Bacteriology Commons^™

Pas Signaling Mechanisms In Aer And Aer2, Darysbel Garcia

Loma Linda University Electronic Theses, Dissertations & Projects

PAS domains are widespread signal sensors that share a conserved three-dimensional αβ fold that consists of a central β-sheet flanked by several α- helices. The aerotaxis receptor Aer from Escherichia coli and the Aer2 chemoreceptor from Pseudomonas aeruginosa both contain PAS domains. Aer senses oxygen (O2) indirectly via an FAD cofactor bound to its PAS domain, while Aer2 directly binds O2 to its PAS b-type heme cofactor. The Aer and Aer2 PAS domains both interact with a signal transduction domain known as a HAMP domain. The PAS-HAMP arrangement differs between Aer and Aer2, with Aer- PAS residing adjacent to its …

Studies In Prolonged Oxidative Stress Resistance In Porphyromonas Gingivalis, Rachelle Mckenzie

Loma Linda University Electronic Theses, Dissertations & Projects

Porphyromonas gingivalis is a gram negative, anaerobic bacterium implicated as a major etiological agent in chronic adult periodontitis. In the inflammatory environment of the periodontal pocket, the organism must overcome oxidative stress as a result of exposure to air in the oral cavity as well as to reactive oxygen species (ROS) generated by host immune cells. A comprehensive mechanism for oxidative stress resistance in P. gingivalis is yet to be fully elucidated. In this study we examined the modulation of gene expression under conditions of oxidative stress by whole-genome DNA microarray analysis. Our findings indicated that numerous genes are involved …

Effect Of Short Exposure Of Naoci/Edta On E. Faecalis In Extracted Human Teeth, Rylan N. Gustafson

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this project was to study the antibacterial effect of the short exposure of 5.25% NaOCl and 17% EDTA on eight strains of Enterococcus faecalis in extracted human teeth. The crowns of 240 single rooted teeth were removed and the canals were instrumented to ISO 0.36. The canals were irrigated with 5.25% NaOCl and 17% EDTA, autoclaved and separated into eight groups of 30 teeth consisting of 20 experimental teeth, 5 positive and 5 negative controls. Each group was inoculated with one of eight different strains of E. faecalis in BHl broth and incubated for four weeks. The …

Detection Of Bacteria To Dental Tissue By Low-Light Imaging, G-Hong Robert Hsu

Loma Linda University Electronic Theses, Dissertations & Projects

Bacteria have been shown to play an important role in the development of pulp and periradicular disease. The source of the infective bacteria is most often the oral cavity. Previous studies have detected bacteria in teeth that are structurally intact that seemingly have no communication intraorally. Anachoresis has been proposed as a mechanism for localizing circulating bacteria to such teeth. In several previous bacteriologic anachoresis studies, bacteria have been found to localize in inflamed dental tissues. The criticism most commonly associated with these investigations has been the potential contribution of contaminant bacteria resulting in false positive findings.

Low-light image analysis …

Identification Of The Polar Flagellum Genes In Azospirillum Brasilense, Enid Thanna Mckinley

Loma Linda University Electronic Theses, Dissertations & Projects

Azospirillum brasilenser, a nitrogen fixing rhizobacterium, can colonize plant roots and increase the yield of economically important cereals, such as rice and grasses. This organism has a mixed pattern of flagellation: a single polar flagellum for motility in liquid medium and lateral flagella which might be involved in motility across the root surface and or attachment to the root hairs of plants. Flagella dictate A. brasilense chemotactic ability and motility, which plays an important role in colonization of plant roots. However, nothing is known about the genes that code for the polar flagellum. To study the polar flagellum, different mutants …

Cellular Responses In Escherichia Coli To Lethal And Sublethal Doses Of Ozone, Indira Ruth Komanapalli

Loma Linda University Electronic Theses, Dissertations & Projects

Ozone is a major component of photochemical smog. High levels of this pollutant, sufficient to affect human health are found in many urban areas worldwide. Though limited studies in humans are supported by extensive findings from animal experiments, a difficulty in interpreting the results of these experiments has lead to an ambiguity on the biochemical mechanism of ozone toxicity. To elucidate the mechanism by which ozone causes cell damage and eventual cell death we conducted a comprehensive study using Escherichia coli K-12 as a model.

