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Biomedical subjects

H Ryu

Publications and source records attributed to H Ryu.

At least 91 records · Page 5Linked to original sources
PubMed1989

Phylogenetic study on the immunoreactive atrial natriuretic peptide in the heart.

Using two antisera against atriopeptin III (AP III) which had different characteristics in cross-reactivities with atrial natriuretic peptide (ANP) analogs, we have measured an immunoreactive ANP (ir-ANP) in the heart extracts of several species. ir-ANP in atrial extracts showed both high and low molecular weights. Serial dilutions of atrial extracts from chickens, turtles, frogs, and fish yielded competition curves which were parallel to the standard curve of AP III with antiserum No. 4. In comparison with two serial dilution curves of atrial extracts made using two antisera, No. 4 and No. 9, we suggest that the amino acid at position 12 of ir-ANP in the atrial extracts of chicken, turtle, frog, and fish is not isoleucine but is some other amino acid.

Animals↗
PubMed1989

Presence of immunoreactive atrial natriuretic peptide in follicular fluid, ovary and ovarian perfusates.

Immunoreactive atrial natriuretic peptide (ir-ANP) was measured in the follicular fluid of pig ovarian follicle, and rabbit ovarian homogenates and perfusates using a specific radioimmunoassay (RIA). Serial dilution curves made with the extracts of follicular fluid, ovarian homogenates and perfusates using SepPak C18 cartridges were parallel with the RIA standard curve. On gel filtration chromatography and reverse phase HPLC, all extracted materials showed high and low molecular weight forms of ir-ANP. The amount of ir-ANP in rabbit ovary was 40.70 +/- 0.39 pg/mg and that in follicular fluid of pig ovarian follicle was 18.88 +/- 2.49 pg/ml.

Animals↗
PubMed1989

Reduction volume dependence of immunoreactive atrial natriuretic peptide secretion in isolated perfused rabbit atria.

A new technique to permit gradual changes in atrial distension has been developed in an isolated perfused rabbit atrium preparation. Graded volume reduction in the atrium was induced by changing the elevation of the outflow catheter tip. Pressure reduction from 6 cm H2O atrial distension resulted in a decrease in atrial distension volume. Atrial distension by 6 cmH2O did not change the release of immunoreactive atrial natriuretic peptide (irANP). The graded reduction in atrial distension from 0.11 +/- 0.03 (1.5 cm H2O) to 1.36 +/- 0.19 microliters/mg wet weight (6.0 cm H2O) resulted in 1.7 (6.76 +/- 2.05 versus 3.83 +/- 1.18 pg/mg per min, n = 9, P less than 0.025) to 40.1-fold (77.66 +/- 17.82 versus 3.0 +/- 1.14 pg/mg per min, n = 11, P less than 0.025) increases in irANP release. IrANP release in response to the reduction of atrial distension was volume dependent. The relation of percentage increase in irANP release with the percentage reduction of atrial distension was exponential. The data suggest that the atrial muscle shortening, but not stretch per se, may be a potent direct stimulus for the regulation of irANP secretion.

Animals↗
PubMed1989

[Unilateral nerve deafness due to rupture of a right vertebral artery aneurysm. Case report].

A 49-year-old female with no history of hearing disturbance developed sudden onset of headache and was admitted with no neurological deficits other than mild nuchal rigidity. Computed tomography (CT) showed subarachnoid hemorrhage. Four-vessel cerebral angiography disclosed no aneurysm. A second angiogram obtained on the 14th day showed vasospasm of the bilateral posterior cerebral arteries and right anterior inferior cerebellar artery, but still failed to demonstrate an aneurysm. Following the second angiography, she developed mild disturbance of consciousness and cerebellar ataxia of the right limbs, and repeat CT showed an infarct in the right cerebellar hemisphere. When she regained consciousness a few days later, she was completely deaf on the right side. The third angiography revealed a right vertebral artery dissecting aneurysm. Following clipping of the proximal portion of the right vertebral artery, she did well and was discharged, although right cerebellar ataxia and deafness persisted. Neuro-otological evaluation, including pure-tone audiography, auditory brainstem responses, electrocochleography, and caloric testing, indicated that her deafness resulted from ischemia in the territory of the right internal auditory artery due to vasospasm.

Deafness↗
PubMed1989

[Intra-operative monitoring with ABR during neurovascular decompression for VIIth and VIIIth cranial nerves: a warning sign for surgeons].

