bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro cytotoxic effect of alpha-hemolytic Escherichia coli on human blood granulocytes
Authors: Gadeberg O V , Orskov I
Published: January 2020

The cytotoxic effect of Escherichia coli bacteria on human blood granulocytes was measured by recording numbers of nonlysed cells and percentages of viable cells after in vitro incubation with bacteria in the presence of plasma. A total of 179 strains from various sources of infection were tested. Of 117 alpha-hemolytic strains, 59 were cytotoxic. Five nonhemolytic mutant strains, derived from alpha-hemolytic cytotoxic strains, were nontoxic. None of the 62 nonhemolytic strains were toxic. Four spontaneously occurring alpha-hemolytic, nontoxic mutant strains were isolated from cytotoxic ones. Cytotoxicity of bacteria reached a maximum after log-phase growth at 30 to 37 degrees C for 2.5 h, and the toxic capacity was equal after growth in various media, including human urine and plasma. The cytotoxic effect increased with the length of exposure of granulocytes to bacteria and with increasing numbers of bacteria per granulocyte. Cytotoxic strains showed different degrees of toxicity, highly cytotoxic strains lysing about 90% of the granulocytes and killing about one-half of nonlysed cells in 1 h. Bacteria killed by heat, formaldehyde, or UV light were nontoxic. Alpha-hemolytic strains of O groups 2, 4, 6, 25, and 75 originating from various infections in humans were more frequently cytotoxic than alpha-hemolytic strains of other O groups derived from human infections. Culture supernatants containing free alpha-hemolysin were highly cytotoxic to human blood granulocytes, monocytes, and lymphocytes in vitro, whether supernatants originated from cytotoxic or noncytotoxic bacteria. Cytotoxicity to phagocytes, which is mediated by or closely linked genetically to alpha-hemolysin, may be a mechanism by which alpha-hemolytic strains of E. coli strengthen their ability to establish and maintain infections.
Microbicidal activity and morphological characteristics of lung macrophages in Mycobacterium bovis BCG cell wall-induced lung granuloma in mice
Authors: Kato K , Yamamoto K , Okuyama H , Kimura T
Published: January 2020

Morphological and functional changes in lung macrophages from mice injected intravenously with Mycobacterium bovis BCG cell walls (CWs) were studied. In BCG CW high-responder mice (C57BL/6 [B6] strain), an increase in the size and the acid phosphatase activity of lung macrophages was observed. These lung macrophages showed greater microbicidal activity to M. bovis Ravenel and Listeria monocytogenes EGD, enhanced superoxide anion production index, and greater macrophage migration inhibition activity, as compared with lung macrophages from BCG CW low-responder mice (C3H/He strain), which were small in size and showed weak acid phosphatase activity, low antimicrobial activity, and low superoxide anion production index upon intravenous injection of the mice with BCG CW. These results indicated that lung macrophages from B6 mice injected with BCG CWs were morphologically and functionally activated, but not those from C3H mice.
Longitudinal study on the in vitro immune response to Plasmodium falciparum in Sudan
Authors: Vande Waa J A , Jensen J B , Akood M A , Bayoumi R
Published: January 2020

Inhibition of Plasmodium falciparum in vitro by human immune serum provides needed information in understanding antimalarial immune mechanisms. Longitudinal, dry season-to-wet season changes in antimalarial activities were studied in sera isolated from 62 individuals living in an area of hyperendemic but unstable malaria. Highly synchronous cultures of P. falciparum were used to distinguish and quantitate two antimalarial activities, merozoite invasion inhibition, and intraerythrocytic parasite retardation. In 54% of the individuals, intraerythrocytic parasite retardation activity increased significantly, nearly threefold, in wet-season sera as compared with dry-season sera. Merozoite invasion inhibition activity was moderate and did not change seasonally. Merozoite invasion inhibition was, however, correlated to parasite-specific immunoglobulin G titers and total serum immunoglobulin G concentrations. These results confirm earlier studies which demonstrate two antimalarial activities in Sudanese sera and provide evidence that intraerythrocytic parasite retardation activity plays a role in antimalarial immunity.
Evidence for pseudomonas exotoxin A receptors on plasma membrane of toxin-sensitive lm fibroblasts
Authors: Manhart M D , Morris R E , Bonventre P F , Leppla S , Saelinger C B
Published: January 2020

Pseudomonas exotoxin A enters mouse LM fibroblasts by receptor-mediated endocytosis and ultimately causes cell death. Here we present evidence for the existence of a specific receptor for the toxin. Toxin association with LM cells at 18 and 37 degrees C, but not at 4 degrees C, was highly specific. At 37 degrees C, the association increased with time, reaching a steady state by 5 h. Binding to paraformaldehyde-fixed cells at 37 degrees C was saturable (Kd = 5.4 nM), was reversible, and indicated ca. 100,000 binding sites per cell. It is believed that receptor-bound toxin is responsible for cell death. Once the kinetics of toxin entry were described, we examined the effect of reduced temperatures on the intracellular processing of toxin and thus its expression. Toxin-induced inhibition of protein synthesis was minimal at temperatures below 20 degrees C. This was seen even though at 20 degrees C sufficient toxin was internalized to kill cells, and toxin enzyme activity was maximal. Internalization of 125I-labeled toxin, but not of 125I-labeled horseradish peroxidase (marker of fluid-phase endocytosis), became rate limiting at 20 degrees C or below. These data suggest that reduced temperatures block a step in the receptor-mediated endocytic pathway essential for the expression of Pseudomonas toxin activity.
Neutralization of tetanus toxin by distinct monoclonal antibodies binding to multiple epitopes on the toxin molecule
Authors: Volk W A , Bizzini B , Snyder R M , Bernhard E , Wagner R R
Published: January 2020

