent in nine of 11 patients tested who were observed before 17 months of age. On follow-up, two of the 13 patients never developed specific antibodies to viral agents, although their serum IgG levels normalized; one patient became serology positive at the same time that the serum IgG normalized. In two patients, the serum IgG levels returned to within the normal range for age before the appearance of specific viral antibodies. In eight patients, the appearance of specific viral antibodies was detected before the serum IgG levels returned to normal. Five of these eight patients were treated for short periods (9 months) with replacement immune serum globulin (intramuscular) therapy and did clinically well. These observations suggest that replacement immune serum globulin for short periods of time does not appear to suppress the production of specific, naturally occurring antibodies and the resolution of the hypogammaglobulinemia.

Cytomegalovirus antibody in the elderly.

Presence of cytomegalovirus (CMV) specific immunoglobulin M (IgM) is generally considered strong evidence of current or recent CMV infection. Sera from 110 elderly individuals (age range 61-100 years) were compared with sera from 87 younger individuals (age range 16-47 years). Prevalence of CMV IgM was found to be 30% in the older group (mean age 83 years) and only 6% in the younger group (mean age 29 years). In spite of increased CMV antibody levels, none of the elderly individuals were symptomatic. Viral cultures of urine from 72 elderly individuals were negative for CMV. These results suggest that the presence of CMV-specific IgM must be interpreted with caution in an elderly population.

Administration of ethylnitrosourea to neonate hamsters increases growth and frequency of SV40-induced fibrosarcomas.

The in vivo interaction between the chemical carcinogen ethylnitrosourea (ENU) and the oncogenic simian virus 40 (SV40) was studied. Inbred newborn Syrian golden hamsters were injected subcutaneously with SV40 (5 x 10(6) plaque-forming units), ENU (0.5% solution, 125 or 25 mg/kg body wt), or equal mixtures of the two. Animals that received SV40 and ENU developed more tumors (100% vs 52%) within a shorter latent period (10 weeks vs 18 weeks) than animals that received SV40 alone. Animals given SV40 and ENU showed increased mortality and increased metastatic tumors (54.2% vs 30.8%) compared with those given SV40 alone. The SV40 and ENU group also exhibited multiple (greater than 10 nodules) pulmonary metastases (33.3% vs 7.7%) and metastases in multiple organs (12.5% vs 0%) compared with animals injected with SV40 alone. No difference in primary tumor size, histology, and SV40 T-antigen content was detected between SV40- and SV40/ENU-induced tumors. Four weeks after SV40 or SV40 plus ENU treatment, animals were challenged intradermally with 2.7 x 10(6) SV40-transformed hamster cells. Five weeks after challenge, 89.5% of the animals treated with SV40 and ENU and 45.4% of animals treated with SV40 developed tumors at the challenge site. Newborn animals given SV40 and ENU developed larger tumors at the challenge site (P less than 0.002) than newborns treated with SV40 alone. Thus, administration of ENU to hamsters during the neonatal stage of development produced a long-lasting systemic effect that enhanced tumor development by transplanted SV40-transformed hamster cells.

Comparative studies of three serologic methods for the measurement of Mycoplasma pneumoniae antibodies.

Antibodies against Mycoplasma pneumoniae in the sera of patients and normal adult controls were measured by a standard complement fixation (CF) test, a commercial immunofluorescence (IF) test (CROWNTITRE), and a commercial enzyme-linked immunosorbent assay (ELISA) (MYCOPLASMELISA). The findings showed that, in the control sera, 269 of 277 (97%) had negative results for CF antibodies. Of the 320 controls tested by the IF assay, all (100%) had negative results for IgM antibodies and 314 (98%) had negative results for IgG antibodies. Only 6 of the 201 (3%) controls by the ELISA were classified as negative/equivocal. Among the 450 patient sera, 105 (23%) had positive results for CF antibodies, and 158 (35%) had positive results for IgG and/or IgM membrane antibodies by the IF test; 424 of these patients' sera were also tested by the ELISA, and 397 (94%) of them were found to have positive results for anti-M. pneumoniae IgG antibodies. If the CF test were chosen as the standard for comparison, the IF test would have a sensitivity of 87% and a specificity of 81% and the ELISA would have a sensitivity of 71% and a specificity of 80%, provided an adjustment in the threshold ELISA-positive value was made. A single positive M. pneumoniae membrane IgM antibody titer appeared to be valuable for a presumptive diagnosis of an ongoing infection; 41 of 47 (87%) of the IgM-positive results in the paired sera were supported by a fourfold increase or a stable high level of CF antibody titer.

Varicella zoster-associated neurologic disease without skin lesions.