Auditory brain stem responses (ABR) were monitored during 18 cases of neurovascular decompression (12 with hemifacial spasm, and 6 with tinnitus, vertigo and/or hearing disturbance). As criteria for warning the surgeon, we adopted such changes as disappearance or marked decrease in amplitude of wave V. ABR changes were classified into 3 types as follows. Type 1 (7 cases): prolongation of latencies without wave form changes, Type 2 (5 cases): temporary disappearance of the waves after wave II, Type 3 (6 cases): temporary loss of all waves. In all cases except in one of the 2, with technical failure, all the waves reappeared within 5 minutes after releasing the retraction and irrigating the cerebellopontine cistern with warm normal saline solution. No patient had severe post-operative hearing deficit, but type 3 patients showed hearing disturbance of statistically significant magnitude (-8.33 +/- 3.16 dB). In type 1 patients, the mean prolongation of wave V latency during operation reached 1.27 +/- 0.44 msec, but the mean hearing loss after operation was only 3.57 +/- 4.4 dB. We believe that as soon as the waves disappear, one should immediately release the retraction and irrigate cisterns with warm normal saline solution, and wait until the waves reappear. Prolongation of latencies alone does not indicate postoperative hearing disturbances, and even if the waves disappear their prompt recovery suggests that hearing will be preserved after operation.

Adult↗
PubMed1989

[Trigeminal nerve dysfunction as a false localizing sign: a case of the choroid plexus papilloma in the IVth ventricle].

Trigeminal nerve dysfunction as a false localizing sign, although rate, is known to occur. A case of choroid plexus papilloma in the 4th ventricle with hemifacial numbness is presented. A 24-year-old woman had been suffering from intermittent facial numbness on the left side for 3 months prior to admission. She noted no other symptoms. Neurological examination disclosed marked papilledema, horizontal nystagmus on both lateral gazes and mild truncal ataxia. CT scans showed a calcified mass lesion in the 4th ventricle on the midline extending into the left lateral recess. It was enhanced homogeneously with contrast material. The pathogenesis of such a false localizing sign and its clinical implications were discussed from the anatomical point of view.

Adult↗
PubMed1988

Epicardial release of immunoreactive atrial natriuretic peptides in inside-out perfused rabbit atria.

An easy and convenient isolated atrial perfusion technique was developed. The effect of stretch of the atrial subpericardial myocytes was investigated in the inside-out perfused rabbit atria. Graded distension of the inverted atria was induced by changing the elevation of the atrial catheter tip. Intra-luminal volume expansion resulted in an increase in release of immunoreactive atrial natriuretic peptides (irANPs). The response was volume, or pressure dependent. Distension-induced release of irANPs occurred at the reduction of the distension. IrANPs in epicardial perfusate showed both high and low molecular weights. The major peak of irANP was observed at the corresponding fraction to the rat ANP-(1-28) in the Sephadex G-50 gel chromatography. The data suggest that the epicardial release of irANP is stretch-induced response and that the release may be involved in the regulation of cardiac function.

Animals↗
PubMed1988

Origins of the short latency somatosensory evoked potentials in cat--with special reference to the sensory relay nuclei.

In order to identify the generators of short latency somatosensory evoked potential (SL-SEP) components, we studied, in cats, the relationship between the latencies of SL-SEP components and those of action potentials travelling along the somatosensory pathway. We also studied the changes of SL-SEPs after small lesions at various levels along the pathway. In the record with a noncephalic reference, four positive peaks (PI, PII, PIII, PIV) and three negative peaks (NI, NII, NIII) were identified. Two to three small negative waves (III-a, III-b, III-c) were superimposed on the waves from PIII to NIII. We concluded as follows: (i) NIII is a near-field component originating in the primary somatosensory cortex. (ii) III-a, III-b, and III-c originate between the decussation of the medial lemniscus and the thalamus. (iii) PIII probably originates from multiple structures rostral and caudal to the decussation of the medial lemniscus. PII, NII, and a part of PIII may originate in the region where C6 to T1 dorsal roots enter the spinal cord. (iv) The earliest components or PI and NI originate in the peripheral nerve at the axilla. (v) No components of SL-SEP originating at the dorsal root ganglia, dorsal column nuclei, thalamic VPL nucleus, or cerebellum were identified. (vi) Most of the SL-SEP components may originate where the volume conductor geometry or the impedance of the conducting medium changes suddenly.

Action Potentials↗
PubMed1988

Characteristics of distension-induced release of immunoreactive atrial natriuretic peptide in isolated perfused rabbit atria.

