Biomedical subjects

H Ryu

Publications and source records attributed to H Ryu.

At least 73 records · Page 4Linked to original sources

PubMed1993

Compression of the left brachiocephalic vein: cause of high signal intensity of the left sigmoid sinus and internal jugular vein on MR images.

To study the asymmetry in signal intensity of the sigmoid sinuses, internal jugular veins (IJVs), or both sets of structures on magnetic resonance (MR) images, the authors reviewed 226 serial sets of routine MR imaging studies. Cerebral digital subtraction angiography was performed in 20 patients with a markedly higher intensity and/or enhancement on the left; 15 of them also underwent venography. With every sequence, the left sigmoid sinus, IJV, or both were higher in signal intensity significantly more often than the right (range, P = .0001 to .0129). Angiography revealed hemostasis in the left IJV in 16 patients that disappeared during full inspiration in 14. In 13, venography revealed that the left brachiocephalic vein was compressed to occlusion between the aortic arch and the sternum during tidal volume ventilation. The occlusion disappeared at full inspiration, when the distance between the aortic arch and the sternum increased. This hemostasis could be the major cause of the frequent increased signal intensity of the left sigmoid sinus and IJV on MR images.

Adolescent↗

PubMed1993

[Athetosis].

Athetosis is a peculiar involuntary movement resulting from pathologic involvement of the basal ganglia. Although mechanism of this movement is still far from established, athetosis is clinically differentiated from chorea and dystonia. The purpose of this article is to review and summarise the classification of this involuntary movement disorder. This movement disorder is classified into double athetosis, chorea-athetosis, unilateral athetosis and pseudo-athetosis. The double athetosis is featured by increased muscle tonus and irregular small amplitude movement, which appears the most frequently in patients of cerebral palsy. In chorea-athetosis, irregular abnormal movement is more prominent and larger than double athetosis. This type of movement appears commonly in patients other than cerebral palsy. Unilateral and pseudo-athetosis are derived not from disturbance of the basal ganglia but from impared sensory pathways of the deep sensation due to cerebro-vascular lesion. Stereotactic VL-thalamotomy is effective to relieve increased muscle tonus but not to decrease involuntary movement.

Athetosis↗

PubMed1992

Presence and release of immunoreactive atrial natriuretic peptide in granulosa cells of the pig ovarian follicle.

Atrial natriuretic peptide (ANP) has been reported to be locally synthesized in the ovary although its physiological roles are still unknown. To define the origin of ovarian ANP, we demonstrated the presence and release of immunoreactive (ir) ANP in pig granulosa cells and characterized its biochemical properties. Serial dilution curves made with the extracts of pig granulosa cells, their perfusates and follicular fluid were paralleled to the standard curve of ANP. The amount of irANP in the granulosa cell was 2 fg/cell. The total amount of irANP in granulosa cells significantly correlated with the levels of irANP in follicular fluid. Additionally, the total content of irANP in the follicle negatively correlated with the follicular size. On reverse phase HPLC, the major form of irANP in granulosa cells and follicular fluid was high molecular weight but that in perfusate was low molecular weight. In Northern blot analysis, ANP mRNA was detected in the pig granulosa cells. Immunohistochemistry showed ANP prohormone location in granulosa cells of rat ovary. These data strongly suggest that the granulosa cells synthesize and secrete ANP.

Animals↗

PubMed1992

Identification of nociceptive neurons in the medial thalamus: morphological studies of nociceptive neurons with intracellular injection of horseradish peroxidase.

Somatosensory neurons including nociceptive ones in the medial thalamus have been studied extracellularly, and are classified into three types: nociceptive-specific, wide dynamic range, and tap neurons. However, the morphological characteristics of these three neurons have not yet been clarified. We studied the morphological characteristics of the neurons by iontophoretic injection of HRP into single neurons in 32 cats. Nine wide dynamic range neurons and two tap neurons were electrophysiologically identified and successfully stained with HRP in and around the parafascicular and subparafascicular nuclei, and in the mediodorsal nucleus. All nine wide dynamic range neurons had fewer dendrites which formed scanter tufts, whereas the two tap neurons had many more dendrites which formed denser tufts: i.e. wide dynamic range neurons were of the isodendritic type, and the tap neurons were of the allodendritic type, according to Ramón-Moliner's classification. The axons of the two tap neurons ran antero-laterally whereas those of wide dynamic range neurons ran in many directions. These morphological differences suggest that tap neurons may have more specialized and fixed functions than wide dynamic range neurons.

Animals↗

PubMed1992

Verbal versus non-verbal visual evoked potentials: Kanji versus line drawings.

