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Biomedical subjects

M H Han

Publications and source records attributed to M H Han.

At least 19 recordsLinked to original sources
PubMed2006

Embolization of wide-necked aneurysms with using three or more microcatheters.

BACKGROUND: A new and relatively simple endovascular technique, in which more than three microcatheters are used for endovascular treatment of cerebral aneurysms for the first time, is described. METHOD: Eight patients with wide necked aneurysms were successfully treated with detachable coils using the multiple microcatheter technique. Three patients presented with subarachnoid haemorrhage and five were unruptured. The aneurysm locations were superior hypophyseal artery (2), posterior communicating artery (2), middle cerebral artery bifurcation (1), distal anterior cerebral artery (1), basilar artery (1) and vertebral artery (1). The average neck size was 7.4 +/- 2.8 mm (3.5-12 mm), average width of the aneurysms was 10.6 +/- 5.7 mm (6.2-23 mm) and depth was 8.9 +/- 5.8 mm (3-22 mm). Three microcatheters (7 patients) and four microcatheters (1 patient) were introduced and used for coil delivery. Three or four coils were deployed and intermingled to stabilize the whole coil mass as well as to occupy the aneurysmal sac. When a relatively stable coil frame was formed, one coil was detached and subsequent coils were inserted. After the coil mass became more stable, other coils were also detached and all microcatheters were used for subsequent coil deployment. FINDINGS: All aneurysms were successfully treated without complications. Postemboilzation angiograms showed no contrast filling in 5 cases (100% occlusion) and a very small residual neck in 3 cases. There was no procedure related complication. CONCLUSION: The multiple microcatheter technique can be one technical option for the endovascular treatment of wide necked aneurysms.

Adult↗
PubMed2006

Clinical analysis of vertebrobasilar dissection.

BACKGROUND: The natural history of vertebrobasilar artery dissection (VAD) is not fully known. The purpose of this study was to review the clinical outcome of the patients with VAD, then to propose an appropriate management strategy for VAD. METHOD: From 1992 to 2004, 35 VAD patients admitted to our institutes were retrospectively reviewed. There were 28 men and 7 women, whose age ranged from 4 to 67 years with a mean age of 44 years. Angiography was assessed to document the shape, and location of the dissecting aneurysm with respect to the posterior inferior cerebellar artery (PICA). A modified Rankin score was assigned for functional outcome. The functional outcome scores were analyzed according to the patient's age, gender, hypertension history, the pattern of initial manifestation, angiographic shape of VAD, angiographic location of VAD, treatment modality. FINDINGS: There was no statistically significant difference between the functional outcome with age, gender, trauma history and past medical history of hypertension. Of 35 patients, 22 presented with SAH, 11 with ischemic symptoms and 2 were incidentally detected. The patients without SAH had a better functional outcome than those with SAH (p = 0.029). There was statistical significance between Hunt-Hess (H-H) grade and clinical outcome (p = 0.032). The shape and location of VAD was not significantly related to the functional outcome (p = 0.294, 0.840). But all the cases of rebleeding and mortality (except one case with initially poor H-H grade) developed exclusively in patients with aneurysms. There was no statistically significant correlation between the treatment modality and the outcome (p = 0.691). CONCLUSION: The VAD patients with SAH would be recommended to be managed by either surgical or endovascular treatment, but those without SAH, could be managed conservatively with antiplatelet therapy and/or anticoagulation.

Adolescent↗
PubMed2006

MRI findings and spreading patterns of necrotizing external otitis: is a poor outcome predictable?

AIM: To evaluate spreading patterns of necrotizing external otitis (NEO) by magnetic resonance imaging (MRI) and to identify spreading patterns related to a poor outcome. MATERIALS AND METHODS: Fourteen patients with NEO were divided into good and poor outcome groups according to their final clinical outcomes. Initial MRI images were retrospectively reviewed for regional abnormalities, and follow-up MRI images were reviewed for ICA flow void abnormality and for the following five spreading patterns: medial, crossed, anterior, intracranial, and combined. The frequencies of the abnormal flow void or spreading patterns were compared between the good and poor response groups. RESULTS: Seven (50%) and seven (50%) patients were respectively allocated to the good and poor outcome groups. Retrocondylar fat infiltration was the most commonest finding on initial MRI images (93%). The frequencies of the abnormal flow void and spreading patterns in the good and poor groups, respectively, were: abnormal flow void, 0 and four (57%); anterior, two (29%) and three (43%); medial, six (86%) and seven (100%); crossed, six (86%) and seven (100%); intracranial middle cranial fossa, one (14%) and four (57%); intracranial posterior cranial fossa, four (57%) and six (86%); intracranial foramen magnum, one (14%) and six (86%). CONCLUSIONS: NEO almost always involves the retrocondylar fat and spreads via various pathways to extracranial or intracranial spaces. The presence of an abnormal flow void and intracranial dural enhancement, particularly in the middle cranial fossa and foramen magnum, may indicate a poor prognosis.

