Search PubMed⌕ Search

Biomedical subjects

Y K Tu

Publications and source records attributed to Y K Tu.

At least 37 records · Page 2Linked to original sources
PubMed1998

Closed management and percutaneous fixation of unstable proximal humerus fractures.

BACKGROUND: In dealing with displaced proximal humerus fractures, there is still much controversy in treatment modalities. The latest investigations emphasize the concept of minimal exposure and rigid fixation. METHODS: The technique of closed reduction and percutaneous fixation with cannulated screws and k-pins was performed on 19 patients with two- and three-part proximal humerus fractures. The outcomes were evaluated with a mean follow-up of 21 months. RESULTS: All except one case had a solid union of the fracture. Sixteen of 19 patients (84%) acquired good or excellent results according to Neer's classification. No further collapse or avascular necrosis was found. CONCLUSION: The method of closed reduction and percutaneous fixation, although technically demanding, yields satisfactory results in displaced proximal humerus fracture. Cannulated screws provided rigid fixation that was the underlying tenet for early functional retrieval.

Adolescent↗
PubMed1998

Function of the vascular endothelium after hypothermic storage at four degrees Celsius in a canine tibial perfusion model. The role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after cold storage at 4 degrees Celsius for one, three, five, and seven days was investigated in a canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure, changes in the concentration of endothelin in the venous effluent from the perfused tibiae, adrenomedullin-induced vascular smooth-muscle relaxation, and norepinephrine-induced pressor responses in the presence of acetylcholine, N(G)-monomethyl-L-arginine acetate (an inhibitor of nitric oxide synthesis), or indomethacin (an inhibitor of prostaglandin synthesis) in phase 1 of the study. In phase 2 of the study, the effect of the infusion of tetraethylammonium (a potassium-channel blocker that inhibits the activity of endothelium-derived hyperpolarized factor) was analyzed. The baseline perfusion pressures increased in a time-dependent manner (p < 0.05). In tibiae that had been stored for one or three days, the production of endothelin-1 was less than one picogram per milliliter, but it markedly increased to a mean (and standard error of the mean) of 8.7 +/- 3.2 and 10.8 +/- 4.3 picograms per milliliter in tibiae that had been stored for five and seven days, respectively (p < 0.05). Acetylcholine attenuated the norepinephrine-induced pressor response in all groups (storage at 4 degrees Celsius for one, three, five, or seven days) compared with the response in the control tibiae (p < 0.05). Perfusion of acetylcholine in the tibiae that had been stored for three days significantly attenuated the pressor response to norepinephrine compared with that in the tibiae that had been stored for five days (p < 0.05). In the presence of N(G)-monomethyl-L-arginine acetate, the norepinephrine-induced pressor response significantly increased only in the tibiae that had been stored for one day (p < 0.05). In the presence of indomethacin, the norepinephrine-induced pressor response significantly decreased in the tibiae that had been stored at 4 degrees Celsius for one, three, or five days (p < 0.05). Infusion of adrenomedullin relaxed vascular smooth muscle in the tibiae that had been stored for one, three, five, or seven days (p < 0.05). In phase 2 of the study, perfusion of tetraethylammonium in the presence of acetylcholine increased the norepinephrine-induced pressor response in the tibiae that had been stored at 4 degrees Celsius for seven days to a mean of 168 +/- 20 per cent, whereas perfusion with acetylcholine alone attenuated the norepinephrine-induced pressor response to a mean of 54.6 +/- 3.7 per cent.

Adrenomedullin↗
PubMed1998

Solitary osteochondroma of the lumbar spine with cord compression: a case report.

Solitary osteochondromas are usually of little significance. However, if they are located near neurologic structures, they may cause irritation due to compression. Spinal cord compression is a rare but potentially catastrophic manifestation of solitary osteochondromas. As far as can be ascertained, a solitary osteochondroma in the lumbar region with spinal cord compression has not been reported in Taiwan. This article includes the treatment of an 11-year-old girl with osteochondromas which was complicated by the late development of kyphoscoliosis and a review of the literature.

Child↗
PubMed1998

Inferior dislocation of the glenohumeral joint combined with the compartment syndrome of the upper arm: case report.

