Yoon Young Chung

Postnatal development of parvalbumin and calbindin D-28k immunoreactivities in the canine hippocampus.

The calcium-binding proteins, parvalbumin and calbindin D-28k, are markers of different classes of GABAergic interneurons and display different functions. The present study was attempted to determine immunoreactivities and colocalization of the parvalbumin and calbindin D-28k in the developing canine hippocampus by immunohistochemistry. The calcium-binding protein-containing neurons showed different developmental patterns. The first appearance of parvalbumin immunoreactive nonpyramidal cells was observed at P7. Parvalbumin immunoreactivity was elicited by the sequence from CA3 to CA1 to reach an adult-like distribution pattern, which was reached at P60, while calbindin D-28k immunoreactivity appeared from P0, including pyramidal and nonpyramidal cells. The characteristic distribution of calbindin D-28k immunoreactive pyramidal cells was clarified by P28, and an adult-like distribution pattern was reached by the end of the second postnatal month. Double-labeled nonpyramidal cells were frequently seen in the subareas, CA3 of P14/CA1-CA2 of P28, where parvalbumin immunoreactive nonpyramidal cells were emerging. These data suggest that the colocalization of the two calcium-binding proteins during development is related closely to the area-specific maturation of parvalbumin expression, although either prenatal expression of calbindin D-28k or parvalbumin was not determined.

Postnatal development of parvalbumin and calbindin D-28k immunoreactivities in the canine anterior cingulate cortex: transient expression in layer V pyramidal cells.

We have examined the ontogeny of parvalbumin (PV) and calbindin D‐28k (CB) immunoreactivities in the canine anterior cingulate cortex (ACC) from the day of birth (P0) through P180. At P7, PV immunoreactivity first appeared in layer VI multipolar cells. The PV immunoreactivity in GABAergic nonpyramidal cells appeared to follow an inside‐out gradient of radial emergence. Although immunoreaction was limited mainly to the developing nonpyramidal cells, pyramid‐like PV immunoreactive cells were transitorily observed in layer V from P14 to P90. The developmental pattern of CB immunoreactivity differed from that of PV immunoreactivity. CB immunoreactivity first developed in layer V pyramidal cells from P0, which continued through P90. CB immunoreactive nonpyramidal cells were located in the infragranular layers and white matter at P0 and maturated in both the supragranular and infragranular layers without clear inside‐out gradient.

Anatomical configuration of the inferior alveolar neurovascular bundle: a histomorphometric analysis

PurposeThe inferior alveolar neurovascular bundle (NVB) is important in implant placement and many other surgeries in dentistry because it is a major supplier of sensation and blood to the mandible via the mandibular canal. The purposes of the present study were to determine the areas and diameters of the NVB, the inferior alveolar nerve (IAN), and the inferior alveolar artery (IAA), and to verify the buccolingual location of the mandibular canal.MethodsThe anatomical configuration of the NVB was examined by histomorphometrically analyzing 20 embalmed dentulous hemimandibles. The areas and maximum horizontal and vertical diameters of the NVB, IAN, and IAA were measured according to tooth region. The distances from the internal border of the mandibular canal to the outer surface of the buccal and lingual cortical plates were also measured.ResultsThe areas of the vertically oval-shaped NVB and IAN appeared to be constant between the molar and premolar regions, which contain the mental branch, and decreased sharply in the lateral incisor after branching off of the mental branch via the mental canal. The mandibular canal was located close to the lingual cortical plate in the posterior tooth region before passing through the mental canal, immediately after which it was situated quite close to the buccal cortical plate, and then closer to the middle toward the anterior tooth region.ConclusionsThe findings of this study provide useful anatomical information that should help to minimize the risk of injury to the NVB during surgical procedures in the mandibular region.

Cortical Neuronal Loss after Chronic Prenatal Hypoxia: A Comparative Laboratory Study

Objective The purpose of this study was to investigate the prenatal hypoxic effect on the fetal brain development. Methods We used the guinea pig chronic placental insufficiency model to investigate the effect of hypoxia on fetal brain development. We ligated unilateral uterine artery at 30-32 days of gestation (dg : with term defined as -67 dg). At 50 dg, 60 dg, fetuses were sacrificed and assigned to either the growth-restricted (GR) or control (no ligation) group. After fixation, dissection, and sectioning of cerebral tissue from these animals, immunohistochemistry was performed with NeuN antibody, which is a mature neuronal marker in the cerebral cortex. Results The number of NeuN-immunoreactive (IR) cells in the cerebral cortex did not differ between the GR and control groups at 50 dg. However, the number of NeuN-IR cells was lesser in GR fetuses than in controls at 60 dg (p<0.05). Conclusion These findings show that chronic prenatal hypoxia affect the number of neuron in the cerebral cortex of guinea pig fetus at 60 dg. The approach used in this study is helpful for extending our understanding of neurogenesis in the cerebral cortex, and the findings may be useful for elucidating the brain injury caused by prenatal hypoxia.

Acute hydrocephalus as a complication of cervical spine fracture and dislocation: a case report.

Hydrocephalus is a well-known complication of head injury, but an uncommon complication of a spinal lesion. Here, we present a rare case of acute obstructive hydrocephalus secondary to a cervical fracture and dislocation. A 60-year-old female patient was transferred to the emergency department with quadriplegia and respiratory difficulty. Imaging studies showed a cervical fracture and dislocation at the C3-4 level. She required intubation and mechanical ventilation. Twenty-four hours after admission, her mental status had deteriorated and both pupils were dilated. Computed tomography of the brain showed acute hydrocephalus; therefore, extraventricular drainage (EVD) was performed. After the EVD, her mental status recovered and she became alert, but she remained quadriplegic and dependent on the ventilator. Two months after injury, she died because of respiratory failure caused by pneumonia.