bluuebunny/crossref_metadata_2025 huggingface dataset:
Pneumocystis carinii: oxygen uptake, antioxidant enzymes, and susceptibility to oxygen-mediated damage
Authors: Pesanti E L
Published: January 2020

The ability of Pneumocystis carinii obtained by alveolar lavage of rats with glucocorticoid-induced pneumocystosis to utilize molecular oxygen, the concentrations of selected antioxidant enzymes, and the susceptibility of P. carinii to in vitro killing by oxygen radical-generating systems have been evaluated. As expected of an organism which has been found to convert radiolabeled glucose to CO2, the parasite utilizes molecular oxygen. No evidence for pathways of oxygen utilization other than the cytochrome pathway was found; cyanide virtually abolished oxygen consumption. Although readily detectable levels of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were present in the P. carinii preparations, only superoxide dismutase was present at levels that suggested that the activity was indeed a property of the parasite. Almost certainly, P. carinii does not possess effective concentrations of catalase. In addition, it was found that P. carinii is susceptible to the lethal actions of hydrogen peroxide and superoxide, but the parasite seems to be resistant to the effects of a hydroxyl radical-generating system.
Characterization of polysaccharide antigens of Streptococcus mutans B13 grown under various conditions
Authors: Linzer R , Campbell L K , Knox K W
Published: January 2020

Bacteria may respond to changes in their environment by varying the synthesis of surface components. This study examined the effects of various culture conditions on two wall polysaccharides of Streptococcus mutans B13 (serotype d): serotype d antigen, a galactose-glucose polymer, and RGP antigen, a rhamnose-glucose polymer. Cells were grown in a chemostat at various dilution rates (D) and pH values, including D = 0.05, 0.1, and 0.5 h-1 at pH 6.0 and D = 0.1 h-1 at pH 5.5, 6.0, 6.5, and 7.5. The cells were examined for protein and carbohydrate content by colorimetric assays and gas-liquid chromatography. Rantz-Randall extracts (120 degrees C, 30 min) and M-1 N-acetylmuramidase digests were prepared and examined for the presence of specific antigens by agar gel diffusion and quantitative precipitation assays. Cell preparations did not vary significantly with respect to total protein or carbohydrate content; however, cells grown at D = 0.1 h-1 and pH 7.5 had a significantly higher rhamnose content than did the other preparations. Rapidly growing cultures appeared to be more resistant to M-1 N-acetylmuramidase digestion than did slower-growing cultures. Agar gel diffusion studies demonstrated that both serotype d and RGP antigens were present in all samples, although significantly less RGP antigen was noted in the pH 7.5 culture. These observations were confirmed by quantitative precipitation assays. M-1 N-acetylmuramidase digests of the pH 7.5 culture were lacking in RGP precipitation activity although RGP inhibition activity was demonstrated. The data suggest that the cell content of serotype d antigen was relatively constant under the growth conditions tested, whereas the synthesis of RGP antigen was modified under conditions of high pH.
Interbacterial adherence between Actinomyces viscosus and strains of Streptococcus pyogenes, Streptococcus agalactiae, and Pseudomonas aeruginosa
Authors: Komiyama K , Gibbons R J
Published: January 2020

Interbacterial adherence was sought between strains of Actinomyces viscosus indigenous to the human mouth and strains of Streptococcus pyogenes, Streptococcus agalactiae, and Pseudomonas aeruginosa. Six of nine strains of S. pyogenes, three of five strains of S. agalactiae, and two of four strains of P. aeruginosa were found to coaggregate with each of five strains of A. viscosus tested. Some coaggregation reactions were inhibited by 0.05 M lactose and were dependent upon heat- and protease-sensitive Actinomyces components. Such reactions appear to involve the galactosyl-binding adhesin previously described in type 2 fimbriae on A. viscosus. Other coaggregation reactions were dependent upon heat- and protease-sensitive components of the pathogen. That such pathogen strains possessed an adhesin(s) was further suggested by the observation that they agglutinated human erythrocytes. The ability of coaggregation-positive and -negative strains of S. pyogenes and S. agalactiae to adhere to Actinomyces-coated agarose beads was also studied. Coaggregation-positive streptococcal strains attached in higher numbers to the Actinomyces-coated beads than did strains which were coaggregation negative. Lactose (0.05 M) inhibited the attachment of those streptococcal strains which coaggregated with A. viscosus in a lactose-sensitive manner. The adherence of those streptococcal strains whose coaggregation appeared to depend upon the galactosyl-binding adhesin of A. viscosus was also reduced by components of human saliva. Crude sonic extracts of coaggregation-positive streptococci or of P. aeruginosa were also effective in aggregating Actinomyces cells. The effect of lactose and of salivary components on this extract-induced aggregation of Actinomyces cells generally paralleled that observed in other assays. The apparent prevalence and diversity of adherent reactions between the pathogens studied and indigenous strains of A. viscosus suggest that some may affect host susceptibility to these infectious agents.
Immunoregulation of genetically controlled acquired responses to Leishmania donovani infection in mice: demonstration and characterization of suppressor T cells in noncure mice
Authors: Blackwell J M , Ulczak O M
Published: January 2020