Compartment syndromes occurring in the forearm and leg are not infrequent. However, reports of compartment syndrome of the upper arm are conspicuously rare. Inferior dislocation of the shoulder combined with compartment syndrome has rarely been reported in the literature. We report our experience with a patient with inferior dislocation of the glenohumeral joint combined with compartment syndrome of the upper arm. A 29-year-old man had traumatic inferior dislocation of the glenohumeral joint combined with severe swelling of the shoulder and upper arm. After close reduction, the shoulder and upper arm were still tensely swollen. Compartment pressure of the upper arm was measured using a digital manometer (Quick Pressure Monitor 295-1, Stryker) and remained very high, thus, fasciotomy was performed. After debridement and skin graft, the arm healed without sequelae. When a patient has a fracture dislocation of the shoulder joint associated with a swollen arm, compartment syndrome of the upper arm should be included as a differential diagnosis. Detecting the compartment pressure can confirm the diagnosis of compartment syndrome objectively.

Adult↗
PubMed1997

Cerebral oxygen transport and metabolism during graded isovolemic hemodilution in experimental global ischemia.

To verify the optimal hematocrit (Hct) level in the treatment of cerebral ischemia, cerebral oxygen transport (CTO2) and cerebral oxygen metabolism (CMRO2) in graded isovolemic hemodilution were evaluated during cerebral ischemia. Isovolemic hemodilution with low molecular weight dextran to stepwise lower Hct from 43% to 36%, 31%, and 26% was carried out in 13 splenectomized dogs, 6 h after global cerebral ischemia. Global ischemia of the animals was produced by multiple intra- and extracranial ligations of cerebral arteries. Cerebral blood flow (CBF) was measured with radioisotope labeled microspheres. CTO2, CMRO2, and oxygen extraction fraction (OEF) were calculated from CBF, arterial oxygen content (CaO2), and venous oxygen content (CvO2). In dogs with global cerebral ischemia, CBF increased with graded isovolemic hemodilution (r=-0.73, P<0.05). CTO2 reached its highest value at a Hct level of 31.3%. CTO2 at Hct of 36.1% and 31.3% was statistically different from the value measured at a Hct of 43.3%, and there was a decrease when Hct was lowered to 25.9%. CMRO2 was the highest when Hct was at 31.3% and differed significantly from the value measured at a Hct of 43.3%. There was a 10% increase of OEF when Hct was at 25.9%; however this change was not statistically significant compared with the OEF at Hct of 36.1% and 31.3%, respectively. These findings indicate that CTO2 and CMRO2 were the highest when Hct was reduced to 31% in hemodilution. Hct at 31% is the optimum for cerebral metabolism in ischemic status. Uncoupling of CTO2, CMRO2 with CaO2 was also observed in this study. This phenomenon suggests that hemodilution to augment cerebral circulation may be at least partially attributed to the beneficial effects of hemorheologic improvement in the microcirculation of the ischemic brain.

Animals↗
PubMed1997

Epidemiological study of moyamoya disease in Taiwan.

From January 1978 to December 1995, 92 cases of Moyamoya disease were collected from seven major medical centers in Taiwan. The data gave an annual incidence rate of 0.048 per 100,000 population. There were 40 males and 52 females and the ages ranged from 2 to 62 years with the peak incidence in the 31-40 year age group (23 cases). Cerebral infarction occurred in 20 out of 24 juvenile patients (83%), and in 24 out of 68 adult patients (35%). The difference was statistically significant. Haemorrhagic stroke was more frequent in adult patients. Computed tomographic scans following stroke showed cerebral infarction in 44 cases, ventricular haemorrhage in 26 cases, intracerebral haemorrhage in 14 cases and pure subarachnoid haemorrhage in eight. The most frequent initial symptom was motor disturbance (59%), followed by headache (49%) and impaired consciousness (35%). This survey showed an incidence rate much lower than that in Japan, but comparable with those in other Oriental countries and higher than those in Western countries. The male-to-female ratio once differed considerably from that of the Japanese series, but from the present study is now quite similar.

Adolescent↗
PubMed1997

Combined encephalo-arterio-synangiosis and encephalo-myo-synangiosis in the treatment of moyamoya disease.

