bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the pseudorabies virus-specific immunoglobulin M response and evaluation of its diagnostic use in pigs with preexisting immunity to the virus
Authors: Kimman T G
Published: January 2020

Despite preexisting immunity to pseudorabies virus (PRV), pigs may become infected and may or may not show clinical signs of disease. To investigate whether detection of immunoglobulin M (IgM) antibodies to PRV is suitable for diagnosis of recent infection in pigs with (or without) preexisting immunity, the IgM responses of pigs were examined after both experimental and natural infections. Upon inoculation of seronegative pigs with a low dose of a mildly virulent strain of PRV, IgM was first detectable at day 7 postinoculation (p.i.), reached a maximum at day 14 p.i., and became undetectable again at about days 32 to 36 p.i. In inoculated pigs with maternal antibodies against PRV, the IgM response began later and ended sooner, and peak titers were also lower. In immune pigs with maternally derived antibodies, there was apparently no correlation between the virulence of the inoculated strain and the IgM response. The suitability of the IgM enzyme-linked immunosorbent assay (ELISA) for detection of recent infection in the field was compared with that of the virus neutralization (VN) assay and with an ELISA which specifically detects antibodies directed to glycoprotein I (gI) of PRV. Paired sera were obtained from pigs suspected of PRV infection in an area endemic for PRV infection in which vaccination against PRV is often applied. Practically all pigs had antibodies to PRV in the acute phase of the disease. Compared with the VN assay, the specificity of the IgM ELISA was high but its sensitivity was low. However, all three serotests apparently failed to detect some PRV infections. The IgM ELISA appeared to be especially useful as a diagnostic aid for detection of recent infections in pigs with high levels of neutralizing and gI antibodies, probably maternally derived, in the acute phase of the disease. Such pigs may fail to develop a significant rise in VN antibody titer. The IgM ELISA may be the only serotest for monitoring infections in such pigs.
Genome macrorestriction analysis of diversity and variability of Pseudomonas aeruginosa strains infecting cystic fibrosis patients
Authors: Struelens M J , Schwam V , Deplano A , Baran D
Published: January 2020

Genome macrorestriction fingerprinting with XbaI and DraI was used to analyze the relatedness of 166 Pseudomonas aeruginosa isolates collected from 31 cystic fibrosis patients over a 1- to 20-month period and to correlate their genotype with patterns of resistance to 14 antimicrobial agents. Quantitative comparison of intra- and interpatient similarities of P. aeruginosa macrorestriction patterns disclosed two discrete ranges that clearly discriminated subclonal variation (> 80% relatedness) and clonal diversity (10 to 70% relatedness). Cloning-derived mutants exhibited up to 20% divergence of genomic macrorestriction patterns during the course of chronic colonization of individual patients. Change of susceptibility to multiple antimicrobial agents developed in 50% of sequential pairs of isolates from individual patients. Only 19% of these susceptibility changes were attributable to strain substitution, while the majority (56%) of resistance changes were associated with minor genomic variations of a persistent strain. Sixty-six percent of patients harbored one strain, and 33% carried two strains. Three common strains colonized 5 (28%) of 18 patients attending a cystic fibrosis clinic, and another two strains colonized two patient pairs (31%) of 13 patients staying at a rehabilitation center, suggesting potential cross-infection in these settings. By indexing regional polymorphisms throughout the chromosome structure, macrorestriction analysis can monitor subclonal evolution of P. aeruginosa and identify isogenic resistance mutants. Quantitative macrorestriction fingerprinting enables discrimination between clonal variants and clones of distinct origins and should therefore provide a reliable tool for investigating the mode of acquisition of P. aeruginosa in cystic fibrosis patients.
Rapid broth macrodilution method for determination of MICs for Mycobacterium avium isolates
Authors: Siddiqi S H , Heifets L B , Cynamon M H , Hooper N M , Laszlo A , Libonati J P , Lindholm-Levy P J , Pearson N
Published: January 2020

A multicenter study was done to investigate the accuracy and reproducibility of a method for determining the MICs of antimicrobial agents against the Mycobacterium avium complex in 7H12 broth with the BACTEC system. In phase I, with eight drugs and 10 strains, intralaboratory reproducibility was 95.7 to 100%, allowing a 1-dilution difference upon repeat testing. The results of phase II testing with 41 additional strains were consistent with those obtained in phase I, with good interlaboratory reproducibility. The radiometric method was validated by sampling and plating of the same broth cultures and determining, by the number of CFU per milliliter, the lowest drug concentration that inhibited more than 99% of the initial bacterial population. Three test concentrations of each drug and the tentative interpretation of results are proposed. Radiometric MIC determination has the potential to become the method of choice for clinical microbiology laboratories and evaluation of new agents for the treatment of M. avium infections, both pulmonary and disseminated.
Evaluation of counterimmunoelectrophoresis for serotyping Actinobacillus pleuropneumoniae isolates and detection of type-specific antigens in lungs of infected pigs
Authors: Mittal K R , Bourdon S , Berrouard M
Published: January 2020

