bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Freshly Isolated Strains of
Streptococcus mutans
and
Streptococcus mitior
to Change in pH in the Presence and Absence of Fluoride During Growth in Continuous Culture
Authors: Hamilton Ian R. , Bowden George H.
Published: January 2020

A study was undertaken to compare the effects of pH and fluoride on the growth and metabolic properties of
Streptococcus mutans
2452 and
Streptococcus mitior
572, strains recently isolated from 8-year-old school children and grown in continuous culture with a glucose limitation. Each experiment had four consecutive stages of growth: (i) pH 7.0, (ii) no pH control, (iii) pH 7.0, and (iv) no pH control plus 50 μg of fluoride per ml in the medium. At a dilution rate (
D
) of 0.13 h
−1
, cells of
S. mitior
possessed high glycolytic activity at pH 7.0 in the initial stage, but were washing out of the chemostat within 24 h after the pH control was shut off and the pH fell to 5.1. Once the culture was reestablished at pH 7.0, fluoride (50 μg/ml) was added to the medium and the pH control was again turned off. Whereas cell numbers fell from 24.0 × 10
8
to 0.9 × 10
8
/ml within 24 h, the culture remained relatively constant during the following 6 days despite the fall in pH to 5.4. The cells from this culture also maintained an intermediate glycolytic rate of 0.44 μmol mg
−1
min
−1
. The cells in this latter stage developed phenotypic resistant to fluoride at concentrations up to 16 mM. Growth of
S. mitior
at
D
= 0.034 h
−1
resulted in a slower response to environmental change such that cells were able to grow to pH values as low as 5.2 in the absence of fluoride. In contrast to
S. mitior, S. mutans
2452 under the same conditions at
D
= 0.13 h
−1
grew to higher cell numbers and higher yields and was able to maintain significant cell numbers to pH 4.8 once the pH control was shut off in the presence and absence of fluoride.
S. mutans
had 40% less glycolytic activity but was fourfold more resistant to fluoride at the start of the experiment, and cells were shown to adapt to growth at low pH and to fluoride at levels as high as 20 mM. This fluoride resistance by freshly isolated
S. mutans
2452 was significantly higher than that of
S. mutans
DR0001 grown under identical conditions in the chemostat.
S. mutans
DR0001 is a strain which has been subcultured in vitro for several years. This study demonstrated that
S. mutans
2452 was more aciduric than
S. mitior
572 and, unlike the latter organism, could grow at pH values below 5.1. The addition of fluoride to the medium stabilized the
S. mitior
culture in the absence of pH control, indicating that whereas fluoride does suppress growth and glycolytic activity it also results in higher environmental pH values, which permit the survival of the less aciduric bacteria.
Trypanosoma cruzi culture used as vaccine to prevent chronic Chagas' disease in mice
Authors: Basombrío M A , Besuschio S
Published: January 2020

The development of chronic pathology in mice at 2 to 10 months after inoculation of 10(2) T. cruzi trypomastigotes can be prevented by preimmunization with live, attenuated culture parasites (strain TCC). Swiss mice received one or three immunizing inoculations of 10(6) TCC organisms and were challenged with 10(2) Tulahuén blood trypomastigotes. Control groups received only the immunizing or the challenge inoculations. Immunized groups as compared with nonimmunized controls had lower mortality rates at 2 months postchallenge (9% versus 23%; P = 0.059), lower early peaks of parasitemia, lower percentages of positive xenodiagnoses at 5.5 months (40 versus 80%; P = 0.061), and lower incidences of tissue lesions in the skeletal muscle (P less than 0.005) at 2,6, and 10 months postchallenge. Tissue lesions in the heart and smooth muscle were also reduced, reaching statistical significance after 10 months (P less than 0.02). Chronic pathology parameters were never enhanced in preimmunized groups. In spite of the putative role that autoimmunity may play in the development of chronic chagasic lesions, the preventive effect of vaccination is readily exerted upon the chronic murine model of Chagas' disease.
F7 and type 1-like fimbriae from three Escherichia coli strains isolated from urinary tract infections: protein chemical and immunological aspects
Authors: Klemm P , Orskov I , Orskov F
Published: January 2020

Fimbriae from three Escherichia coli strains, C1212, C1214, and C1023, isolated from urinary tract infections, have been purified and characterized by determination of the N-terminal sequences, amino acid composition, and molecular weights of their respective subunits. Furthermore, their immunological interrelationships have been investigated. The three strains all harbored more than one fimbrial species each. Immunologically different type 1-like fimbriae, termed 1A, 1B, and 1C, with highly homologous N-terminal sequences were isolated, of which strain C1212 possessed 1A and 1C, strain C1214 possessed 1A and 1B, and strain C1023 possessed 1A and 1C. Type 1A is known to cause a mannose-sensitive hemagglutination similar to that described for type 1 fimbriae, whereas the functions of types 1B and 1C are not yet known. Strain C1212, in addition, harbored the F7 fimbrial antigen which causes mannose-resistant hemagglutination and adherence to urinary epithelial cells. The N-terminal structure of this antigen seems to indicate a possible evolutionary kinship to the type 1-like fimbriae, although they are immunologically unrelated. Our results indicate that fimbriation of pathogenic wild-type strains can be of an intricate variety.
Effect of cimetidine and antacid on gastric microbial flora
Authors: Snepar R , Poporad G A , Romano J M , Kobasa W D , Kaye D
Published: January 2020