Studies on the comparative inactivation of bacteriophage lambda (λ), Escherichia coli, and Candida albicans …

Characterization Of Restriction-Modification Systems In Klebsiella Pneumoniae, Boontar Valinluck

Loma Linda University Electronic Theses, Dissertations & Projects

Two restriction-modification (R-M) systems KpnAI and KpnBl, found in Klebsiella pneumoniae strains M5a1 and GM236, respectively, have been studied and confirmed to he different from other R-M systems reported in K. pneumoniae. Mutant studies that the KpnAl and KpnBI systems may belong to either a type I or type III systems since approximately equal numbers of r^-m⁺ and r^-m^- mutants were obtained. However, a DNA hybridization study using representative type I and type III probes from E. coli and S. typhimurium failed to show homologies to either KpnAI or KpnBI. The restriction endonuclease …

The Expression And Regulation Of The Hsdk Genes Of Escherichia Coli K-12, Ainu Prakash

Loma Linda University Electronic Theses, Dissertations & Projects

The DNA restriction and modification of (R-M) genes in bacteria play a defensive role in the organism, offering protection to the host from invaders such as bacteriophages. The expression of these genes in E. coli K-12 has no previously been studied due to the complexity of EcoK R-M enzymes. The use of lacZ gene fusion techniques allowed studies of the expression of the hsdK genes for the first time. Operon fusions of Mu(lac) to the hsdK genes show that the two hsdK promoters, P_res and Pmod, are weak (50 Miller units) and that both operate …

The Expression And Regulation Of The Hsdk Genes Of Escherichia Coli K-12, Ainu Parkash

Loma Linda University Electronic Theses, Dissertations & Projects

The DNA restriction and modification (R-M) genes in bacteria play a defensive role in the organism, offering protection to the host from invaders such as bacteriophages. The expression of these genes in E. coli K-12 had not previously been studied due to the complexity of the EcoK R-M enzymes. The use of lacZ gene fusion techniques allowed studies of the expression of the hsdK genes for the first time. Operon fusions of Mu(/ac) to the hsdK genes show that the two hsdK promoters, p _res and p _mod, are weak (50 Miller units) and that …

Concentration Of Leukotrienes B4 And C4 In Human Periradicular Lesions, Elisabetta Cotti

Loma Linda University Electronic Theses, Dissertations & Projects

The 5-lipoxygenase metabolites of arachidonic acid such as leukotrienes (LT) B₄ and C₄, are potent mediators of inflammation. The purpose of this investigation was to determine the concentrations of LTB₄ and LTC₄ in human periradicular lesions. Specimens from asymptomatic and symptomatic patients were obtained and immediately frozen in liquid nitrogen. Periradicular tissues from unerupted third molars as well as chronically inflamed gingival tissues were also obtained, frozen and were used as negative and positive controls respectively. The concentrations of LTB₄ and LTC₄ were determined by the reverse phase high pressure liquid chromatography. Representative …

Characterization Of Hsd::Mudx128 Operon Fusion Mutant Of Escherichia Coli K-12, Marjorie Ann T. Reyno

Loma Linda University Electronic Theses, Dissertations & Projects

The study of the regulation of gene expression in complex genes can be facilitated by the use of operon fusions which place a well characterized lacZ gene under the control of a promoter of interest. An hsd::MudX128 operon fusion mutant of E. coli K-12 isolated by Prakash (1986) was observed to have a high β-galactosidase activity (1000 units), ten to twenty times higher than other hsd::MudX mutants. This β-galactosidase activity was suppressed to a very low level (25 units) by the introduction of an F’ plasmid, F'101, which carries the 98 min to 2 min region of the …

Genetic Transformation In Salmonella Typhimurium, Siao Ping Tasi

Loma Linda University Electronic Theses, Dissertations & Projects

Plasmid transformation is an essential step in many gene cloning experiments. In Salmonella tynhimurium, mutants of rough strain have shown improved transformation frequency previously. In this work a stable restriction-minus (r^-) and modification-plus (m⁺) strain and its derivatives were constructed. Effect of restriction barrier on transformation of plasmid pBR322 was tested. Several factors which may affect transformation frequency have been systematically examined to determine the optimum conditions for transformation in S. tvphimurium. Efforts were made to simplify the procedure.