Aged↗
PubMed2006

Mechanically-induced proximal arterial occlusion and stent-within-a-stent technique for the treatment of bilateral vertebral artery dissecting aneurysms.

Several endovascular approaches have been used in the treatment of dissecting aneurysms of the vertebrobasilar system. We present a case of a bilateral spontaneous vertebral artery (VA) dissecting aneurysms presenting with a subarachnoid haemorrhage. The dominant left VA aneurysm was treated with a stent-within-a-stent construct and the contralateral VA aneurysm was proximally occluded, with no complications, by an unintentional mechanically-induced arterial occlusion.

Aortic Dissection↗
PubMed2006

Kaposiform hemangioendothelioma arising from the internal auditory canal.

Kaposiform hemangioendothelioma is a rare vascular tumor and locally aggressive endothelial-derived spindle cell neoplasm, which occurs almost exclusively in infants and adolescents. Radiologically, hemangioendothelioma, including Kaposiform hemangioendothelioma, is seen as a highly vascularized well-enhancing tumor, but no characteristic findings differentiate Kaposiform hemangioendothelioma from other soft-tissue tumors, particularly when the tumor is too small to have any locally aggressive features or identifiable large vessels. We present a case of Kaposiform hemangioendothelioma in the internal auditory canal that had no differential features on initial MR images and rapidly grew into a huge mass in a few months.

Ear Neoplasms↗
PubMed2006

3T 1H-MR spectroscopy in grading of cerebral gliomas: comparison of short and intermediate echo time sequences.

BACKGROUND AND PURPOSE: Echo time (TE) can have a large influence on the spectra in proton MR spectroscopy ((1)H-MR spectroscopy). The purpose of this study was to comparatively assess the diagnostic value of 3T single-voxel (1)H-MR spectroscopy with short or intermediate TEs in grading cerebral gliomas. METHODS: Single voxel (1)H-MR spectroscopy was performed at 3T in 35 patients with cerebral glioma. The spectra were obtained with both short (35 ms) and intermediate TEs (144 ms). Metabolite ratios of choline (Cho)/creatine (Cr), Cho/N-acetylaspartate (NAA), lipid and lactate (LL)/Cr and myo-inositol (mIns)/Cr were calculated and compared between short and intermediate TEs in each grade. After receiver operating characteristic curve analysis, diagnostic accuracy for each TE in differentiating high-grade glioma from low-grade glioma was compared. RESULTS: At short TE, Cho/Cr and Cho/NAA ratios were significantly lower, and LL/Cr and mIns/Cr were significantly higher, compared with those at intermediate TE, regardless of tumor grade. Lactate inversion at intermediate TE was found in only 2 patients. At both TEs, there were significant differences in Cho/Cr and LL/Cr ratios between low- and high-grade gliomas. Diagnostic accuracy was slightly higher at short TE alone or combined with intermediate TE than intermediate TE alone (85.7% versus 82.9%). CONCLUSION: Metabolite ratios were significantly different between short and intermediate TE. Cho/Cr and LL/Cr ratios at either TE were similarly useful in differentiating high-grade gliomas from low-grade gliomas. If only a single spectroscopic sequence can be acquired, short TE seems preferable because of poor lactate inversion at intermediate TE on 3T single-voxel (1)H-MR spectroscopy.

Adult↗
PubMed2003

Procedure-related haemorrhage in embolisation of intracranial aneurysms with Guglielmi detachable coils.

