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Biomedical subjects

D H Han

Publications and source records attributed to D H Han.

At least 73 records · Page 4Linked to original sources
PubMed1994

Diastematomyelia--clinical manifestation and treatment outcome.

Diastematomyelia is a rare congenital anomaly characterized by a division of the spinal cord or the filum terminale into two parts. In Korea, only one case has been reported. The authors have operated on 5 cases of diastematomyelia with septum since July, 1978. The ages ranged from 1 to 44 years (median; 11 years). There were 2 boys, 2 girls and an adult man. The disease manifested by cutaneous abnormalities and neurological or orthopedic deficits. Pain was a chief complaint in the adult patient. The symptoms had progressed in 3 cases. The diagnosis was made correctly by CT myelography or MRI in 4 cases. The median septum was located at the lumbar area in 4 cases and at the lumbosacral region in 1 case. Associated abnormalities included low lying conus (5 cases), lipoma (2 cases), thickened filum terminale (1 case), hemilipomyelomeningocele (1 case) and syrinx (1 case). The median septum was removed. The dural sleeve adjoining the septum was resected and the dural sac was reconstructed. The role of MRI in the diagnosis and planning of surgery and the high frequency of associated low lying conus were emphasized. Though the surgical treatment relieved pain, it did not reverse the neurological deficits or orthopedic deformities significantly, which suggests the beneficial effects of early surgical intervention in the cases with progressive symptoms.

Adolescent↗
PubMed1994

Preembolization functional evaluation in supratentorial cerebral arteriovenous malformations with superselective intraarterial injection of thiopental sodium solution.

Superselective intraarterial injections of thiopental sodium solution for evaluation of local brain function were performed before embolization in 38 consecutive patients with supratentorial arteriovenous malformations to evaluate the role of the test using thiopental sodium solution. Thiopental sodium (30-50 mg) was injected in 68 arteries (44 middle cerebral arteries, 13 anterior cerebral arteries, 7 posterior cerebral arteries, 3 external carotid arteries, and 1 thalamo-perforating artery) through superselective microcatheters just before the injection of cyanoacrylate mixture for the embolization. The test was negative in 57 arteries and there were neurologic dysfunctions in 3 of them after embolization. The neurologic deficits in these cases were caused by reflux of embolic material, spasm of the main arterial trunk, or neglected mild sensory change, respectively, and there was no real false-negative test. The embolization could not be performed due to positive test in 9 arteries. Two arteries with positive tests but acceptable symptoms were embolized and the same neurologic deficits developed immediately after embolization. There was no local arterial complication by an injection of the thiopental sodium solution. All neurologic deficits caused by positive tests developed immediately and were completely relieved within 5 min without specific management. Superselective intraarterial injection of thiopental sodium solution is a safe and reliable test for the evaluation of local brain function before embolization of supratentorial arteriovenous malformations.

Adolescent↗
PubMed1993

MRI of intracranial subependymoma: report of a case.

Subependymoma is a rare, benign intraventricular tumour and a case of septum pellucidum origin examined with CT and MR is reported. Well demarcated non-enhancing mass with multiple small intratumoral cysts is demonstrated on CT and MR images. The differential diagnosis from ependymoma has some therapeutic implications but may not be possible by CT or MRI.

Cerebral Ventricle Neoplasms↗
PubMed1993

Cerebral aspergillosis in immunologically competent patients.

Aspergillosis of the central nervous system is a rare disease, especially if the patient's immune system is not compromised. The authors report three cases of cerebral aspergillosis in the immunocompetent state: a rhinocerebral form in a diabetic patient, a direct extension from chronic Aspergillus otitis media, and a postoperative Aspergillus brain abscess after brain tumor surgery. In spite of the poor prognosis of cerebral aspergillosis, two of the patients survived. The pathogenesis, predisposing factors, radiologic findings including magnetic resonance image, and the outcome are presented. The pertinent literature of cerebral aspergillosis is also reviewed.

Adult↗
PubMed1993

Measurement of the interface between bone and immediate endosseous implants: a pilot study in dogs.

This study developed methodology to evaluate the healing of 15 IMZ implants placed in the sockets of freshly extracted mandibular premolars in three adult mongrel dogs. Six surgical sites were prepared in each animal and one site was left as a control. Porous hydroxyapatite was placed around the top half of two implants in each animal; one implant was also covered with polytetrafluoroethylene membrane. All implants were covered with a mucoperiosteal flap and sutured closed. Upon animal sacrifice, the mandibles were retrieved for block dissection and the blocks were embedded in plastic. Serial longitudinal wafers were ground to 50 to 100 microns and stained. Standard photomicrographs were taken so that tracings of the implant-bone interface could be measured on a sonic digitizer. The mean percent amount of bone to plasma-sprayed portion of the implant on the longitudinal sections was 47.9% +/- 5.2% with a range of 17.4% to 84.7%. The horizontal sections were measured at 53.5% +/- 3.7% with a range of 0.0% to 100%. This pilot study suggests that IMZ implants placed in fresh extraction sockets can achieve a degree of intimate contact with bone; however, wide variation in the implant-to-bone interface was found even in the same specimen.