A rapid, simple, and accurate counterimmunoelectrophoresis technique was developed for serotyping cultures of Actinobacillus pleuropneumoniae as well as for detection of their type-specific antigens in the lung tissues of infected pigs. The counterimmunoelectrophoresis test correctly identified all of the reference antigens and more than 99% of 1,200 field isolates of A. pleuropneumoniae representing the 12 established serotypes within 1 h. Counterimmunoelectrophoresis and coagglutination tests did not differ broadly in sensitivity from each other. Both procedures were more rapid and more sensitive than immunodiffusion and indirect hemagglutination tests. A total of 355 lung tissue samples (130 lungs of pigs that died because of acute respiratory problems, 125 lungs of pigs from herds with chronically infected pleuropneumonia, and 100 lungs from apparently healthy pigs at the slaughterhouse) were examined for the presence of A. pleuropneumoniae type-specific antigens by counterimmunoelectrophoresis, coagglutination, and immunodiffusion tests. A. pleuropneumoniae type-specific antigen was found in all 55 samples from which the bacteria had earlier been isolated and in 27 specimens in which they had not been found. Detection of antigen in the lung tissues by coagglutination and counterimmunoelectrophoresis tests was found to be much simpler and much more rapid than conventional culture isolation. Both counterimmunoelectrophoresis and coagglutination tests were found extremely useful in the diagnosis of acute cases of porcine pleuropneumonia. However, these techniques were able to detect only some of the chronically infected carrier pigs.
Immune response to synthetic peptides of hepatitis delta antigen
Authors: Poisson F , Baillou F , Dubois F , Janvier B , Roingeard P , Goudeau A
Published: January 2020

Hepatitis delta antigen (HDAg) is the only viral protein known to be expressed during hepatitis delta virus (HDV) infection. Detection of antibody to HDAg (anti-HD) is the usual method for diagnosis of HDV infection since viremia lasts only a few weeks. In an effort to identify the major epitopes recognized by humans during natural infection, four oligopeptides including residues 2 to 17 (SP1), 155 to 172 (SP2), 168 to 182 (SP3), and 189 to 211 (SP4) of the HDAg molecule were synthesized and probed by enzyme-linked immunosorbent assay with a panel of 80 serum specimens from 45 patients suffering from either HDV-hepatitis B virus coinfections (n = 17) or HDV superinfections (n = 28). Sera from infected patients recognized these relatively short peptides. Peptide SP2 was the most antigenic; 71% of serum specimens reacted. Antibody to SP2 was also the commonest in sera taken early in the course of the disease. Peptide SP2 corresponds to one of the two regions which is highly conserved between different isolates. Among the 63 serum specimens which scored anti-HD positive by a commercial assay, all but 3 reacted to at least one of the peptides (95% agreement). Peptide assays appeared to be significantly more sensitive than the commercial assay with native HDAg early in the course of HDV infection since 14 of 17 (82%) serum specimens which scored anti-HD negative in the commercial assay reacted to one or more peptides. All serum specimens giving one or more positive results with the various peptides were confirmed as being HDV positive by an inhibition assay with free peptide in solution. The immune response to HDAg peptides vared greatly between individuals. No specific reactivity profile could be assigned to those with either HDV-hepatitis B virus coinfections or HDV superinfections. Overall, HDAg peptides appeared to be convenient reagents in addition to native antigen for the development of new and improved diagnostic tests for HDV infection.
Preventing false positives: quantitative evaluation of three protocols for inactivation of polymerase chain reaction amplification products
Authors: Rys P N , Persing D H
Published: January 2020

False-positive results because of carryover contamination by previously amplified nucleic acids are currently the greatest impediment to routine implementation of nucleic acid amplification protocols. We evaluated three methods for inactivation of a 156-bp Borrelia burgdorferi polymerase chain reaction (PCR) product: (i) post-PCR cross-linking with isopsoralen (IP), (ii) pre-PCR treatment of a dU-containing PCR product with uracil N-glycosylase (UNG), and (iii) post-PCR alkaline hydrolysis (primer hydrolysis) of PCR products synthesized by using primers containing 3' ribose residues. The sensitivities of the PCR performed under the conditions of each protocol were comparable. Inactivation of amplified DNA was highly efficient for all three protocols; the IP and UNG protocols eliminated at least to 3 x 10(9) copies of the product. The primer hydrolysis protocol varied in efficiency depending on the number and position of the 3' ribose residues, but inactivation ranged from 10(4) to 10(9) copies. We conclude that with some modifications, all three systems are effective for eliminating amplified DNA products. Routine implementation of at least one method should help to avoid false-positive results because of carryover contamination.
Epidemiological study of an Acinetobacter baumannii outbreak by using polymerase chain reaction fingerprinting
Authors: Gräser Y , Klare I , Halle E , Gantenberg R , Buchholz P , Jacobi H D , Presber W , Schönian G
Published: January 2020

A polymerase chain reaction (PCR) technique was applied to the fingerprinting of different strains of Acinetobacter baumannii from a cluster of patients infected or colonized with the incriminated pathogen. The DNA was extracted by boiling and was subjected to PCR amplification by using the core sequence of the M13 phase as a single primer. The amplified products were separated by agarose gel electrophoresis and were detected by staining with ethidium bromide. In 1990, 49 multiresistant A. baumannii strains were isolated from 13 patients from the same intensive care unit of the Charité Hospital; 45 of these outbreak isolates obtained from 12 patients showed the same PCR patterns, indicating an epidemiological relatedness of these strains. Four strains isolated from the same patient belonged to another genetic group, as revealed by a distinct amplification pattern. Another single subtype of A. baumannii was identified as the causative agent in patients during a second outbreak at a different intensive care unit in the same hospital. Seventeen isolates recovered from 10 immunocompromised patients had the same amplification patterns, which were distinct from all other PCR profiles. Five strains were obtained from two other hospitals; three isolates from the hospital of Magdeburg, Germany, had identical PCR patterns which, however, could be clearly distinguished from the patterns of all other strains. The remaining two isolates displayed individual patterns of amplified fragments. PCR fingerprinting may provide a useful and particularly rapid identification technique for epidemiological investigations of nosocomial infections.
Reactogenicity and immunogenicity of a high-titer rhesus rotavirus-based quadrivalent rotavirus vaccine
Authors: Flores J , Perez-Schael I , Blanco M , Rojas A M , Alfonzo E , Crespo I , Cunto W , Pittman A L , Kapikian A Z
Published: January 2020