Using pBR322 plasmid as an experimental model, the r^- strain demonstrated 10⁵ to …

The Effects Of Certain Oral Bacteria On The In Vitro Growth Of Bacteroides Gingivalis, Steven G. Morrow

Loma Linda University Electronic Theses, Dissertations & Projects

The effect of nine gram positive and grain negative cocci and bacilli, which are indigenous to the oral cavity, on the in vitro growth of Bacteroides gingivalis was examined in this study. A pure culture of B. gingivalis is was obtained from the American Type Culture Collection. The nine oral test organisms were Streptococcus mitis, Streptococcus mutans, Streptococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus, Corynebacteriurn hofmanii, Lactobacillus acidophilus, Branhamella catarrhalis, and Escherichia coli. The effect on the growth of B. gingivalis of the nine test organisms was evaluated on a solid medium by use of …

Restriction Analysis Of Bacteriophage, Ali Reza Mostaghimi

Loma Linda University Electronic Theses, Dissertations & Projects

A restriction map of DNA from bacteriophage P3-C₁ for the endonucleases BamH I, Bgl II, EcoR I, Hind III, Sac I and Sca I is described in this study. The phage DNA was determined to be a linear double stranded molecule with a unit genomic length of 31 kb. After electrophoresis in 0.5% agarose gels, the undigested DNA appeared as three molecules of 31, 62 and 93 kb in length. The Hind III digestion pattern of the individual 31 kb molecule was identical to the 62 kb and 93 kb Hind III pattern. With all enzymes except Hind III, …

A Study Of Transferable Antibiotic Resistance In Enteric Bacteria, Charles H. Regeski

Loma Linda University Electronic Theses, Dissertations & Projects

A group of 48 enteric bacteria was selected from a total of 170 at Loma Linda University Medical Center because of resistance to three or more antibiotics. They were examined to see if any of the antibiotic resistances were transferred by conjugation to either of two recipient bacteria. These were a restrictionless, antibiotic sensitive, azide resistant mutant of Escherichia coli K 12 designated E. coli 1228 and a similar phenotypic strain of Salmonella typhimurium LT2 designated LB 5000. Forty-three transferred one or more antibiotic resistances to either or both recipients, a frequency of 25.3% of the total bacteria and 89.6% …

Cell Mediated Immunity By Cytotoxicity Assay And The Effect Of Corynebacterium Parvum And Radiation On Mice Bearing Herpes-Induced Tumors, Robert B. Stagg

Loma Linda University Electronic Theses, Dissertations & Projects

Cell mediated immune (CMI) cytotoxic reactivity of Balb/c mice against H238 cells, a Herpes simplex virus (HSV) Type 2 - induced sarcoma, was measured by the ¹²⁵IUdR release assay. The Balb/c mouse response to the growing HSV-induced tumor, treated with radiation and , was measured by survival rate, tumor growth and immune cytotoxicity of spleen and peritoneal exudate cells (PEC) as determined by ¹²⁵IUdR release assay. Subcutaneous (s.c.) inoculation of 1 x 10⁶ H238 cells (high dose) produced progressive tumor growth while s.c. inoculation of 1 x 10⁴ H238 cells (low dose) produced no tumors. A …

The Germfree Culture Of Three Species Of Triatominae: Triatoma Protracta (Uhler), Triatoma Rubida (Uhler), And Rhodnius Prolixus Stål, Stephen A. Nyirady

Loma Linda University Electronic Theses, Dissertations & Projects

Triatoma protracta protracta, Triatoma riibida rubIda, and two strains of Rhodnius prolixus were successfully reared germfree into the fourth generation. Triatominae eggs were disinfected externally with iodine and the nymphs reared in vinyl plastic germfree modules. Germfree mice were used as the host. This is the first report of Triatominae having been reared in a germfree environment. These bugs were never exposed to bacteria internally or externally to the fourth generation.

Comparisons of conventional control bugs with replicate germfree groups in the first two generations revealed but slight differences in developmental periods. The mean adult longevity of all …

Bacteriuria As A Precursor Of Intracatheter Encrustation, Namcy Moll

Loma Linda University Electronic Theses, Dissertations & Projects

The problem with which this study was concerned was the development of criteria that could be used to determine when urinary catheter changes were necessary. By determining when encrustation occurred, it was felt that some complications could be eliminated by changing catheters before obstruction occurred due to encrustation.

It was the purpose of this study to: 1) explore some indications for catheter change, 2) determine if encrustation of urinary catheters necessitates catheter change, and 3) estimate potential criteria for a routine time for catheter changes.

Forty-five catheters were examined after their removal from patients. Flow rates were determined on 33 …

The Effect Of Elevated Glucose On Neutrophilic Phagocytosis In Genetically Diabetic Mice, Larry B. Thompson

Loma Linda University Electronic Theses, Dissertations & Projects

Infiltration to an injury site or area of bacterial contamination by polymorphonuclear leucocytes (or neutrophils) is an early and essential phase of the early inflammatory reaction. Their action on foreign matter is the most critical step taken by body defense mechanisms in the first 24 hours. Anything which interferes with that action, phagocytosis, greatly hampers early inflammation. This study was designed to see the effect of elevated glucose levels on neutrophil phagocytosis in a unique strain of genetically diabetic mice.