On a B10 genetic background, genes in the I region of H-2 influence the development of acquired T-cell mediated immunity to Leishmania donovani infection in mice. In previous studies, noncure in H-2d mice could be abrogated by pretreatments with cyclophosphamide or sublethal irradiation. The prophylactic effect of these pretreatments was consistent with deletion of the precursors of suppressor T cells suppressing T-cell-mediated immune responses. In this study, cell transfer experiments provide direct evidence for the role of suppressor T cells in the noncure response. T-cell-enriched populations isolated from the spleens of B10.D2/n mice infected 30, 61, or 85 days previously reversed the prophylactic effect of sublethal irradiation when injected before infection into B10.D2/n mice that had received 550 rads. B-cell-enriched populations failed to transfer suppression in this manner, and T-cell-enriched populations from the spleens of normal B10.D2/n mice had only a transient effect on liver parasite loads. Transfer of suppression with the T-cell-enriched populations from infected donors was abrogated by pretreatment with anti-Thy-1.2 and anti-Lyt-1.2 antisera plus complement but not by pretreatment with anti-Lyt-2.2 plus complement, indicating that the suppressor T cell involved has an Lyt-1+2- surface phenotype. Results are discussed in relation to the possible mechanism of H-2-linked control.
Inhibition of growth of Toxoplasma gondii in cultured fibroblasts by human recombinant gamma interferon
Authors: Pfefferkorn E R , Guyre P M
Published: January 2020

The growth of Toxoplasma gondii in cultured human fibroblasts was inhibited by recombinant human gamma interferon at concentrations of 8 to 16 U/ml. The interferon was titrated by observing a total inhibition of parasite plaque formation 7 days after infection. Inhibition of the growth of T. gondii in the early days after infection was measured by marked reductions in the incorporation of radioactive uracil, a precursor that can only be used by the parasites. This assay showed that when cells were pretreated with gamma interferon for 1 day and then infected, inhibition of T. gondii growth could be readily detected 1 or 2 days after infection. When the pretreatment was omitted and parasites and gamma interferon were added at the same time, no inhibition of parasite growth could be detected 1 day later, although it was apparent after 2 days. Cultures from which the gamma interferon had been removed by washing after a 1-day treatment showed inhibition of T. gondii growth. Gamma interferon had no effect on the viability of extracellular parasites, but it did inhibit the synthesis of host cell RNA and protein by ca. 50% 3 days after treatment. This degree of inhibition is unlikely, of itself, to compromise the growth of T. gondii. Recombinant alpha and beta interferons had no effect on the growth of T. gondii.
Biosynthetic capacity for type-specific antigen synthesis determines the virulence of serotype III strains of group B streptococci
Authors: Yeung M K , Mattingly S J
Published: January 2020

The level of type-specific antigen (that covalently associated with the cell wall peptidoglycan and that released extracellularly) synthesized by virulent and avirulent strains of type III group B streptococci was quantitated and compared. Additionally, the effect of the physiological age of the cells and the influence of the exogenous phosphate ion concentration on the level of antigen synthesis by these organisms were also examined. Approximately 4% of the total antigen synthesized by the organism is noncovalently bound to the cell surface, and the difference in level of the noncovalently associated type-specific antigen between virulent and avirulent strains was negligible. In contrast, when the cell-associated covalently bound type antigens were evaluated, virulent strains were demonstrated to have two- to threefold higher levels than those of avirulent strains during the exponential and stationary phases of growth under various growth conditions. Furthermore, virulent strains that had high levels of cell-associated type antigen also secreted more extracellular type antigen than did avirulent strains. Thus, the data were consistent with the hypothesis that an overall production of type-specific antigen correlated with virulence in mice. However, the cell-associated type-specific antigen probably represented a better indicator for virulence potential since the addition of purified extracellular type-specific antigen to a mutant strain that lacks cell surface type antigen did not alter the 50% lethality value of the organism. To account for variation in the level of type-specific antigen produced by these strains, the kinetics of both the group- and type-specific antigens synthesis was investigated at the cell membrane level by utilizing an intact protoplast system.(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of staphylococcal enterotoxin A on the rat gastrointestinal tract
Authors: Beery J T , Taylor S L , Schlunz L R , Freed R C , Bergdoll M S
Published: January 2020

Staphylococcal enterotoxin A (SEA) was administered orally (15 micrograms) to two groups of rats. A marked immune reaction was evoked in the stomach and proximal small intestine of the first group. The second group of rats was used to study the absorptive fate and sites of action of orally administered SEA, utilizing immunoperoxidase staining. After oral dosing of the second group of rats. SEA-related immunoperoxidase staining was confined to: (i) neutrophils and macrophages, principally in the duodenum, and (ii) glomerular neutrophils and cells of the proximal convoluted tubules. Peroxidase staining of the kidney was noted within 15 min of exposure, indicating that SEA or some major postabsorption antigenic product can promptly pass through an intact gastrointestinal mucous membrane and become renally localized. Intestinal and renal detoxification and removal was indicated by an absence of detectable antigen in rats 180 min postexposure. Neuronal binding of SEA in the gastrointestinal tract was not demonstrable.
Optimization of an hydroxyapatite adhesion assay for Streptococcus sanguis
Authors: Eifert R , Rosan B , Golub E
Published: January 2020

