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Microbial Invasion (microbial + invasion)
Selected AbstractsSalient virulence factors in anaerobic bacteria, with emphasis on their importance in endodontic infectionsENDODONTIC TOPICS, Issue 1 2004Ingar Olsen Endodontic infections by microbial invasion of the necrotic pulp lead to apical periodontitis of both acute and chronic forms. Acute lesions often develop from multiplication of bacteria in primary infections. Such lesions may also occur as exacerbations of chronic forms provoked for example in conjunction with endodontic treatment measures. The clinical course appears related to the character of the microflora. While primary infections are predominated by a mixed flora of anaerobic bacteria and resembles that of aggressive marginal periodontitis, chronic forms of apical periodontitis emerge following regression of the acute infection, whereupon prevailing bacteria have assumed low activity. The significance of virulence factors is easy to understand as far as acute inflammatory conditions are concerned. The role of virulence factors for sustaining chronic inflammation is more unclear and complex. This review is about salient virulence factors in some selected bacterial genera such as Peptostreptococcus, Porphyromonas, Prevotella and Fusobacterium, which often predominate the root canal microbiota in the acute phase of endodontic infections. [source] Acholeplasma laidlawii up-regulates granulysin gene expression via transcription factor activator protein-1 in a human monocytic cell line, THP-1IMMUNOLOGY, Issue 3 2001Yutaka Kida Summary An antimicrobial protein granulysin is constitutively expressed in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. However, little is known about the precise regulatory mechanisms underlying granulysin gene expression. In this study, we examined the regulatory mechanisms underlying granulysin gene expression using a human monocytic cell line, THP-1, treated with Acholeplasma laidlawii. The level of granulysin mRNA expression in THP-1 cells was significantly augmented in response to stimulation with A. laidlawii. The transfection of reporter gene constructs into THP-1 cells indicated that DNA sequences between residues ,329 and ,239, relative to the transcriptional start site of the granulysin gene, are responsible for mediating gene induction. In addition, mutagenesis of a putative activator protein-1 (AP-1)-binding site between residues ,277 and ,271 in the granulysin promoter resulted in the reduction of granulysin promoter activity. Electrophoretic mobility shift assays (EMSA) demonstrated that nuclear extract prepared from A. laidlawii- treated THP-1 cells can generate specific binding to DNA oligonucleotides encompassing the AP-1-binding site, whereas unstimulated nuclear extract from the cells failed to do so. Furthermore, competition and supershift assays confirmed that A. laidlawii can induce the activation of AP-1. These results indicate that AP-1 dominantly participates in the regulation of inducible granulysin gene expression in THP-1 cells. Therefore, the finding of inducible granulysin gene expression by A. laidlawii suggests that inducible granulysin in macrophages may function as a protective weapon when microbial invasion occurs. [source] The inflammatory reflex , IntroductionJOURNAL OF INTERNAL MEDICINE, Issue 2 2005J. ANDERSSON Abstract. Sepsis is the third leading cause of death in the developed world. Despite recent advances in intensive care treatment and the discovery of antibiotics, sepsis remains associated with a high mortality rate. The pathogenesis of sepsis is characterized by an overwhelming systemic inflammatory response that is central to the development of lethal multiple organ failure. This volume of the Journal of Internal Medicine contains three reviews addressing novel aspects of a system we are only beginning to understand , the interactions between the immune and the nervous systems, the ,neuro-immune axis'. Tracey (Nature 2002; 420: 853) recently discovered that the nervous system, through the vagus nerve, can modulate circulating TNF- , levels induced by microbial invasion or tissue injury. This cholinergic anti-inflammatory pathway is mediated primarily by nicotinic acetylcholine receptors on tissue macrophages , the pathway leads to decreased production of proinflammatory cytokines. The author reports that treatment with the acetylcholine receptor agonist, nicotine, modulates this system and reduces mortality in ,established' sepsis. Watkins and Maier (J Intern Med 2005; 257: 139) illustrate that pathological pain (induced by inflammation) is not simply a strict neuronal phenomenon, but is a component of the immune response, and is modulated by peripheral immune cells and