Propriospinal pathways in the dorsal horn (laminae I-IV) of the rat lumbar spinal cord.

The spinal dorsal horn is regarded as a unit that executes the function of sensory information processing without any significant communication with other regions of the spinal gray matter. Within the spinal dorsal horn, however, the different rostro-caudal and medio-lateral subdivisions intensively communicate with each other through propriospinal pathways. This review gives an overview about these propriospinal systems, and emphasizes that the medial and lateral parts of the spinal dorsal horn show the following distinct features in their propriospinal interconnectivities: (a) A 100-300µm long section of the medial aspects of laminae I-IV projects to and receives afferent fibers from a three segment long compartment of the spinal dorsal gray matter, whereas the same length of the lateral aspects of laminae I-IV projects to and receives afferent fibers from the entire rostro-caudal extent of the lumbar spinal cord. (b) The medial aspects of laminae I-IV project extensively to the lateral areas of the dorsal horn. In contrast to this, the lateral areas of laminae I-IV, with the exception of a few fibers at the segmental level, do not project back to the medial territories. (c) There is a substantial direct commissural connection between the lateral aspects of laminae I-IV on the two sides of the lumbar spinal cord. The medial part of laminae I-IV, however, establishes only a minor commissural propriospinal connection with the gray matter on the opposite side.

Osteoprotegerin expression and sensitivity in otosclerosis with different histological activity.

Otosclerosis is a complex bone dystrophy of the human otic capsule leading to conductive and sensorineural hearing loss. Since otosclerosis may, at least in part, be considered as an autoimmune-inflammatory disease, disturbed balance of TNF-alpha and osteoprotegerin (OPG) expression has been implicated in the pathological bone remodeling. It has been supposed that active otosclerosis is characterized by decreased or missing local OPG production with invariable OPG sensitivity of the otosclerotic foci. Ankylotic stapes footplates (n = 41) removed by stapedectomy were processed to histological examination, OPG-specific RT-PCR, tissue culturing and alkaline-phosphatase (AP) activity assessment, respectively. OPG concentration of serum specimens (n = 41) was measured by ELISA. Cortical bone fragments harvested from the external ear canal were used as negative controls of otosclerosis. Among 41 ankylotic stapes footplates, 22 active and 19 inactive otosclerosis cases were histologically diagnosed. OPG expression was significantly lower (p < 0.001) in active otosclerosis compared to inactive cases. Osteoclast cultures originated from active otosclerotic foci showed a considerable susceptibility against external OPG dosage, which resulted in a significant decrease of AP activity (p < 0.001). In contrast, OPG serum levels were in the normal range (5-100 ng/ml) indicating a non-systemic bone resorption. In conclusion, secondary decreased local OPG production might play an important role in the pathogenesis of otosclerotic bone remodeling disorder. As to previous and current results, decreased OPG sensitivity of lesion-forming cells should be excluded. These observations may indicate the potential role of recombinant OPG treatment in early stages of otosclerosis.

Histopathology of nonotosclerotic stapes fixations.

HYPOTHESIS: Different diseases without exact histopathologic classification can cause stapes ankylosis. BACKGROUND: Otosclerosis is a complex bone remodeling disorder of the otic capsule due to persisting measles virus infection and consecutive inflammatory reaction. In fact, clinical and demographic features of otosclerosis have reference to stapes ankylosis. In the clinical practice, otosclerosis and stapes ankylosis are incorrect synonyms. METHODS: Nonotosclerotic stapes footplates (n = 284) removed during stapedectomy were analyzed histologically. Otosclerosis was excluded during the histologic preselection (n = 437). Total RNA was extracted, and measles virus-specific reverse-transcriptase-polymerase chain reaction was performed. RESULTS: Nonotosclerotic stapes ankylosis was associated with total absence of measles virus RNA. Six main types of nonotosclerotic stapes fixations could be distinguished histologically: annular calcification (n = 152; 53.5%), globular fibrosis (n = 49; 17.25%), lymphocytic infiltration (n = 31; 10.9%), hemosiderosis (n = 22; 7.75%), granulomas (n = 17; 6%) and amyloidosis (n = 13; 4.6%). Fragmentation of nonotosclerotic stapes footplates was infrequent (7%) during stapes surgery. Only 1 floating footplate (0.35%) was reported. CONCLUSION: Two thirds of nonotosclerotic stapes footplates represented complete pathologic bone remodeling. Unlike otosclerosis, nonotosclerotic stapes fixations were characterized by basic histopathologic findings without organ specificity that can also be identified in case of different diseases. Prevalence of nonotosclerotic stapes ankylosis is approximately 30 to 40% among stapes fixation cases. The long-term prognosis and surgical considerations theoretically differ from those of otosclerosis.