Twenty-two diabetic and twenty-four control female mice were used. Blood glucose determinations and total white counts were made on each …

Properties Of Salmonella Phage P3 After Subjection To Host-Controlled Modification By Passage Through E. Coli K-12, Benjamin J. Siapco

Loma Linda University Electronic Theses, Dissertations & Projects

Five new bacteriophages were isolated from lysogenic S. potsdam in this laboratory. Group B phages (P3 and P9a) were found to have unique properties, including their capability to infect strains of E. coli K-12 and E. coli C⁺/L. Passage of the phages through these hosts modified them (host-controlled modification) so that their ability to infect their original host, S. potsdam, was reduced and only 1-4 per million were able to form plaques.

To help elucidate the biochemical basis of host-controlled modification in the Salmonella potsdam group of bacteriophages, the clear plaque mutant of one of them, P3-c …

The Nature Of Salmonella Phage P3 Modification And Restriction By Growth In Escherichia Coli, Clark A. Pearson

Loma Linda University Electronic Theses, Dissertations & Projects

The Salmonella potsdam group B bacteriophage P3, which grows in the rough variant strain of S. potsdam (SP2-R) and E. coli K_CS11, K_W117, and C⁺/L with similar efficiencies, was restricted by SP2-R after a passage though E. coli. The entrance of restricted E. coli-grown phage DNA into nonpermissive SP2-R cells was confirmed by the finding that after adsorption of restricted ³²P-labeled P3-C₁·C⁺/L to SP2-R and removal of the adsorbed phage heads from cells, 80.3% of the labeled DNA activity sedimented with the cells. Thus restricted P3 DNA …

Infectivity And Development Of Trichinella Spiralis In Germ-Free, Monocontaminated And Conventional Mice, Daulat Sitanggang

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of the experiment was to compare the development of Trichinella spiralis in germ-free, Lactobacillus casei monocontaminated, Escherichia coli monocontaminated and conventional mice. The criteria used in the experiments were the recovery of adults and larvae of T. spiralis after 72 hours and one month post-infection, respectively. which gave an indication of the effects of no bacteria or only a certain, single species of bacterium on the development of this nematode in mice.

Germ-free T. spiralis larvae were obtained by washing them several times with sterile normal saline, and treatment with antibiotics. The gavaging procedure was done without anesthetization …

The Effectiveness Of Camphorated Paramonochlorophenol, Metacresyl Acetate, And Prednisolone In Combination As An Antimicrobial Agent, Maurice Cutler

Loma Linda University Electronic Theses, Dissertations & Projects

Post-treatment discomfort following endodontic procedures can be caused by inflammation due to injudicious use of intracanal medicaments. Camphorated paramonochlorophenol, metacresyl acetate, and prednisolone in combination is advocated to reduce the inflammatory potential of the germicide and thus reduce the occurrence of post-operative pain. It is imperative that a medicament retain antimicrobial activity while reducing inflammatory potential.

This investigation was undertaken toward determining on an in vitro quantitative bactericidal versus bacteriostatic basis by use of the broth dilution test tube method whether camphorated paramonochlorophenol, metacresyl acetate, and prednisolone in combination retains antimicrobial activity comparable to selected other commonly used nonspecific germicides. …

The Intestinal Flora Of Triatoma Protracta Protracta (Uhler) (Hemiptera: Reduviidae) Including New Bacterial Isolation Techniques, Stephen A. Nyirady

Loma Linda University Electronic Theses, Dissertations & Projects

A bacteriological procedure for the removal of the intestinal flora of Triatominae is described. Immersion of Triatoma protracta adults and fifth instar nymphs in 5% aqueous formaldehyde for three hours was sufficient to free the integument of these insects of viable bacteria without penetration into the alimentary tract.

Twenty-two adults and 17 fifth instar nymphs of Triatoma protracta protracta were collected from Neotoma lodges in southern California. Eleven of the 17 nymphs molted into adults in the laboratory. With the use of a 2% peracetic acid sterilized custom built plastic germ-free isolator the Triatoma were dissected and various sections of …

Complementarity Between The Deoxyribonucleic Acid Of Bacteriophage P4/2 And That Of Its Naturally Lysogenic Host Salmonella Potsdam Strain 4, Londa Liseli Schmidt

Loma Linda University Electronic Theses, Dissertations & Projects

Complementarity studies were conducted between bacteriophage P4/2 DNA and the DNAs of its naturally lysogenic host Salmonella potsdam strain 4 (SP4) and its sensitive host Salmonella potsdam strain 2 (SP2). Calf thymus DNA was used as a control.

