ABSTRACT
HYPOTHESIS: The JNK/c-Jun cell death pathway is a major pathway responsible for the loss of oxidative stress-damaged auditory neurons. BACKGROUND: Implantation of patients with residual hearing accentuates the need to preserve functioning sensorineural elements. Although some auditory function may survive electrode insertion, the probability of initiating an ongoing loss of auditory neurons and hair cells is unknown. Cochlear implantation can potentially generate oxidative stress, which can initiate the cell death of both auditory neurons and hair cells. METHODS: Dissociated cell cultures of P4 rat auditory neurons identified the apoptotic pathway initiated by oxidative stress insults (e.g., loss of trophic factor support) and characterized this pathway by arresting translation of pathway-specific mRNA with antisense oligonucleotide treatment and with the use of pathway specific inhibitors. The presence or absence of apoptosis-specific protein and changes in the level of neuronal survival measured the efficacy of these interventional strategies. RESULTS: These in vitro studies identified the JNK/c-Jun cascade as a major initiator of apoptosis of auditory neurons in response to oxidative stress. Neurons pretreated with c-jun antisense oligonucleotide and exposed to high levels of oxidative stress were rescued from apoptosis, whereas neurons in treatment control cultures died. Treatment of oxidative-stressed cultures with either curcumin, a MAPKKK pathway inhibitor, or PD-098059, a MEK1 inhibitor, blocked loss of neurons via the JNK/c-Jun apoptotic pathway. CONCLUSION: Blocking the JNK/c-Jun cell death pathway is a feasible approach to treating oxidative stress-induced apoptosis within the cochlea and may have application as an otoprotective strategy during cochlear implantation.
Subject(s)
Apoptosis/drug effects , Cochlear Implantation/adverse effects , Hair Cells, Auditory/drug effects , Hair Cells, Auditory/pathology , Oligonucleotides, Antisense/pharmacology , Proto-Oncogene Proteins c-jun/antagonists & inhibitors , Spiral Ganglion/drug effects , Spiral Ganglion/pathology , Animals , Animals, Newborn , Antibodies/immunology , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/adverse effects , Cell Culture Techniques , Cisplatin/administration & dosage , Cisplatin/adverse effects , Curcumin/administration & dosage , Curcumin/adverse effects , Cytoskeletal Proteins/metabolism , Hair Cells, Auditory/metabolism , Immunohistochemistry , Ischemia/chemically induced , Oligonucleotides, Antisense/administration & dosage , Oxidative Stress/physiology , Proto-Oncogene Proteins c-jun/administration & dosage , Rats , Rats, Wistar , Spiral Ganglion/metabolism , Transcription Factor AP-1/metabolismABSTRACT
Fluorescence in situ hybridization (FISH) using peptide nucleic acid (PNA) probes targeting Staphylococcus aureus 16S rRNA is a novel method for direct identification of S. aureus from positive blood culture bottles. The test (S. aureus PNA FISH) is performed on smears made directly from positive blood culture bottles with gram-positive cocci in clusters (GPCC) and provides results within 2.5 h. A blinded comparison of S. aureus PNA FISH with standard identification methods was performed in collaboration with eight clinical microbiology laboratories. A total of 564 routine blood culture bottles positive for GPCC recovered from both aerobic and anaerobic media from three different manufacturers (ESP, BACTEC, and BacT/Alert) were included in the study. The sensitivity and specificity of S. aureus PNA FISH were 100% (57 of 57) and 99.2% (116 of 117), respectively, with 174 GPCC-positive ESP blood culture bottles, 98.5% (67 of 68) and 98.5% (129 of 131), respectively, with 200 GPCC-positive BACTEC blood culture bottles, and 100% (74 of 74) and 99.1% (115 of 116), respectively, with 190 GPCC-positive BacT/Alert blood culture bottles. It is concluded that S. aureus PNA FISH performs well with commonly used continuously monitoring blood culture systems.