Disease-associated novel CD46 splicing variants and pathologic bone remodeling in otosclerosis.

OBJECTIVE/HYPOTHESIS: Otosclerotic bone is supposed to show unique CD46 expression pattern because otosclerosis is an organ-specific disease with viral etiology. STUDY DESIGN: Otosclerosis is a complex bone remodeling disorder of the human otic capsule, which is associated with persisting measles virus infection. The general cellular receptor of measles virus is the CD46, which has 14-known splicing isoforms. METHODS: Nucleic acid was extracted from ankylotic stapes footplates (N = 99) removed during stapedectomies. Consecutive histological, CD46 specific immunohistologic analysis, and multiple polymerase chain reaction (PCR) amplifications were performed. Measles virus was detected by seminested reverse transcriptase-PCR. Splicing variants of CD46 were identified by nested reverse transcriptase-PCR and finally determined by mass sequencing of complementary DNA. RESULTS: Measles virus RNA was detectable only in histologically otosclerotic stapes footplates. Virus negative-fixed stapes represent degenerative disorders of variable histopathology. Otosclerosis is featured by an increased number of osteoclasts showing strong CD46 immunoreaction in contrast to nonotosclerotic stapes fixations. Normal and nonotosclerotic stapes footplates show consistent expression of "c," "d," "e," "f," and "l" CD46 splicing isoforms. In contrast, four novel CD46 splicing variants were additionally detected in otosclerosis: os1, os2, os3, and os4. CONCLUSIONS: Newly described CD46 isoforms have shorter or missing transmembrane domain and a rare cytoplasmic tail with pathological or uncommon signal transduction; however, virus binding ability remains equal and invariable. These changes may be responsible for the smooth virus replication. A special expression pattern and altered functions of CD46 could explain the organ-specific and virus-associated pathogenesis of otosclerosis.

Expression of measles virus receptors in otosclerotic, non-otosclerotic and in normal stapes footplates.

Otosclerosis is a bone remodeling disorder of complex etiology. Persistent measles virus infection of the otic capsule could increase the expression level of measles virus receptors (CD46) on the osteoclasts and endothelial cells of the otosclerotic foci. Presence of measles virus RNA was demonstrated in the footplates of histologically diagnosed otosclerotic patients by RT-PCR; however, no reports were available about the CD46 expression pattern and level in otosclerosis. Nucleic acid was extracted from stapes footplates of clinically otosclerotic patients (N = 116). Genomic RNA of measles virus was amplified by RT-PCR. Amplification results were correlated with postoperative histologic and CD46 specific immunhistologic findings. Among 116 stapes fixation cases, 87 otosclerotic stapes contained measles virus RNA. Histology for virus negative stapes (N = 29) represented degenerative disorders with heterogeneous histopathology. Active otosclerosis was featured by increased numbers of osteoclasts showing strong CD46 expression. In virus negative, non-otosclerotic stapes fixation and in normal stapes footplates weak CD46 immunoreaction was demonstrated on the osteocytes and fibroblasts. In otosclerosis, it is reasonable to assume that measles virus increases the expression level of its own cellular receptor. Furthermore, intensive CD46 reaction could relate to active virus replication and continuous receptor internalisation. Otosclerosis is a disease of disturbed osteoid turnover due to persistent measles virus infection and special CD46 receptor pattern of the otic capsule.

Activated osteoclasts with CD51/61 expression in otosclerosis.

HYPOTHESIS: Stapes ankylosis is supposed to be a disease with variable histopathology caused by otosclerosis or pseudo-otosclerosis. Persistent measles virus infection of the otic capsule could induce reactivation of quiescent embryonic osteoclasts in otosclerosis. BACKGROUND: Presence of measles virus RNA was demonstrated in the footplates of otosclerotic patients by reverse-transcription polymerase chain reaction (RT-PCR). Histology of active otosclerosis is featured by the presence of numerous osteoclasts with unknown phenotype. METHODS: Nucleic acid was extracted from stapes footplates of clinically otosclerotic patients (n = 261). Genomic RNA of measles virus was amplified by RT-PCR. Amplification results were correlated to postoperative histologic and CD51/61 specific immunohistologic findings. A parallel alcalic phosphatase activity assessment was performed to evaluate the metabolic activity of osteoclasts in each section. RESULTS: Among 261 stapes fixation cases, 175 otosclerotic stapes contained measles virus RNA. Histology for virus negative stapes (n = 86) represented nonotosclerotic, degenerative disorders. Histologically confirmed otosclerosis was featured by the presence of osteoclasts with renewed, embryonic phenotype. In otosclerosis, alcalic phosphatase activity was significantly higher compared with nonotosclerotic stapes ankylosis (P < .001). CONCLUSION: The presence of CD51/61 positive osteoclasts in otosclerotic bone containing viral sequences provides the basis for an inflammatory bone remodeling disorder. Otosclerosis is a disease caused by persistent measles virus infection and reactivation of resting embryonic osteoclasts in the otic capsule.