We evaluated the reactogenicity and antigenicity of a quadrivalent rotavirus vaccine composed of serotype 3 rhesus rotavirus (RRV) and three single-gene-substitution reassortants of RRV and human strain D (D x RRV, serotype 1), DS1 (DS1 x RRV, serotype 2), or ST3 (ST3 x RRV, serotype 4) in a double-masked study with 302 infants in Caracas, Venezuela. Three doses of the quadrivalent vaccine composed of either 10(5) PFU (low titer) or 10(6) PFU (high titer) of each component were administered to 99 and 101 infants, respectively, at 4-week intervals starting at the second month of age; 102 infants received a placebo. Postvaccination reactions were monitored by home visits every other day during the week postvaccination. The vaccine was associated with the occurrence of mild, short-lived febrile episodes in 26 and 23% of the recipients after the first doses of high- or low-titer vaccine, respectively, in comparison with 13% of the infants receiving the placebo. Febrile reactions occurred less frequently in vaccinees after the second or third dose than after the initial dose. The vaccine was not significantly associated with diarrhea or any additional symptom or sign. Serum specimens obtained shortly before the first, 4 weeks after the first, and 4 weeks after the third dose of vaccine or placebo were tested by an immunoglobulin A enzyme-linked immunosorbent assay and by neutralization assays. Seroresponses occurred significantly more often after 3 doses than after a single dose of either vaccine. Immunoglobulin A responses were observed in 80 and 79% of the infants after 3 doses of high- or low-titer vaccine, respectively. Most of the infants tested developed a neutralization response to RRV after 3 doses of the high- (90%) or low-(88%) titer vaccine. Neutralization response rates to human rotavirus serotypes 1 to 4 after 3 doses were similar in both vaccine and 87 of 90 receiving the high-titer vaccine developed seroresponses, as detected by any of the assays employed. The study indicates that 3 doses of quadrivalent vaccine at a titer of 10(6) PFU of each component offered no advantage over the lower-titer preparation for use in efficacy trials.
Serologic analysis of dogs, horses, and cottontail rabbits for antibodies to an antigenic flagellar epitope of Borrelia burgdorferi
Authors: Fikrig E , Magnarelli L A , Chen M , Anderson J F , Flavell R A
Published: January 2020

Enzyme-linked immunosorbent assays (ELISA) and immunoblots using either whole-cell lysates of Borrelia burgdorferi or an antigenic region of flagellin (41-G) as the antigen were performed, and the abilities of the two assays to detect antibodies to this spirochete in dog, cottontail rabbit, and horse sera were compared. Assays using whole-cell B. burgdorferi lysates as the antigen were more sensitive for detecting antibodies. ELISA with 41-G as the antigen were specific for Borrelia antibodies but were not as sensitive as the assays with whole-cell lysates coated to the solid phase. Use of recombinant full-length flagellin, rather than 41-G, as the antigen in immunoblots increased the sensitivity of each assay. However, antibodies to other bacterial antigens cross-react with whole flagellin and may account for false-positive results. Antibodies to B. burgdorferi outer surface protein A or B were usually undetected when the sera were tested by immunoblotting methods. Borrelia lysates or the 41-G antigen may be used in ELISA or immunoblots to document host exposure to this spirochete. The use of 41-G as the antigen may increase the specificity of an assay or help confirm the serologic diagnosis of Lyme borreliosis in dogs, horses, and cottontail rabbits.
Species identification of oral viridans streptococci by restriction fragment polymorphism analysis of rRNA genes
Authors: Rudney J D , Larson C J
Published: January 2020

Oral streptococci formerly classified as Streptococcus sanguis have been divided into six genetic groups. Methods to identify those species by genotype are needed. This study compared restriction fragment polymorphisms of rRNA genes (ribotypes) for seven S. gordonii, three S. sanguis, four S. oralis, three S. mitis, one S. crista, and seven S. parasanguis strains classified in previous DNA hybridization studies, as well as one clinical isolate. DNA was digested with HindIII, PvuII, HindIII and PvuII combined, EcoRI, BamHI, AatII, AlwNI, and DraII. DNA fragments were hybridized with a digoxigenin-labeled cDNA probe obtained by reverse transcription of Escherichia coli 16S and 23S rRNA. S. oralis, S. mitis, and S. parasanguis all showed an isolated 2,290-bp band in AatII ribotypes that was absent from S. gordonii, S. sanguis, and S. crista. The last three groups showed species-specific bands with AatII and also with PvuII. S. oralis could be distinguished from S. mitis and S. parasanguis in AlwNI and DraII ribotypes. S. mitis and S. parasanguis could not be distinguished, since they shared multiple bands in PvuII, AlwNI, and EcoRI patterns. The clinical isolate in the panel was very similar to S. sanguis by all enzymes used. Our findings suggest that ribotyping may be useful for genotypic identification of oral viridans streptococci. Initial digests of clinical isolates might be made with AatII, followed by PvuII or AlwNI. Isolates then could be identified by comparing ribotype patterns with those of reference strains. This approach could facilitate clinical studies of these newly defined species.
New cause for false-positive results with the Pastorex Aspergillus antigen latex agglutination test
Authors: Kappe R , Schulze-Berge A
Published: January 2020