Previous studies have compared the adhesion of [3H]thymidine-labeled Streptococcus sanguis to saliva-coated hydroxyapatite (SHA) and buffer-coated hydroxyapatite (HA) beads. Although the hypotonic buffer used in these assays was adjusted to simulate saliva, it does not necessarily provide the optimal parameters for the quantitative estimate of adhesion under in vitro conditions. Optimization is necessary to provide the maximum sensitivity of the assay for detecting the effects of various salivas as well as for quantitating the effect of environmental growth conditions on the adhesion of S. sanguis to SHA and HA. A major distinction between the adhesion of S. sanguis to SHA and HA was observed when the bacterial concentration was varied. At high cell concentrations, the number of cells adhering to SHA was twice the number adhering to HA. Such differences were not detected at low cell concentrations. The optimal pH for the adsorption to both SHA and HA was 6. Changes in the ionic strength or addition of mono- or divalent cations found in saliva had little effect on adhesion to HA. In contrast, high concentrations of monovalent cations inhibited adhesion to SHA. Anions such as carbonate, chloride, and sulfate did not have specific effects on adhesion, whereas acetate inhibited adhesion to both SHA and HA. Fluoride inhibited adhesion to both SHA and HA, suggesting an interaction between fluoride and hydroxyapatite. These results indicated that 2 mM phosphate buffer at a pH of 6 containing 5 mM KCl and 1 mM CaCl2 was the optimal buffer for studying the in vitro adhesion of S. sanguis to SHA.
Evidence for the participation of N-acetylated amino sugars in the coaggregation between Cytophaga species strain DR2001 and Actinomyces israelii PK16
Authors: Kagermeier A S , London J , Kolenbrander P E
Published: January 2020

Coaggregation between Cytophaga sp. strain DR2001 and Actinomyces israelii PK16 was partially inhibited by certain N-acetylated amino sugars (N-acetylneuraminic acid, N-acetylgalactosamine, and N-acetylglucosamine) and was completely inhibited by the trisaccharide neuraminin-lactose. The monosaccharides exerted their effect at concentrations between 30 to 100 mM, whereas the trisaccharide was an effective inhibitor at significantly lower concentrations. Outer membrane preparations caused A. israelii PK16 cells to aggregate; however, vesicles released from the cell envelope during growth failed to do so. Adherence studies with a non-coaggregating mutant of the cytophaga suggest that the spheroidal hydroxyapatite attachment sites and coaggregation receptors are separate entities.
Interleukin 2 augmentation of natural killer cell activity in homosexual men with acquired immune deficiency syndrome
Authors: Reddy M M , Pinyavat N , Grieco M H
Published: January 2020

Natural killer cell activity of peripheral blood mononuclear cells against K562 myeloid cells was studied in 8 normal heterosexual men, 5 healthy homosexual men, and 11 homosexual men with acquired immune deficiency syndrome. The overall natural killer cell activity was lower in healthy homosexual men and in homosexual men with acquired immune deficiency syndrome. Peripheral blood mononuclear cells from four normal heterosexual men were preincubated overnight in complete medium supplemented with various concentrations of lectin-free interleukin 2 lacking interferon. Cells from these cultures exhibited a dose-dependent augmentation of natural killer cell activity. Peripheral blood mononuclear cells obtained from 8 normal heterosexuals, 5 healthy homosexuals, and 11 homosexual men with acquired immune deficiency syndrome were preincubated overnight in complete medium supplemented with 20% interleukin 2. Natural killer cell activity cultured in 20% interleukin 2 increased to 78.4 +/- 8.4 (mean +/- standard deviation) from 30.8 +/- 11.0 in normal heterosexual men, to 68.3 +/- 17.6 from 16.8 +/- 13.6 in healthy homosexual men and to 49.3 +/- 15.3 from 11.6 +/- 6.1 in homosexual men with acquired immune deficiency syndrome at a 100:1 effector/target cell ratio. These results suggest that interleukin 2 is capable of directly stimulating natural cell-mediated cytotoxicity. Consideration of the use of interleukin 2 as a potential therapeutic agent to modify immune responses in disorders such as acquired immune deficiency syndrome appears warranted.
Multiphasic interactions of Mycoplasma pulmonis with erythrocytes defined by adherence and hemagglutination
Authors: Minion F C , Cassell G H , Pnini S , Kahane I
Published: January 2020

The mechanism(s) of interaction between Mycoplasma pulmonis and eucaryotic cells was studied by adherence to and hemagglutination of erythrocytes. Simple and complex carbohydrates and glycoproteins were unable to inhibit either adherence or hemagglutination, indicating that neither was a lectin activity. Both interactions appeared to be hydrophobic due to their requirement for salt and their sensitivity to temperature. Hemagglutination, but not adherence, was inhibited by both trypsin and glutaraldehyde treatment of the mycoplasma, suggesting that adherence and hemagglutination are qualitatively different. The erythrocyte receptor sites for the two activities were also separable since hemagglutination, but not adherence, required trypsinization of erythrocytes. The hemagglutinin was shown to be an integral mycoplasma component and not a broth contaminant. Once removed, hemagglutinating activity could not be replenished by incubation in serum or broth at 4 degrees C, but could be regenerated during protein synthesis under nonreplicative conditions. Thus, a mycoplasma membrane protein was detected which was capable of interacting with opposing membrane surfaces through hydrophobic interactions. Consequently, a multiphasic model of M. pulmonis-eucaryotic cell interactions was proposed.
In vivo effect of staphylococcal enterotoxin A on peripheral blood lymphocytes
Authors: Zehavi-Willner T , Shenberg E , Barnea A
Published: January 2020