Cortical areas related to perception of verbal and non-verbal stimuli were studied using VEPs. Kanji characters, line drawings (LD), or a blank were displayed. Verbal VEPs were obtained by subtracting the blank-VEPs from the Kanji-VEPs, and non-verbal VEPs by subtracting the blank-VEPs from the LD-VEPs. Both the verbal and non-verbal VEPs showed a negative peak (100-300 msec) focally over bilateral occipital, posterior temporal and parietal areas, and a positive peak diffusely over frontal halves. Differences between the non-verbal from the verbal VEPs showed an initial peak (100-200 msec) focally over bilateral occipital and posterior temporal areas, followed by a peak (200-300 msec) focally over bilateral posterior temporal areas. The frontal areas diffusely showed peaks at 100-200, 200-300 and 300-400 msec. Left-right asymmetries of both the verbal and non-verbal VEPs showed peaks between 100 and 300 msec over posterior temporal, parietal, and occipital areas. Left-right asymmetries of the subtraction to the non-verbal from the verbal VEPs showed a peak (100 msec) over occipital and parietal areas, and a broader peak over posterior temporal area (100-200 msec). Bilateral occipital, posterior temporal, and parietal areas are focally activated by the two perceptions (100-300 msec), while frontal areas are activated diffusely. Further, different processes may be focally involved between the hemispheres over occipital (100-200 msec) and posterior temporal (100-200 and 200-300 msec) regions. Initial left-right asymmetries of the subtracted VEP between the two perception would occur over occipital and parietal areas (100 msec) and last for 200 msec over posterior temporal area.

Acoustic Stimulation↗

PubMed1992

Frog lymph heart synthesizes and stores immunoreactive atrial natriuretic peptide.

The presence of immunoreactive atrial natriuretic peptide (irANP) and ANP gene expression in the frog lymph heart was examined by a radioimmunoassay (RIA) combined with HPLC and by Northern blot hybridization of total RNA. Serial dilution curve of the lymph heart extract was paralleled with the RIA standard curve. The lymph heart contained 153.32 +/- 35.80 pg of irANP/mg of wet tissue. The major form of irANP in the frog lymph heart was high molecular weight on reverse-phase and gel permeation high performance liquid chromatography as in the frog atria and ventricles. The frog lymph heart, as well as frog atria and ventricles, was shown to express mRNA coding for ANP. Dense core secretory granules similar to those observed in the mammalian atria were also found in the frog lymph heart. The presence of irANP and the expression of ANP gene in the frog lymph heart suggest that the lymph heart may participate in the regulation of homeostasis of lymph circulation and blood volume change through the synthesis and release of ANP.

Animals↗

PubMed1992

Interstitial laserthermia in neurosurgery.

Deep-seated brain tumor is difficult to treat surgically. Hyperthermia using various energy sources has been tried, but has failed to gain wide use because of equipment problems and poor temperature control. It is possible now to use Nd:YAG laser with a stable low-energy supply as an energy source for laser hyperthermia (laserthermia). Animal study and clinical study were done using SLT CL50, Computer-control Laserthermia System to treat deep-seated brain tumors. Experimental study revealed that laserthermia produced minimal edema, temperature control was satisfactory, and blood-brain barrier opened up for 6 days following laserthermia. Five patients with brain tumors were treated with laserthermia. Follow-up CT scan revealed disappearance of tumor in 4 patients and decrease in volume in 1 patient. Long-term neurological follow up revealed no deterioration. Laserthermia using Nd:YAG laser is safe and easy to use and it is beneficial to treat deep-seated brain tumors.

Adult↗

PubMed1992

Multilevel anterior cervical fusion using skull bone grafts. Case report.

The successful use of autogenous skull bone grafts for a C3-7 anterior cervical fusion is reported and compared with results using other bone grafts. A 51-year-old man with C4-7 anterior cord compression due to spurs and ossified posterior longitudinal ligaments developed progressive tetraparesis following a minor head injury. He underwent anterior decompression and fusion. On two occasions an iliac graft had failed; however, a graft of autogenous skull bone was successful. The skull bone was found superior to bone from other sites, such as the iliac crest, rib, tibia, and fibula, showing sufficient strength and less morbidity. The skull may be a better source of graft material for multilevel anterior cervical fusion, which requires long and strong grafts.

Cervical Vertebrae↗

PubMed1991

Chlamydia trachomatis and Chlamydia pneumoniae bind specifically to phosphatidylethanolamine in HeLa cells and to GalNAc beta 1-4Gal beta 1-4GLC sequences-found in asialo-GM1 and asial-GM2.