Fifty-seven hybridomas producing antibodies to tetanus toxoid or to the Ibc or B-IIb fragment of the toxin were isolated independently. Competitive inhibition studies demonstrated that monoclonal antibodies from mice immunized with the toxoid bound to at least 20 different epitopes on the toxoid molecule. Similar competitive binding studies revealed eight distinct epitopes on the B-IIb fragment and three to five epitopes on the Ibc fragment of the toxin. Neutralization of toxicity was effected by nine distinct monoclonal antibodies from hybridomas of toxoid-immunized mice and by one monoclonal antibody from B-IIb-immunized mice. Mixtures of two, three, and four different monoclonal antibodies in a variety of combinations exerted a synergistic effect of ca. 200-fold over that observed with individual monoclonal antibodies, indicating that efficient neutralization may involve the simultaneous binding of at least two antibody molecules to different specific regions of the toxin molecule. Only one toxoid-induced monoclonal antibody failed to bind to tetanus toxin. All neutralizing antibodies bound to epitopes on the heavy chain of tetanus toxin. Six of these were directed toward epitopes on the NH2-terminal half, whereas four bound to epitopes on the carboxy-terminal half of the heavy chain. Only one monoclonal antibody bound preferentially to the light chain, but two other monoclonal antibodies appeared to bind to both chains, indicating some homology between these two chains.
In vitro and in vivo studies of cellular lysis of oral bacteria by a lysozyme-protease-inorganic monovalent anion antibacterial system
Authors: Pollock J J , Shoda J , McNamara T F , Cho M I , Campbell A , Iacono V J
Published: January 2020

Compared with anion-activated cell lysis of oral bacteria damaged with either lysozyme or trypsin, cells which were treated with both of these enzymes showed a far greater degree of lysis. This was true regardless of whether turbidimetric, DNA release, or electron microscopic assays were used to monitor the lytic process. At an acidic pH of 5.2 and an NaHCO3 concentration of 100 mM, the kinetics of lysis for two different serotype c strains of Streptococcus mutans were similar. At 0 to 100 mM bicarbonate, however, differences in the lytic susceptibilities of the two strains were evident. At pH 5.2, NaHCO3, but not NaSCN, NaCl, or NaF, was effective in promoting cell lysis of the oral bacteria. At apparent sublytic concentrations of NaHCO3, lysis was achieved by adding appropriate concentrations of NaSCN, NaCl, or NaF to the lysozyme-protease-damaged cells. In in vivo studies, hamsters given a combination of NaHCO3, NaCl, and NaSCN were found to have significantly reduced levels of S. mutans on their molar teeth compared with that found in controls or animals exposed to any one of the salts alone or to a combination of chloride and thiocyanate only. The results suggest that bicarbonate is an essential anion which, together with the other major salivary inorganic monovalent anions, plays an active role in the lysis and ultimate elimination of cariogenic bacteria.
Growth in mouse peritoneal macrophages of Yersinia pestis lacking established virulence determinants
Authors: Straley S C , Harmon P A
Published: January 2020

Cultured mouse resident peritoneal macrophages were challenged with strains of Yersinia pestis differing only with respect to the absence of one or more of the virulence determinants established for the species. Guanine-auxotrophic (Pur-) yersiniae were unable to survive within the macrophages; exogenous hypoxanthine and guanosine permitted intracellular growth. This finding supports the idea that Pur- yersiniae are avirulent due to inability to obtain sufficient free purines in host tissues for growth and maintenance and indicates that net biosynthesis is necessary to counteract the intracellular microbicidal environment of macrophages. Yersiniae unable to pigment in medium containing the dye Congo red (Pgm-) or lacking either of the plasmids associated with the pesticin or calcium dependence virulence determinants (Pst- and Vwa-, respectively) were taken up as efficiently into macrophages and grew as well within these cells as did bacteria having all invasive virulence determinants intact. Opsonization with 100% homologous normal serum before infection of macrophages did not affect the ability of Pgm- or Vwa- Pgm- yersiniae to grow within macrophages. Accordingly, attributes independent of these virulence determinants mediate the survival and growth of yersiniae in serum and within resident macrophages, and components of the mammalian environment other than serum and macrophages must interact with Pgm-, Pst- and Vwa- yersiniae to cause their avirulence in vivo.
Antibody in host defense against mouse pneumonitis agent (murine Chlamydia trachomatis)
Authors: Williams D M , Schachter J , Weiner M H , Grubbs B
Published: January 2020

In a murine model of chlamydial pneumonia employing murine Chlamydia trachomatis, immune serum given intranasally delayed death in nude (nu/nu) mice and prevented death in nu/+ mice. Serum-derived immunoglobulin G and A fractions and immune lavage fluid fractions containing immunoglobulins G and A were effective in producing protection when used to opsonize the murine C. trachomatis inoculum. In hyperclean mice (previously made germfree and then colonized with a limited flora nonpathogenic to mice) antibody given intravenously was ineffective. The effects of antibody and nonspecific stimulation of cell-mediated immunity (after previous infection with Histoplasma capsulatum) were additive in increasing host resistance to murine C. trachomatis.
Pulmonary cellular response to chronic irritation and chronic Pseudomonas aeruginosa pneumonia in cats
Authors: Thomassen M J , Klinger J D , Winnie G B , Wood R E , Burtner C , Tomashefski J F , Horowitz J G , Tandler B
Published: January 2020