Alveolar Process↗
PubMed1992

Cerebral sparganosis: analysis of 34 cases with emphasis on CT features.

Cerebral sparganosis is a rare parasitic CNS disease, producing chronic active granulomatous inflammation. We retrospectively reviewed the clinical data, CT scans and histopathologic specimens in 34 patients with cerebral sparganosis. The majority of the patients (89%) were rural inhabitants; 75% had a history of ingestion of frogs and/or snakes. The major presenting symptoms were seizure (84%), hemiparesis (59%) and headache (56%) of chronic course. On CT scans, the disease most frequently involved the cerebral hemispheres, particularly frontoparietal lobes, with occasional extension to the external and internal capsules and basal ganglia. The cerebellum was rarely involved. Bilateral involvement was seen in 26%. The main CT findings consisted of white matter hypodensity with adjacent ventricular dilatation (88%), irregular or nodular enhancing lesion (88%), and small punctate calcifications (76%). In combination, the CT triad above appears to be specific for this disease, and was noted in 62% of cases. Of 16 follow-up CT scans, 5 (38%) showed a change in the location of the enhancing nodule. With a single CT scan, it does not appear to be possible to determine whether the worm is alive or dead, information important for deciding whether to intervene surgically. Change in the location of the enhancing nodule and/or worsening of the other CT findings on sequential CT scans would suggest that the worm is alive and that the patient is a candidate for surgery.

Adult↗
PubMed1992

Intraventricular neurocytoma: clinicopathological analysis of seven cases.

A retrospective analysis of seven patients with intraventricular neurocytoma is presented. Patient age at diagnosis ranged from 15 to 38 years (mean 24.6 years) and the male:female ratio was 6:1. Raised intracranial pressure due to hydrocephalus was the main cause of the clinical manifestations. An isodense mass with multiple intratumoral cysts and homogeneous contrast enhancement was the characteristic computerized tomography finding. The lesions commonly involved the lateral ventricle with or without extension to the third ventricle. Cerebral angiography showed homogeneous vascular staining in five patients. Magnetic resonance images revealed a mass isointense with the cerebral cortex on both T1- and T2-weighted images. Gadolinium-diethylenetriaminepenta-acetic acid-enhanced images showed homogeneous enhancement. Total removal of the tumor was possible in four patients. Pathologically, six cases were initially diagnosed as oligodendroglioma and the remaining case as ependymoma. However, immunohistochemical studies demonstrated strong positivity for neuron-specific enolase in all seven cases and for synaptophysin in five cases. On electron microscopy, three cases showed well-defined neurosecretory granules and 10-nm microtubules in their cytoplasm and cytoplasmic processes. One patient developed a recurrent tumor 18 months after surgery. The remaining six patients are free of recurrent tumors at 2 to 62 months after surgery. It is suggested that neurocytoma must be included in the differential diagnosis of intraventricular lesions, and that electron microscopic and immunohistochemical studies should be undertaken.

Adolescent↗
PubMed1992

Malignant triton tumor of the acoustic nerve. Case report.

The authors present the clinical, radiological, pathological features, and autopsy findings of a patient with malignant triton tumor of the acoustic nerve, which probably arose from a pre-existing acoustic schwannoma. The term "malignant triton tumor" is applied to malignant schwannomas with rhabdomyoblastic differentiation. A cerebellopontine angle tumor with spinal drop metastasis occurred in this patient 10 months after near-total removal of the original tumor.

Female↗
PubMed1991

Effects of cocaine, exercise, and resting conditions on plasma corticosterone and catecholamine concentrations in the rat.

Cocaine and exercise are both known as stressors, but little is known about the combined effects of these two treatments. In this study, rats under the influence of cocaine (12.5 mg/kg, intraperitoneally [IP]) or saline were exposed to a variety of resting conditions, as well as exercise (running, 26 m/min, 10% grade, for 30 minutes), to evaluate the amount of stress imposed by these conditions as determined by the changes in the plasma concentrations of corticosterone (C) and catecholamines (norepinephrine [NE], epinephrine [E], dopamine [DA]). After injection of saline, resting near the operating treadmill for 30 minutes caused the concentration of C to increase from 0.07 +/- 0.03 to 0.30 +/- 0.05 microgram/mL (P less than .05), compared to the increase to only 0.15 +/- 0.04 micrograms/mL after resting in a cage. This increase due to proximity to the treadmill subsided after 50 minutes. After cocaine, the 30-minute resting values were 0.70 +/- 0.15 (treadmill) and 0.55 +/- 0.13 (cage) (P less than .05), and did not subside after 50 minutes. Cocaine also increased levels of E, NE, and DA above those in saline under all rest conditions. With exercise, the value for C in saline increased to 0.61 +/- 0.18, but, in cocaine, the value went to 0.93 +/- 0.05 (P less than .05). The concentrations of E (946 +/- 74 v 603 +/- 101 pg/mL, cocaine v saline) and NE (1,027 +/- 102 v 440 +/- 153, cocaine v saline) during exercise also were exaggerated by cocaine treatment (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of cocaine on plasma catecholamine and muscle glycogen concentrations during exercise in the rat.