Staphylococcal enterotoxin A (SEA) administration to monkeys produced an initial lymphocytic leukopenia lasting approximately 24 h. Lymphocytes isolated from blood circulation (PBL) during this stage had normal or decreased [3H]thymidine incorporating activity. After 48 h, however, a significant increase (five- to sixfold) in [3H]thymidine incorporating activity into PBL was apparent. The peak of incorporating activity (seven- to eightfold) was reached 3 to 4 days after SEA administration, followed by a gradual decline, reaching the baseline after 2 weeks. The increased levels of [3H] thymidine incorporation in PBL were concomitant with the conversion of lymphopenia into lymphocytosis, accompanied by the release of many immature cells into the circulation. Lymphocytes isolated 24 h after SEA administration in vivo did not respond to the mitogenic action of SEA in vitro. Lymphocytes isolated at later stages after SEA challenge were fully activated by toxin. From a series of studies, it was concluded that SEA administered to monkeys caused, during the initial 24 h, the removal of a great proportion of lymphocytes from the circulation, followed by the release of new immature cells with augmented DNA synthesis activity. The lymphocytic leukocytosis state declined gradually and reached normal levels between 3 and 4 weeks after the SEA challenge. The biological implications of the hematological changes occurring after SEA challenge in vivo are discussed.
Biological activities of synthetic lipid A analogs: pyrogenicity, lethal toxicity, anticomplement activity, and induction of gelation of Limulus amoebocyte lysate
Authors: Tanamoto K , Zähringer U , McKenzie G R , Galanos C , Rietschel E T , Lüderitz O , Kusumoto S , Shiba T
Published: January 2020

Chemically synthesized lipid A analogs were investigated for several endotoxic activities, including pyrogenicity, lethal toxicity, anticomplement activity, and the capacity to gelate Limulus amoebocyte lysate in comparison to natural lipid A. The synthetic preparations contained D-glucosamine or D-glucosamine-beta-1,6-D-glucosamine disaccharide substituted by ester- and amide-bound hydroxylated or non-hydroxylated fatty acids and by phosphate groups in different combinations. Some preparations which were insoluble in water were succinylated and thus rendered more soluble. Strong biphasic pyrogenic responses with a maximal increase in body temperature of 1 to 2 degrees C were obtained with 50 micrograms/kg doses of 3 disaccharide preparations of 15 tested. With two preparations (50 micrograms/kg) moderate pyrogenicity with monophasic fever curves and a maximal temperature increase of about 0.6 degrees C was obtained. Lethal toxicity tests were carried out in galactosamine-sensitized mice. Of 15 synthetic preparations, 4 exhibited lethal toxicity under these conditions. The effective doses of the lipid A analogs in both in vivo tests were, however, several hundred times higher than those of bacterial lipid A. For the activities in vivo, hydroxyacyl residues seemed to be important. Anticomplement activity was demonstrable in seven preparations, one of which expressed an activity comparable to that of lipid A. Preparations containing non-hydroxylated fatty acids seemed to be most active in this test. None of the synthetic preparations was found to exhibit gelation activity for Limulus amoebocyte lysate when tested in doses up to 0.4 micrograms, whereas bacterial free lipid A was active in doses of about 2 pg. None of the monosaccharide derivatives exhibited any of these activities.
In vitro synthesis of the delta-lysin of Staphylococcus aureus
Authors: Lee K Y , Birkbeck T H
Published: January 2020

The stability of mRNA for the delta-lysin of Staphylococcus aureus was determined by measuring the residual lysin synthesis after inhibition of DNA-dependent RNA polymerase activity with rifampin. At the late logarithmic-early stationary phase of growth the delta-lysin mRNA was very stable, with a half-life of ca. 20 min. Total cellular RNA was extracted from S. aureus and translated with a modified Escherichia coli S-30 system; delta-lysin was identified amongst the translation products by immunoprecipitation and immunoabsorption. The delta-lysin synthesized in vitro was of a size similar to mature delta-lysin and did not require a signal sequence for secretion from the cell.
Evaluation of the human immune response to outer membrane proteins of Vibrio cholerae
Authors: Sears S D , Richardson K , Young C , Parker C D , Levine M M
Published: January 2020

The immune response of 114 volunteers with diarrhea after experimental challenge with four strains of Vibrio cholerae O1 was characterized in a microtiter enzyme-linked immunosorbent assay antibody detection system by using a partially purified outer membrane preparation (OMP) from these strains as an antigen. Analysis of paired sera from 29 persons with noncholera diarrhea (negative control population), demonstrated that a rise in net optical density greater than 0.10 was significant. A total of 50% of the 79 cholera volunteers challenged with El Tor biotype and 54% of the 35 volunteers challenged with classical biotype had significant rises in immunoglobulin G anti-OMP. Paired sera that showed significant rises when tested against homologous OMP all manifested significant rises when also tested against a serotype-heterologous OMP. Immunoblotting techniques showed that the antigens to which antibodies were reacting were mainly protein in nature, not lipopolysaccharide. Furthermore, absorption with lipopolysaccharide decreased the optical density by a mean of only 12% (0 to 30%), corroborating that antibody was mainly directed against OMP and not lipopolysaccharide. This study indicates that there is a human immunoglobulin G response to OMP during clinical cholera infection and that this response is constant among bio- and serotypes.
Inhibition of cell-free oxidative bactericidal activity by erythrocytes and hemoglobin
Authors: Hand W L
Published: January 2020