A model of chronic pulmonary infection was used for studying cellular events in a sequential manner. In this model, agarose beads containing Pseudomonas aeruginosa were instilled endotracheally into cats. Nine cats were inoculated with agarose beads containing P. aeruginosa, and four others were inoculated with sterile beads. With a fiberoptic bronchoscope, bronchial washings were obtained biweekly for up to 30 weeks. The quantitative pulmonary inflammatory cell response and alveolar macrophage morphology of the animals exposed to P. aeruginosa were compared with those for the animals exposed to a chronic irritant (agarose beads). Bronchial washings of all animals before inoculation showed that 70 to 90% of the cells were macrophages. After inoculation with P. aeruginosa, a persistent inflammatory response was observed (60 to 70% granulocytes). In the sterile-bead-inoculated group, the response was less prominent (30 to 40% granulocytes). As early as 2 weeks after inoculation, alveolar macrophages from infected animals were larger and had cytoplasmic features that differed from those of controls. Electron microscope examination showed prominent surface alterations in alveolar macrophages from the infected cats. These alterations persisted from 2 to 12 weeks after infection. In animals inoculated with sterile beads, alveolar macrophages exhibited less extensive surface changes that had resolved by week 8. Histologically, chronic bronchiolitis and pneumonia were more severe in the infected animals than in controls. This model of chronic inflammation and macrophage stimulation, which is similar to the chronic pneumonia of cystic fibrosis, may be a useful approach to answer questions on the role of macrophage activation in chronic lung disease.
Identification of a high-affinity binder for estradiol and a low-affinity binder for testosterone in Coccidioides immitis
Authors: Powell B L , Drutz D J
Published: January 2020

Coccidioides immitis cytosol contains a specific estrogen binder with kinetic characteristics (Kd = 2.1 X 10(-8) to 3.7 X 10(-8) M; n = 0.5 to 1.56 pmol/mg of protein) appropriate for interaction with levels of estrogen encountered during pregnancy. The Kd of a separate androgen binder (ca. 10(-7) M) is probably too low to allow interaction with physiological levels of testosterone.
Brucellacidal activity of human and bovine polymorphonuclear leukocyte granule extracts against smooth and rough strains of Brucella abortus
Authors: Riley L K , Robertson D C
Published: January 2020

The microbicidal activities of freeze-thaw and high-salt extracts of human and bovine polymorphonuclear leukocyte (PMN) granules were tested against a smooth intermediate strain (45/0) and a rough strain (45/20) of Brucella abortus which differ in virulence and survival within PMNs. Freeze-thaw extracts of human PMN granules were more brucellacidal than high-salt extracts when supplemented with hydrogen peroxide (H2O2) and potassium iodide (KI), whereas the opposite was found with freeze-thaw and high-salt extracts of bovine PMN granules. There was no oxygen-independent killing of either the smooth or rough strain of B. abortus by amounts of granule extracts which caused 100% killing of a deep rough mutant (Re) of Salmonella typhimurium. The oxygen-dependent brucellacidal activity of granule extracts was dependent on concentrations of myeloperoxidase (MPO) units, H2O2, and KI. Maximal brucellacidal activity was observed at pH 5.5 to 6.0. The smooth strain, 45/0, was more resistant to oxygen-dependent killing by granule extracts than was the rough strain, 45/20. Granule extracts were more brucellacidal than purified MPO at equivalent levels of MPO enzyme units, suggesting that at least one other reaction enhances killing by the MPO-H2O2-I- system.
Unique and common protective epitopes among different serotypes of group A streptococcal M proteins defined with hybridoma antibodies
Authors: Dale J B , Beachey E H
Published: January 2020

A set of four monoclonal antibodies was produced against a highly purified pepsin extract of type 5 streptococcal M protein. Three of the four antibodies cross-reacted with purified M proteins from heterologous serotypes and opsonized the respective heterologous organisms. Our studies suggest that monoclonal antibodies may be useful in identifying subpeptides of various M proteins containing common, protective epitopes that are capable of evoking antibodies that would protect against several different potentially "rheumatogenic" serotypes.
Induction of immune and adjuvant immunoglobulin G responses in mice by Brucella lipopolysaccharide
Authors: Moreno E , Kurtz R S , Berman D T
Published: January 2020

The immunogenic and adjuvant properties of Brucella abortus and Escherichia coli lipopolysaccharides (LPSs) were studied in endotoxin-responsive, athymic, and euthymic BALB/c mice and in responsive C3H/HeAu mice and congenic nonresponsive C3H/HeJ mice. Consistent with previous reports, E. coli LPS did not stimulate significant primary or secondary antibody responses in C3H/HeJ mice and induced the production of immunoglobulin M (IgM) and low levels of IgG in C3H/HeAu mice. In contrast, B. abortus smooth and rough LPS stimulated primary and secondary antibody responses and induced the production of IgM and high levels of IgG in both responsive and nonresponsive strains of C3H/He mice and in nude mice. When used as adjuvant, B. abortus LPS augmented the IgG plaque-forming-cell response of C3H/HeAu and BALB/c euthymic mice to the T-dependent antigen sheep erythrocytes. E. coli LPS augmented only the IgM plaque-forming-cell response in the same mouse strains. Neither B. abortus nor E. coli LPS was adjuvant for C3H/HeJ or nude mice. The dichotomy between the antibody and adjuvant responses of both C3H/HeJ mice and athymic mice to B. abortus LPS may be a function of the true thymus independence and dependence of these responses. In addition, the refractiveness of C3H/HeJ and nude mice to B. abortus LPS as adjuvant, but not as mitogen or polyclonal B cell activator, clearly dissociates these phenomena.
Monoclonal antibody detection of IncF group plasmid-encoded TraT protein in clinical isolates of Escherichia coli
Authors: Bitter-Suermann D , Peters H , Jürs M , Nehrbass R , Montenegro M , Timmis K N
Published: January 2020