Phe-met-arg-phe (FMRF)-amide is a substrate source of NO synthase in the gastropod nervous system.

The possible involvement of the L-arginine-containing Phe-met-arg-phe (FMRF)-amide (FMRFa) in neuronal nitric oxide (NO) biosynthesis was studied in a gastropod species. We found NADPH-diaphorase-positive neurons and FMRFa-containing fibers in close proximity in the enteric nervous system. Administration of L-arginine and FMRFa induced quantitatively similar nitrite production in both intact intestinal tissues and tissue homogenates. These changes could be prevented by the presence of NOARG (an NO synthase inhibitor). Neither chemically modified FMRFa (D-arginine instead of L-arginine) nor amino acid constituents of FMRFa (methionine, phenylalanine) affected basal nitrite production. FMRFa-induced alterations were reduced in the presence of Na+ channel blockers (tetrodotoxin, amiloride, lidocaine), the Na+/K+ATPase inhibitor ouabain, or protease inhibitors (leupeptine, pepstatine-a). FMRFa and its amino acid constituents were analyzed by paper chromatography. When FMRFa was added to tissue homogenates, the peptide was eliminated within 1-2 min, whereas methionine, phenylalanine, arginine, and citrulline levels were elevated simultaneously. We tested the effects of FMRFa, L-arginine, and NOARG on intestinal contractile activity. FMRFa relaxed the intestine for 1-2 min and then induced contractions for 20-40 min. In the presence of NOARG, no relaxant effect of FMRFa was recorded. As administration of L-arginine strongly inhibits the mechanical activity of the intestinal muscle, NO production presumably plays a substantial role in the action of FMRFa, at least in the initial phase. Our biochemical data indicate a direct involvement of FMRFa in NO biosynthesis. FMRFa might be hydrolyzed by extracellular peptidases and then the locally released arginine might be transported into the cells and broken-down to produce NO. Depolarization-induced NO production attributable to the activation of amiloride-sensitive Na+ channels might also be involved.

Antimeasles immunoglobulin g for serologic diagnosis of otosclerotic hearing loss.

HYPOTHESIS: Persistent measles virus infection of the otic capsule is suggested to be an etiologic factor in otosclerosis. Otosclerosis is a disease of complex unknown etiology causing progressive conductive and/or sensorineural hearing loss (HL). BACKGROUND: Diagnostic methods of otosclerosis are sensitive to ossicular chain fixation with low specificity for otosclerotic stapes ankylosis. METHODS: Nucleic acid was extracted from stapes foot plates of clinically stapes fixation patients (N = 213). Measles virus nucleoprotein RNA was amplified by reverse-transcriptase polymerase chain reaction. Amplification results were correlated to histologic findings in 49 cases. Antimeasles IgG levels of all clinically stapes fixation as well as control sera specimens were measured by enzyme-linked immunosorbent assay. RESULTS: Among clinically stapes fixation patients, 141 stapes foot plates contained measles virus RNA. Among 49 histologic specimens, viral RNA was detectable only in histologically otosclerotic stapes foot plates (n = 35). Histology for virus-negative foot plates (n = 14) excluded otosclerosis. Antimeasles IgG levels were significantly lower in the sera of patients with virus-positive stapes than in control sera. CONCLUSIONS: Combination of decreased antimeasles IgG serum level and conductive HL has a great specificity and sensitivity as a diagnostic method in the preoperative evaluation of ossicular chain fixations otosclerosis. Low antimeasles IgG level indicates otosclerosis, whereas high level suggests non-otosclerotic ossicular chain fixations. Preoperative elucidation of the cause of a conductive HL may suggest optional medical treatment in preference to surgical methods.

Two subgroups of stapes fixation: otosclerosis and pseudo-otosclerosis.