The effect of a standard regimen of cimetidine on the gastric flora of 20 male volunteers was studied in a double-blind manner and compared with the effects of a standard antacid regimen. Postprandial microbial titers in gastric aspirates were significantly higher at 4, 8, and 16 weeks of therapy in subjects taking antacids and at 4 weeks in subjects taking cimetidine when compared with their pretreatment titers. Although not significant, there was a tendency for fasting microbial titers to be higher in subjects receiving cimetidine as compared with pretreatment titers. The higher titers were primarily related to increases in survival of mouth flora (viridans streptococci and Neisseria spp.); Enterobacteriaceae and other nitrate-reducing organisms were unusual isolates. There was no significant difference in the total titers or types of organisms isolated when subjects taking cimetidine were compared with those taking antacid.
Role for Endotoxin in the Leukocyte Infiltration Accompanying
Escherichia coli
Inflammation
Authors: Issekutz Andrew C. , Bhimji Shabir
Published: January 2020

Escherichia coli
organisms induce polymorphonuclear leukocyte (PMNL) infiltration during clinical infection and also in a rabbit dermal model of inflammation. We investigated the factors which may mediate this host response to
E. coli
. In vitro incubation of Formalin-killed
E. coli
in heat-inactivated rabbit plasma or balanced salt solution generated in the supernatant factors which induced in vivo PMNL infiltration upon intradermal injection into rabbits. However, these supernatants, in the presence or absence of plasma, did not induce PMNL migration in vitro. The in vivo activity was stable at 100°C and of high molecular weight (30,000). Antiserum to O antigen or to core glycolipid, but not to K or H antigen, as well as polymyxin B inhibited the release or activity of these
E. coli
-derived factors. The intradermal injection of 0.02 to 0.2 μg of four different endotoxin preparations or lipid A also induced marked PMNL infiltration in vivo. However, these preparations did not stimulate PMNL migration in vitro and failed to generate chemotactic activity in plasma except at very high concentrations (500 μg/ml). Anti-O serum inhibited PMNL infiltration induced by endotoxins with the corresponding O antigen and anti-core glycolipid serum inhibited all four endotoxins tested, whereas polymyxin B inhibited the activity of the endotoxins as well as that of lipid A. Base hydrolysis of endotoxin abolished PMNL infiltration. It is concluded that (i) endotoxin shed from
E. coli
(killed or live) may be one factor mediating the PMNL infiltration induced by this organism, (ii) endotoxin probably acts independent of in vivo complement activation, (iii) the activity is dependent on the lipid A moiety, and (iv) antibody binding to O or core glycolipid antigens can modify endotoxin so as to diminish its capacity to induce PMNL infiltration in vivo.
Degradation of intestinal glycoproteins by pathogenic Shigella flexneri
Authors: Prizont R
Published: January 2020

Intestinal mucin glycoproteins were examined for their ability to sustain growth of pathogenic shigella. Inoculation of germfree cecal mucin glycoproteins with Shigella flexneri 4b resulted at 48 h in a 940-fold increase in the enteropathogen concentration. Investigation in vitro of enzymatic degradation by the pathogen led to the identification of a blood group B-degrading glycosidase produced by the bacteria. In in vivo experiments, fecal supernatants of mice monocontaminated with S. flexneri 4b contained an alpha-galactosidase active against the p-nitrophenyl-glycoside. This fecal alpha-galactosidase peaked 5 days after shigella contamination, showing 2.8 +/- 1.4 mU of enzyme activity per mg of protein. Contaminated fecal supernatants similarly destroyed the blood group B reactivity of cecal mucin glycoproteins. These data suggested that S. flexneri 4b could proliferate within ileocolonic environment by enzymatically degrading mucin glycoprotein sugars.
Capsular material of Mycoplasma gallisepticum and its possible relevance to the pathogenic process
Authors: Tajima M , Yagihashi T , Miki Y
Published: January 2020

A ruthenium red-staining capsule was observed on two pathogenic strains, but not on one nonpathogenic strain of Mycoplasma gallisepticum. The capsule appeared to mediate cytadsorption of mycoplasmas to the chicken tracheal epithelium without evidence of membrane fusion. No relationship was seen between the presence of capsule and hemagglutination titers of the strains examined.
Humoral immunity in leprosy: immunoglobulin G and M antibody responses to Mycobacterium leprae in relation to various disease patterns
Authors: Touw J , Langendijk E M , Stoner G L , Belehu A
Published: January 2020

A solid-phase radioimmunoassay, applying whole Mycobacterium leprae as antigen and radiolabeled protein A from Staphylococcus aureus as antibody-detecting reagent, was used for the determination of specific immunoglobulin G (IgG) and IgM antibody responses in leprosy patients. High IgG anti-M. leprae antibody levels were found in lepromatous leprosy patients, whereas the antibody response in tuberculoid leprosy patients varied from negative, i.e., comparable with responses measured in normal individuals, to strongly positive. In tuberculoid leprosy patients, a significant increase in IgG anti-M. leprae antibody levels was observed in the more widespread forms of the disease, but positive antibody responses were especially predominant among patients with active lesions. Lepromatous leprosy patients generally demonstrated high levels of both IgG and IgM anti-M. leprae antibodies, but no relation was found between the antibody responses and bacillary load or other clinical parameters. A marked decrease in specific IgG and IgM antibody levels was observed in lepromatous leprosy patients during their first year of treatment. Differences in mechanisms regulating the humoral immune response in tuberculoid and lepromatous leprosy patients were indicated, and the application of antibody assessments in leprosy control programs is discussed.
Physicochemical surface properties of elementary bodies from different serotypes of chlamydia trachomatis and their interaction with mouse fibroblasts
Authors: Söderlund G , Kihlström E
Published: January 2020