The TraT protein specified by IncF group plasmids mediates surface exclusion and bacterial resistance to the lethal activities of serum. In this study, an anti-TraT protein monoclonal antibody was generated which failed to react with TraT+ bacteria but which efficiently detected solubilized TraT protein in Western blots and in an enzyme-linked immunosorbent assay. Use of this antibody to screen clinical and nonclinical isolates of Escherichia coli for the production of TraT protein revealed its presence in a modest proportion (38%) of normal fecal strains, a significantly higher proportion of clinical strains (51 to 73%), and an even higher proportion (78 to 88%) of clinical strains concomitantly producing the K1 capsule, an important virulence factor of E. coli.
Correlation between toxin binding and hemolytic activity in membrane damage by staphylococcal alpha-toxin
Authors: Bhakdi S , Muhly M , Füssle R
Published: January 2020

The binding of Staphylococcus aureus alpha-toxin to rabbit and human erythrocytes was studied by hemolytic assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting. Hemolytic assays showed that toxin binding to 10% cell suspensions at neutral pH was very ineffective in the concentration range 3 X 10(-8) to 3 X 10(-7) M (1 to 10 micrograms/ml), and less than 5% of added toxin became cell bound. However, binding was augmented as toxin levels were raised, abruptly increasing to 50 to 60% at 2 X 10(-6) to 3 X 10(-6) M (60 to 100 micrograms/ml). When rabbit erythrocytes were lysed with 1 to 5 micrograms of toxin per ml, both monomeric and hexameric forms of the toxin could be detected on the membranes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting. In contrast, human erythrocytes treated with 1 to 6 micrograms of toxin per ml did not lyse, and membrane-bound toxin was not detectable. When toxin concentrations were raised to 30 to 100 micrograms/ml, human erythrocytes also lysed and toxin hexamers became membrane bound in comparable amounts as on rabbit cell membranes. Lowering the pH led to a marked increase in susceptibility of human, but not rabbit erythrocytes towards alpha-toxin. When human cells were lysed at pH 5.0 with 5 micrograms of toxin per ml, membrane-bound hexameric toxin became detectable. The demonstrated correlation between the presence of hexameric, cell-bound toxin and hemolytic activity supports the channel concept of toxin-mediated cytolysis. The results also show that toxin binding does not exhibit overall characteristics of a simple receptor-ligand interaction.
Monocyte suppression of Fusobacterium nucleatum-induced human polyclonal B-lymphocyte activation
Authors: Mangan D F , Won T , Lopatin D E
Published: January 2020

Previous studies reported that Fusobacterium nucleatum induced polyclonal B-lymphocyte activation (PBA) as determined by immunoglobulin M production in cultures of human peripheral blood mononuclear cells. However, the PBA response was greatly enhanced when the cells were depleted of esterase-positive, adherent cells (i.e., monocytes). The purpose of this study was to confirm and further examine the suppression of F. nucleatum-induced PBA (F. nucleatum-PBA) by blood monocytes. For comparison, PBA induced by pokeweed mitogen (PWM-PBA), which is enhanced by monocytes, was assessed in some experiments. We found the removal of monocytes from unfractionated cells by (i) Sephadex G-10, (ii) anti-monocyte specific OM-1 monoclonal antibody plus complement, or (iii) L-leucine methyl ester, a compound which selectively kills lysosome-rich cells, resulted in a population of cells responsive to F. nucleatum-PBA and unresponsive to PWM-PBA. The addition of double adherence-purified monocytes (greater than 85% esterase-positive cells), particularly in concentrations of greater than 10%, to lymphocytes depleted of monocytes by G-10, OM-1, or L-leucine methyl ester treatments, suppressed F. nucleatum-PBA and enhanced PWM-PBA. Monocytes also suppressed a mixture of isolated T and B cells combined in a T/B cell ratio of 3:1, which is an optimal ratio for F. nucleatum-PBA. Allogeneic monocytes suppressed F. nucleatum-PBA, although at low numbers these cells were not as suppressive as autologous monocytes. Heating at 56 degrees C for 15 min, sonicating, or freeze-thawing the monocyte preparations resulted in an abrogation of monocyte-induced suppression of F. nucleatum-PBA. Kinetic studies in which fresh monocytes were added daily to lymphocytes stimulated with F. nucleatum or PWM showed that the monocytes must be added within the first 2 days of culture to suppress F. nucleatum-PBA or enhance PWM-PBA. Monocytes incubated with F. nucleatum for 48 h released into the culture medium a soluble factor that suppressed F. nucleatum-PBA. The results from this study demonstrate a potent mechanism by which the host might prevent exaggerated nonspecific immunoglobulin responses when exposed to PBA-inducing concentrations of F. nucleatum. On the other hand, the induction of suppressive monocytes (or monocyte-mediated suppressive factors) by interaction with F. nucleatum might result in the inhibition of host protective immune reactions.
Enhancement of experimental actinomycosis in mice by Eikenella corrodens
Authors: Jordan H V , Kelly D M , Heeley J D
Published: January 2020

