ABSTRACT
OBJECTIVE: Assessment of the efficacy of ossicular reconstruction using a cartilage-connecting hydroxyapatite prosthesis designed with a spearhead to reduce extrusion and dislocation of the implant. PATIENTS: All patients undergoing ossicular reconstruction after chronic ear surgery, connecting the cartilage to the prosthesis, with a minimum of 1 year of postoperative follow-up. MAIN OUTCOME MEASURES: Postoperative change in pure-tone averages. Air-bone gap closures, and implant extrusion rates. RESULTS: Overall mean pure-tone averages improved by 12.2 dB (ranged between -40 and 60 dB). In total, 68.4% of the patients achieved an air-bone gap less than 20 dB. Gains in the mean air conduction thresholds were 9.5 dB in cases of partial ossicular reconstruction and 14.9 dB in cases with total ossicular reconstruction (p < 0.05). The overall extrusion rate was 4.21%. CONCLUSION: The cartilage-connecting hydroxyapatite prosthesis with a spearhead was found to restore hearing to a satisfactory level. The extrusion rate was relatively low. The cartilage-connecting hydroxyapatite prosthesis with a spearhead is an effective ossicular implant and offers an attractive alternative for ossicular reconstruction, particularly for total ossicular reconstructions.
Subject(s)
Biocompatible Materials , Durapatite , Ear Cartilage/surgery , Ear Ossicles/surgery , Hearing/physiology , Ossicular Prosthesis , Ossicular Replacement , Otologic Surgical Procedures , Plastic Surgery Procedures , Audiometry, Pure-Tone , Bacterial Infections/epidemiology , Bacterial Infections/etiology , Follow-Up Studies , Humans , Prosthesis Failure , Treatment Outcome , TympanoplastyABSTRACT
An orphan receptor of ligand-gated ion-channel type (L2, also termed ZAC according to the presence of zinc ion for channel activation) was identified by computer-assisted search programs on human genome database. The L2 protein shares partial homology with serotonin receptors 5HT3A and 5HT3B. We have cloned L2 cDNA derived from human caudate nucleus and characterized the exon-intron structure as follows: (1) The L2 protein has four transmembrane regions (M1-M4) and a long cytoplasmic loop between M3 and M4. (2) The sequence is conserved in species including chimpanzee, dog, cow, and opossum. (3) Nine exons form its protein-coding region and especially exon 5 corresponds to a disulfide bond region on the amino-terminal side. Our analysis using multiple tissue cDNA panels revealed that at least two splicing variants of L2 mRNA are present. The cDNA PCR amplification study revealed that L2 mRNA is expressed in tissues including brain, pancreas, liver, lung, heart, kidney, and skeletal muscle while 5HT3A mRNA could be detected in brain, heart, placenta, lung, kidney, pancreas, and skeletal muscle, and 5HT3B mRNA in brain, kidney, and skeletal muscle, suggesting different significance in tissue expression of these receptors. Regional expression of L2 mRNA and protein was examined in brain. The RT-PCR studies confirmed L2 mRNA expression in hippocampus, striatum, amygdala, and thalamus in adult brain. The L2 protein was immunolocalized by using antipeptide antibodies. Immunostained tissue sections revealed that L2-like immunoreactivity was dominantly expressed in the hippocampal CA3 pyramidal cells and in the polymorphic layer of the dentate gyrus. We analyzed the expression of L2 protein in HEK293 cells using GFP fusion protein reporter system. Western blots revealed that L2 protein confers sugar chains on the extracellular side. In transfected HEK293 cells, cellular membranes and intracellular puncta were densely labeled with GFP, suggesting selective dispatch to the final destination.