Aqueous biphasic partitioning, hydrophobic interaction chromatography, and ion-exchange chromatography were used to characterize the surface properties of Renografin-purified elementary bodies of Chlamydia trachomatis serotypes E and L1. The two serotypes differed with respect to liability to hydrophobic interaction and negative surface charge. Furthermore, the mutual relative magnitude of these parameters differed between the two serotypes, depending on the chromatographic technique used. This indicates that these chromatographic techniques register different aspects of charge and hydrophobicity on the chlamydial surface. DEAE-dextran and dextran sulfate affected association of, penetration, and intracellular development of C. trachomatis in mouse fibroblasts (McCoy cells). DEAE-dextran affected the association of C. trachomatis serotype E with McCoy cells mainly by charge-dependent forces, whereas both DEAE-dextran and dextran sulfate influenced the association of C. trachomatis serotype L1 mainly by charge-independent forces. These results indicate that the numerous biological differences between lymphogranuloma venereum and non-lymphogranuloma venereum strains of C. trachomatis may be assigned to differences in surface properties between the two strains.
Monoclonal antibodies to human cytomegalovirus: three surface membrane proteins with unique immunological and electrophoretic properties specify cross-reactive determinants
Authors: Pereira L , Hoffman M , Gallo D , Cremer N
Published: January 2020

Seventy-seven clones of hybridomas selected for reactivity by immunofluorescence with human cytomegalovirus (CMV)-infected cells were produced by fusing mouse myeloma cells with the spleen cells of mice immunized with CMV strain AD169. The clones were classified into seven groups on the basis of the electrophoretic properties of the polypeptides immune precipitated from extracts of CMV-infected cells. Studies on the three groups of monoclonal antibodies directed against CMV surface membrane antigens showed the following. Clones in each group were differentiated by immunoglobulin subclass, neutralizing activity, and reactivity with the antigenic domains of proteins exposed on the surface membranes of intact CMV-infected cells. Monoclonal antibodies in each group precipitated one slowly migrating protein and multiple faster migrating forms which shared antigenic determinants. The first group of monoclonal antibodies precipitated four glycosylated polypeptides with apparent molecular weights of 130,000, 110,000, 100,000, and 60,000. Monoclonal antibody CH51 of this group neutralized infectious virus but failed to react with antigenic domains on the surfaces of infected cells. The second group of monoclonal antibodies precipitated four polypeptides with apparent molecular weights of approximately 66,000, 55,000, 50,000, and 46,000. Monoclonal antibodies CH65 and CH134 in this group had neutralizing activity and reacted with antigenic domains of proteins exposed on the surface of CMV-infected cells. The third group of monoclonal antibodies precipitated four polypeptides with apparent molecular weights of 49,000, 48,000, 34,000, and 25,000. Serological analysis of 15 naturally occurring CMV strains with a panel of monoclonal antibodies to surface membrane proteins showed that the antigenic determinants reactive with the antibodies tested were conserved in all of the strains. Monoclonal antibodies to surface membrane proteins on CMV-infected cells may prove to be valuable reagents for identification of virus isolates.
Effect of lymphocytosis-promoting factor from Bordetella pertussis on cerebellar cyclic GMP levels
Authors: Askelöf P , Gillenius P
Published: January 2020

Dermonecrotic toxin (DNT), lipopolysaccharide (LPS), and lymphocytosis-promoting factor (LPF) were isolated from Bordetella pertussis and tested for neuroactivity. When injected intraperitoneally into rats, a dose of 0.13 mg of LPF per kg elevated the cyclic GMP level in cerebellum by approximately 70%, whereas DNT (0.5 mg/kg) and LPS (1.5 mg/kg) were without effect. This action of LPF on the central nervous system was dose dependent and did not require the administration of any additional agent, such as histamine.
Protective properties of anticholera antibodies in human colostrum
Authors: Majumdar A S , Ghose A C
Published: January 2020

A comparative immunological study between two colostrum pools of Indian and Swedish mothers was carried out to evaluate their protective properties against Vibrio cholerae. Antibacterial and antitoxin titers were significantly higher in the Indian colostrum pool (ICP) than in the Swedish colostrum pool (SCP). Antilipopolysaccharide as well as antitoxin antibodies belonged to secretory immunoglobulin A (IgA) and IgM classes as determined by the enzyme-linked immunosorbent assay. ICP could significantly inhibit the adherence of V. cholerae to intestinal slices in vitro, whereas such activity was virtually absent in SCP. Moreover, ICP could induce significant protection against live vibrio challenge in rabbit ileal loops, whereas only a weak protective activity was observed with SCP. A secretory IgA fraction was obtained from ICP by using gel filtration and immunoadsorbent techniques. Human secretory IgA thus obtained exhibited antiadherence as well as protective activities against V. cholerae.
Modulation of natural killer cell activity in mice after interferon induction: depression of activity and depression of in vitro enhancement by interferon
Authors: Melder R J , Ho M
Published: January 2020