The infectivity of Actinomyces israelii in a susceptible-weanling-mouse was increased by the presence of Eikenella corrodens in the inoculum. A minimal infecting dose of 1.7 X 10(7) CFU of A. israelii was required to establish chronic lesions after an intraperitoneal injection. When E. corrodens (3.8 X 10(7) CFU) was included in the inoculum, chronic lesions were established with a dose of 8.5 X 10(4) CFU of A. israelii. E. corrodens alone did not produce persistent lesions. Viable E. corrodens could be recovered from chronic mixed actinomycotic lesions in numbers that often equaled or exceeded the populations of A. israelii in the lesions. The duration of acute actinomycotic infections caused by A. viscosus was temporarily extended by the presence of E. corrodens. The cellular inflammatory response and overall morphology of mixed experimental lesions containing A. israelii and E. corrodens did not appear to be significantly different from those of pure-culture lesions containing A. israelii alone. E. corrodens cells could not be readily discerned in stained histological sections of mixed experimental lesions.
Oral vaccination of monkeys with an invasive Escherichia coli K-12 hybrid expressing Shigella flexneri 2a somatic antigen
Authors: Formal S B , Hale T L , Kapfer C , Cogan J P , Snoy P J , Chung R , Wingfield M E , Elisberg B L , Baron L S
Published: January 2020

A living oral vaccine, designed to protect against Shigella flexneri 2a infections, was constructed by using Escherichia coli K-12 as a carrier strain. The hybrid strain, designated EC104, contained both chromosomal and plasmid genes from S. flexneri donor strains. In addition to expressing the S. flexneri 2a somatic antigen, it had inherited the property of epithelial-cell invasion. After the oral administration to rhesus monkeys, EC104 was isolated from the feces for up to 3 days, but by day 4 all stool cultures were negative. The serum antibody response against S. flexneri 2a somatic antigen was variable, but the vaccine conferred significant protection against an oral challenge with virulent S. flexneri 2a.
Colony-stimulating activity induced by synthetic muramyl peptides: variation with chemical structure and association with anti-infectious activity
Authors: Galelli A , Lefrancier P , Chedid L
Published: January 2020

The in vivo induction of colony-stimulating activity (CSA) by N-acetylmuramyl-L-alanine-D-isoglutamine has been demonstrated recently. In this study we increased our understanding of this property by testing muramyl peptides of several structures and activities for their capacity to induce CSA in vivo. A comparison of the anti-infectious and adjuvant activities of these molecules revealed no correlation between the capacities of these compounds to be adjuvant active and to induce CSA: all adjuvant-inactive compounds induced CSA, and certain adjuvant-active molecules did not induce CSA. In contrast, all anti-infectious compounds induced CSA, but the reverse was not true; some compounds devoid of anti-infection activity were able to induce CSA only if they were adjuvant active.
In vitro effects of natural killer cells against Paracoccidioides brasiliensis yeast phase
Authors: Jimenez B E , Murphy J W
Published: January 2020

Recently, data have been reported suggesting natural killer (NK) cells may function in natural resistance against a fungus, Cryptococcus neoformans. The primary objective of this study was to examine the reactivity of murine splenic cells against another fungus, Paracoccidioides brasiliensis. Levels of NK activity in effector cell pools were varied by: (i) removing nylon wool-adherent cells, (ii) fractionating splenic cells on Percoll discontinuous gradients, (iii) using old and young effector cell donor mice, (iv) using donors from different strains, and (v) pretreating donors with NK-augmenting and -depressing agents. The various effector cell pools were simultaneously used in the 4-h 51Cr release assay with YAC-1 targets to determine the NK reactivity and in the in vitro growth inhibition assay against P. brasiliensis yeast phase targets. In each case, the level of NK reactivity correlated with the ability of the effector cells to inhibit the in vitro growth of P. brasiliensis. NK activity and P. brasiliensis growth-inhibiting ability could be augmented by fractionation of splenic cells through nylon wool or Percoll gradients. The effector cells responsible for the NK activity and P. brasiliensis growth inhibition were characterized as being nylon wool nonadherent, being found in the low-density fractions from Percoll discontinuous gradients, and having no detectable Thy-1 antigen or immunoglobulin but having asialo GM1 on their surface. These data support the contention that NK or NK-like cells are responsible for limiting the in vitro growth of P. brasiliensis.
Does enteropathogenic Escherichia coli produce heat-labile enterotoxin, heat-stable enterotoxins a or b, or cholera toxin A subunits?
Authors: Long-Krug S A , Weikel C S , Tiemens K T , Hewlett E L , Levine M M , Guerrant R L
Published: January 2020