Nitrocellulose membranes were used to adsorb varying concentrations of unlabeled DNA, using P4/2 DNA, SP4 DNA, SP2 DNA, and calf thymus DNA. A constant amount of P³² -labeled P4/2 DNA was added to each membrane and the hybrids were allowed to form. After thorough rinsing to get rid of unbound labeled DNA, radioactivity of the samples was read in a liquid …

Some Phage Associated Properties In Salmonella Potsdam, Thomas B. Seifert

Loma Linda University Electronic Theses, Dissertations & Projects

The non-lysogenic strain and several lysogenic strains of S. potsdam were tested biochemically and antigenically to detect any possible phage related property.

Fermentation reactions and citrate utilization tests were identical for all strains.

Tubes agglutination tests showed the non-lysogenic and lysogenized strains of SP2-S to be similar, and different from the naturally lysogenic strains SP3, SP4, SP9, and SP10. Absorption tests confirmed the SP2-s strains, either non-lysogenic or lysogenized, to possess an additional antigen SP3 and SP4 did not possess. SP9 and SP10 may contain small amounts of this antigen. From variation may explain the antigenic difference between these strains. …

The Effect Of Glucose On Neutrophilic Phagocytosis, Donald F. Adams

Loma Linda University Electronic Theses, Dissertations & Projects

Samples of blood were obtained from thirty healthy young adult males (Loma Linda University School of Dentistry), and contaminated with bacteria. Varying concentrations of pure glucose were added to this mixture to observe the effect of the glucose on in vitro neutrophilic phagocytosis. As the glucose levels increased a statistically significant suppression was noted in the ability of the neutrophilic leukocytes to engulf Staphylococcus epidermidis.

It was not possible, however, to predict the degree of suppression for any particular level of glucose added nor is it possible to state that suppression will occur in any one individual.

Two methods of …

Host And Prophage Modifications Of Ultraviolet Induction In Salmonella Potsdam, Bela B. Toth

Loma Linda University Electronic Theses, Dissertations & Projects

In induction experiments with naturally occurring and artificially lysogenic strains of S. potsdam, cells were irradiated in buffer, transferred to complete medium, and then assayed for free phage. Irradiation was followed by half hourly samples for free phage from the growing populations of irradiated cells. For an estimation of burst sizes, the irradiated cells were diluted out to a final concentration of 1 cell per ml and distributed to tubes in 0.5 ml quantities. All assays were done by the top-layer method with streptomycin incorporated in the top-layer and SP2-str^r as the bacterial indicator. The non-lysogenic strain S. …

Biochemical Properties Of Salmonella Potsdam Bacteriophage P4/2, Clyde L. Roggenkamp

Loma Linda University Electronic Theses, Dissertations & Projects

Over 90% recovery of phage P4/2 was realized with differential centrifugation concentration and purification, whereas only about 16% was recovered from the aqueous two-phase polymer - Genetron - ECTEOLA-cellulose column system. Purity of preparations was greatest with the density gradient centrifugation (A₂₆₀ = 2.66 and A₂₈₀ = 1.80 per 10¹² plaque-forming units). With the chemical system of concentration and purification followed by an ECTEOLA anion exchange run, the A₂₆₀ was 6.6 and the A₂₈₀ was 4.3.

Three tests were employed to determine the configuration of P4/2 DNA: (1) a formalin denaturation test, (2) a thermal …

The Fecal Shedding Of Listeria Monocytogenes By Conventional And "Germ Free" Mice, Margaret Joyce Ramsay

Loma Linda University Electronic Theses, Dissertations & Projects

A series of experiments involving Listeria monocytogenes was undertaken to study first the fecal shedding of Listeria by conventional mice challenged intraperitoneally with Listeria and second the fecal shedding and ability to survive of germ free mice with similar challenge. In addition, mites infesting Listeria infected mice were cultured for their possible contamination by Listeria.

Conventional mice were challenged intraperitoneally with a single near LD₅₀ dose of Listeria. Fecal Listeria were detected by collecting specimens from each mouse daily for the first 4 days and every second day thereafter. The feces was held at 7°C for 14 …