Splenic natural killer (NK) cell activity of BALB/c and C3H mice was assayed after administration of the interferon inducers Escherichia coli endotoxin or Newcastle disease virus (NDV). As expected, the NK cell activity rose early in response to the interferon inducers. At 1 to 3 days after an injection of endotoxin, NK activity was hyperesponsive to interferon stimulation. At 5 to 9 days after injection of either endotoxin or NDV, splenic NK activity was depressed, and the spleen cells showed a relative refractoriness to in vitro interferon stimulation. It is postulated that this phenomenon may be related to hyporeactivity, the inability to reinduce interferon after an initial period of interferon production.
Fibrinogen-mediated adherence of group A Streptococcus to influenza A virus-infected cell cultures
Authors: Sanford B A , Davison V E , Ramsay M A
Published: January 2020

A quantitative radioassay was used to study the adherence of group A Streptococcus to Madin-Darby canine kidney cells infected with influenza A virus (strains FM1, Jap 305, and NWS) and reacted with fibrinogen. Treatment of virus-infected cell cultures with human fibrinogen significantly enhanced streptococcal adherence (P less than 0.0005) compared with adherence to untreated, virus-infected cells and uninfected control cells. Enhanced adherence was not seen with NWS virus-infected cell cultures or with virus-infected cells treated with human fibronectin, canine fibrinogen, or porcine fibrinogen. Human fibrinogen was shown to bind directly to surface membranes of virus-infected cells. Virus-infected cell cultures were incubated in the presence of tunicamycin, an antibiotic that inhibits glycosylation of virus-specific surface membrane glycoproteins. We found that with increasing antibiotic concentration there was a progressive decrease in fibrinogen-mediated streptococcal adherence. Adherence of 3H-labeled streptococci to fibrinogen-treated, virus-infected cell cultures showed saturation kinetics and could be blocked with monospecific antibodies against fibrinogen. These results suggest that human fibrinogen binds to a glycoprotein moiety on the surface of influenza A virus-infected cells, and that once bound the fibrinogen molecule acts as an "acquired" receptor for the attachment of group A Streptococcus. We postulate that this mechanism, it if occurs in vivo, might help explain the observed association between influenza A virus infection and subsequent bacterial superinfection with group A Streptococcus.
Hydrophobic interactions and the adherence of Streptococcus sanguis to hydroxylapatite
Authors: Nesbitt W E , Doyle R J , Taylor K G
Published: January 2020

Streptococcus sanguis demonstrated a high affinity for hydrocarbon solvents. When aqueous suspensions of the organism were mixed with either hexadecane or toluene, the cells tended to bind to the nonaqueous solvent. Increases in temperature resulted in a greater affinity of cells for hexadecane. Interaction between the cells and hexadecane was also enhanced by dilute aqueous sodium chloride and by low pH (pH less than 5). The results suggest that the cell surface of S. sanguis has hydrophobic properties. Isolated cell walls also tended to partition into the nonaqueous solvent. Amino acid analyses of the walls revealed the presence of several amino acids which possess hydrophobic side chains. It is likely that the hydrophobic amino acids associated with the cell wall contribute to the hydrophobicity of intact S. sanguis. When the adherence of S. sanguis to saliva-coated hydroxylapatite was measured, it was found that hydrophobic bond-disrupting agents, such as the Li+ cation, the SCN- anion, and sodium dodecyl sulfate, were capable of inhibiting the cell-hydroxylapatite union. In addition, it was observed that both urea and tetramethylurea were inhibitors of the adherence, although the latter reagent was the superior inhibitor. The results suggest that the adherence of S. sanguis to saliva-coated smooth surfaces is at least partially dependent on the formation of hydrophobic bonds between the cell and adsorbed salivary proteins. Hydrophobic bonding may contribute to cooperative interactions involving S. sanguis and saliva-coated hydroxylapatite (Nesbitt et al., Infect. Immun. 35:157-165, 1982).
Pathogenicity of avian reoviruses: examination of six isolates and a vaccine strain
Authors: Gouvea V , Schnitzer T J
Published: January 2020

Six avian reovirus isolates and a vaccine reovirus strain were compared for invasiveness, virulence, and pathological characteristics upon infection of day-old specific-pathogen-free chicks by the footpad, subcutaneous, and oral routes of inoculation. No significant differences were noted regarding the ability of individual isolates to infect target tissues. However, virulence (measured as the 50% lethal dose) among the isolates varied markedly from 2 x 10(5) to less than 10 PFU per chick for the most virulent isolate; between the parental wild-type virus and the derivative vaccine virus strain, a million-fold (10(6)) difference in virulence was demonstrated. All strains revealed, with considerable variation, arthrogenic potential.
Antigenic quantitation of type 1 fimbriae on the surface of Escherichia coli cells by an enzyme-linked immunosorbent inhibition assay
Authors: Dodd D C , Eisenstein B I
Published: January 2020