Although most enteropathogenic Escherichia coli strains do not produce recognized enterotoxins, we wished to examine whether they produce any factors like heat-stable enterotoxin b or cholera toxin active subunits that might be missed by conventional assay methods. E. coli strains E851 (O142) and E2348 (O127) that had caused diarrhea in volunteers were negative for heat-labile enterotoxin and heat-stable enterotoxin a in Chinese hamster ovary cell and suckling mouse assays, failed to cause secretion in ligated small bowel loops from 6- to 8-week-old pigs after 4 to 5 h (used to show heat-stable enterotoxin b), and did not activate adenylate cyclase in pigeon erythrocyte lysates (used to demonstrate cholera toxin A subunit). We conclude that crude, unconcentrated culture filtrates and sonicates do not mimic heat-labile or heat-stable enterotoxins or cholera toxin or its A subunit and that enteropathogenic strains of E. coli probably have yet another mechanism or group of mechanisms by which they cause diarrhea.
Phorbol myristate acetate-induced modulation of antibody-dependent cellular cytotoxicity by human polymorphonuclear leukocytes
Authors: Ichinose Y , Yagawa K , Kaku M , Hara N , Ohta M
Published: January 2020

The effect of phorbol myristate acetate (PMA) on the antibody-dependent cellular cytotoxicity (ADCC) of human polymorphonuclear leukocytes (PMNs) against human erythroleukemic K562 cells was studied by the use of a 3-h 51Cr-release assay. Pretreatment of PMNs with PMA (10 ng/ml) for 60 min resulted in inhibition of subsequent ADCC. This inhibition was dependent on doses of PMA. The effect of pretreatment of PMNs with PMA on O2- generation of the cells was also studied. The ability of the cells to generate O2- was not suppressed, and the expression of Fc receptors on the cell membrane was well preserved. In contrast, the addition of PMA to the ongoing ADCC (5 to 30 min after the start of the ADCC assay) enhanced the activity of the cells for ADCC. This augmentation was abolished by catalase, whereas ADCC itself was not affected by the agent. These results imply divalent effects of PMA on the ADCC of PMNs. The suppression of ADCC activity of PMNs by pretreatment with PMA is not due to inhibition of the reactive oxygen burst of the cells. The augmentation of ongoing ADCC by the addition of PMA is due to secretion of hydrogen peroxide from the cells induced by PMA, and this augmentation occurs only when the interaction between effector and target cells exists through Fc receptor.
Murine natural resistance to Trypanosoma lewisi involves complement component C3 and radiation-resistant, silica dust-sensitive effector cells
Authors: Albright J W , Albright J F
Published: January 2020

The phenomenon of natural (innate) resistance is exemplified by the solid resistance of mice to infection with the rat-specific Trypanosoma lewisi. We provide more information about the mechanism of resistance in this model system. Resistance was not diminished in aged mice or reduced by ionizing radiation or splenectomy. There was no difference in resistance of C5-deficient mice (B10.D2/oSn and AKR) compared with their normocomplementemic counterparts (B10.D2/nSn and C57BL/6). Treatment of mice with cobra venom factor resulted in greatly prolonged survival of T. lewisi in mice. Combined treatment of mice with cobra venom factor and silica dust resulted in not only prolonged survival but also considerable intravascular growth of the parasite and resultant death of the mice. T. lewisi cells from irradiated donor rats, or after surface coat removal with trypsin, were eliminated by inoculated mice more efficiently than were parasites acquired from normal rats. Incubation of trypanosomes obtained from irradiated rats in normal rat serum restored their resistance to rapid elimination. From the results of these studies and other recent investigations, we have concluded that murine resistance to T. lewisi involves activation and binding of C3b by uncoated trypanosomes and concomitant participation of radiation-resistant, silica dust-sensitive effector cells (probably macrophages and neutrophils), and rat plasma proteins, integrated into the trypanosome surface coat, stabilize the coat, make it less susceptible to removal when the trypanosome is present in the mouse bloodstream, and thus delay exposure of underlying molecules (receptors?) that activate murine C3.
Effects of ovarian hormones on manifestation of purulent endometritis in rat uteruses infected with Escherichia coli
Authors: Nishikawa Y , Baba T
Published: January 2020

To assess the influence of hormones on uterine infections, Escherichia coli was infused into uterine lumens of ovariectomized or adrenoovariectomized rats receiving exogenous administration of various doses of ovarian hormones. Large numbers of E. coli were recovered from the rat uterine lumens, irrespective of hormonal influences. The number of leukocytes in the uterine flushings, representing the magnitude of purulent inflammation, differed significantly depending upon the hormonal regimen given to each host. Purulent endometritis was induced by E. coli in ovariectomized rats receiving progesterone or corn oil (hormone vehicle). Infections were asymptomatic in rats receiving estradiol, but promethazine-treated uterine horns were susceptible to infection. When progesterone was administered along with estradiol, purulent inflammation was caused by E. coli, but the number of leukocytes in the uterine lumens was significantly less than that obtained from the rats treated with progesterone or corn oil. These effects of ovarian hormones on uterine infections were observed in adrenoovariectomized rats as well as in ovariectomized rats. It is suggested that estradiol alters the nature of endometrial epithelium and prevent manifestation of purulent endometritis; progesterone antagonizes estradiol. Adrenal hormones appear not to participate in the pathogenesis of endometritis induced by E. coli.
Multiple forms of genes in pyelonephritogenic Escherichia coli encoding adhesins binding globoseries glycolipid receptors
Authors: Hull S , Clegg S , Sanborg Eden C , Hull R
Published: January 2020

Earlier studies have shown that the majority of Escherichia coli isolates from urinary tract infections which possess a D-mannose-resistant adhesin contain gene sequences homologous to the pap pilus gene sequences encoded on the recombinant plasmid pRHU845. In this report, several E. coli isolates from urinary tract infections were examined to determined the arrangement of pap-related sequences. Copies of gene sequences homologous to the entire pap operon were found to exist at multiple sites in the chromosomes of some strains. The position of the pap operon(s) with respect to adjacent sequences was also found to be variable.
Immunity and protection of mice against Neisseria meningitidis group B by vaccination, using polysaccharide complexed with outer membrane proteins: a comparison with purified B polysaccharide
Authors: Moreno C , Lifely M R , Esdaile J
Published: January 2020