The Pastorex Aspergillus antigen test for detection of Aspergillus galactomannan antigen in the sera of patients with invasive aspergillosis is used in many clinical laboratories. A serum sample contaminated with Penicillium chrysogenum gave a strongly positive reaction (1:128) which was heat stable, was not eliminated by pronase treatment, and was not detected by a normal rabbit globulin control. This observation was shown to be due to cross-reactions of the monoclonal antibody EB-A2 used by the kit with several airborne fungi likely to contaminate serum samples, including Penicillium chrysogenum, Cladosporium herbarum, Acremonium species, Alternaria alternata, Fusarium oxysporum, Wangiella dermatitidis, and Rhodotorula rubra.
Circulating Candida antigens and antibodies: useful markers of candidemia
Authors: Gutiérrez J , Maroto C , Piédrola G , Martín E , Perez J A
Published: January 2020

To investigate the utility of the 48-kDa antigen from Candida albicans in its commercial form (Directigen; Becton Dickinson) and three other serodiagnostic methods (detection of one antigen by Pastorex Candida [Sanofi Diagnostics Pasteur] and detection of immunoglobulin G [IgG] and IgM antibodies to C. albicans blastoconidia [bioMerieux]) for diagnosis of invasive Candida infection, we conducted a prospective clinical trial among 10 patients with candidemia (group 1), 30 patients colonized by C. albicans (group 2), 20 patients with bacteremia (group 3), and 20 subjects without clinical or microbiological evidence of infection. The Directigen system was positive for at least one serum sample each from eight patients in group 1. In groups 2, 3, and 4, it was positive for only three patients. There was no reaction to the Pastorex system in any of the patients infected with or colonized by C. albicans or in the non-Candida-carrying controls. The IgG antibody concentration oscillated between 100 and 800 (mean, 510 +/- 268) IU/ml for the patients in group 1. In this group, eight patients had IgG antibody levels of > 400 IU/ml. The percentages of persons with IgG antibody levels of > 400 IU/ml in groups 2, 3, and 4 were 43.3, 0, and 0, respectively. Specific IgM antibody was present in all group 1 patients but not in those in groups 2, 3, and 4. The sensitivity and specificity of the Directigen test were 65 and 97.1%, respectively. For the Pastorex test, the sensitivity was 0%. The sensitivity of IgG antibodies was 80%, with a specificity of 81.4%, while the IgM antibodies were 100% specific and sensitive. Both the positive and negative predictive values of specific IgM antibodies appeared to be superior to those of the other three tests.
Application of PCR to multiple specimen types for diagnosis of cytomegalovirus infection: comparison with cell culture and shell vial assay
Authors: Miller M J , Bovey S , Pado K , Bruckner D A , Wagar E A
Published: January 2020

Human cytomegalovirus (CMV) is a herpesvirus that is responsible for significant morbidity and mortality in congenitally infected infants and immunocompromised patients. Antiviral therapies are available, thus making timely diagnosis of significant importance to at-risk patients. A PCR system was devised. The newly devised system, unlike previously described systems, can be applied to a wide variety of specimen types in a clinical microbiology laboratory setting. Specimens from all sites routinely accepted for CMV culture were shown to be acceptable for CMV PCR. Sensitivity and specificity were established in comparison with those of both monolayer culture and shell vial assay (SVA). The sensitivity and specificity of PCR for detection of CMV in specimens exclusive of urine and blood were 97.5 (77 of 79 specimens) and 87.2% (41 of 47 specimens), respectively. The sensitivity and specificity of PCR for urine and blood specimens were 100 (10 of 10) and 95.7% (45 of 47) and 66.7 (4 of 6) and 78.8% (41 of 52), respectively. Discrepancies of positive PCR results with negative culture or SVA results occurred for specimens flanked chronologically by other culture- or SVA-positive specimens and were likely culture failures, increasing the specificity (100%) of PCR. Discrepancies of negative PCR results with positive culture or SVA results occurred in specimens with few cells or infectious foci by SVA or culture and may represent sampling variability associated with low virus titers.
Immediate-Early Expression of the Gene Causing Superinfection Breakdown in Bacteriophage T4B
Authors: Yutsudo Masuo , Okamoto Koji
Published: January 2020

Superinfection breakdown appears to belong to the “immediate-early” functions induced by T4 phage.
Inhibition of a Vesicular Stomatitis Virus Mutant by Rifampin
Authors: Moreau Marie-Claude
Published: January 2020

Rifampin reversibly inhibits the intracellular replication of a VSV mutant, whereas a revertant variant selected from this viral population, as well as the wild strain, are not affected by this drug. Rifampin inhibits transcriptase activity of the sensitive mutant only and, consequently, total viral RNA synthesis decreases significantly in the cells.
Further characterization of intracytoplasmic A particle-associated DNA
Authors: Longfellow D G , Smith G H
Published: January 2020

