Rous sarcoma virus (RSV)-derived retroviral vectors have allowed for efficient gene transfer into the chicken embryo which is a classical model for studying vertebrate development. Current evidence reveals that this method can be used for regionally restricted expression, inducible expression, and for interfering with endogenous gene function, suggesting that gain-of-function and loss-of-function strategies for specific genes can be achieved spatially and temporally in the avian embryo. Thus, retroviral-mediated gene transfer into the chicken embryo coupled with a wide variety of strategies is now an important tool to address specific biological questions in the vertebrate.

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Multiple dural sac and spinal cord indentations are often observed on MRI in cervical spondylotic myelopathy. However, it is rare that all of the indented levels contribute to clinical symptoms. Pathological changes in cervical compression myelopathy have previously been reported. Still the critical degree of spinal cord compression needed to induce pathologic changes is unknown. To clearfy this matter the relationships between the spinal cord as well as the dural sac indentations, and pathological changes of the cervical spinal cord were investigated in cadavers. Sixty-eight cadavers were used for this study. The dural sac and the spinal cord were observed especially regarding presence of indentations. The spinal cord was removed from the specimens in order to perform histopathological examination. The indentations of the dural sac and the spinal cord were observed at C4/5, C5/6, C6/7 and C3/4 intervertebral levels in order of incidence. However, all of the dural sac indentations were not correlated with spinal cord indentations. Pathological changes in the spinal cord were observed in two specimens with less than 30% of the AP compression ratio. One specimen with 20.9% in the AP compression ratio had remarkable histopathological changes. In the other specimen with 29.6% in the AP compression ratio, diffuse demyelination was distributed in the lateral white matter. The results indicate that the critical degree of the AP compression ratio is 30% to induce histopathological changes in the spinal cord. If a spinal cord indentation in the patient with cervical spondylotic myelopathy on imaging, i.e. MRI, show less than 30% in the AP compression ratio, the clinical symptoms, i.e. numbness, tickling and paresthetic pain, may not be improved after the surgery because of some histopathological changes in the spinal cord.

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Contractile responses of rabbit and guinea pig vasa deferentia to electrical field stimulation (EFS) are compared. A muscarinic receptor blocking agent, 1 μM atropine markedly reduced phasic and tonic contraction induced by EFS (20 Hz, 0.5 msec, 30 V, for 30 sec) in rabbit vas deferens, while it only slightly depressed those in guinea pig vas deferens. Further addition of an adrenergic α1 receptor blocking agent, 1 μM prazosin markedly depressed the second tonic contraction in both rabbit and guinea pig vasa deferentia. In the presence of atropine and prazosin, further addition of a P2X purinoceptor desensitizing agent, 10 μM α,β-methylene ATP (α,β-MeATP) abolished the residual phasic contractile response in guinea pig vas deferens, while it partially depressed that in rabbit vas deferens. The administration of 10 μM α,β-MeATP in the absence of atropine and prazosin markedly potentiated the phasic contractile response of rabbit vas deferens to EFS, while it depressed that of guinea pig vas deferens. Contractile response of rabbit vas deferens to α,β-MeATP was more potent than those of ATP and 2-methylthioATP (2-Me-thioATP), while these nucleotides had almost same potency in guinea pig vas deferens. These findings may indicate that contribution of cholinergic, adrenergic and purinergic neurotransmission to the contractile response of rabbit vas deferens to EFS is different from that of guinea pig vas deferens.

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Localization and ultrastructural features of immunoreactive fibers and terminals against RT-97, a mouse monoclonal antibody that recognizes subunit of a 200-kD neurofilament, were examined in the spinal dorsal horn of adult rats. Under a light-microscope, many RT-97 immunoreactive fibers were detected in the dorsal root, collaterals of the dorsal root in the dorsal funiculus, and laminae III and IV in the dorsal horn. Few immunoreactive fibers were found in laminae I and II. Electron microscopic observation demonstrated that almost all RT-97 immunoreactive fibers in the dorsal root were myelinated, and unmyelinated fibers immunonegative. The immunoreactive fibers entered into the dorsal horn passing through the collaterals of the dorsal root along the superficial gray lamina. In the dorsal horn, these fibers ascended into and then terminated in lamina II. RT-97 immunoreactive central terminals were semicircular or ellipsoid in appearance and contained many fiat-type presynaptic vesicles. Some terminals made synaptic contact with dendritic profiles in lamina II.
Our present results indicate that RT-97 is a useful marker for ultrastructural examination of terminals served by non-nociceptive A-fibers.

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Annular pancreas is a rare congenital anomaly, which consists of a ring of pancreatic tissue partially or completely encircling the descending portion of the duodenum. We reported a case of symptomatic annular pancreas in a 40 year-old man admitted to our hospital complaining of abdominal pain, nausea and vomiting without body weight loss in January 2000. The patient underwent laparoscopic cholecystectomy for acalculous cholecystitis in September 1996. Initially, he was diagnosed with duodenal stenosis due to a duodenal ulcer scar, but laboratory data showed no abnormalities. His symptoms did not improve with medication or endoscopic balloon dilatation. Duodenograpy revealed a narrow segment with a smooth mucosal surface in the 2nd portion of the duodenal loop in the duodenum, and a computed tomography (CT) scan demonstrated a thickened pancreas head around this narrow segment. We were therefore able to diagnose annular pancreas. A duodeno-duodenostomy was performed in March 2000. The patient's postoperative course was uneventful, and he was discharged from our hospital on the 19th postoperative day. Although define diagnosis of annular pancreas is frequently made at laparotomy, the development of a recurrent imaging modality might assist in the preoperative diagnosis.

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