A methodology for preparing outer membrane proteins (type specific) complexed to group B polysaccharide of Neisseria meningitidis is described. These complexes, low in nucleic acid and lipopolysaccharide content, were immunogenic in mice with induction of humoral antigroup B and antiprotein responses. Immunized mice were also protected against challenge with N. meningitidis group B strains of the same or a different type from that used for vaccination. Both immunity and protection were enhanced when the mice received a secondary immunization with the protein-polysaccharide complex. Additional data have shown the capacity of purified B polysaccharide to induce immunological memory, even though it is incapable of inducing a humoral response when given alone.
Relative hydrophobicities of Actinomyces viscosus and Actinomyces naeslundii strains and their adsorption to saliva-treated hydroxyapatite
Authors: Clark W B , Lane M D , Beem J E , Bragg S L , Wheeler T T
Published: January 2020

The present study examined 42 strains of Actinomyces spp. to determine whether adsorption to saliva-treated hydroxyapatite (SHA) of the selected strains of this prominent group of dental-plaque bacteria correlated with hydrophobicity. The relative hydrophobicity of the strains was determined by their adsorption to hydrophobic gels (i.e., phenyl-Sepharose) and their aggregation in ammonium sulfate. Within serogroups the relative hydrophobicity for the strains was similar. The relative adsorption of strains to SHA was also similar within the respective serogroups. Strains which were relatively hydrophobic, as judged by their binding to the hydrophobic gel and aggregation in low concentrations of ammonium sulfate, adsorbed well to SHA. Strains which adsorbed poorly to SHA were relatively hydrophilic since they did not bind well to the hydrophobic gel and were only aggregated in relatively high concentrations of ammonium sulfate. Tween 80, a nonionic detergent known to inhibit hydrophobic interactions, blocked binding of cells to the hydrophobic gel, suggesting that hydrophobic interactions had been inhibited. However, Tween 80 exhibited no influence on the adsorption of cells to SHA. Thus, although there was a strong statistical correlation between the relative hydrophobicity of a strain and its adsorption to SHA, the data were consistent with the view that other interactions, such as ionic bonds and interactions between complimentary macromolecules, are involved in adsorption of the Actinomyces strains to SHA.
Susceptibility to staphylococcal alpha-toxin of Friend virus-infected murine erythroblasts during differentiation
Authors: Harshman S , Bondurant M
Published: January 2020

Splenic erythroblasts obtained from BALB/c mice infected with the anemia strain of Friend virus were compared with "matured" cells and adult erythrocytes for their sensitivity to staphylococcal alpha-toxin. Matured cells were obtained by treating erythroblasts in culture with erythropoietin for 48 h. Sensitivity to staphylococcal alpha-toxin, measured both by release of 86Rb and by cell lysis, failed to demonstrate significant differences among the cell types. Since maturation of erythroblasts to matured cells or erythrocytes is associated with synthesis of band 3, hemoglobin, and spectrin and the loss of transferrin receptors, we conclude that none of these compounds serves as the specific receptor for staphylococcal alpha-toxin in BALB/c mice.
Distinct bacteriocin groups correlate with different groups of Streptococcus mutans plasmids
Authors: Caufield P W , Childers N K , Allen D N , Hansen J B
Published: January 2020

A correlation between the presence of 5.6-kilobase plasmids and bacteriocin activity was found in human-derived strains of Streptococcus mutans. Compared with bacteriocin activity of randomly selected clinical isolates of plasmid-negative strains, bacteriocin activity of plasmid-positive strains significantly inhibited not only two laboratory strains of S. mutans, OMZ176 and AHT (P less than 0.0001 and P = 0.038, respectively), but most plasmid-negative clinical isolates as well (P = 0.0005). Comparisons of inhibition between pairs of plasmid-positive strains revealed two groups, group I and group II, that produced distinct bacteriocins we designated as mutacin I and mutacin II, respectively. Within each group, a strain produced inhibitory activity against all the members of the other group but against no members of its own group. Plasmid DNA from plasmid-positive strains of each group was isolated and analyzed by restriction endonuclease digestion. Plasmids from the two groups that were apparently identical in size differed in digestion patterns for EcoRI, HaeIII, and TaqI, even though six TaqI fragments appeared to be common to all. Based on bacteriocin profiles and restriction enzyme digests, two distinct groups of plasmid-positive S. mutans strains emerged. Although the bacteriocin activity of plasmid-positive strain LM7 (serotype e) placed it in group I, clear differences in restriction digests distinguished it from the other plasmid-containing strains.
Nucleotide sequence comparison between heat-labile toxin B-subunit cistrons from Escherichia coli of human and porcine origin
Authors: Leong J , Vinal A C , Dallas W S
Published: January 2020