A DNA species with buoyant densities greater than mouse cellular DNA was found associated with intracytoplasmic A particles (CAP) isolated from mouse mammary tumor virus-infected mouse mammary tumors and mouse Leydig cell tumors which produce CAP but no complete mouse mammary tumor virus virions. This DNA species was absent in identically prepared tissue fractions from tumors which did not contain CAP. Treatment of CAP-associated DNA with pancreatic RNase A did not alter the buoyant density although a reduction in apparent molecular weight (broadening of the DNA band at equilibrium) was observed upon analytical equilibrium sedimentation in CsCl. The molecular weight of untreated CAP-associated DNA was estimated to range from 0.8 x 10(6) to 3.1 x 10(6). Base composition analysis showed CAP-DNA to possess an approximate guanine plus cytosine content of 38%. Ninety percent of CAP-associated DNA eluted as single-stranded molecules upon hydroxyapatite column chromatography, a characteristic that accounts in part for its higher buoyant density in neutral CsCl compared to native double-stranded mouse DNA. In two preparations, CAP-DNA had a sedimentation coefficient of 7 to 8S.
Genetic characterization of a phi80 transducing bacteriophage carrying the histidine operon of Salmonella typhimurium
Authors: Isaki L S , Voll M J
Published: January 2020

A phi 80 transducing phage, phi 80imm lambdadhis, carrying the Salmonella his-gnd region, was characterized by immunity studies, tonB deletion analysis, and marker rescue analysis. Phi 80imm lambdadhis retains the phage immunity region of the phi 80-lambda hybrid phage from which it was derived. Bacterial genes replace most late phage genes. Deletion analysis shows the prophage gene order to be immlambda-his-gnd and indicates the orientation of the his operon to be hisOGDCBHAFIE-gnd. The structure of phi 80imm lambdadhis is remarkably similar to two independently isolated phi 80 phages that carry the his-gnd region of Escherichia coli and that, like phi80imm lambdahis, were derived by directed gene transposition to the tonB locus. A derivative of phi 80imm lambdadhis that is phi 80 immune is also reported.
Simian virus 40 DNA replication in nuclear monolayers
Authors: Le Blanc D J , Singer M F
Published: January 2020

Simian virus 40 DNA replication has been studied in nuclear monolayers prepared by treatment of monolayers of BSC-1 monkey kidney cells with Nonidet P-40. These nuclear monolayers incorporated [3H]TTP into two types of viral replicative intermediates that sediment as 25-26S and 22-23S species, respectively, in neutral sucrose gradients. The 22-23S species behaves, in dye buoyant density equilibrium gradients, as a late replicative intermediate. Examination of both species in alkaline sucrose gradients revealed the presence of two types of newly synthesized strands: (i) 4-7S strands and (ii) full-length, or nearly full-length, 10-16S strands. At low TTP concentrations (less than 0.5 muM), the two size classes were found in approximately equal amounts. However, at 10 to 50 muM TTP, the proportion of the longer strands increased, with a corresponding decrease in the relative amount of the 4-7S species. Thus, the joining of small, Okazaki-like fragments to the growing chain appears to require a much higher concentration of TTP than the synthesis of the fragments themselves. Replicating simian virus 40 DNA synthesized in the nuclear monolayers is is associated with "M bands", as previously demonstrated for replicating simian virus 40 DNA in cultured whole cells.
Regulation of Bacteriophage P22 DNA synthesis and repressor levels in P22cly infections
Authors: Tokuno S I , Gough M
Published: January 2020

A rifampin-resistant mutant of Salmonella typhimurium carries an altered RNA polymerase. Wild-type (c+) phage P22 displays clear plaques and a reduced lysogenization frequency on this mutant host. The cly mutants of P22 were isolated on the basis of their ability to lysogenize such mutant hosts. Two classes of regulatory events, both of which are dependent on P22 gene c1 activity, are necessary for the establishment of lysogeny in P22. The positive events culminate in repressor synthesis; the negative events cause a retardation in phage DNA synthesis. Neither the positive nor the negative events are observed in P22c+ infections of the mutant host. Both effects are found in P22cly infections of the mutant host. Observable results of both the negative and the positive events are exaggerated in P22cly infections of wild-type hosts as compared to P22c+ infections. The cly mutation apparently increases the positive and negative regulatory events so that they are detectable in the mutant host and exaggerated in wild-type hosts. Possible mechanisms that result in the high frequency of lysogenization that characterizes the cly mutation and the nature of the cly mutation are discussed.
Bacteriophage T4D Head Morphogenesis. VIII. DNA-Protein Associations in Intermediate Head Structures That Accumulate in Gene 49
−
Mutant-Infected Cells
Authors: Glinert Susan J. , Luftig Ronald B.
Published: January 2020

We have utilized the gene 49
−
mutant-infected cells of bacteriophage T4D to accumulate large numbers of nucleic acid-protein intermediate head structures. These heads were used as substrates for experiments in the investigations of the mechanism of DNA packaging. Specifically, we have examined: (i) the susceptibility of the DNA in these structures to digestion by a variety of nucleases after a series of increasing temperature pulses from 25 to 100°C, (ii) the physicochemical characteristics of the DNA inside these heads, and (iii) the mechanism by which proteins are displaced from the interior of the head after treatment with basic proteins. We isolated DNA from these gene 49
−
heads by use of gradient centrifugation procedures. The DNA had a molecular weight of 8 × 10
6
and a density of 1.697 ± 0.005 g/cm
3
, and it contained a short resistant fraction (SRF) which, when associated with the gene 49
−
heads, exhibited AT-protected regions that were not susceptible to micrococcal nuclease digestion. Such a fraction may contain pieces which are important in the initial association of the DNA with the prohead. Exposure of the gene 49
−
intermediate capsid structures to basic proteins, such as bovine trypsin inhibitor, lysozyme, and
l
-polylysine-70, caused a displacement of an amorphous-appearing structure which may be a complex of the gene 49
−
DNA and interior components of the capsid (e.g., internal proteins, polyamines). Our general conclusion is that in the gene 49
−
intermediate head structures which are only partly filled with DNA, this DNA is held inside the head by strong electrostatic linkages with interior polypeptides and polyamines.
Glycoproteins of measles virus under reducing and nonreducing conditions
Authors: Hardwick J M , Bussell R H
Published: January 2020