We reviewed the haemorrhagic complications of the endovascular treatment of intracranial aneurysms, in terms of frequency, pre-embolisation clinical status, clinical and radiological manifestations, management and prognosis. In 275 patients treated for 303 aneurysms over 7 years we had seven (one man and six women--2.3%) with haemorrhage during or immediately after endovascular treatment. All procedures were performed with a standardised protocol of heparinisation and anaesthesia. Four had ruptured aneurysms, two at the tip of the basilar artery, and one ach on the internal carotid and posterior cerebral artery, treated after 12, 5, 14, and 2 days, respectively, three were in Hunt and Hess grade 2 and one in grade 1. Bleeding occurred during coiling in three, after placement of at least four coils, and during manipulation of the guidewire to enter the aneurysm in the fourth. Haemorrhage was manifest as extravasation of contrast medium, with a sudden rise in systolic blood pressure in three patients. The other three patients had unruptured aneurysms; they had stable blood pressure and angiographic findings during the procedure, but one, under sedation, had seizures immediately after insertion of four coils, and the other two had seizures, headache and vomiting on the day following the procedure. Heparin reversal with protamine sulphate was started promptly started when bleeding was detected in four patients, and the embolisation was completed with additional coils in three. Emergency ventricular drainage was performed in the two patients with ruptured aneurysm and one with an unruptured aneurysm who had abnormal neurological responses or hydrocephalus. The bleeding caused a third nerve palsy in one patient, which might have been due to ischaemia and progressively improved.

Adult↗
PubMed2003

Bioterrorism and the nervous system.

Recent events of war, terrorist attacks, and mail-borne anthrax exposure have produced increasing awareness of potential bioterrorism attacks in the United States and other parts of the world. Physicians and healthcare personnel play a key role in identifying potential bioterrorist attacks. Early recognition and preparedness for bioterrorism-associated illnesses is especially important for neurologists because most bioterrorism agents can directly or indirectly affect the nervous system. This article reviews the neurologic manifestations, diagnosis, and treatments of syndromes caused by potential bioterrorism agents, as well as the potential side effects of vaccines against some of these agents.

Anthrax↗
PubMed2003

Similarity and disparity of obsessive-compulsive disorder and schizophrenia in MR volumetric abnormalities of the hippocampus-amygdala complex.

OBJECTIVES: Given that obsessive-compulsive disorder (OCD) and schizophrenia may share clinical symptoms as well as functional brain abnormalities, this study was designed to clarify common and different morphological abnormalities in OCD and schizophrenia. METHODS: Volumes of the hippocampus, the amygdala, and the thalamus were measured in three age and sex matched groups of 22 patients with OCD, 22 patients with schizophrenia, and 22 normal subjects using three dimensional magnetic resonance imaging. Volume tracing was performed manually on serial coronal slices with the references of sagittal or axial planes using internal landmarks. RESULTS: Hippocampal volume was bilaterally reduced in both OCD and schizophrenic patients versus the normal controls. Left amygdala volume was significantly enlarged in patients with OCD but not in patients with schizophrenia versus the normal controls. The thalamus did not show any volumetric group differences. CONCLUSIONS: Non-specific hippocampal reduction in both the OCD and schizophrenic groups is likely to link to a clinical overlap between the two illnesses, whereas the left amygdala enlargement observed only in the OCD patients seems to be suggestive of a unique role for the amygdala in the pathophysiology of OCD.

Adult↗
PubMed2002

Volume of cervical lymph nodes using 3D ultrasonography. Differentiation of metastatic from reactive lymphadenopathy in primary head and neck malignancy.

PURPOSE: To assess the usefulness of volume measurement using 3D US for depicting metastatic cervical lymph nodes. MATERIAL AND METHODS: Thirty-five cervical lymph nodes in 13 patients with primary head and neck malignancy were included in this study. US with volume acquisition was prospectively performed with a 5-10 MHz linear mechanical volume probe. Volume measurement of the node was calculated using a 3D automatic volume calculation program. The excised nodes matched on US were examined histopathologically. RESULTS: The volume of malignant nodes ranged from 0.444 to 4.442 cm3, the volume of the benign nodes from 0.143 to 1.176 cm3. Combinations of high positive (>80%) and negative (>90%) predictive values were obtained at a cut-off value of 0.7 cm3. CONCLUSION: Volume measurement of cervical nodes using 3D US can be a useful tool for differentiating metastatic from benign nodes in patients with primary head and neck malignancy.

Adult↗
PubMed2001

Miniature postsynaptic currents depend on Ca2+ released from internal stores via PLC/IP3 pathway.