Type 1 fimbriae from two strains of Escherichia coli, K-12-derived CSH50 and a clinical isolate VL-2, were purified by a simplified procedure, which should be applicable to a variety of bacterial strains. After mechanical removal from the cells, the fimbriae were sedimented in the ultracentrifuge and resuspended in 5 M urea to disaggregate cell membranes and flagella, leaving the urea-resistant fimbriae intact. After several hours at 37 degrees C, this crude fimbrial suspension was diluted to 1 M urea, and the intact fimbriae were sedimented through a 1 M urea-1 M sucrose cushion. The pellet was found to be pure fimbriae by sodium docecyl sulfate-polyacrylamide gel electrophoresis, with apparent subunit molecular weights of 17,000 for the fimbriae from K-12 strain CSH50 and 19,000 for those from the clinical isolate VL-2. High-titer rabbit antiserum raised against CSH50 fimbriae was specific for fimbriae by indirect ferritin labeling and immunoprecipitation and was used to develop an enzyme-linked immunosorbent assay. Competitive inhibition of antifimbrial antiserum in the enzyme-linked immunosorbent assay by a known amount of either purified fimbriae or fimbriae-bearing bacteria permitted precise quantitation of fimbrial antigen in cultures of strain CSH50, thereby providing a simple means of determining the effects of environmental conditions on the synthesis of type 1 fimbriae.
Immunological identity of brucella native hapten, polysaccharide B, and yersinia enterocolitica serotype 9 native hapten
Authors: Fernandez-Lago L , Moriyon I , Toyos J , Diaz R
Published: January 2020

Yersinia enterocolitica serotype 9 contained an antigenic component giving a reaction of total identity with Brucella native hapten and polysaccharide B. This component was present in a phenol-water extract (fraction 5; M. Redfearn, Ph.D. Thesis, University of Wisconsin, Madison, 1960) along with the smooth lipopolysaccharide. The native hapten could be purified free of lipopolysaccharide and proteins by gel filtration.
Familial clustering of the Streptococcus mutans cryptic plasmid strain in a dental clinic population
Authors: Caufield P W , Wannemuehler Y M , Hansen J B
Published: January 2020

Of Streptococcus mutans strains from 100 pedodontic patients, 13% contained the common cryptic plasmid. Family members of four plasmid-positive patients harbored plasmid-positive S. mutans at a significantly greater frequency compared with the pedodontic population, but there was not a one-to-one correlation of strains between mothers and children.
Comparison of systemic and local immunity in dogs with canine parvovirus gastroenteritis
Authors: Rice J B , Winters K A , Krakowka S , Olsen R G
Published: January 2020

To determine whether resistance to canine parvovirus (CPV) gastroenteritis is mediated by local or systemic immunity or both, an enzyme-linked immunospecific antibody assay (ELISA) was developed that quantitated different classes of antibody to CPV. Antibody levels in serum and feces of dogs with CPV-associated gastroenteritis were compared with their clinical signs and viral hemagglutination (HA) titers. Dogs with high levels of CPV coproantibody had a favorable clinical prognosis, high serum antibody levels (hemagglutination inhibition [HI] and ELISA), and low viral HA titers in feces. Conversely, dogs with little or no detectable CPV coproantibody had severe clinical signs and associated mortality rates and high viral HA titers in feces. Many of these dogs had high HI antibody titers. Statistical analysis revealed that only coproantibody level correlated (inversely) with HA titer; serum antibody, whether measured by HI or ELISA, did not. These data suggest that local intestinal immunity is more important than humoral immunity in developing immunological resistance to CPV gastroenteritis.
Induction of phagocytic inhibitory activity in cats with chronic Pseudomonas aeruginosa pulmonary infection
Authors: Winnie G B , Klinger J D , Sherman J M , Thomassen M J
Published: January 2020

Chronic pulmonary infection has been established in cats by repeated intrapulmonary inoculation of viable Pseudomonas aeruginosa enmeshed in agarose beads. In the serum of all chronically infected animals, a substance(s) developed which inhibited phagocytosis of P. aeruginosa by normal cat alveolar macrophages. Phagocytosis was measured by incubating macrophage monolayers (5 X 10(5) alveolar macrophages) for 20 min in the presence of 3H-labeled bacteria and 5% serum from control or infected animals. Inhibitory activity developed 4 to 16 weeks after initial infection, and inhibition of phagocytosis of P. aeruginosa in the presence of infected cat serum ranged from 30 to 79%. After inhibitory activity developed, it persisted throughout the remainder of the experiment in each animal. The activity was specific for P. aeruginosa of the infecting serotype and did not affect phagocytosis of gram-positive organisms. Inhibitory activity was unchanged by heating serum at 56 degrees C for 30 min. We have previously described a P. aeruginosa-specific, heat-stable, phagocytosis-inhibitory activity in the serum of patients with cystic fibrosis. Since inhibitory activity also develops in cats with chronic P. aeruginosa pulmonary infection, such activity may not be a primary intrinsic abnormality in patients with cystic fibrosis. The animal model described here offers a system for following the development of and for characterization of the P. aeruginosa-specific phagocytosis-inhibitory activity.
Cross-protection by Pseudomonas aeruginosa polysaccharides
Authors: Pier G B
Published: January 2020

High-molecular-weight polysaccharide from Pseudomonas aeruginosa immunotypes 1 and 2 gave cross-protection in outbred CD-1 mice challenged with the heterologous immunotype organism. Both active immunization with 50 micrograms of polysaccharide, as well as passive transfer of immune serum were effective. The basis for this cross-protection is the ability of high doses of polysaccharide to induce antibody formation to both homologous and heterologous immunotype determinants.
Polymorphonuclear leukocyte activation by a synthetic muramyl dipeptide analog
Authors: Osada Y , Otani T , Sato M , Une T , Matsumoto K , Ogawa H
Published: January 2020

