实验基础

Candida albicans is a pleiomorphic fungal pathogen whose morphogenetic plasticity has long been considered as a major virulence factor. In addition to the yeast-filament transition, C. albicans cells also have the unique ability to switch between two epigenetic phases referred to as wh ...

Methods and procedures in molecular biology used to study fungal pathogenesis have significantly improved during the last decade. In this chapter, we provide step-by-step procedures for performing genetics and biochemical studies in the human pathogenic fungal microorganism C ...

Since Helicobacter pylori was first described in 1983 (1), the study of genomic DNA has been central to the development of its microbiology and molecular genetics. For instance, DNA base composition estimation (mol% G+C) was crucial in demonstrating affinities of the microorganism to the ge ...

There are a number of techniques available for the detection and characterization of mutations that take advantage of the flexibility and power of polymerase chain reaction (PCR) (Table 1). Sequencing remains the gold standard, but it is not very efficient as a screening tool, in particular wh ...

The discovery of polymorphic DNA in Mycobacterium tuberculosis has led to several methods to differentiate climcal isolates. The most widely used method is based on the mobility of the insertion element IS6110, which is present in virtually all M tuberculosis isolates, usually in multip ...

Helicobacter pylori establishes chronic infections in the human gastric mucosa that can last for decades, and that are a major cause of gastritis and peptic ulcer disease (PUD) and a risk factor for gastric cancer. The importance of H. pylori as a human pathogen has led to major efforts to understand its ...

Certain nonconserved genotypic and phenotypic characteristics of H. pylori are associated with increased risk of peptic ulceration in the human host. These characteristics can be divided into two groups: first, those relating to vacuolating cytotoxin activity (1,2), and differen ...

An ability to distinguish individual strains of Helicobacter pylori with sensitivity and efficiency is valuable for studies of the epidemiology, population genetic structure, and evolution of this gastric pathogen. The arbitrarily primed polymerase chain reaction (AP-PCR), or ...

There is a great need to develop molecular techniques for the typing of Helicobacter pylori isolates since classical bacteriological assays, such as serotyping or lysotyping, are lacking. Such techniques would provide the microbiologist with the tools necessary to differentiate ...

Helicobacter pylori strains have been shown to display considerable heterogeneity with respect to DNA sequence. Diverse restriction fragment length polymorphism (RFLP) patterns are generated among strains by restriction endonuclease digestion of whole chromosomal DNA ( ...

Ribotyping, a method used to type strains of bacteria by analyzing the restriction enzyme digestion patterns of the ribosomal RNA (rRNA) genes, was first developed and proposed as a taxonomical tool for the identification and differentiation of bacteria by Grimont and Grimont, in 1986 (1). Si ...

Transposable elements are well-known genetic tools that enable the geneticist to generate mutations by disrupting the linear continuity of a specific gene and, consequently, affect its expression. This approach, in addition to providing an efficient way to create mutants, which are ea ...

Helicobacter pylori is an important etiological pathogen of human stomach diseases, such as gastritis, peptic ulcer, and gastric carcinoma (1). In the past few years, great progress has been made in the cloning and characterization of H. pylori genes. Success of these studies stems in part from the ...

Bacterial attachment to host receptors is a prerequisite for colonization of epithelial cell surfaces, in particular, continuously renewing mucosal surfaces, such as the gastrointestinal tract. Microbes express adhesion molecules for interactions with eukaryotic cell su ...

The outer membranes of Gram-negative bacteria represent selective, permeability barriers to environmental molecules. This function is accomplished in two ways. First, outer membranes exclude many larger hydrophilic molecules, including enzymes and other proteins, and most ...

Until the discovery of Helicobacter pylori in 1982, the normal human stomach was generally considered to be sterile, or transiently populated by oropharyngeal bacteria carried there by peristalsis. However, we now know that from one-third to one-half of the human population carries H. pyl ...

Despite its clinical significance, relatively little is known about the components of Helicobacter pylori that allow it to colonize, persist, and elicit an inflammatory response within the host. Bacterial surface components frequently influence colonization and persistence ...

The inability of conventional gel electrophoresis to separate DNA molecules exceeding 50 kb in size led to the development of pulsed-field gel electrophoresis (PFGE) by Schwartz et al, (1)in 1982. He introduced the concept of applying two alternating electric fields (i.e., pulsed-field) to ...

Ever since the realization that Helicobacter pylori was intimately associated with the development of gastritis and peptic ulcer disease in humans, there has been a need for a simple animal model in which modes of pathogenicity, transmission, immunization, and chemotherapeutic inte ...

The selectivity of Helicobacter pylori for the antral mucosa of the stomach and gastric metaplasia in the duodenum combined with the inaccessibility of those sites has hindered the investigation of this infection. Consequently, the study of the epidemiology and treatment of H. pylori has ...