Miniature postsynaptic currents (mPSCs) were examined on autaptic innervation of single rat retinal ganglion cells in low density cultures. Removal of Ca2+ from bath solution or blocking of Ca2+ channels by Cd2+ had no detectable effect on mPSC frequency or amplitude. Thapsigargin, an agent for mobilization of Ca2+ from internal stores, increased mPSC frequency 3-5-fold in control, Ca2+-free or Cd2+-containing solutions. The inositol 1,4,5-triphosphate (IP3) receptor antago- nist, heparin; the phospholipase C (PLC) inhibitor, U73122; and caffeine abolished mPSC or decreased mPSCs frequency. Calcium imaging showed that cytosolic Ca2+ was increased by thapsigargin and decreased by caffeine. These data demonstrate that internal store-released Ca2+ regulated by the PLC/IP3/IP3-receptor pathway has critical contribution to generation and control of miniature release in retinal ganglion cells.

Animals↗
PubMed2001

Mutational and kinetic evaluation of conserved His-123 in dual specificity protein-tyrosine phosphatase vaccinia H1-related phosphatase: participation of Tyr-78 and Thr-73 residues in tuning the orientation of His-123.

Active-site cysteine strategically positioned in the P-loop of protein-tyrosine phosphatases has been suggested to be further stabilized by hydrogen bonding arrays radiating out from the P-loop to neighboring residues. In this work, we investigated the structural role of histidine array in HC(X)(5)RS motif of the vaccinia H1-related protein phosphatase (VHR), using site-directed mutagenesis in conjunction with an extensive kinetic analysis. Conserved His-123 was mutated along with neighboring residues Tyr-78 and Thr-73. The increased pK(a) values of active-site Cys-124 found in Y78F and T73A mutants (6.51 and 6.75, respectively) were comparable to those of H123A and H123F mutants. Kinetic evaluation of Y78F and T73A mutants further implicates that the mutations perturb the relative position of Cys-124 within the P-loop. These results imply that Tyr-78 and Thr-73 make up an essential part of the His-123 array and structurally tune the Cys-124 position. Tyr-78 of VHR turns out to be the invariant Tyr reported in several protein-tyrosine phosphatases by a structure-based sequence alignment. Therefore, orientation of the imidazole ring of His-123 by the invariant Tyr-78 is crucial for maintaining the proper position of Cys-124 in the P-loop.

Base Sequence↗
PubMed2001

Effects of protein kinase CK2, extracellular signal-regulated kinase 2, and protein phosphatase 2A on a phosphatidic acid-preferring phospholipase A1.

A soluble, phosphatidic acid-preferring phospholipase A1, expressed in mature bovine testes but not in newborn calf testes, may contribute to the formation or function of sperm. Here we incubated a recombinant preparation of the phospholipase in vitro with several enzymes including protein kinase CK2 (CK2), extracellular signal-regulated kinase 2 (ERK2), and protein phosphatase 2A (PP2A) to identify effects that might be of regulatory importance in vivo. Major findings were that 1) CK2 phosphorylated the phospholipase on serines 93, 105, and 716; 2) ERK2 phosphorylated the enzyme on serine 730; 3) there was cross-antagonism between the reactions that phosphorylated serines 716 and 730; 4) PP2A selectively hydrolyzed phosphate groups that were esterified to serines 716 and 730; 5) CK2alpha formed a stable, MgATP/MgGTP-dependent complex with the phospholipase by a novel mechanism; and 6) the complex showed reduced phospholipase activity and resembled a complex identified in homogenates of macaque testis. These results provide the first available information about the effects of reactions of phosphorylation and dephosphorylation on the behavior of the phospholipase, shed light on properties of CK2alpha that may be required for the formation of complexes with its substrates, and raise the possibility that a complex containing CK2alpha and the phospholipase may play a special biological role in the testis.

Amino Acid Sequence↗
PubMed2001

An angiographic lesion mimicking pseudo-aneurysm in cerebral arteriovenous malformation.

In cerebral arteriovenous malformations (AVMs), a pseudo-aneurysm represents rupture site, and its presence is known as a factor for rebleeding. We report a case of cerebral AVM presenting with intracerebral haemorrhage in which cerebral angiography showed a lesion mimicking pseudo-aneurysm. Although the patient needed urgent surgical decompression, it was delayed because early haematoma evacuation would induce rebleeding from the rupture site. The authors attempted to occlude the pseudoaneurysm interventionally before surgery. After surgical excision, the lesion that was believed to be a pseudo-aneurysm was revealed as a partially thrombosed venous sac having a thick fibrous wall. In this report, the authors discuss the pitfalls in the interpretation of pseudo-aneurysms in angiographic AVM architecture.