We have investigated a group of cases with inflammatory neurologic disease and serologic evidence of varicella zoster virus activity without cutaneous vesicles. In agreement with experience, a case of cranial polyneuropathy with facial palsy and cases of aseptic meningitis were found. However, cases of acute polyneuropathy, myelitis, and encephalitis were also identified. Thus, it seems that the spectrum of neurologic disease associated with varicella zoster virus in the absence of skin lesions is considerably broader than previously recognized.

Rapid and accurate viral diagnosis.

In recent years, there has been increased recognition of the importance of viral infections. In addition, new antiviral agents have become available. These factors have led to a marked increase in utilization of viral diagnostic services. In this review, both conventional and rapid methods for viral diagnosis are presented, with emphasis on recent advances. The antiviral agents currently available and the major drugs under investigation are also briefly discussed. It is hoped that this review will serve as a useful adjunct for the management of patients with virus infections.

The group A streptococcal carrier state. A reexamination.

Streptococcal infection usually is defined as a positive throat culture with a serologic response to group A beta-hemolytic streptococci, and a patient with a positive throat culture and no serologic response is a streptococcal carrier. Studies suggest that streptococcal carriers should show little clinical response to antibiotic therapy when compared with patients with true streptococcal infections. Patients with acute pharyngitis were divided into three groups: group 1--38 patients with negative throat cultures; group 2--72 patients with a positive throat culture and a significant rise in streptococcal antibody titers; and group 3--77 patients with positive throat cultures and no significant rise in streptococcal antibody titers. Patients in group 2 and group 3 had a comparable and dramatic clinical response to antibiotic therapy that was considerably greater than the clinical response in the patients in group 1. These findings raise questions about the appropriateness of using streptococcal antibody responses to distinguish between the streptococcal carrier state and a true streptococcal infection.

Effect of 10 minutes heat treatment on HIV antibody testing from alternate testing sites.

One hundred and thirty-five sera were tested for the presence of antibody to human immunodeficiency virus (HIV) by enzyme immunoassay (EIA) with the Abbott Diagnostics HTLV-III test before and after heating at 56 degrees C for 10 min. Only one serum specimen was repeatedly reactive after heating when compared with the unheated portion (1/135). The specimen was a low level positive (ratio of test over cutoff = 1.6). Fifty-eight different sera, selected to yield a high percentage of positive results, had both their heated and unheated Western blot (WB) results agree completely with repeated EIA testing. An additional 4,244 sera heated at 56 degrees C for 10 min were tested. Of the 330 repeatable EIA positives, only 38 were not confirmed by WB. HIV infectivity in sera was reduced from 10(3.5) TCID50 to 10(1) TCID50 by the same heat treatment. We conclude that heating sera at 56 degrees C for 10 min significantly reduces HIV infectivity and does not significantly affect the results of HIV antibody testing.

Comparison of fluorescent-antibody-to-membrane-antigen test, indirect immunofluorescence assay, and a commercial enzyme-linked immunosorbent assay for determination of antibody to varicella-zoster virus.

The demand for sensitive and specific assays to determine immune status to varicella can be expected to increase with the anticipated availability of a varicella-zoster virus vaccine for use in nonimmune adults, especially health care personnel, and in immunosuppressed children. Although the fluorescent-antibody-to-membrane-antigen (FAMA) test remains the reference standard to which other tests are compared, simpler alternative assays are needed. In this study, the FAMA was compared with a simple indirect immunofluorescence assay (IFA) and a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to varicella-zoster virus. One hundred and twelve serum samples were screened by the FAMA test and IFA at a 1:5 dilution, and 100% agreement was found. Of these samples, 101 were available for testing by ELISA, and identical results were obtained with 97 samples (96% agreement). When the samples were screened at a 1:2 dilution, 99 of 101 results agreed. In addition, 31 spinal fluid samples were tested by all three methods. When screening was at a 1:2 dilution, there was 96.8% agreement between the FAMA test and IFA. When the cutoff value established for sera was used for the spinal fluid samples, there was 90.3% agreement between the ELISA and the FAMA test. Thus, both IFA and ELISA can be considered sensitive and specific alternatives to the FAMA test, and in addition, both use commercially available reagents.

Role of Chlamydia trachomatis and Mycoplasma pneumoniae in acute pharyngitis in children.

In a group of children with acute, nonstreptococcal pharyngitis, only one (2%) of the 44 children tested showed serologic or direct-immunofluorescence evidence of a recent Chlamydia trachomatis infection. Only two (5%) of the 43 children tested showed serologic evidence of a recent Mycoplasma pneumoniae infection. Neither C. trachomatis nor M. pneumoniae appears to be an important cause of acute pharyngitis in children.