N alpha-(N-Acetylmuramyl-L-alanyl-D-isoglutaminyl)-N epsilon -stearoyl-L-lysine, a synthetic derivative of muramyl dipeptide, stimulated the chemotactic mobility, phagocytic activity, and superoxide anion (O2-) productivity of peritoneal polymorphonuclear cells in mice. The chemotactic mobility of both cells preincubated with the adjuvant in vitro and those derived from the mice previously treated with the adjuvant was significantly enhanced. The phagocytic activity of cells preincubated in vitro with the adjuvant was also enhanced transiently, and that of the cells derived from the mice treated subcutaneously with the adjuvant 24 h before intraperitoneal inoculation with Escherichia coli was significantly greater than that of cells from the mice given phosphate-buffered saline instead of the adjuvant. The release of O2- from the cells derived from the adjuvant-treated mice was also greater than that from the cells of untreated control mice. However, the exposure of the cells derived from untreated mice to the adjuvant in vitro did not stimulate O2- generation by the cells.
Enhanced phagocytic response of macrophages to bacteria by physical impact caused by bacterial motility or centrifugation
Authors: Tomita T , Kanegasaki S
Published: January 2020

The mechanism of enhanced phagocytic and chemiluminescent responses of macrophages caused by bacterial motility (T. Tomita, E. Blumenstock, and S. Kanegasaki, Infect. Immun. 32:1242, 1981) was studied. Both responses increased up to a certain level with an increased number of motile bacteria, such as Salmonella typhimurium, Escherichia coli, or Pseudomonas aeruginosa, added. In contrast, only a slight increase was observed with the motility (mot) mutants of these bacteria, even when 4,000 bacteria per single macrophage were added. If nonmotile bacteria were centrifuged together with a monolayer culture of macrophages, the number of bacteria ingested per macrophage increased dramatically. This phenomenon was not observed in the presence of cytochalasin B or at a low temperature, and about half of the associated bacteria were killed within 30 min of prolonged incubation, indicating that the bacteria were not simply embedded on the macrophage surface. An observed biphasic increase of ingestion with an increase in centrifugal force suggested the existence of a threshold velocity for efficient phagocytosis. The minimum centrifugal force required for maximal response was determined under the conditions in which equalized collision frequency between bacteria and macrophages was maintained when different centrifugal forces were employed. From the value obtained (5 x g), the required rate of movement was calculated as approximately 2.5 microns/s, supposing that the bacterium is spherical and has a 1-micron radius. This value is much lower than the velocity of movement of motile bacteria (20 to 50 microns/s). The results indicate that physical impact caused by bacterial motility is enough to induce a high response of macrophages.
Role of competition for substrate in bacterial antagonism in the gut
Authors: Guiot H F
Published: January 2020

Small slices of agar, each containing about 10(5.5) Escherichia coli organisms, were preincubated either in the contents of rat cecum or in brain heart infusion broth for 2 h and then were transferred to a small sample of saline. The purpose of these experiments was to examine the ability of E. coli to grow on the substrate that penetrated from the contents of rat cecum into the agar slices. It appeared that preincubation in brain heart infusion broth gave rise to abundant growth, whereas only poor growth occurred after preincubation in the contents of rat cecum. This poor growth was completely reversed by adding brain heart infusion. The same experiments were repeated under anaerobic conditions, in which growth on substrate that penetrated from the contents of rat cecum into the agar slices was extremely poor. This extremely poor growth under anaerobic conditions was reversed to abundant growth by adding brain heart infusion broth. The addition of nitrate as an electron acceptor also stimulated growth of E. coli. Similar results were obtained with other bacteria and with human feces. The results can be interpreted as a demonstration that under anaerobic conditions such as occur in large intestines, bacterial antagonism is caused in a high degree by competition for substrate.
Passive protection of mice and sheep against bluetongue virus by a neutralizing monoclonal antibody
Authors: Letchworth G J , Appleton J A
Published: January 2020

A murine hybridoma antibody, 6C2A.4.2, previously characterized as an immunoglobulin G class 2a that binds in radioimmunoassay to bluetongue virus serotype 17 (BTV-17) but not the other 19 BTV serotypes, neutralizes BTV-17, inhibits hemagglutination with BTV-17, and precipitates viral polypeptides 2 and 3 from BTV-17-infected cells, was produced as an ascites in the peritoneal cavities of hybridoma-inoculated mice. This ascitic fluid, but not those containing other, non-neutralizing anti-BTV-17 antibodies of the same isotype, provided serotype-specific passive protection against BTV-17-induced death of neonatal mice. Antibody 6C2A.4.2-containing ascitic fluid was injected intravenously into sheep that were later inoculated with BTV-17. These sheep remained free of clinical signs, did not develop viremia or detectable levels of antibodies reactive in the immunodiffusion test used for routine BTV diagnosis in the United States, and developed only low levels of neutralizing antibodies. Control animals became viremic and developed immunodiffusion test reactions and high levels of neutralizing antibodies during recovery, and two of three had lesions and fevers. These results provide evidence that antibodies directed against a single epitope on BTV-17 can prevent bluetongue disease.
Experimental model for dermal granulomatous hypersensitivity in Q fever
Authors: Ascher M S , Berman M A , Parker D , Turk J L
Published: January 2020

