ABSTRACT
Telomere maintenance is an important genetic mechanism controlling cellular proliferation. Normally, telomeres are maintained by telomerase which is downregulated upon cellular differentiation in most somatic cell lineages. Telomerase activity is upregulated in immortalized cells and cancers to support an infinite lifespan and uncontrolled cell growth; however, some immortalized and transformed cells lack telomerase activity. Telomerase-negative tumors and immortalized cells utilize an alternative mechanism for maintaining telomeres termed alternative lengthening of telomeres (ALT). This research explored evidence for the ALT pathway in chicken cell lines by studying nontransformed immortalized cell lines (DF-1 and OU2) and comparing them to a normal (mortal) cell line and a transformed cell line (DT40). The research consisted of molecular and cellular analyses including profiling of telomeric DNA (array sizing and total content), telomerase activity, and expression of genes involved in the telomerase, recombination, and ALT pathways. In addition, an immunofluorescence analysis for an ALT marker, i.e. ALT-associated promyelocytic leukemia bodies (APBs), was conducted. Evidence for ALT was observed in the telomerase-negative immortalized cell lines. Additionally, the APB marker was also found in the other cell systems. The attributes of the chicken provide an additional vertebrate model for investigation of the ALT pathway.
Subject(s)
Chickens/genetics , Cytogenetics/methods , Telomerase/deficiency , Telomere/metabolism , Telomeric Repeat Binding Protein 2/genetics , Tumor Suppressor Proteins/genetics , Animals , Cell Line , Cell Proliferation , Chick Embryo , Chickens/metabolism , DNA/analysis , DNA/genetics , Fibroblasts/cytology , Fibroblasts/metabolism , Fluorescent Antibody Technique , Gene Expression , Humans , In Situ Hybridization, Fluorescence , Karyotyping , Polymerase Chain Reaction , RNA, Messenger/analysis , Telomerase/genetics , Telomere/chemistry , Telomeric Repeat Binding Protein 2/metabolism , Transfection , Tumor Suppressor Proteins/metabolismABSTRACT
Blow-out fractures are a relatively common injury seen in the emergency department (ED). The diagnosis is based on clinical grounds, but defined radiographically. For the emergency physician, it is important to recognize the associated signs and symptoms in order that the diagnosis not be missed. Once the diagnosis is made, appropriate referrals need to be made. This article reviews diagnostic criteria, both clinical and radiographic, as well as an ED treatment protocol for blow-out fractures.
Subject(s)
Orbital Fractures/diagnosis , Wounds, Nonpenetrating/diagnosis , Diagnostic Imaging , Facial Bones/anatomy & histology , Humans , Orbital Fractures/surgery , Orbital Fractures/therapy , Physical ExaminationABSTRACT
Subarachnoid hemorrhage from the rupture of a saccular aneurysm remains a major neurosurgical problem that affects 25,000 to 28,000 people yearly. Unfortunately, the mortality from this devastating disease process has not changed significantly in the last 30 years. For emergency physicians, the early detection and diagnosis of subarachnoid hemorrhage is critical to the potential of reducing the mortality from such an event. This article reviews and updates the natural history of subarachnoid hemorrhage, its incidence, presentation, diagnosis, and management from the standpoint of the emergency physician. It does not explore all controversial areas in exhaustive depth, but rather summarizes material that is of importance to emergency physicians in their approach to the problem.