Measles virus has two glycoproteins. The larger glycoprotein (HA) is composed of 76,000-dalton subunits that are bound by disulfide bonds. The smaller glycoprotein (F) appears to contain a glucosamine-rich portion that is linked to an unglycosylated protein by disulfide bonds.
Solubilization and characterization of Herpesvirus saimiri-induced membrane antigens
Authors: Qaultiere L F , Pearson G R
Published: January 2020

Treatment of Herpesvirus saimiri (HVS)-infected owl monkey cells by limited papain digestion removed the HVS-induced membrane antigen (MA) as determined by membrane immunofluorescence and antibody-dependent lymphocyte cytotoxicity (ADLC). Soluble antigenically active HVSMA was detected by inhibition of ADLC and by the decreased binding of 125I-labeled staphylococcus protein A to HVS-infected cells after absorption of an anti-MA-positive serum with papain extracts. Approximately 38% of the inhibitory activity of the papain extracts was sedimentable at 100,000 X g, indicating that the released MA was heterogeneous in size. Preliminary investigations by gel filtration chromatography identified a major peak of MA with a molecular weight between 20,000 and 50,000.
Mutagenic specificity in reovirus
Authors: Ray U R , Fields B N
Published: January 2020

Mutagenic specificity in response to chemical mutagens has been observed with certain temperature-sensitive mutants of reovirus type 3. One mutant induced by nitrous acid reverted specifically with nitrous acid. Three nitrosoguanidine-induced mutants reverted after nitrous acid treatment. These findings thus suggest that analysis of chemical induction of reversion from the temperature-sensitive phenotype may be a useful approach for studying the nature of mutation in animal viruses.
Correlation between cell killing and massive second-round superinfection by members of some subgroups of avian leukosis virus
Authors: Weller S K , Joy A E , Temin H M
Published: January 2020

Avian leukosis viruses of subgroups B, D, and F are cytopathic for chicken cells, whereas viruses of subgroups A, C, and E are not. The amounts of unintegrated linear viral DNA in cells at different times after infection with cytopathic or noncytopathic viruses were determined by hybridization and transfection assays. Shortly after infection, there is a transient accumulation of unintegrated linear viral DNA in cells infected with cytopathic avian leukosis viruses. By 10 days after infection, the majority of this unintegrated viral DNA is not present in the infected cells. The transient cytopathic effect seen in these infected cells also disappears by this time. Low amounts of unintegrated linear viral DNA persist in these cells. Cells infected with noncytopathic viruses do not show this transient accumulation of unintegrated viral DNA. Cells infected with cytopathic viruses and subsequently grown in the presence of neutralizing antibody do not show the transient accumulation of unintegrated viral DNA or cytopathic effects. These results demonstrate a correlation between envelope subgroup, transient accumulation of unintegrated linear viral DNA, and transient cell killing by avian leukosis viruses. The cell killing appears to be the result of massive second-round superinfection by the cytopathic avian leukosis viruses.
Partial replication of UV-irradiated T4 bacteriophage DNA results in amplification of specific genetic areas
Authors: Ling S K , Vogelbacker H H , Restifo L L , Mattson T , Kozinski A W
Published: January 2020

Upon infection of Escherichia coli with bromodeoxyuridine-labeled t4 phage that had received 10 lethal hits of UV irradiation, a sizable amount of phage DNA was synthesized (approximately 36 phage equivalent units of DNA per infected bacterium), although very little multiplicity reactivation occurs. This progeny DNA was isolated and analyzed. This DNA was biased in its genetic representation, as shown by hybridization to cloned segments of the T4 genome immobilized on nitrocellulose filters. Preferentially amplified areas corresponded to regions containing origins of T4 DNA replication. The size of the progeny DNA increased with time after infection, possibly due to recombination between partial replicas and nonreplicated subunits or due to the gradual overcoming of the UV damage. As the size of the progeny DNA increased, all of the genes were more equally represented, resulting in a decrease in the genetic bias. Amplification of specific genetic areas was also observed upon infection with UV-irradiated, nonbromodeoxyuridine-substituted (light) phage. However, the genetic bias observed in this case was not as great as that observed with bromodeoxyuridine-substituted phage. This is most likely due to the higher efficiency of multiplicity reactivation of the light phage.
Isolation and characterization of c-myc, a cellular homolog of the oncogene (v-myc) of avian myelocytomatosis virus strain 29
Authors: Vennstrom B , Sheiness D , Zabielski J , Bishop J M
Published: January 2020