From January 1990 to December 1995, a total of nine cases of Moyamoya disease were treated at the National Taiwan University Hospital with combined encephalo-arterio-synangiosis (EAS) and encephalo-myo-synangiosis (EMS). There were five males and four females and their ages ranged from 6 months to 31 years. Of these, two cases had their first symptom as intracranial hemorrhage and the rest of the cases had ischemic manifestations. Surgical treatment with combined EAS and EMS was performed on 16 hemispheres of the nine cases. The superficial temporal artery with its anterior and posterior branches was isolated and fixed to the pial surface. Then, the muscle pedicle from the bivalved temporal muscle was used as a dural graft to cover the artery. All the cases showed good neovascularization on follow-up angiography performed at 2-3 months after surgery. These two patients with hemorrhagic symptoms were followed for 52 and 61 months, respectively. Neither of these two cases showed recurrent bleeding. For patients with ischemic symptoms, the follow-up period ranged from 8 to 73 months (mean 41.7 months). All the patients showed improvement in their clinical symptoms.

Adolescent↗
PubMed1997

Direct surgery of carotid cavernous fistulae and dural arteriovenous malformations of the cavernous sinus.

OBJECTIVE: To save the patency of the internal carotid artery (ICA) during the treatment of carotid cavernous fistulae or cavernous sinus dural arteriovenous malformations, direct surgery of the cavernous sinus after failure of endovascular treatment was attempted in this study. METHODS: A total of 78 patients with carotid cavernous fistulae or cavernous sinus dural arteriovenous malformations were treated. Obliteration of the fistulous rent and preservation of the ICA were the therapeutic goals. All patients, except one in whom acute bleeding occurred, received endovascular treatment as the first treatment. In 18 (23.4%) of these 77 patients, it was not possible to obliterate the fistulous rents without sacrificing the ICAs. The 18 patients and the 1 patient with acute bleeding underwent direct surgery to open the cavernous sinus. RESULTS: Various methods, including suturing or clipping the fistulae, sealing the fistulae with fascia and acrylate glue, and packing the cavernous sinus were applied. In each of three complicated cases, the cavernous segment of the ICA was trapped and an intracranial bypass from the petrous segment to the supraclinoid segment was performed. There was nor mortality, and the most common morbidity was transient oculomotor palsy, which occurred in eight patients. Follow-up angiography revealed that the ICAs or bypass grafts were thrombosed in 5 of the 19 patients who had undergone surgery. CONCLUSION: In this series, the overall ICA patency rate of patients who underwent embolization and surgery was 94%, and the obliteration rate of the fistulae was 100%. Direct surgery of the cavernous sinus as a complimentary treatment of embolization can increase the preservation rate of the ICA.

Adolescent↗
PubMed1997

Effect of the duration of room-temperature ischemia on function of the vascular endothelium: the role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after storage at room temperature (24 degrees Celsius) for four, eight, and twenty-four hours was investigated with use of an ex vivo canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure and changes in the concentration of endothelin-1 in the venous effluent of the perfused tibiae. Endothelin-1 is a potent vasoconstrictor that is produced in low concentrations by normal endothelial cells and in increased concentrations by injured vascular endothelial cells. The mean perfusion pressures at flow rates of 1.0 and 1.5 milliliters per minute were significantly higher in the tibiae that had been stored for eight hours than in the tibiae that had been stored for four hours (p < 0.05), and they were significantly higher in the tibiae that had been stored for twenty-four hours than in the tibiae that had been stored for four or eight hours (p < 0.05). The increase in perfusion pressure with increasing duration of storage was associated with an increase in production of endothelin-1. The production of endothelin-1 in the tibiae that had been stored for eight hours (10.6 +/- 0.46 picograms per milliliter) was approximately ten times greater than that in the tibiae that had been stored for four hours (1.1 +/- 0.29 picograms per milliliter). The tibiae that had been stored for twenty-four hours had 19.1 +/- 1.5 picograms of endothelin-1 per milliliter, nearly twice that produced in the tibiae that had been stored for eight hours. Injection of acetylcholine demonstrated muscarinic receptor-mediated vasodilation in the tibiae that had been stored for four hours. In contrast, the tibiae that had been stored for eight and twenty-four hours had no evidence of acetylcholine-induced vasodilation of baseline perfusion vascular smooth-muscle tone. However, there was some preservation of endothelium-dependent vascular smooth-muscle relaxation in the tibiae that had been stored for eight and twenty-four hours, as norepinephrine-induced vascular smooth-muscle contraction was significantly greater in the presence of N(G)-monomethyl-L-arginine acetate (p < 0.05). Moreover, in the second phase of the study, a bolus injection of calcium ionophore A23187 in tibiae that had been stored for twenty-four hours relaxed vascular smooth muscle. Adrenomedullin, a novel peptide with known vasodilator properties, relaxed vascular smooth muscle in all three groups and also attenuated the pressor response to norepinephrine. In conclusion, the function of the vascular endothelium was impaired after storage at room temperature for four hours. However, the vascular endothelium in the tibiae that had been stored for twenty-four hours maintained some function with regard to the production of nitric oxide. The effect of adrenomedullin as a potent vasodilator was observed in the tibiae that had been stored for four, eight, and twenty-four hours.