Q fever has been associated with granulomatous changes in clinical biopsy material obtained from liver and bone marrow. Local reactions to skin testing have been described in previously sensitized humans, but histological studies of such reactions have not been reported. We note that delayed hypersensitivity reactions to whole-cell phase I Q fever vaccine in immunized guinea pigs have a time course of development of induration characteristic of granulomatous hypersensitivity. Histological examination of such skin reactions on day 9 after testing revealed epithelioid cell infiltration and the presence of large numbers of multinucleated giant cells. Prominent in the sections were fragments of disintegrating polymorphonuclear leukocytes having the appearance of leukocytoclasis. Electron microscopic studies confirmed the presence of epithelioid changes in cells of the mononuclear phagocyte series, as well as extensive collagen deposition. This animal system affords a readily reproducible model of dermal granulomatous hypersensitivity and an opportunity to analyze the immunological basis of this reaction.
Enhanced susceptibility of mice with streptozotocin-induced diabetes to type II group B streptococcal infection
Authors: Edwards M S , Fuselier P A
Published: January 2020

Since diabetes mellitus predisposes adults to group B streptococcal (GBS) bacteremia, a murine model of streptozotocin-induced diabetes and type II GBS bacteremia was developed to assess certain immune factors which might influence susceptibility to infection. In diabetic mice, the 50% lethal dose for two strains of type II GBS was significantly lower (greater than 1 log10 decrease in CFU per milliliter) than in control animals. This enhanced virulence of GBS for diabetic animals was associated with prolonged bacteremia, persistent sequestration of organisms in the splanchnic reticuloendothelial system, and a shift from splenic to hepatic clearance. Although immunization of control and diabetic animals resulted in high concentrations of type-specific serum antibody, it had no effect on late reticuloendothelial system sequestration in diabetics. In contrast, depletion of complement by treatment of mice with cobra venom factor blocked reticuloendothelial system clearance and resulted in fatal infection in both diabetic and control mice. These results indicate that neither type-specific antibody nor an intact complement system is adequate for effective clearance of type II GBS bacteremia in mice with experimentally induced diabetes. This clearance deficit could be the result of a defect in hepatocyte membrane receptors necessary for removal of this encapsulated microorganism.
Characterization of the murine immune response to type 6 pneumococcal polysaccharide
Authors: Fairchild R L , Braley-Mullen H
Published: January 2020

The antibody response to type 6 (Danish type 6A) pneumococcal capsular polysaccharide (S6) was determined in various strains of mice. S6 elicited a very low plaque-forming cell (PFC) response in most strains of mice. BALB/c mice responded better than most other strains, and the response to S6 was further characterized in BALB/c mice. Immunization with 1 to 5 micrograms of S6 induced a plaque-forming cell response of short duration which consisted totally of immunoglobulin M-producing PFC. Athymic nude mice produced three- to fivefold more PFC in response to S6 than their euthymic littermates, suggesting that thymus-derived (T) cells negatively influence the S6 response. Regulation of the response by T cells was further suggested by the ability of antilymphocyte serum to enhance the S6 PFC response and by the suppressed response induced by priming with a low dose of S6 3 days before immunization with an optimal dose of S6 (low dose paralysis). When concanavalin A was given 2 days after immunization with S6, the response was enhanced two- to sevenfold, suggesting that the response is also positively influenced by T amplifier cells. When the avidity of the antibody produced by S6-specific PFC was measured by a plaque inhibition test, the avidity of the anti-S6 antibody was found to be very low. These results suggest that S6 is a poor immunogen because the affinity of the S6-specific antibody and B cell surface receptors is low.
Continuous-flow cultures as in vitro models of the ecology of large intestinal flora
Authors: Freter R , Stauffer E , Cleven D , Holdeman L V , Moore W E
Published: January 2020

An anaerobic continuous-flow (CF) culture method has been developed which reproduces a number of bacterial interactions that occur in the large intestine of mice. These were determined in the following ways. (i) Bacterial counts in smears stained with 37 specific fluorescent antisera showed that the numeric balance between 37 strict anaerobes isolated from conventional mice was maintained in CF culture of conventional mouse flora in the same manner as in conventional mice. (ii) Mixed populations of various complexity of bacteria isolated from conventional mice were able to suppress Escherichia coli populations to similar levels in gnotobiotic mice and in CF cultures. (iii) Contents of CF cultures when fed to germfree mice were found to redress the germfree abnormalities studied, namely, cecal size and size of the E. coli population. Furthermore, dense layers of bacterial growth formed on the wall of CF cultures of mouse cecal flora, in a manner analogous to the colonization of mouse large intestinal mucosa. In the absence of such bacterial layers, the culture no longer exhibited these interactions. Because of the complexity and diversity of the interactions studied it is highly probable that at least the major underlying ecological control mechanisms operating in the culture model resemble those of the mouse intestine. We speculate that the somewhat surprising similarity between the ecology of the mouse large intestine and that of a CF culture in a glass vessel is due to the fact that both are dominated by thick layers of complex bacterial flora, the composition of which is controlled by their metabolic activities and by their relative ability to adhere to each other.
Survival and Implantation of
Escherichia coli
in the Intestinal Tract
Authors: Freter Rolf , Brickner Howard , Fekete Janet , Vickerman Mary M. , Carey Kristen E.
Published: January 2020