This study was designed to test the hypothesis that cocaine (C) alters the normal physiological responses to exercise. Male rats were injected with saline (S) or C (12.5 mg/kg) either intravenously (iv) or intraperitoneally (ip). After injection the animals were allowed to rest for 30 min or were run on the treadmill (26 m/min, 10% grade). At rest plasma epinephrine values were 245 +/- 24 pg/ml in the S group and 411 +/- 43 (ip) and 612 +/- 41 (iv) pg/ml in the C groups (P less than 0.05 between S and C). During exercise plasma epinephrine levels were 615 +/- 32 pg/ml in S and 1,316 +/- 58 (ip) and 1,208 +/- 37 (iv) pg/ml in the C groups (P less than 0.05 between S and C). Similar results were obtained for norepinephrine. Glycogen content in the white vastus lateralis muscle was reduced to 31 +/- 2 mumol/g in S after exercise, but after C and exercise the values were 12 +/- 4 (ip) and 16 +/- 3 (iv) mumol/g (P less than 0.05 between S and C). There was no effect of the drug on this parameter at rest. Blood lactate rose to 4.8 +/- 1.0 (ip) and 5.8 +/- 1.3 (iv) mM in the C groups but to only 3.0 +/- 0.2 in the S group after exercise (P less than 0.05 between S and C). These results show that C and exercise combined exert a more dramatic effect on plasma catecholamine, muscle glycogen, and blood lactate concentrations than do C and exercise alone. They provide further insight into explaining the adverse effects of C on exercise endurance observed previously (Bracken et al., J. Appl. Physiol. 66: 377-383, 1989).

Animals↗
PubMed1990

S-(N-methylcarbamoyl)glutathione: a reactive S-linked metabolite of methyl isocyanate.

S-(N-methylcarbamoyl)glutathione, a chemically-reactive glutathione conjugate, has been isolated from the bile of rats administered methyl isocyanate and characterized, as its N-benzyloxycarbonyl dimethylester derivative, by tandem mass spectrometry. The ability of this glutathione adduct to donate an N-methylcarbamoyl moiety to the free -SH group of cysteine was evaluated in vitro with the aid of a highly specific thermospray LC/MS assay procedure. The glutathione adduct reacted readily with cysteine in buffered aqueous media (pH 7.4, 37 degrees C) and after 2 hr, 42.5% of the substrate existed in the form of S-(N-methylcarbamoyl)cysteine. The reverse reaction, i.e. between the cysteine adduct and free glutathione, also took place readily under these conditions. It is concluded that conjugation of methyl isocyanate with glutathione in vivo affords a reactive S-linked product which displays the potential to carbamoylate nucleophilic amino acids. The various systemic toxicities associated with exposure of animals or humans to methyl isocyanate could therefore be due to release of the isocyanate from its glutathione conjugate, which thus may serve as a vehicle for the transport of methyl isocyanate in vivo.

Animals↗
PubMed1989

Application of liquid chromatography/thermospray mass spectrometry to studies on the formation of glutathione and cysteine conjugates from monomethylcarbamate metabolites of bambuterol.

Liquid chromatography/thermospray mass spectrometry (LC/TSP-MS) has been used to identify and study the rates of formation of S-(N-methylcarbamoyl)cysteine and S-(N-methylcarbamoyl)glutathione as products of the in vitro reaction of cysteine and glutathione, respectively, with two monomethylcarbamate metabolites of the bronchodilator pro-drug bambuterol. The conjugates of interest afforded MH+ species and yielded abundant structurally informative fragment ions which were employed in the development of quantitative, selected-ion monitoring assays. It is concluded that LC/TSP-MS represents a rapid and convenient approach to the direct aqueous-phase analysis of the class of S-(N-alkylcarbamoyl) conjugates of cysteine and glutathione.

Bronchodilator Agents↗
PubMed1989

Cocaine does not alter cardiac glycogen content at rest or during exercise.