Sickle cell anemia and other chronic hemolytic anemias are associated with an increased frequency of bacterial infections. There is evidence to suggest that in hemolytic states massive erythrocyte (RBC) ingestion by macrophages interferes with their antibacterial function, thereby predisposing infection. Stimulated by this possibility, we recently demonstrated that erythrophagocytosis by macrophages markedly inhibited intracellular killing of bacteria, and that zymosan-stimulated superoxide generation and chemiluminescence were also suppressed by RBC ingestion. We examined the effects of RBC components on generation of chemiluminescence, superoxide, and bactericidal activity by cell-free oxidative systems. Generation of chemiluminescence by hypoxanthine-xanthine oxidase was depressed in the presence of human RBC lysate or column-fractionated hemoglobin but not crystallized human hemoglobin (methemoglobin) (peak cpms of 15,522 [P = 0.00024], 28,360 [P = 0.0088], and 50,041 [P = 0.37], respectively, compared with 59,898 for positive controls). Similarly, hypoxanthine-xanthine oxidase production of superoxide was inhibited in the presence of column-fractionated human hemoglobin (43.8 versus 17.4 nmol per tube, P = 0.000001). A cell-free bactericidal system, acetaldehyde and xanthine oxidase with or without myeloperoxidase and Cl-, was markedly inhibited by column-purified hemoglobin. For example, after 2 h of incubation, surviving numbers of Staphylococcus aureus were: control (buffer only), 2.5 X 10(6)/ml; bactericidal system, none; bactericidal system plus hemoglobin, 2.2 X 10(6)/ml (P less than or equal to 0.03, bactericidal system versus other systems). Our studies have documented that interactions between RBC (hemoglobin) and reactive products of oxygen metabolism inhibit oxidative bactericidal mechanisms in cell-free systems as well as in macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)
Glucose phosphoenolpyruvate-dependent phosphotransferase system of Streptococcus mutans GS5 studied by using cell-free extracts
Authors: Liberman E S , Bleiweis A S
Published: January 2020

The glucose phosphotransferase system (PTS) of Streptococcus mutans GS5 has been partially characterized, using fractions derived from cells treated with the muramidase mutanolysin. Membranes retained functional PTS enzymes for the phosphoenolpyruvate-dependent phosphorylation of glucose, fructose, and mannose. This was confirmed by assaying membranes directly for enzyme I (EI) and enzyme IIglc (EIIglc) by employing specific phosphoryl-exchange reactions for each factor. Membranes prepared from glucose PTS- mutants, however, were either deficient in glucose phosphorylation or reflected the "leakiness" displayed by whole cells. Mutant membranes were unable to catalyze the glucose:glucose 6-phosphate transphosphorylation reaction, indicating a defective EIIglc in these fractions. Although total cellular EI activities in the mutant clones were about the same as that measured for the wild-type strain by employing the pyruvate:phosphoenolpyruvate phosphoryl-exchange reaction, mutant membranes were found to possess less than 10% of the specific EI activity of wild-type membranes. The cytoplasmic fractions of mutants, however, displayed markedly increased specific activities for this enzyme when compared with wild-type extracts. These results strongly suggest a molecular association of EI with a normal membrane protein, perhaps EIIglc, that is absent in mutants. This would explain the absence of fructose PTS activity in glucose PTS- mutant membranes despite the fact that whole cells of these clones are normal for this transport function.
In vitro adhesion of enterotoxigenic Escherichia coli to human intestinal epithelial cells from mucosal biopsies
Authors: Knutton S , Lloyd D R , Candy D C , McNeish A S
Published: January 2020

An adhesion assay with isolated human enterocytes prepared from duodenal biopsies has been developed and tested by using human enterotoxigenic Escherichia coli expressing colonization factor antigens I and II (CFA/I and CFA/II) and type 1 fimbriae. Enterotoxigenic E. coli strains H10407 (CFA/I) and B2C (CFA/II) bound to duodenal enterocytes to a much greater extent (mean of 4.6 and 4.0 bacteria per brush border) than did strain H10407P, a CFA/I- mutant of H10407 (mean of 0.1 bacteria per brush border). Type 1 fimbriae also promoted adhesion of strain H10407P to duodenal enterocytes but attachment was to basolateral rather than brush border surfaces. CFA/I and CFA/II, on the other hand, promoted adhesion only to human enterocyte brush borders.
Toxic effect of the peroxidase-hydrogen peroxide-halide antimicrobial system on Mycobacterium leprae
Authors: Klebanoff S J , Shepard C C
Published: January 2020

Mycobacterium leprae are killed by myeloperoxidase (or eosinophil peroxidase), H2O2, and a halide, thus suggesting a mechanism for their destruction by peroxidase-containing phagocytes.
Rickettsia rickettsii-induced cellular injury of human vascular endothelium in vitro
Authors: Silverman D J
Published: January 2020

The endothelial cell is the putative primary target cell in humans infected with Rickettsia rickettsii, the etiological agent of Rocky Mountain spotted fever. Although the clinical manifestations of infection by this organism are well documented, the mechanism of injury to the endothelial cell is not understood. The ability to culture human endothelial cells in vitro provides a unique system with which to study this host-parasite interaction directly. Human vascular endothelial cells derived from the umbilical vein, when infected by R. rickettsii, became severely damaged within a few days postinfection. The primary lesion observed at the ultrastructural level appeared to occur at intracellular membranes, specifically, the rough-surfaced endoplasmic reticulum. Widespread dilatation of these membranes eventually led to the creation of large intracellular cisternae and the apparent circumscription of rickettsiae and cellular organelles by the rough-surfaced endoplasmic reticulum. Small membrane-bound fragments of host cytosol created by dilating membranes also were present within the cisternae. Within 5 to 6 days postinfection, cells lost their osmoregulatory control and lysed. Some possible mechanisms of cell injury directed at the level of intracellular membranes are discussed.
Biochemical and immunochemical analysis of Rickettsia rickettsii strains of various degrees of virulence
Authors: Anacker R L , Philip R N , Williams J C , List R H , Mann R E
Published: January 2020