HYPOTHESIS: Stapes ankylosis is a disease with variable histopathology and can be caused by otosclerosis or pseudo-otosclerosis. Viral pathogenesis of otosclerosis could be established only by correlative analysis: histologic examination of the stapes footplate and reverse-transcriptase polymerase chain reaction (RT-PCR) amplification of the viral RNA. BACKGROUND: Presence of the RNA genome of measles virus was demonstrated in the footplates of clinically otosclerotic patients by RT-PCR, and also viral proteins were detected by immunohistochemistry. METHODS: Nucleic acids were extracted from ankylotic stapes footplates of clinically stapes fixation patients (n = 104). Measles virus genomic nucleoprotein (NP) RNA was amplified by seminested RT-PCR. Amplification results were correlated to postoperative histologic and audiologic findings. RESULTS: Measles virus RNA was detectable only in histologically otosclerotic stapes footplates (n = 67). Histology for virus negative footplates (n = 37) excluded otosclerosis. Virus negative stapes footplates showed nonotosclerotic, degenerative disorders. CONCLUSIONS: Stapes ankylosis is a heterogeneous disease causing conductive hearing loss with different etiologies. Nonotosclerotic stapes fixations could be established as pseudo-otosclerosis and may belong to nonspecific, degenerative disorders with variable and noncharacteristic histopathology. Otosclerosis is an inflammatory disease caused by persisting measles virus infection of the otic capsule.

Histologic otosclerosis is associated with the presence of measles virus in the stapes footplate.

HYPOTHESIS: Persistent measles virus infection of the otic capsule is presumed to be one of the etiologic factors in otosclerosis. The viral pathogenesis of otosclerosis could be established only by correlative analysis: histologic examination of the stapes footplates and reverse-transcriptase polymerase chain reaction amplification of the viral RNA. At present, histologic analysis of the removed stapes footplates is the only appropriate method of distinguishing otosclerotic and nonotosclerotic stapes fixations. BACKGROUND: The presence of measles virus was shown in otosclerotic patients by reverse-transcriptase polymerase chain reaction amplification of the viral RNA and detecting the viral proteins by immunohistochemistry. METHODS: Nucleic acids (mRNA, vRNA, and DNA) were extracted from ankylotic stapes footplates of stapes fixation patients (n = 44). Measles virus genomic nucleoprotein RNA was amplified by seminested reverse-transcriptase polymerase chain reaction. Amplification results were correlated to postoperative histologic findings. RESULTS: Measles virus RNA was detectable only in histologically otosclerotic stapes footplates (n = 32). Histology for virus-negative footplates (n = 12) excluded otosclerosis. Virus-negative stapes footplates showed annular calcification (n = 8), bone resorption with increased numbers of hemosiderophages (n = 2), and mononuclear cell infiltration with osteolysis (n = 2). CONCLUSION: Stapes ankylosis is a heterogenous disease causing conductive hearing loss with different causes. Nonotosclerotic stapes fixations may belong to degenerative disorders with variable histopathology. Otosclerosis is an inflammatory disease resulting from persisting measles virus infection of the otic capsule.

Commissural propriospinal connections between the lateral aspects of laminae III-IV in the lumbar spinal cord of rats.

It has been established that there is a strong functional link between sensory neural circuits on the two sides of the spinal cord. In one of our recent studies we provided a morphological confirmation of this functional phenomenon, presenting evidence for the presence of a direct commissural connection between the lateral aspects of the dorsal horn on the two sides of the lumbar spinal cord. By using a combination of neural tracing and immunocytochemical detection of neural markers like vesicular glutamate transporters, glutamic acid decarboxylase, glycine transporter, and met-enkephalin (which are characteristic of various subsets of excitatory and inhibitory neurons), we investigated here the distribution, synaptic relations, and neurochemical characteristics of the commissural axon terminals. We found that the cells of origin of commissural fibers in the lateral aspect of the dorsal horn were confined to laminae III-IV and projected to the corresponding area of the contralateral gray matter. Most of the commissural axon terminals established synaptic contacts with dendrites. Axospinous or axosomatic synaptic contacts were found in limited numbers. We demonstrated that interactions among commissural neurons also exist. More than three-fourths of the labeled axon terminals were immunostained for glutamic acid decarboxylase and/or glycine transporter, but none of them showed positive immunoreaction for met-enkephalin and vesicular glutamate transporters. The results indicate that there is a substantial reciprocal commissural synaptic interaction between the lateral aspects of laminae III-IV on the two sides of the lumbar spinal cord and that this pathway may transmit both inhibitory and excitatory signals to their postsynaptic targets.