Atrial pressure- or distension-induced release of atrial natriuretic peptide (ANP) has been considered as an important regulatory mechanism of ANP release in cardiac atria. A new technique to permit graded continuous atrial distension has been developed in an isolated perfused single rabbit atrium. Graded atrial distension was induced by changing the elevation of the outflow catheter tip. Intra-atrial volume expansion resulted in an increase in immunoreactive ANP release. The graded increase in atrial distension from 43.9 +/- 10.2 to 207.7 +/- 29.1 microliter resulted in 6.2-27.1-fold increases in volume-dependent immunoreactive ANP release. A rise in immunoreactive ANP release induced by increasing atrial distension did not occur in the state of atrial distension but occurred only after return to the reduced distension. However, in the case of atrial distension with pacing, an increase in immunoreactive ANP release was observed during atrial distension with pacing and after return to the basal level. The present study shows that the new technique is applicable to the study of the 'stretch-secretion coupling' mechanism of ANP release in vitro, and that the more important factor involved in the release of immunoreactive ANP induced by atrial distension may be the atrial reduction to basal level after distension rather than the stretch itself.

Animals↗
PubMed1988

[Cerebral lateralization in two cases of crossed dextral aphasia with right-hemisphere arteriovenous malformation].

This paper reports two cases of crossed dextral aphasia. The first patient was a 60-year-old right-handed male with no family history of sinistrality. He experienced sudden onset of left hemiplegia and loss of consciousness. A CT scan showed high-density area in the right fronto-parietal region. An angiography revealed an arteriovenous malformation (AVM) in the right parietal lobe. It was fed by a branch of the middle cerebral artery and drained through a cortical vein. Neuropsychological examination one week after the surgery showed severe defects of all language moderalities. He was alert and cooperative, but completely mute. He recognized common words by auditory and visual stimuli, but could not perform simple command. He wrote some meaningless letters when asked to write his own name. Auditory and reading comprehension gradually improved thereafter, but Broca's type of aphasia with non-fluent hesitant and effortful output was still present four months after the surgery. The second patient was a 38-year-old right-handed male. All members of this family are right-handed except for one sister who is left-handed. He suddenly suffered left hemiparesis and loss of consciousness. A CT scan disclosed a right parietal intracerebral hematoma. And an AVM which was fed by the angular artery and drained through a cortical vein was angiographically demonstrated in the same area. Postoperatively the left hemiparesis rapidly disappeared, but left homonymous hemianopsia and anomic type of aphasia still persisted. His speech was fluent and daily communication was possible in spite of circumlocutory paraphasic output.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[The findings of auditory and somatosensory evoked potentials in brain death confirmed by the apnea test].

The findings of AEP and SEP in the cases with brain death confirmed by the apnea test had not been reported. We studied the features and the characteristic changes of those evoked potentials in 7 cases of brain death. The etiology of brain death in those cases were the primary intracranial lesions in six and the brain ischemia secondary to cardiac arrest in the others. The apnea test and the recordings of AEP and SEP were performed in the same day in most cases. The mean intervals from the application of the respirator to the apnea test and to cardiac arrest were 5.8 +/- 7.1 days and 5.9 +/- 7.2 days, respectively. Cardiac arrest occurred with mean of 11.8 +/- 8.0 days after the application of the respirator. AEP showed absent responses in six cases (86%) and wave I only in the other (14%). SEP showed P 1-N 1 in four cases (57%) and no responses in three (43%). The components of AEP were disturbed earlier than those of SEP and cases were classified into three types according to those findings. Type I (one case, 13%): wave I only in AEP and P 1-N 1 in SEP. Type II (three cases, 28%): no wave in AEP and P 1-N 1 in SEP. Type III (three cases, 28%): no wave in AEP and SEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Cerebral metastasis from malignant thymoma].

Thymoma with extrathoracic metastasis is very rare, especially to the central nervous system. As far as we know, this is the 15th reported case of cerebral metastasis from malignant thymoma. The prognosis is very poor and almost all of them die in one to one and half years. We have experienced such a case, who is 56 years old man, presenting Gerstmann's syndrome and right-hemiparesis 8 months later after thoracotomy for removal of thymoma. At the admission time in this hospital, CT findings proved the tumor in the left temporoparietal area, left ventricle deformity and slight midline shift to right side. The average of CT density in the low density area was 20. Peripheral region of the tumor was enhanced by contrast CT. Left carotid angiography showed the ACA shift to the right side and abnormal vascularity of peripheral branches of angular artery (arterial phase) and also tumor strain in late artery (arterial phase) and also tumor strain in late arterial phase. Brain scintigram revealed accumulation in the left parietal region. The rt-hemiparesis was rapidly going to be rt-hemiplegia. Therefore, we have performed needle puncture to prevent rt-hemiplegia at the first time. In the course of needle puncture, 90 ml of dark and red fluid was gained at 3.0 cm depth from the cerebral surface. Immediately, the above two symptoms have improved remarkably. Post operative CT showed the reduction of tumor and improvement of the midline shift. The radical operation have been done 2 days after the needle puncture. The tumor was elastic-soft and hemorrhagic and appeared dark-red.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Neoplasms↗
PubMed1987

Study of the constant wave form of ML-AEP in humans.