Six strains of Rickettsia rickettsii from Montana and North Carolina were examined in an effort to identify rickettsial constituents associated with virulence. Fever responses, scrotal reactions, and mortalities of male guinea pigs inoculated intraperitoneally with 1,000 PFU of rickettsial strains revealed that the two Montana patient strains ( Sheila Smith and Norgaard ) and one Montana strain ( Sawtooth female 2) from the wood tick, Dermacentor andersoni, could be placed in the group of highest virulence, the two North Carolina strains (Morgan and Simpson) in the group of lesser virulence, and the Montana strain (HLP) from the rabbit tick, Haemaphysalis leporispalustris , in the group of lowest virulence. The HLP strain was differentiated from the other strains by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by staining with Coomassie brilliant blue or with silver. The patient strains could not be differentiated from each other by these procedures. All of the strains apparently had three heat-modifiable proteins. Analysis of proteinase K-digested rickettsial lysates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggested that the strains had a complex mixture of polysaccharides. These putative polysaccharides probably were not related to the differences in virulence of the strains, since the patterns for all of the strains were identical. At least five antigens (molecular weights of 128,000, 105,000, 84,000, 30,500, and 20,500) were demonstrated by radioimmune precipitation tests employing extracts from radioiodine-labeled rickettsiae and antibodies from infected guinea pigs. With these same sera a minimum of 14 antigens was detected in these strains by an immunoblotting procedure. The apparent molecular weights of several of the HLP antigens differed from those of the presumed corresponding antigens of the other strains. The electrophoretic techniques utilized in this study were not sufficiently sensitive to demonstrate compositional differences in the patient strains which differed in their virulence for guinea pigs.
Altered expression of human monocyte Fc receptors in Plasmodium falciparum malaria
Authors: Ward K N , Warrell M J , Rhodes J , Looareesuwan S , White N J
Published: January 2020

The state of activation of human peripheral blood monocytes was examined by using a rosette assay that detects changes in Fc receptor expression. Monocytes from patients with uncomplicated Plasmodium falciparum malaria showed a significant increase in the number of rosettes relative to healthy controls. In addition, the monocytes from these patients were tested for their ability to phagocytose Candida albicans, but this ability did not differ from that of normal individuals. Finally, the monocytes from patients with cerebral malaria were also tested for Fc receptor expression. In contrast to the results from uncomplicated cases, the activity of the monocytes from these patients was no different from that of controls. We concluded that uncomplicated P. falciparum malaria caused an increase in monocyte Fc receptor expression which did not occur in cerebral malaria and that this difference in activation may be important in the pathogenesis of cerebral malaria.
Quantitative vaginal microflora in women convalescent from toxic shock syndrome and in healthy controls
Authors: Chow A W , Bartlett K H , Goldring A M
Published: January 2020

We performed sequential and quantitative vaginal cultures obtained from 8 women within 4 days to 3 years (average, 15.8 months) after their recovery from classic menstrual toxic shock syndrome (TSS) and from 11 healthy women who served as age-matched controls. Apart from tampon use, which was significantly less frequent in TSS women after their acute illness, no demographic differences were observed in the two groups. Significantly lower total aerobic and anaerobic bacterial counts were found in TSS women than in healthy controls (P less than 0.05, Mann-Whitney test). These differences were most profound during the menstrual (aerobes) and premenstrual (aerobes and anaerobes) sample times, whereas no difference in bacterial counts was observed in the mid-cycle samples. Although the less frequent usage of tampons among TSS women after their acute illness might explain the lower aerobic counts in menstrual specimens, this is unlikely to explain the significantly lower aerobic and anaerobic counts observed in premenstrual samples when tampons were not used in either group. It is possible that these differences in the quantitative vaginal microflora were a direct result of recent TSS in these women. Alternatively, disruption of the normal indigenous microflora could have predisposed these women to acute TSS by alteration of the resistance of vaginal colonization to pathogenic microorganisms.
Resolution of the phosphotransferase enzymes of Streptococcus mutans: purification and preliminary characterization of a heat-stable phosphocarrier protein
Authors: Mimura C S , Eisenberg L B , Jacobson G R
Published: January 2020

The sucrose phosphotransferase system of Streptococcus mutans catalyzes the phosphorylation of sucrose to sucrose-6-phosphate with concomitant translocation of this disaccharide across the cytoplasmic membrane in reactions requiring intracellular phosphoenolpyruvate. Soluble proteins released by vigorous homogenization of cells with glass beads are shown to be necessary for the phosphoenolpyruvate-dependent phosphorylation of sucrose in combination with one or more proteins that remain tightly associated with the membrane fraction. We have partially purified phosphotransferase enzyme I and have purified a heat-stable phosphocarrier protein (HPr) to apparent homogeneity, by gel filtration and ion-exchange chromatography from the soluble fraction. HPr from S. mutans has an apparent molecular weight larger than that of Escherichia coli HPr but has properties similar to those of Staphylococcus aureus HPr. Furthermore, it appears to be partially complexed with a heat-stable enzyme III-like protein in cell-free fractions from S. mutans, and we also report the purification of this complex. Enzyme I from S. mutans is a protein (native Mr greater than 100,000) that cross-complements enzyme I from S. aureus. Preliminary characterizations of homogeneous HPr and its complex with the putative enzyme III are also presented.
Recombinant cold-adapted attenuated influenza A vaccines for use in children: molecular genetic analysis of the cold-adapted donor and recombinants
Authors: Ghendon Y Z , Polezhaev F I , Lisovskaya K V , Medvedeva T E , Alexandrova G I , Klimov A I
Published: January 2020