The nucleotide sequence of the LT-BH cistron (eltBH) from an enterotoxigenic Escherichia coli strain infectious for humans was determined and compared with the LT-B cistron sequence from a porcine E. coli isolate. Both cistrons were shown to comprise 375 nucleotide base pairs, and discrepancies were detected at eight positions. Of the nonhomologous base pairs, six resulted in codon changes that would lead to amino acid variations. The nucleotide sequence distal to both LT-B cistrons was also determined, and only three differences were detected in 197 base pairs. An HhaI site unique to eltBH was shown to be present in all the heat-labile (LT) genes from 31 human isolates surveyed, whereas the restriction enzyme recognition site was absent in the gene from 46 porcine E. coli isolates. The results suggest that two genetically discernable LT groups are identifiable and that the groups are also distinguishable by the isolation source (human or porcine) of the infecting E. coli strains.
Morphology of three strains of contagious equine metritis organism
Authors: Hitchcock P J , Brown T M , Corwin D , Hayes S F , Olszewski A , Todd W J
Published: January 2020

Examination of recently isolated cultures of three strains of Contagious Equine Metritis Organism grown on specially formulated, serum-free, clear typing medium revealed the presence of numerous colonial opacity variants. These colonies were prepared by a number of fixation and staining techniques and examined by scanning and transmission electron microscopy. Opaque and transparent phenotypes produced copious amounts of extracellular material compared with intermediate-opacity phenotypes which produced little or none. Also unique to intermediate colonies were numerous thin intercellular strands, which may represent pili or polymers of extracellular material. The presence of an unusual fibrillar layer (with similar electron density to the extracellular material) on the outer leaf of the outer membrane also was confirmed. A number of other ultrastructural features also were noted, including an epilayer, a thin nonmembranous layer which covered colonies and adjacent agar.
Inhibition of growth of Chlamydia trachomatis by human gamma interferon
Authors: Shemer Y , Sarov I
Published: January 2020

Treatment of HEp-2 cell cultures with highly purified human gamma interferon before infection resulted in the reduction of Chlamydia trachomatis (L2/434/Bu) infectious particle yield. Electron microscope studies showed that interferon did not affect chlamydial conversion to reticulate bodies but influenced the extent of maturation to elementary bodies. High interferon concentrations (greater than 350 IU/ml) inhibited inclusion body formation and resulted in the appearance of aberrant reticulate bodies.
Coaggregation of oral Bacteroides species with other bacteria: central role in coaggregation bridges and competitions
Authors: Kolenbrander P E , Andersen R N , Holdeman L V
Published: January 2020

Seventy-three freshly isolated oral strains representing 10 Bacteroides spp. were tested for their ability to coaggregate with other oral gram-negative and gram-positive bacteria. None coaggregated with any of the gram-negative strains tested, which included Capnocytophaga gingivalis, C. ochracea, C. sputigena, and Actinobacillus actinomycetemcomitans. Strains of Bacteroides buccae, B. melaninogenicus, B. oralis, and B. gingivalis failed to coaggregate with any of the gram-positive strains tested. However, six Bacteroides spp. coaggregated with one or more species of gram-positive bacteria. Most isolates of B. buccalis, B. denticola, B. intermedius, B. loescheii, B. oris, and B. veroralis coaggregated with strains of Actinomyces israelii, A. viscosus, A. naeslundii, A. odontolyticus, Rothia dentocariosa, or Streptococcus sanguis. The strongest coaggregations involved B. denticola, B. loescheii, or B. oris; 22 of 25 strains coaggregated with A. israelii. Only B. loescheii interacted with certain strains of S. sanguis; these coaggregations were lactose inhibitable and were like coaggregations between A. viscosus and the same strains of S. sanguis. In fact, B. loescheii and A. viscosus were competitors for binding to S. sanguis. Many bacteroides also acted as coaggregation bridges by mediating coaggregations between two noncoaggregating cell types (e.g., S. sanguis and A. israelii). Evidence for binding-site competition and coaggregation bridging involving noncoaggregating cell types from three different genera provides support for the hypothesis that these intergeneric cell-to-cell interactions have an active role in bacterial colonization of the oral cavity.
Multiplication of Mycobacterium marinum within phagolysosomes of murine macrophages
Authors: Mor N
Published: January 2020

Both in vivo and in vitro, Mycobacterium marinum organisms were found to multiply within phagolysosomes of murine macrophages. It thus appears that M. marinum are neither killed nor inhibited from multiplying by lysosomal enzymes.
Isolation of Actinomyces bacteriophage from human dental plaque
Authors: Tylenda C A , Calvert C , Kolenbrander P E , Tylenda A
Published: January 2020

Human dental plaque samples were screened for the presence of bacteriophage for Actinomyces viscosus and Streptococcus sanguis. None of the 336 samples yielded phage for S. sanguis, but 10 contained virulent actinomyces phage. A high host cell specificity was observed in that one phage isolate infected only A. viscosus T14V, eight phage isolates infected only A. viscosus MG-1, and one infected both strains. None was capable of productively infecting various other actinomyces strains that represented the six actinomyces coaggregation groups. Because phage-containing samples occurred randomly in this survey, no correlation between the individual collecting the samples, dental clinic, or type of patient and the presence of phage in the sample was noted. Examination of one of the samples that yielded phage for the presence of a natural host strain for that particular phage resulted in the isolation of two strains which were identified as A. viscosus serotype II and Actinomyces naeslundii serotype I. This is the first report of an A. naeslundii host strain and actinomyces bacteriophage of human dental plaque origin. The finding of both phage and host strains in the same dental plaque sample along with the observation of high host cell specificity by these phage provide indicators that support an active role for actinomyces bacteriophage in oral microbial ecology. The use of these freshly isolated phage as probes to study actinomyces coaggregation properties is discussed.