Acetylcholine↗
PubMed1996

Diagnosis and follow-up of carotid-cavernous fistulas by carotid duplex sonography and transcranial color Doppler imaging.

To investigate the suitability of extracranial carotid duplex (ECD) and transcranial color Doppler imaging (TCDI) in the diagnosis and follow-up of treatment in patients with carotid-cavernous fistulas (CCF), combined ECD and TCDI examinations were studied in seven patients with traumatic CCF. According to angiography, four patients had direct CCF, two indirect CCF and one both direct and indirect CCF. In ECD, hemodynamic parameters of the feeding artery showed an abnormally increased flow volume and decreased resistivity indices in five direct CCFs from the internal carotid artery and one indirect CCF from the external carotid artery. Direct visualization of the CCF was achieved in patients with direct CCF only, and revealed itself as a heterogeneous mosaic flash resulting from high flow velocities and turbulence. Patterns of venous drainage were detected via the transorbital and transforaminal windows in seven and five patients (four direct and one indirect CCF patients), respectively. These abnormal findings were improved or even normalized after successful treatment. In conclusion, combined ECD and TCDI examinations appear to be useful for the diagnosis and follow-up of CCF.

Adult↗
PubMed1996

Primary hemangiopericytoma in the axis bone: case report and review of literature.

OBJECTIVE AND IMPORTANCE: To the best of our knowledge, this is the first reported case of primary hemangiopericytoma in the axis bone. With this report, we attempt to better characterize this uncommon lesion in the vertebral column. CLINICAL PRESENTATION: This report describes a case of primary heman-giopericytoma in the axis bone of a 16-year-old female patient who presented with acute torticollis. Her neurological status was unimpaired. A lateral radiograph of the cervical spine demonstrated an odontoid neck fracture and a C1-C2 rotatory deformity. The magnetic resonance imaging study showed a hypodense lesion with moderate enhancement on T1- and T2-weighted images on the dens and body of the axis with an odontoid neck fracture. Reviewing the literature, primary hemangiopericytoma in the spine is rare; 9 cases of hemangiopericytoma with vertebral bone involvement and 44 cases of this tumor with intraspinal meningeal involvement have been reported. INTERVENTION: The patient was treated with odontoidectomy via the transoral approach, along with posterior fixation using the Halifax clamp. She was followed up 17 months after surgery, and no evidence of tumor recurrence was found. CONCLUSION: The treatment for osseous hemangiopericytoma is still controversial. At present, adequate surgical removal with postoperative radio-therapy is recommended. In addition, although hemangiopericytoma is rare in the spine, it should be kept in mind in the differential diagnosis of spinal tumors.

Adolescent↗
PubMed1996

Effects of isovolemic hemodilution on hemodynamics, cerebral perfusion, and cerebral vascular reactivity.

BACKGROUND AND PURPOSE: To verify the hemorheological effects of isovolemic hemodilution on hemodynamics and cerebral perfusion of normal humans, we tested the efficacy of isovolemic hemodilution in systemic hemodynamics and cerebral bood flow augmentation and its influences in vascular reserve. METHODS: Isovolemic hemodilution was studied in a total of 13 normal healthy subjects. Regional cerebral blood flow was measured by the xenon-enhanced CT method. Cerebral vascular activity was measured by acetazolamide challenge. These measurements, in association with hemorheological and hemodynamic monitoring, were analyzed before and after isovolemic hemodilution with low-molecular-weight dextran. RESULT: Our results showed significant change in hemodynamic parameters after isovolemic hemodilution, including tachycardia, a 24% increase of cardiac index, and decrease of peripheral vascular resistance. Both left and right heart work index increased as a consequence of increased cardiac index. Regional cerebral blood flow increased 35.0 +/- 2.5% at 3 hours after hemodilution and 20.2 +/- 3.9% at 1 week after hemodilution. Cerebral vascular reactivity decreased from 32.1 +/- 4.1% to 25.3 +/- 4.0% after hemodilution, implicating a certain degree of vasodilation in the process of hemodilution. The whole procedure of hemodilution was completed in 52 +/- 6 minutes, and the subjects did not report discomfort during the procedure. CONCLUSIONS: Isovolemic hemodilution in subjects with normal cerebral perfusion can augment cerebral blood flow efficiently in a rapid fashion, and this effect can last for at least a week. The mechanism of flow augmentation may be partially attributed to vasodilation, which could be manifested as tachycardia, increased cardiac output, and decreased cerebral vascular reactivity.