A previously described cold-adapted attenuated virus, A/Leningrad/134/17/57 (H2N2), was further modified by 30 additional passages in chicken embryos at 25 degrees C. This virus had a distinct temperature-sensitive (ts) phenotype, grew well in chicken embryos at 25 degrees C, and failed to recombine with reference ts mutants of fowl plague virus containing ts lesions in five genes coding for non-glycosylated proteins (genes 1, 2, 5, 7, and 8). Recombination of A/Leningrad/134/47/57 with wild-type influenza virus strains A/Leningrad/322/79 (H1N1) and A/Bangkok/1/79(H3N2) yielded ts recombinants 47/25/1(H1N1) and 47/7/2 (H3N2). These recombinants inherited their ts phenotype and ability to reproduce in chicken embryos at 25 degrees C from the cold-adapted parent. Analysis of the genome composition of the recombinants obtained by recombination of the cold-adapted donor with wild-type influenza virus strains A/Leningrad/322/79(H1N1) and A/Bangkok/1/79(H3N2) showed that recombinants 47/25/1(H1N1) and 47/7/2 (H3N2) inherited five and six genes, respectively, from the cold-adapted parent, and hemagglutinin and neuraminidase genes from the wild-type strains.
Distribution of oral Haemophilus species in dental plaque from a large adult population
Authors: Liljemark W F , Bloomquist C G , Uhl L A , Schaffer E M , Wolff L F , Pihlstrom B L , Bandt C L
Published: January 2020

The periodontal status of maxillary first molars in 284 young adults demonstrating near-health to early disease was evaluated, and supragingival and subgingival plaque samples were collected. Plaque samples were processed anaerobically, enumerated microscopically for bacterial morphotypes, and cultivated on various media to enumerate the microflora. Although haemophili were ubiquitous (recovered in 98.5 and 96.2% of the supragingival and subgingival plaque samples, respectively), 50% of the respective samples had proportions of less than or equal to 1.5% and less than or equal to 0.33% total Haemophilus spp. based on total cultivable microflora. To study the distribution of Haemophilus spp., 377 colonies were identified from modified chocolate agar (selective for oral haemophili) from 14 supragingival and corresponding subgingival samples from 14 subjects. The most prevalent species, Haemophilus parainfluenzae, was found in significantly higher proportions, based on total haemophili on modified chocolate agar, in supragingival and subgingival samples from teeth with shallower probing depths (less than or equal to 3.0 mm) versus deeper probing depths (greater than or equal to 3.0 mm). Additional statistically significant findings included Haemophilus segnis in higher proportions in supragingival samples from deeper sites, Haemophilus aphrophilus in higher proportions in subgingival samples from deeper sites, and Haemophilus paraphrophilus in higher proportions in subgingival samples from shallower sites. Scatter diagrams illustrating the bivariate distributions of proportions of haemophili with proportions of dark-pigmented Bacteroides spp., spirochetes, and streptococci demonstrated that high proportions of haemophili were never recovered from sites with high proportions of Bacteroides spp. or spirochetes. All levels of haemophili, however, were recovered from sites with all levels of streptococci. Two potential systems for interpreting haemophili data were hypothesized for predicting periodontal probing depths. There was highly significant agreement between the two systems. Small but statistically significant correlations were found between the gingival index, probing depth, and attachment level, and proportions of total Haemophilus species in the respective samples.
Phenolic glycolipid 1 of Mycobacterium leprae causes nonspecific inflammation but has no effect on cell-mediated responses in mice
Authors: Brett S J , Lowe C , Payne S N , Draper P
Published: January 2020

The involvement of the phenolic glycolipid from Mycobacterium leprae in cell-mediated immunity has been investigated in this study. The phenolic glycolipid itself does not appear to stimulate cell-mediated immunity directly, as shown by its failure to elicit a classical delayed-type hypersensitivity response in mice immunized with M. leprae or to stimulate M. leprae-immune lymph node cells in a lymphoproliferative assay. Intradermal vaccination with the phenolic glycolipid failed to influence the growth of M. leprae in mouse footpads. A nonspecific inflammatory response to the sonicated glycolipid was observed in mice vaccinated with whole M. leprae and in control animals. No evidence was obtained for any adjuvant or suppressive effect on cell-mediated immunity by the phenolic glycolipid either to M. leprae or an unrelated antigen (sheep erythrocytes); neither sensitization nor elicitation to either antigen was affected.
Flagella of Salmonella typhimurium are a virulence factor in infected C57BL/6J mice
Authors: Carsiotis M , Weinstein D L , Karch H , Holder I A , O'Brien A D
Published: January 2020

