Intravitreal injection analysis at the Bascom Palmer Eye Institute: evaluation of clinical indications for the treatment and incidence rates of endophthalmitis

To report the incidence of endophthalmitis, in addition to its clinical and microbiological aspects, after intravitreal injection of vascular-targeting agents. A retrospective review of a consecutive series of 10,142 intravitreal injections of vascular targeting agents (bevacizumab, ranibizumab, triamcinolone acetonide, and preservative-free triamcinolone acetonide) between June 1, 2007 and January 31, 2010, performed by a single service (TGM) at the Bascom Palmer Eye Institute. One case of clinically-suspected endophthalmitis was identified out of a total of 10,142 injections (0.009%), presenting within three days of injection of bevacizumab. The case was culture-positive for Staphylococcus epidermidis. Final visual acuity was 20/40 after pars plana vitrectomy surgery. In this series, the incidence of culture-positive endophthalmitis after intravitreal injection of vascular agents in an outpatient setting was very low. We believe that following a standardized injection protocol, adherence to sterile techniques and proper patient follow-up are determining factors for low incidence rates

Editing of hnRNP K protein mRNA in colorectal adenocarcinoma and surrounding mucosa

The heterogeneous nuclear ribonucleoprotein K (hnRNP K) protein is an RNA-binding protein involved in many processes that compose gene expression. K protein is upregulated in the malignant processes and has been shown to modulate the expression of genes involved in mitogenic responses and tumorigenesis. To explore the possibility that there are alternative isoforms of K protein expressed in colon cancer, we amplified and sequenced K protein mRNA that was isolated from colorectal cancers as well as from normal tissues surrounding the tumours. Sequencing revealed a single G-to-A base substitution at position 274 that was found in tumours and surrounding mucosa, but not in individuals that had no colorectal tumour. This substitution most likely reflects an RNA editing event because it was not found in the corresponding genomic DNAs. Sequencing of RNA from normal colonic mucosa of patients with prior resection of colorectal cancer revealed only the wild-type K protein transcript, indicating that G274A isoform is tumour related. To our knowledge, this is the first example of an RNA editing event in cancer and its surrounding tissue, a finding that may offer a new diagnostic and treatment marker

Proofreading of pre-40S ribosome maturation by a translation initiation factor and 60S subunits

In the final steps of yeast ribosome synthesis, immature translation-incompetent pre-40S particles that contain 20S pre-rRNA are converted to the mature translation-competent subunits containing the 18S rRNA. An assay for 20S pre-rRNA cleavage in purified pre-40S particles showed that cleavage by the PIN domain endonuclease Nob1 was strongly stimulated by the GTPase activity of the cytoplasmic translation initiation factor eIF5b/Fun12. Cleavage of the 20S pre-rRNA was also inhibited in vivo and in vitro by blocking binding of Fun12 to the 25S rRNA through specific methylation of its binding site. Cleavage competent pre-40S particles stably associate with Fun12 and form 80S complexes with 60S ribosomal subunits. We propose that recruitment of 60S subunits promotes GTP-hydrolysis by Fun12, leading to structural rearrangements within the pre-40S particle that bring Nob1 and the pre-rRNA cleavage site together

Sequencing of the Sea Lamprey (Petromyzon marinus) Genome Provides Insights into Vertebrate Evolution

Lampreys are representatives of an ancient vertebrate lineage that diverged from our own ∼500 million years ago. By virtue of this deeply shared ancestry, the sea lamprey (P. marinus) genome is uniquely poised to provide insight into the ancestry of vertebrate genomes and the underlying principles of vertebrate biology. Here, we present the first lamprey whole-genome sequence and assembly. We note challenges faced owing to its high content of repetitive elements and GC bases, as well as the absence of broad-scale sequence information from closely related species. Analyses of the assembly indicate that two whole-genome duplications likely occurred before the divergence of ancestral lamprey and gnathostome lineages. Moreover, the results help define key evolutionary events within vertebrate lineages, including the origin of myelin-associated proteins and the development of appendages. The lamprey genome provides an important resource for reconstructing vertebrate origins and the evolutionary events that have shaped the genomes of extant organisms

Listeria pathogenesis and molecular virulence determinants

The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis derives largely from studies with the mouse infection model. Pathogenic listeriae enter the host primarily through the intestine. The liver is thought to be their first target organ after intestinal translocation. In the liver, listeriae actively multiply until the infection is controlled by a cell-mediated immune response. This initial, subclinical step of listeriosis is thought to be common due to the frequent presence of pathogenic L. monocytogenes in food. In normal indivuals, the continual exposure to listerial antigens probably contributes to the maintenance of anti-Listeria memory T cells. However, in debilitated and immunocompromised patients, the unrestricted proliferation of listeriae in the liver may result in prolonged low-level bacteremia, leading to invasion of the preferred secondary target organs (the brain and the gravid uterus) and to overt clinical disease. L. monocytogenes and L. ivanovii are facultative intracellular parasites able to survive in macrophages and to invade a variety of normally nonphagocytic cells, such as epithelial cells, hepatocytes, and endothelial cells. In all these cell types, pathogenic listeriae go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. In this way, listeriae disseminate in host tissues sheltered from the humoral arm of the immune system. Over the last 15 years, a number of virulence factors involved in key steps of this intracellular life cycle have been identified. This review describes in detail the molecular determinants of Listeria virulence and their mechanism of action and summarizes the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listeria infection. This article provides an updated perspective of the development of our understanding of Listeria pathogenesis from the first molecular genetic analyses of virulence mechanisms reported in 1985 until the start of the genomic era of Listeria research