The chicken genome contains nucleotide sequences homologous to transforming genes (oncogenes) of a number of avian retroviruses. We have isolated chicken DNA (c-myc) that is homologous to the oncogene (v-myc) of the avian myelocytomatosis virus MC29 and have compared the structures of the cellular and viral genes. Results from restriction endonuclease mapping of c-myc and from analysis of heteroduplexes between the DNAs of the cellular and viral genes show that c-myc is homologous to 1,500 nucleotides in v-myc DNA. This homologous region is interrupted in c-myc by an intron-like sequence of 1,100 nucleotides which is absent from v-myc. Nuclear RNA from normal chicken cells contains at least five species of transcripts from c-myc ranging from 2.5 to 6.5 kilobases in length. By contrast, cytoplasm contains only the 2.5-kilobase c-myc RNA. These features of the c-myc gene and its nuclear transcripts are characteristic of normal cellular genes and suggest that the myc gene is of cellular rather than viral origin. The exons in c-myc may define two functional domains in the gene and may therefore facilitate the dissection of the different oncogenic potentials of the MC29 virus.
Evidence for an early evolutionary origin and locus polymorphism of mouse VL30 DNA sequences
Authors: Courtney M G , Elder P K , Steffen D L , Getz M J
Published: January 2020

The VL30 sequences of mouse DNA are a family of sequences with retrovirus-like structure which code for a 30S RNA transcript that can be packaged into the virions of murine leukemia viruses and thereby transmitted from cell to cell. A Southern blot analysis of these sequences revealed that multiple copies are present in the DNA of all mice examined, regardless of species or geographic origin. Considerable locus polymorphism was also apparent, and at least one of these polymorphisms appeared to reflect the differing chromosomal location of a complete VL30 sequence. These data indicated that VL30 elements are not recent additions to the mouse genome and suggested that the evolution of the VL30 multigene family has been accompanied by duplication and dispersion of VL30 sequences to diverse genomic sites. In addition, we reexamined the issue of genetic relatedness between mouse VL30 sequences and a physically similar family of virus-like elements in the rat genome. We found that many, if not all, rat and mouse VL30 loci contain regions of sequence homology. These data suggested that rodent VL30 sequences have evolved from a common ancestral sequence.
Bacteriophage T7 defective in the gene 6 exonuclease promotes site-specific cleavages of T7 DNA in vivo and in vitro
Authors: Lee D D , Sadowski P D
Published: January 2020

Site-specific cleavages of intracellular DNA were demonstrated in bacteriophage T7 6am-infected cells. The sites of the cleavages were located at 46.8 and 68.7% (1% of the T7 DNA length = 400 base pairs) from the left end of the T7 genome. These cleavages required the products of genes 3 (endonuclease), 4 (DNA primase), and 5 (DNA polymerase). However, the product of gene 6 (exonuclease) must be absent. Site-specific cleavage was also shown to occur in vitro in extracts of T7 6am-infected cells, although at a different site: 82.8% from the left end of the T7 genome.
AKR Thymic Lymphomas Involving Mink Cell Focus-Inducing Murine Leukemia Viruses Have a Common Region of Provirus Integration
Authors: Yoshimura Fayth K. , Levine Kathryn L.
Published: January 2020

Newly acquired proviruses related to a mink cell focus-inducing murine leukemia virus were detected in low copy number in restriction endonuclease-digested DNAs from thymic lymphomas of AKR/J mice. These extra proviruses were not present in DNAs of either normal thymus or leukemic brain tissues. Extra tumor-specific DNA fragments generated by restriction endonucleases either were identical in size or fell into similar size classes, suggesting a common site(s) of provirus integration. Characterization of extra
Eco
RI DNA fragments for mink cell focus-inducing viral sequences revealed that all of them contained large terminal repeat sequences and that a significant number represented proviruses with deletions.
Editor's Welcome
Authors: Vivacqua Adriana S. , Erickson Ingrid , Christensen Lars Rune , Barkhuus Louise , Robert Lionel P.
Published: January 2020

It is our pleasure to welcome you to this PACMHCI GROUP issue. For over 25 years, the GROUP research community has supported the development of robust scholarship at the intersection of Computer Supported Cooperative Work, Human Computer Interaction, Computer Supported Collaborative Learning and Socio-Technical Studies. This volume is the latest product of our efforts to validate and integrate the strong work happening within this broadly-conceived community.

We hope that the range of papers presented here reflects our intent to be international, interdisciplinary, and inclusive, both in our organization of the review process as well as within the set of accepted papers. This PACMHCI journal volume in the GROUP series features studies of collaboration in multiple settings, including social media, online communities and game development. It also showcases architectures and frameworks for collaboration, and sociotechnical studies in domains ranging from sports to fake news.

As Editors, we are particularly pleased to continue the legacy of presenting and disseminating the new and exciting work being developed in our community. We come together every two years to creatively display and build off of ideas from a wide range of disciplinary and topical areas including computer science, design, engineering, information science, management science, sociology, work and labor studies, and values-in-design, among others.
Echo State Network for Extended State Observer and Sliding Mode Control of Vehicle Drive Motor with Unknown Hysteresis Nonlinearity
Authors: Gao Xuehui , Sun Bo , Hu Xinyan , Zhu Kun
Published: January 2020