Preliminary experiments established that a 0.5-ml inoculum that is introduced directly into the stomach of mice was cleared rapidly into the small intestine. Bicarbonate buffer, but not skim milk, protected such an inoculum from stomach acid until at least 90% of it had entered the small intestine. Passage and survival of various
Escherichia coli
strains through the mouse gut were tested by introducing a buffered bacterial inoculum directly into the stomach, together with the following two intestinal tracers: Cr
51
Cl
3
and spores of a thermophilic
Bacillus
sp. Quantitative recovery of excreted bacteria was accomplished by collecting the feces overnight in a refrigerated cage pan. The data show that wild-type
E. coli
strains and
E. coli
K-12 are excreted rapidly (98 to 100% within 18 h) in the feces without overall multiplication or death.
E. coli
ϰ1776 and DP50supF, i.e., strains certified for recombinant DNA experiments underwent rapid death in vivo, such that their excretion in the feces was reduced to approximately 1.1 and 4.7% of the inoculum, respectively. The acidity of the stomach had little bactericidal effect on the
E. coli
K-12 strain tested, but significantly reduced the survival of more acidsensitive bacteria (
Vibrio cholerae
) under these conditions. Long-term implantation of
E. coli
strains into continuous-flow cultures of mouse cecal flora or into conventional mice was difficult to accomplish. In contrast, when the
E. coli
strain was first inoculated into sterile continuous-flow cultures or into germfree mice, which were subsequently associated with conventional mouse cecal flora, the
E. coli
strains persisted in a large proportion of the animals at levels resembling
E. coli
populations in conventional mice. Metabolic adaptation contributed only partially to the success of an
E. coli
inoculum that was introduced first. A mathematical model is described which explains this phenomenon on the basis of competition for adhesion sites in which an advantage accrues to the bacterium which occupies those sites first. The mathematical model predicts that two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available. The specific rate constant of
E. coli
growth in monoassociated gnotobiotic mice was 2.0 h
−1
, whereas the excretion rate in conventional animals was −0.23 h
−1
. Consequently, limitation of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine. The beginnings of a general hypothesis of the ecology of the large intestine are proposed, in which the effects of the competitive metabolic interactions described earlier are modified by the effects of bacterial association with the intestinal wall.
Analysis of cell wall and membrane contamination of ribosomal preparations from Streptococcus mutans
Authors: Gregory R L , Shechmeister I L
Published: January 2020

A ribosomal preparation from a cariogenic strain of Streptococcus mutans was examined for cell wall and membrane contamination. A biochemical characterization established that the preparation contained 61.0% RNA and 39.0% protein. Carbohydrate was not detected by phenol-sulfuric acid or methyl pentose assays. Glucosyltransferase and D-succinate dehydrogenase, which are cell wall- and membrane-associated enzymes, respectively, were not found. However, D-lactate dehydrogenase, another membrane-associated enzyme, was present in the preparation. A comparison of two-dimensional gel electropherograms of a mixture of cell walls and membranes and the S. mutans ribosomal preparation revealed contamination of the latter sample with at least six cell wall- or membrane-associated proteins. Adsorption of a rabbit antiserum raised against the ribosomal preparation with whole S. mutans cells abrogated antibodies directed against at least two proteins from the ribosomal preparation. Immunodiffusion plates showed reactivity of this antiserum against preparations of purified lipoteichoic acid from Streptococcus pyogenes and S. mutans. Adsorption of rat and rabbit antisera against the ribosomal preparation with the cell wall-derived materials glucosyltransferase, lipoteichoic acid, glucan, and a Rantz-Randall extract reduced the concentration of antibodies against the ribosomes by as much as 10-fold. These data indicated that the preparation was contaminated with at least six cell wall proteins, one cell membrane-associated enzyme, and lipoteichoic acid.
Experimental
Campylobacter jejuni
Infection of Adult Mice
Authors: Blaser Martin J. , Duncan Deborah J. , Warren George H. , Wang Wen-Lan L.
Published: January 2020

HA-ICR adult mice were studied to develop an animal model for
Campylobacter jejuni
enteritis in humans. Fecal and ileal cultures made by selective and nonselective methods showed that
C. jejuni
and related organisms are not bowel commensals. Intragastric feeding of 10
8
CFU of three different strains of
C. jejuni
produced infection in 100% of the animals, and infection rates were dose dependent. Pretreatment with antibiotics or opiates was not necessary to induce infection. Fresh isolates and strains passed on artificial media yielded similar infection rates. Infected mice did not show signs of illness, but transient bacteremia within 10 min of oral infection was observed in nearly 100%. The small intestine was the principal target organ, with epithelial inflammation seen 48 h after infection. Control mice of four species had undetectable serum immunoglobulin G antibody specific for the infecting strain, but infected mice showed peak titers at 1 week with rapid decline. Immunoglobulin M titers rose minimally, and immunoglobulin A titers did not rise. Infected mice uniformly became chronic asymptomatic excretors, shedding 10
4
to 10
6
CFU/g of feces; a minority were biliary carriers. Intestine carriage was most pronounced in the stomach and proximal small intestine. Because this experimental infection led to bacteremia, transient pathological changes, and immunoglobulin G titer rises, this model may be useful for evaluating the effects of prophylactic and therapeutic interventions.