Subject(s)
Central Nervous System/metabolism , Gene Expression Regulation , Ion Channels/biosynthesis , Ion Channels/genetics , Nerve Tissue Proteins/biosynthesis , Nerve Tissue Proteins/genetics , Aged , Aged, 80 and over , Alternative Splicing , Amino Acid Sequence , Animals , Blotting, Southern , Blotting, Western , Brain/metabolism , Cattle , Caudate Nucleus/metabolism , Cell Line , Cell Membrane/metabolism , Cloning, Molecular , Cysteine Loop Ligand-Gated Ion Channel Receptors , Cytoplasm/metabolism , DNA, Complementary/metabolism , Dogs , Exons , Genes, Reporter , Green Fluorescent Proteins/metabolism , Hippocampus/metabolism , Humans , Introns , Ions , Kidney/metabolism , Male , Middle Aged , Molecular Sequence Data , Muscle, Skeletal/metabolism , Opossums , Pan troglodytes , Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase/chemistry , Polymerase Chain Reaction , Protein Sorting Signals , Protein Structure, Tertiary , RNA, Messenger/metabolism , Receptors, Serotonin/chemistry , Receptors, Serotonin/physiology , Recombinant Fusion Proteins/chemistry , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Amino Acid , Tissue Distribution , TransfectionABSTRACT
Hearing deficit induced by mechanical cochlear damage, intense noise or ototoxic drugs produces a variety of structural and functional changes in the inner ear and the auditory brainstem. In the present study, we identified a novel gene that has activity dependent plasticity in the superior olivary complex by using suppression subtractive hybridization. We cloned a gene that encodes mouse homolog of KIAA0143 protein, one derived from a series of unidentified human genes. This gene termed mKIAA0143 shows differential expression of mRNA in the lateral superior olive between mice with hearing deficit and those with normal hearing ability. The mRNA thus obtained encodes a unique membrane-bound protein that consists of 819 amino acids. The gene locus was mapped using genomic DNA databases to the mouse chromosome 15D1. Green fluorescent protein-tagged mKIAA0143 was expressed in COS-1 cells. It was amply seen in the cellular plasma membrane.
Subject(s)
Brain Stem/cytology , Gene Expression Regulation , Hearing Loss/genetics , Neurons/metabolism , Acoustic Stimulation/methods , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern/methods , Blotting, Western/methods , Brain Stem/metabolism , Brain Stem/physiopathology , COS Cells , Chlorocebus aethiops , Cloning, Molecular/methods , Cochlear Diseases/genetics , Cochlear Diseases/physiopathology , Cochlear Nucleus/metabolism , Dose-Response Relationship, Radiation , Evoked Potentials, Auditory, Brain Stem/physiology , Evoked Potentials, Auditory, Brain Stem/radiation effects , In Situ Hybridization/methods , Male , Malleus/injuries , Malleus/physiology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Molecular Sequence Data , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction/methods , Sensory Thresholds/physiology , Sequence Alignment/methods , Time Factors , Transfection/methodsABSTRACT
It has been proposed that the N-methyl-d-aspartate (NMDA)-type glutamate receptor (GluR) plays an important role in synaptic plasticity, learning, and memory. The four GluRepsilon (NR2) subunits, which constitute NMDA receptors with a GluRzeta (NR1) subunit, differ both in their expression patterns in the brain and in their functional properties. In order to specify the distinct participation of each of these subunits, we focused on the GluRepsilon2 subunits, which are expressed mainly in the forebrain. We investigated delay and trace eyeblink conditioning in GluRepsilon2 heterozygous mutant mice whose content of GluRepsilon2 protein was decreased to about half of that in wild-type mice. GluRepsilon2 mutant mice exhibited severe impairment of the attained level of conditioned response (CR) in the delay paradigm, for which the cerebellum is essential and modulation by the forebrain has been suggested. Moreover, GluRepsilon2 mutant mice showed no trend toward CR acquisition in the trace paradigm with a trace interval of 500 ms, in which the forebrain is critically involved in successful learning. On the other hand, the reduction of GluRepsilon2 proteins did not disturb any basic sensory and motor functions which might have explained the observed impairment. These results are different from those obtained with GluRepsilon1 null mutant mice, which attain a normal level of the CR but at a slower rate in the delay paradigm, and showed a severe impairment in the trace paradigm. Therefore, the NMDA receptor GluRepsilon2 plays a more critical role than the GluRepsilon1 subunit in classical eyeblink conditioning.
Subject(s)
Blinking/physiology , Conditioning, Psychological/physiology , Learning Disabilities/physiopathology , Receptors, N-Methyl-D-Aspartate/physiology , Analysis of Variance , Animals , Behavior, Animal , Blinking/genetics , Female , Learning Disabilities/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Motor Activity/genetics , Motor Activity/physiology , Psychomotor Performance/physiology , Reaction Time/genetics , Reaction Time/physiology , Receptors, N-Methyl-D-Aspartate/geneticsABSTRACT
Nociceptin/orphanin FQ (N/OFQ) is an endogenous peptide agonist for the opioid receptor homolog, N/OFQ receptor, and serves for the central control of autonomic functions. Morphological details including the cell types that may account for such N/OFQ functions, however, remain unclear. By using X-gal histochemistry for the detection of receptor-expressing cells at both light and electron microscopic levels, we examined the hypothalamus from the receptor-deficient mice bearing a lacZ insertional mutation in the N/OFQ receptor gene. The N/OFQ receptor reflected by lacZ expression was seen at high levels in the anterior hypothalamic area. With electron microscopy, lacZ expression was observed in a subset of neurons showing large cell size and indented nucleus.