spinal cord glia cells. This may be of importance for future development of novel drugs for neuropathic pain as well as our understanding of increased risks for infections in anaesthetic skin areas. Blalock (J Immunol 1984; 132: 1067) elucidates the possibility that the immune system actually functions as the sixth sense, sensing microbes and microbial toxins that we cannot see, hear, taste, touch or smell. Activation of the sympathetic nervous system also has predominantly anti-inflammatory effects that are mediated through direct nerve to immune cell interaction or through the adrenal neuro-endocrine axis. [source] Prevalence and Diversity of Microbes in the Amniotic Fluid, the Fetal Inflammatory Response, and Pregnancy Outcome in Women with Preterm Pre-Labor Rupture of MembranesAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2010Daniel B. DiGiulio Citation DiGiulio DB, Romero R, Kusanovic JP, Gómez R, Kim CJ, Seok K, Gotsch F, Mazaki-Tovi S, Vaisbuch E, Sanders K, Bik EM, Chaiworapongsa T, Oyarzún E, Relman DA. Prevalence and diversity of microbes in the amniotic fluid, the fetal inflammatory response, and pregnancy outcome in women with preterm pre-labor rupture of membranes. Am J Reprod Immunol 2010; 64: 38,57 Problem, The role played by microbial invasion of the amniotic cavity (MIAC) in preterm pre-labor rupture of membranes (pPROM) is inadequately characterized, in part because of reliance on cultivation-based methods. Method of study, Amniotic fluid from 204 subjects with pPROM was analyzed with both cultivation and molecular methods in a retrospective cohort study. Broad-range and group-specific polymerase chain reaction (PCR) assays targeted small subunit ribosomal DNA (rDNA), or other gene sequences, from bacteria, fungi, and archaea. Results were correlated with measurements of host inflammation, as well as pregnancy and perinatal outcomes. Results, The prevalence of MIAC was 34% (70/204) by culture, 45% (92/204) by PCR, and 50% (101/204) by both methods combined. The number of bacterial species revealed by PCR (44 species-level phylotypes) was greater than that by culture (14 species) and included as-yet uncultivated taxa. Some taxa detected by PCR have been previously associated with the gastrointestinal tract (e.g., Coprobacillus sp.), the mouth (e.g., Rothia dentocariosa), or the vagina in the setting of bacterial vaginosis (e.g., Atopobium vaginae). The relative risk for histologic chorioamnionitis was 2.1 for a positive PCR [95% confidence interval (CI), 1.4,3.0] and 2.0 for a positive culture (95% CI, 1.4,2.7). Bacterial rDNA abundance exhibited a dose relationship with gestational age at delivery (R2 = 0.26; P < 0.01). A positive PCR was associated with lower mean birthweight, and with higher rates of respiratory distress syndrome and necrotizing enterocolitis (P < 0.05 for each outcome). Conclusion, MIAC in pPROM is more common than previously recognized and is associated in some cases with uncultivated taxa, some of which are typically associated with the gastrointestinal tract. The detection of MIAC by molecular methods has clinical significance. [source] Diagnostic imaging tests and microbial infectionsCELLULAR MICROBIOLOGY, Issue 10 2007Christopher J. Palestro Summary Despite significant advances in the understanding of its pathogenesis, infection remains a major cause of patient morbidity and mortality. While the presence of infection may be suggested by signs and symptoms, imaging tests are often used to localize or confirm its presence. There are two principal imaging test types: morphological and functional. Morphological tests include radiographs, computed tomography (CT), magnetic resonance imaging, and sonongraphy. These procedures detect anatomic, or structural, alterations produced by microbial invasion and host response. Functional imaging tests reflect the physiological changes that are part of this process. Prototypical functional tests are radionuclide procedures such as bone, gallium, labelled leukocyte and fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging. In-line functional/morphological tomographic imaging systems, PET/CT and single photon emission tomography (SPECT)/CT, have revolutionized diagnostic imaging. These devices consist of a functional imaging device (PET or SPECT) joined together with a CT scanner. The patient undergoes both tests sequentially without leaving the examination table. Images from each study can be viewed separately and as fused images, providing precisely localized anatomic and functional information. It must be noted, however, that none of the current morphological or functional tests, either alone or in combination, are specific for infection and the goal of finding such an imaging test remains elusive. [source] | ||||||||||