Adolescent↗
PubMed2001

Grey matter abnormalities in obsessive-compulsive disorder: statistical parametric mapping of segmented magnetic resonance images.

BACKGROUND: Although a number of functional imaging studies are in agreement in suggesting orbitofrontal and subcortical hyperfunction in the pathophysiology of obsessive-compulsive disorder (OCD), the structural findings have been contradictory. AIMS: To investigate grey matter abnormalities in patients with OCD by employing a novel voxel-based analysis of magnetic resonance images. METHOD: Statistical parametric mapping was utilised to compare segmented grey matter images from 25 patients with OCD with those from 25 matched controls. RESULTS: Increased regional grey matter density was found in multiple cortical areas, including the left orbitofrontal cortex, and in subcortical areas, including the thalamus. On the other hand, regions of reduction were confined to posterior parts of the brain, such as the left cuneus and the left cerebellum. CONCLUSIONS: Increased grey matter density of frontal-subcortical circuits, consonant with the hypermetabolic findings from functional imaging studies, seems to exist in patients with OCD, and cerebellar dysfunction may be involved in the pathophysiology of OCD.

Adult↗
PubMed2001

Carotid artery involvement in Takayasu's arteritis: evaluation of the activity by ultrasonography.

The purpose of this study was to investigate the ultrasonographic criteria for determining the activity of carotid lesions in Takayasu's arteritis. In 10 consecutive patients, common carotid arteries with active lesions (n = 8) and inactive lesions (n = 9) were included in the study. The activity of the carotid lesions was determined on the basis of clinical and laboratory findings and computed tomographic scans. Special focus was placed on thickness and echogenicity of the involved arterial wall and outer diameter of the involved arterial segment. All 17 common carotid arteries evaluated showed segmental or diffuse circumferential thickening of the involved wall. The wall thickness was 2.5 to 5.0 mm (mean +/- SD, 3.3 +/- 0.8 mm) in active lesions and 1.1 to 2.0 mm (mean, 1.6 +/- 0.4 mm) in inactive lesions. The outer diameter of the involved segment was 7.0 to 15.0 mm (mean, 10.0 +/- 2.4 mm) in active lesions and 4.9 to 9.5 mm (mean, 6.8 +/- 1.4 mm) in inactive lesions. Active lesions showed hyperechogenicity in the full thickness of the involved wall (n = 6) or concentric triple layers with a hyperechoic middle layer (n = 2). Inactive lesions showed hyperechogenicity (n = 7) or isoechogenicity (n = 2) of the involved wall. One active lesion showed intramural arteries. Although precise measurement to tenths of a millimeter is impossible with the transducer used, prominent wall thickening with a maintained outer diameter in the common carotid artery suggests an active lesion, whereas mild wall thickening with a decreased outer diameter suggests an inactive lesion. Triple layers of a thickened wall with intramural arteries can be an ultrasonographic finding of an active lesion.

Adolescent↗
PubMed2001

Lateralizing ability of single-voxel proton mr spectroscopy in hippocampal sclerosis: comparison with mr imaging and positron emission tomography.

BACKGROUND AND PURPOSE: Proton MR spectroscopy (MRS) is still in the early stages in the evaluation of epilepsy, and comparisons with MR imaging and positron emission tomography (PET) in the same patients have rarely been documented. The purpose of this study was to evaluate the lateralizing ability of single-voxel MRS in comparison with MR imaging and PET in patients with hippocampal sclerosis. METHODS: Thirty-three patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis and who underwent anterior temporal lobectomy and had good postsurgical outcome over 1-year follow-up were included in the study. MR spectra were obtained from the hippocampus bilaterally, using the point-resolved spectroscopy sequence. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from the relative peak height measurements. An NAA/Cho ratio of 0.8 or less and an NAA/Cr ratio of 1.0 or less were regarded as abnormal. The MRS results were compared retrospectively with those of MR imaging and PET as to the ability to lateralize the epileptogenic focus. RESULTS: The sensitivity of MRS and PET (concordance with MR imaging) was 85% each in the lateralization of the ipsilateral lesion side. Bilateral abnormalities were seen in 30% of the patients. False-lateralization rates for MRS and PET were 3% and 6%, respectively. The concordance rate of MRS and PET was 73%, when comparing the results of the ipsilateral lesion side. CONCLUSION: MRS may be used as an adjunct tool in the evaluation of hippocampal sclerosis, like PET, although its sensitivity has to be improved and the clinical significance of bilateral abnormality is still to be determined.

Adolescent↗