An echo state network (ESN) for extended state observer (ESO) and sliding mode control (SMC) of permanent magnet synchronous motor (PMSM) in an electric vehicle system is investigated in this paper. For the PMSM model, most researches neglect the hysteresis loss and other nonlinear factors, which reduces the accuracy of the PMSM model. We present a modified PMSM model considering the hysteresis loss and then transform the new PMSM model to a canonical form to simplify the controller design. In order to deal with the hysteresis loss, an ESN is utilized to estimate the nonlinearity. Considering that some states cannot be directly obtained, an ESO with ESN is proposed to estimate unknown system states of the electric vehicle PMSM system. Afterwards, an SMC is adopted to control the closed-loop system based on the ESO with ESN, and a double hyperbolic function instead of the sign function is used to suppress the chattering of the SMC. The stabilities of the observer and the controller are all guaranteed by Lyapunov functions. Finally, simulations are presented to verify the validity of the echo state network for extended state observer and the neural network sliding mode control.
Fast Synthesis of Co3O4 by Microwave-Assisted Hydrothermal Treatment
Authors: Medina Midilane S. , Zenatti Alessandra , Escote Marcia T.
Published: January 2020

This work describes a fast and simple procedure that combines the virtues of the microwave-assisted hydrothermal method with an oxidizing agent to produce Co3O4 nanocubes and nanoplates. We observed that particle morphology and size depend on the synthesis time and oxidizing agent (urea and hydrogen peroxide). The X-ray diffraction results showed that the samples are single phase, with crystallite sizes of approximately 30 nm. A similar crystalline domain is observed in the transmission electronic images. Magnetic measurements revealed the influence of the size and morphology of the particles on the magnetic curves. These measurements on the nanoplate samples revealed a paramagnetic behaviour at higher temperatures, and the presence of a cusp at that temperature was defined as TP. The TP decreases from 36 K to 21 K when the size of the plate particles decreases from ~70 nm to 10 nm. These samples also present weak ferromagnetism below TP, which is attributed to a superparamagnetic blockade state. The nanocube samples have a lower magnetic susceptibility magnitude and weak ferromagnetism behaviour at room temperature. Our results show that this synthesis produces Co3O4 nanoplates and nanocubes with interesting magnetic properties related to their shape and size.
The Association of Autoimmune Diseases with Type 1 Diabetes Mellitus in Children Depends Also by the Length of Partial Clinical Remission Phase (Honeymoon)
Authors: Ozen Gulsum , Zanfardino Angela , Confetto Santino , Piscopo Alessia , Casaburo Francesca , Tinto Nadia , Iafusco Fernanda , Ozen Gulsah , Miraglia del Giudice Emanuele , Tasar Medine Aysin , Yilmaz Arzu , Iafusco Dario
Published: January 2020

Type 1 diabetes mellitus (DM) is characterized by irreversible, autoimmune, pancreatic β-cell destruction. During the disease, some patients experience a phase of Partial Clinical Remission (PCR) known as “honeymoon.” This is a transitory period that is characterized by insulin production by residual β cells following DM diagnosis and initiating the insulin therapy. In this study, we aimed to evaluate the influence of insulin production on immune system after the onset of diabetes, and we showed that the duration of honeymoon period could be related to the onset of other autoimmune conditions. For this retrospective study, 159 children aged between 11 and 18 years with type 1 DM were eligible. They have been diagnosed diabetes at least 10 years ago and use exogenous insulin. Our results showed that younger age at the onset of Type 1 DM in children, predicts Celiac Disease. Female sex and low HCO3 levels at the onset of DM had a high predictive value on patients who did not experience longer Partial Clinical Remission phase. Patients with higher BMI at the diagnosis of DM experienced shorter honeymoon period than the average. Smaller of our patients who diagnosed just DM have more than 297 days honeymoon period with respect to patients with one associated autoimmune disease. This may be due to a continuous and prolonged stimulation of immune system during the period of honeymoon that predispose the patient to develop other TH1 diseases. The patients who experienced more than 297 days Partial Clinical Remission seem under risk of developing one other autoimmune disease more than the patients who experienced less than 297 days Partial Clinical Remission. We have to consider that this observation is very intriguing because many protocols spring-up to try prolonging the honeymoon period in patients with autoimmune DM. If this aim is important from a metabolic point of view, long follow-ups are needed to be sure that the risk of other autoimmune diseases does not increase.
Direct Method-Based Transient Stability Analysis for Power Electronics-Dominated Power Systems
Authors: Che Yanbo , Lv Zihan , Xu Jianmei , Jia Jingjing , Li Ming
Published: January 2020

With the extensive application of power electronics interfaced nonsynchronous energy sources (NESs) in modern power systems, the system stability especially the transient stability is prominently deteriorated, and it is crucial to find a comprehensive and reasonably simple solution. This paper proposes a direct method-based transient stability analysis (DMTSA) method which concludes the key steps as follows: (1) the system modeling of Lyapunov functions using mixed potential function theory and (2) the stability evaluation of critical energy estimation. A voltage source converter- (VSC-) based HVDC transmission system is simulated in a weak power grid to validate the proposed DMTSA method under various disturbances. The simulation results verify that the proposed method can effectively estimate the transient stability with significant simplicity and generality, which is practically useful to secure the operation and control for power electronics-dominated power systems.
Long Term Behavior for a Class of Stochastic Delay Lattice Systems inXρSpace
Authors: Zhang Yijin , Lin Zongbing
Published: January 2020

In this paper, we focus on the asymptotic behavior of solutions to stochastic delay lattice equations with additive noise and deterministic forcing. We first show the existence of a continuous random dynamical system for the equations. Then we investigate the pullback asymptotical compactness of solutions as well as the existence and uniqueness of tempered random attractor inXρspace. Finally, ergodicity of the systems is achieved.