Wave forms of ML-AEP were studied in 21 healthy subjects and in 4 cases with well localized lesions in the brain. In order to obtain and define the constant wave form we used 5 mg of diazepam in these subjects. In awake state (before administration of diazepam) two types of muscle activity were observed. Postauricular muscle reflex (PMR), which follows high amplitude Na, Pa and Nb potentials, decreases its amplitude and seems to disappear when No and Po come out in light sleep (after administration of diazepam). The other type of muscle activity is derived from facial and other extracranial muscles associated with face or neck movements and deforms wave form in which we are unable to identify each component. These muscle activities cause the variability of wave form in awake state. In light sleep, wave forms were classified as follows: A, includes all components of ML-AEP; B, no Nb component; C, no No and Po components. The most constant waves are Na and Pa potentials and No, Po are variable in appearance. Sequential recordings from awake to light sleep suggested that No, Po are the remnants of PMR in light sleep. Studies of ML-AEP in 4 cases revealed attenuated or absent Na, Pa and Nb potentials. No and Po are variable in appearance in these cases in spite of different locations of lesions in the brain. These studies seemed to support the idea that No and Po are remnants of PMR in light sleep and the constant wave form of ML-AEP consists of Na, Pa and Nb potentials.

Adolescent↗
PubMed1987

[Apnea test essential in the diagnosis of brain death].

We experienced 11 cases of brain death for the past two years, in six of whom we performed the apnea test to confirm the cessation of the medullary respiratory functions. The cause of brain death was primary intracranial lesions in four, subarachnoidal hemorrhages in three and meningitis in one. Hypoxia of the brain secondary to cardiac arrest resulted brain death in the remaining two cases. Blood gases were analysed before (control) and after pre-oxygenation, after having adjusted PaCO2 around 40 mmHg, and every three minutes after disconnection from the respirator. Blood pressure and other vital signs were monitored through out the test. PaCO2 was brought to 40 mmHg by reducing the respiratory rate in three cases, by decreasing the tidal volume following the reduction of the respiratory rate in one case and by applying the bicarbonate gas in one case. The mean PaCO2 level was 46.2 +/- 6.0 mmHg. No one regained the respiration during 10 minutes of the apnea test. In one case, the oxygen catheter was not inserted deeply enough into the tracheal tube, resulting the fall of blood pressure and necessitating termination of the test six minutes after disconnection from the respirator. This case was not included for further analysis. The pH and PaCO2 did not change significantly after pre-oxygenation and after adjusting of PaCO2. Only the PaO2 increased significantly after preoxygenation. PaCO2 increased with the rate of 3.04 +/- 1.2 mmHg/min up to 73.4 +/- 15.6 mmHg and pH decreased with the rate of 0.016 +/- 0.007 down to 7.1 +/- 0.03 after disconnection from the respirator.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[The meningioma within the lateral ventricle in infancy--a case report].

Meningiomas within the lateral ventricle in infancy are extremely rare. The authors report such a case because of its rarity. The presented case is a 23-month-old boy, who had gait disturbance as an initial symptom. At the beginning of May, 1985, his mother found his limping, therefore he admitted to our hospital on May 23. On his admission, clinical features were the left mild hemiparesis, the hyperreflexia of left extremities, and the papilloedema on the both sides. A CT scan revealed a homogeneously enhanced mass at the right trigon. Cerebral angiography showed enlargement and displacement of the left anterior and posterior choroidal arteries. On May 27, an operation was performed with the temporal approach, and the tumor was totally removed. A histological diagnosis is confirmed a fibroblastic meningioma. The postoperative course was uneventful and he was made an almost complete recovery. Intracranial meningiomas in children put the incidence 0.4-2.2% of all primary intracranial tumors. Besides, intraventricular meningiomas in infant younger the age of two years are only five cases (including our case) have been reported in the literature. The three cases of them were reported vaguely, and the other one was an angioblastic meningioma. Therefore, we think that our case is very extremely rare one. Meningiomas of the ventricles are generally become large before symptoms appear. The point agrees with our case, but which had a specific initial complaint of gait disturbance, we think. CT scan and angiography are quite useful for the diagnosis of intraventricular meningiomas. Early diagnosis and surgical removal permits better results.

Cerebral Ventricle Neoplasms↗