To examine the possible role of lipids as adhesion receptors for infection, Chlamydia trachomatis and Chlamydia pneumoniae were labeled with 125I and layered on thin-layer chromatograms (tlc) of separated lipids isolated from target cells, and bound bacteria were detected by autoradiography. Elementary bodies from both species bound specifically and with high affinity to one lipid in HeLa 229 cells. Purification of this receptor by column chromatography on DEAE Sepharose followed by continuous preparative tlc, and structural analysis by 500-MHz 1H-NMR spectroscopy and fast atom bombardment mass spectrometry confirmed the HeLa cell chlamydial receptor to be phosphatidylethanolamine (PE). The chlamydiae also bound strongly to purified asialo-GM1 and asialo-GM2, but not to other neutral or acidic lipids tested. The relative binding of chlamydiae to human PE and asialo-GM1 was modified in the presence divalent cations, suggesting that chlamydiae have two interrelated receptor binding sites.

Bacterial Adhesion↗

PubMed1991

Facial nerve monitoring by monopolar low constant current stimulation during acoustic neurinoma surgery.

Electrophysiological characteristics of monopolar low constant current stimulation, and evoked facial muscle responses to such stimulation, were evaluated in 34 cases of acoustic neurinoma. Our study, using stimulus parameters of 0.1-ms-duration pulse wave with 0.5-0.6 mA intensity, revealed that extent of spreading current depends on the current intensity, being about 1 mm from the electrode with 0.5-0.6 mA, and insulation of the electrode prevented the current from spreading through the cerebrospinal fluid, giving a reliable amount of current to the tissue. Evoked facial muscle responses to facial nerve stimulation in the internal auditory meatus and over the pons were analyzed and revealed the following: (1) The responses to stimulation in the internal auditory meatus showed no amplitude attenuation throughout the operation. (2) The responses to stimulation over the pons gradually decreased in amplitude as tumor dissection from the nerve proceeded, especially in large tumors. (3) Anatomical continuity of the nerve was obtained in 100% of small, 91.7% of medium, and 88.2% of large tumors. Our data show that monopolar low constant current stimulation is effective in obtaining the precise anatomical orientation of the facial nerve during tumor removal.

Electric Stimulation↗

PubMed1991

Identification of immunoreactive atrial natriuretic peptide in bulbus arteriosus of freshwater teleostean fish.

1. The presence and partial characterization of immunoreactive atrial natriuretic peptide (ir-ANP) in the bulbus arteriosus were investigated using high performance liquid chromatography (HPLC) and radioimmunoassay (RIA) in several freshwater teleostean fish (catfish, silver crusian carp, snakehead, and rice eel). 2. The level of ir-ANP in the bulbus arteriosus was comparable with that in the atria at about 5-15 pg/mg, 6-13 pg/mg wet wt, respectively, but was 2-4-fold higher than that in the ventricles in all species observed. 3. The HPLC profile of ir-ANP showed two main peaks corresponding to low and high mol. wt rat ANPs. 4. Our results provide evidence for the presence of ir-ANP with high as well as low mol. wts in the bulbus arteriosus of freshwater teleostean fish.

Animals↗

PubMed1991

Photodynamic therapy using pheophorbide a and Nd:YAG laser.

The authors describe a new photodynamic therapy (PDT) method for malignant brain tumors. Pheophorbide a (Ph-a), the photosensitizer, has low toxicity, causes no skin sensitization and is activated with an acoustic Q switched neodymium yttrium-argon-garnet (Nd:YAG) laser which achieves deep tissue penetration. The Ph-a distribution in Fisher 344 (F344) rats bearing rat T9 glioma at 24 hours after intravenous injection was very low in the normal brain tissue, but significantly higher in the T9 glioma giving a tumor to normal brain tissue concentration ratio of 7.5:1. The in vitro survival rate of T9 glioma cells pretreated with Ph-a was 68.8 +/- 5.4% after laser irradiation for 20 minutes, significantly lower than in the control groups. This indicates that Ph-a was activated with the acoustic Q switched Nd:YAG laser causing the photodynamic effect. The survival rate after Ph-a pretreatment and laser irradiation in a waterbath at 44.0 degrees C was further reduced to 15.8 +/- 3.3%. In vivo PDT studies using T9 glioma cells inoculated into the dorsal region of F344 rats showed tumor eradication in four of six rats. The combination of PDT and laser hyperthermia produced tumor eradication in all six rats. The combination of PDT and hyperthermia is a promising method for tumor treatment.

Animals↗

PubMed1991

Post-irradiation vasculopathy of intracranial major arteries in children--report of two cases.