Cocaine is a potent sympathomimetic drug, and has been implicated as a causative factor in cardiac seizures. However, little is known about the effect of the drug on myocardial substrate utilization. In the present study, rats were injected intravenously with saline solution or one of three doses of cocaine-HCl (1.25, 5.0, 10.0 mg/kg) and subsequently rested or exercised (22 m/min at 15% grade) for 20 minutes. Hearts were removed and frozen within 30 seconds after the injection of anesthetic and within 10 seconds after opening the thoracic cavity. The mean values for resting glycogen content ranged from 24.9 to 27.0 mumol/g, and for glucose-6-phosphate, from 0.27 to 0.30 mumol/g across groups. These values were unaffected by cocaine or exercise. We conclude, based on the conditions of this study, that cocaine has no direct or indirect effect on glycogen storage of the myocardium at rest or during exercise.

Animals↗
PubMed1989

[Experimental study on bond strength of gold plated etched-metal surfaces of resin bonded restorations].

The purpose of this study was to compare the tensile bond strength of the resin-metal interface between etched only and etched & goldplated metal specimens. Etched only and etched & goldplated metal specimens were treated or were not treated with bonding agent and bonded to metal specimens with Comspan and MBAS. Also, electrochemically only etched metal surface and etched & goldplated metal surface was observed by SEM. The following results were obtained: 1. The tensile bond strength of the electrochemically etched only and gold-plated specimens were not significantly different in Comspan group, but the gold-plated specimens in MBAS group demonstrated slightly lower values than the etched only specimens. 2. The tensile bond strengths were not significantly different between the treated group with bonding agent and not-treated group with bonding agent. 3. The tensile bond strengths were not significantly different between the Comspan and MBAS groups. 4. The basic microretentive structures, maintained obviously in the etched and goldplated metal surfaces by SEM.

Acid Etching, Dental↗
PubMed1988

Acute cerebral infarction and changes of regional cerebral blow flow (rCBF) following experimental middle cerebral artery (MCA) occlusion.

An unanaesthetized cat model of acute focal cerebral ischaemia has been established by the technique of transorbital snare ligature for middle cerebral artery (MCA) occlusion. The model was used to investigate the patterns of changes of regional cerebral blood flow (rCBF) for up to 16 h following MCA occlusion by the hydrogen clearance technique and to explore the correlation among changes of rCBF, neurological deficits, and pathological changes. The animals were divided into 2 groups according to the size of infarct which was identified by 2% triphenyl tetrazolium chloride (TTC) solution stain. Infarct larger than 10% of coronal section surface of ipsilateral hemisphere was found in 18 cats (Group A), and a smaller infarct was found in the remaining 7 cats (Group B). Between these 2 groups, there was a statistically significant difference in the average rCBF value of the ipsilateral MCA territory. The increasing grade of contralateral paralysis correlated well with the decreasing rCBF in the ipsilateral MCA territory, and the increasing grade of cerebral hemispheric swelling was directly proportional to the increasing grade of paralysis. Three patterns of changes of rCBF were observed: persistent severe ischaemia (15 cats, Group A); persistent mild to moderate ischaemia (7 cats, Group B); and immediate severe ischaemia followed by early post-ischaemic hyperaemia and death (3 cats, Group A). During the initial stage of ischaemia, a significant decrease in rCBF of the contralateral hemisphere was observed in both groups, however, in Group A rCBF gradually increased to preocclusion level, while Group B presented a further decrease in rCBF suggesting the occurrence of interhemispheric diaschisis. Thus, Group B appeared to take advantage of diaschisis during the late phase of infarct development, as well as the substantial collateral flow from the surrounding anterior and posterior cerebral artery territories.

Animals↗
PubMed1988

Effects of glucose infusion in exercising rats.

To determine whether feedforward control of liver glycogenolysis during exercise is subject to negative feedback by elevated blood glucose, glucose was infused into exercising rats at a rate that elevated blood glucose greater than 10 mM. Liver glycogen content decreased 22.4 mg/g in saline-infused rats compared with 13.6 mg/g in glucose-infused rats during the first 40 min of treadmill running (21 m/min, 15% grade). Liver adenosine 3',5'-cyclic monophosphate (cAMP) concentration was significantly lower in the glucose-infused rats during the exercise bout. The concentration of hepatic fructose 2,6-bisphosphate remained elevated throughout the exercise bout in glucose-infused rats but decreased markedly in saline-infused rats. Plasma insulin concentration was higher and plasma glucagon concentration lower in glucose-infused rats than in saline-infused rats during exercise. Early in exercise, liver glycogenolysis proceeds in the glucose-infused rats despite the fact that glucose and insulin concentrations are markedly elevated and liver cAMP is unchanged from resting values. These observations suggest the existence of a cAMP-independent feedforward system for activation of liver glycogenolysis that can override classical negative feedback mechanisms during exercise.

Animals↗