To determine whether flagella, chemotaxis, and motility of Salmonella typhimurium are virulence factors in infected C57BL/6J mice, we constructed isogenic pairs of derivatives of the nonfimbriated virulent strain SL3201. Of each pair, one member contained a mutation in a single gene that is required for expression of normal chemotactically directed motility, whereas the other member contained the wild-type form of the gene. No additional differences between the members of a pair were evident. The phenotypic parameters examined for all derivatives included in vitro growth rate, sensitivity to P22 phage, amino acid auxotrophy, and biotype. For a flagellated and nonflagellated pair, the electron microscopic appearance of each member was examined as well as its lipopolysaccharide and outer membrane profiles by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The virulence of the various derivatives was then assessed in mice challenged orally, intraperitoneally, or intravenously. The results established that flagella, whether functional or nonfunctional as organelles of motility, were S. typhimurium virulence factors and that neither chemotaxis nor motility was required for virulence.
Immunity against infection with Trypanosoma cruzi in mice correlates with presence of antibodies against three trypomastigote polypeptides
Authors: Zweerink H J , Weston H D , Andersen O F , Garber S S , Hayes E C
Published: January 2020

Repeated immunizations of CF1 mice with irradiated noninfectious Trypanosoma cruzi trypomastigotes resulted in partial protection against infection with live parasites. It also induced a limited number of antibody species that were reactive in Western blots with trypomastigote but not with epimastigote or amastigote polypeptides. These antibody species were strongly reactive with a 100,000-dalton polypeptide and much less reactive with at least two polypeptides greater than 200,000 daltons. Immunization with epimastigotes induced antibodies against a 57,000-dalton epimastigote-specific polypeptide but did not induce protective immunity.
Identification and properties of distinct sucrose and glucose phosphotransferase enzyme II activities in Streptococcus mutans 6715g
Authors: Jacobson G R , Mimura C S , Scott P J , Thompson P W
Published: January 2020

We investigated phosphoenolpyruvate-dependent phosphotransferase system enzyme II activities for sucrose and glucose in Streptococcus mutans 6715g. Two integral membrane proteins, enzyme IIscr and enzyme IIglc, each specific for its sugar substrate, sucrose or glucose, were identified by their abilities to catalyze specific sugar:sugar-phosphate exchange reactions. Some of the properties of these two transport proteins are also presented.
Specific mediation of cellular immunity to Toxoplasma gondii in somatic cells of mice
Authors: Chinchilla M , Frenkel J K
Published: January 2020

Lymphocytes from mice immunized against Toxoplasma gondii protected T. gondii-infected macrophage and kidney cell cultures. After contact with antigens, supernatants of such immune lymphocytes, also contained a factor protective for T. gondii-infected macrophages and kidney cells. Supernatants were protective only when the lymphocytes and kidneys cells were isogeneic. Protection was specific in that supernatants from only T. gondii-immune, but not Besnoitia jellisoni-immune, lymphocytes provided protection against toxoplasmosis. Sixteen to 24 h were required for an appreciable amount of protective factor to be secreted; a similar absorption time was necessary for kidney cells to be protected. Peritoneal lymphocyte lysates, prepared as transfer factor, contained protective substances with a potency similar to that of lymphocyte supernatants, which were also strain restricted in their effect.
Role of Pseudomonas aeruginosa mucoid exopolysaccharide in adherence to tracheal cells
Authors: Ramphal R , Pier G B
Published: January 2020

The mucoid exopolysaccharide of Pseudomonas aeruginosa is thought to confer antiphagocytic properties on mucoid strains of P. aeruginosa, thus allowing them to persist in the respiratory tract. It has also been speculated that the mucoid exopolysaccharide may be the adhesin for mucoid strains, but proof is lacking. We studied the role of the mucoid exopolysaccharide in adherence of mucoid strains in competitive experiments with purified mucoid exopolysaccharide, by measuring the binding of 14C-labeled mucoid exopolysaccharide to injured tracheas and testing whether an antibody against the major epitope of the mucoid exopolysaccharide inhibits adherence of these organisms. Our data show that the purified mucoid exopolysaccharide increased the adherence of four of the mucoid strains tested (by 50 to 300%; P less than 0.001) instead of inhibiting adherence. Radiolabeled mucoid exopolysaccharide bound much better to injured tracheal cells than to normal tracheal cells (P less than 0.001), and antibody against the antigen of strain 2192, the strain from which mucoid exopolysaccharide was prepared, inhibited the adherence of four of five mucoid strains but not the strain lacking this antigen. This antibody also failed to inhibit a nonmucoid revertant from strain 2192, which was previously shown to be inhibited by pili. These data strongly support the thesis that the mucoid exopolysaccharide is the adhesion for mucoid strains of P. aeruginosa.
Hydrophobic interaction in Candida albicans and Candida tropicalis adherence to various denture base resin materials
Authors: Minagi S , Miyake Y , Inagaki K , Tsuru H , Suginaka H
Published: January 2020

The effects of hydrophobicities of substrate surfaces on microbial adherence were examined by using Candida albicans and Candida tropicalis and 21 denture base resin materials. With increasing surface free energy of resin plates, increasing adherence of C. albicans and decreasing adherence of C. tropicalis were observed. The surface free energy of C. albicans is higher than that of all resin material surfaces, and C. tropicalis has surface free energy lower than that of all materials used. In calculation of the changes of free energy accompanying the adherence, the higher adherence tendency was accompanied by a lower value for the free energy change in both species. From a different standpoint, the closer the surface free energy of the substrate surface and the microorganism, the higher was the probability of adherence.