We report two rare cases of post-irradiation vasculopathy of intracranial major arteries in children. A 13-year-old girl suffered from transient right hemiparesis 1 year after irradiation for suprasellar germinoma. Left carotid angiograms revealed marked stenoses of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries, which were previously normal, and moyamoya vessels. A 2.5-year-old girl underwent internal irradiation with 198Au colloid for cystic craniopharyngioma. At the age of 10 years, she suddenly became unconscious after vomiting. Computed tomographic scans showed a right frontal intracerebral hematoma. Right carotid angiograms disclosed complete obstruction of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries and moyamoya vessels, previously not present. The danger of radiation therapy causing occlusive vasculopathy in small and major cerebral arteries in children is emphasized. To prevent permanent ischemic neurological deficits, vasculopathy should be treated either medically or surgically as early as possible.

Adolescent↗

PubMed1991

Cerebellar ganglioglioma--case report.

A 14-year-old boy presented with cerebellar ganglioglioma manifesting as severe headache and confusion. Computed tomographic scans showed a huge, partly enhanced cystic cerebellar tumor. The tumor was totally removed. Histological examination disclosed glial cells and mature ganglion cells. The latter were identified by Nissl's staining and immunostaining for neurofilaments. Ganglion cells were present in the cerebellum and the surrounding subarachnoid space. This heterotopic growth of ganglion cells enabled a firm diagnosis of cerebellar ganglioglioma.

Adolescent↗

PubMed1990

Stereotactic interstitial laser-hyperthermia using Nd-YAG laser.

Laser hyperthermia using Nd-YAG laser was studied experimentally and clinically to treat deep-seated brain tumors. Histological changes, temperature profile, and modification of the blood-brain barrier were studied using cat and rat brains. In a clinical study 5 patients with brain tumors were treated with laser hyperthermia using this computed tomography-stereotactic technique. All tumors of these patients disappeared on computed tomography, and 3 of the 5 patients are still alive without recurrence. It was possible to make optimal lesion and to have accurate peripheral temperature control by using the combination of the Komai stereotactic method and the SLT Nd-YAG laser system. Interstitial laser hyperthermia using this method is easy and safe to use, and it is beneficial to treat deep-seated brain tumors.

Adult↗

PubMed1990

Lipoma in the cerebellopontine angle--case report.

The authors report a case of a cerebellopontine (CP) angle lipoma with a very unusual histological appearance. The 38-year-old male patient suffered vertigo, left tinnitus, and left hearing disturbance. Computed tomography and magnetic resonance imaging showed a nonenhanced low-density area and a high-intensity region in the left CP angle, respectively. The tumor, which was only partially removed because of its tight adhesion to the VIIIth nerve and brainstem, consisted of mature lipocytes and contained a piece of cartilage, which is highly unusual.

Adult↗

PubMed1990

[Angiographic findings of vertebral dissecting aneurysm. Report of two cases and review of literature].

The authors report two cases of vertebral dissecting aneurysm. The first case, a 49-year-old female, developed severe headache and computed tomography scan showed subarachnoid hemorrhage (SAH), but 4-vessel cerebral angiography failed to show an aneurysm. The second angiograms obtained 2 weeks later showed possible aneurysmal dilatation on the right vertebral artery. The third angiograms, 2.5 months after SAH, disclosed a right vertebral fusiform aneurysm on the arterial phase and it was diagnosed as a dissecting aneurysm since the contrast medium remained until the very late venous phase. The previous angiograms were reviewed using the subtraction technique, which revealed retention of the contrast medium. The second case, a 42-year-old female, suffered from SAH. Left vertebral angiography revealed a fusiform aneurysmal tapered narrowing just distal to the aneurysm, which was a typical "pearl and string sign." The subtraction film of the venous phase also showed retention of the contrast medium in the aneurysmal portion. These findings accurately diagnosed dissecting aneurysm of the vertebral artery. Since the classical true diagnostic "double lumen sign" was rarely observed in the angiograms, it was not easy to diagnose dissecting aneurysm of the vertebral artery. The authors emphasize the angiographic findings of retention of the contrast medium in the venous phase as a "true diagnostic sign" for correct diagnosis of dissecting aneurysm.

Aortic Dissection↗

PubMed1990

Line-drawing test across ages.

A line-drawing test was standardized for normal subjects to examine effects of normal aging. For this purpose, the results of the test for 168 normal volunteers were quantified using a digitizer and a microcomputer across ages from 9 to 78 yr. Three sets of parallel vertical lines were presented to every subject, the distances between the parallel vertical lines (5, 10, and 15 cm) differed in the three sets. A subject drew an horizontal line starting exactly on the left vertical line and stopped exactly on the right one, and the computer could detect minute inaccuracy at the start and at the stop, which inaccuracy was expressed in mm. In this study, effects of four parameters were evaluated, i.e., ages, sex, distances from the paired vertical lines, and order of trials; all were nonsignificant. The normal range of the deviations was within 2.1 mm (average + 2 SD).

Adolescent↗