Acetazolamide↗
PubMed1996

Evaluation of intracranial and extracranial carotid steno-occlusive diseases in Taiwan Chinese patients with MR angiography: preliminary experience.

BACKGROUND AND PURPOSE: We attempted to evaluate the location of vascular lesions in cases of cerebrovascular steno-occlusive diseases in Chinese persons living in Taiwan. METHODS: With three-dimensional time-of-flight magnetic resonance angiography (MRA) as a screening tool, 108 symptomatic patients with cerebrovascular steno-occlusive diseases were examined. Cardioembolic disease and cerebral hemorrhage cases were excluded. The degrees of stenosis of bilateral cervical carotid arteries and their major intracranial tributaries were recorded. They were categorized as nonsignificant stenosis (0% to 49%), significant stenosis (50% to 99%), and total occlusion. RESULTS: Our data revealed that 32.4% of the cases were normal in either cervical carotid arteries or their intracranial tributaries. In 24.1% of the cases, significant extracranial carotid stenosis or occlusion was the only finding on MRA. In 25.9% of the cases, only significant intracranial-tributary stenosis was found. In 17.6% of them, significant lesions were found in both extracranial and intracranial carotid artery tributaries. CONCLUSIONS: A racial difference between Chinese and white patients in location of lesion in cerebrovascular steno-occlusive diseases was confirmed. About one third of symptomatic Chinese patients living in Taiwan showed small-vessel disease. Approximately 24% of patients had only extracranial carotid disease, and about 26% had only intracranial carotid tributary disease. We need a larger series of patients to confirm these findings. However, MRA might be a good screening tool for steno-occlusive cerebrovascular disease, especially in persons of a race with more intracranial carotid disease, such as the Chinese.

Adult↗
PubMed1996

Posterior bow and vanishing line signs in diagnosis of burst fractures of the spine on plain radiographs.

It is not uncommon to misdiagnose a burst fracture as a wedge compression fracture initially on plain film, resulting in a late progressive deformity and neurologic damage. The purpose of this study was to analyze the sensitivity, specificity and positive predictive value of plain radiographs in the diagnosis of thoracic and lumbar burst fractures using the posterior bow (PB) and vanishing line (VL) signs. Seven independent examiners, comprising three chief orthopedic residents, two radiologic third-year residents and two emergency attending physicians (orthopedists), randomly reviewed 26 sets of admission anteroposterior and lateral thoracolumbar spine radiographs taken in association with back injuries. They were asked to decide whether patients had a burst or a wedge compression fracture. All patients had computed tomography (CT) scans for diagnostic confirmation. The overall initial sensitivity using discriminant analysis in the diagnosis of burst fractures was 80%. This increased to 90% after the examiners were requested to use the PB and VL signs. The specificity decreased slightly from 75% to 71%, while the positive predictive value remained at 88%. Overdiagnosis of wedge compression fractures as burst fractures occurred, especially when the quality of the films was not ideal. We conclude that, with careful reading, the PB and VL signs help in identifying burst fractures on the initial plain film evaluation.

Adult↗
PubMed1995

Changes of brainstem and perimesencephalic cistern: dynamic predictor of outcome in severe head injury.

OBJECTIVES: Based on the findings in computed tomography scans, we defined a grading system that is well correlated to the changes of the brainstem and its perimesencephalic cistern during intracranial hypertension. MATERIALS AND METHODS: The grades are defined as follows: Grade 0 is normal, grade 1 represents widening of the perimesencephalic cistern without brainstem change, grade 2 represents obliteration of the cistern without brainstem change, grade 3 represents a deformed brainstem; grade 4 represents brainstem density change, and grade 5 represents any combination of grades 3 and 4. As a comparison to the Glasgow Coma Scale (GCS) system, we examined this new system in 334 cases, in which 138 cases were classified as severe head injuries. RESULTS: In cases of mild head injury (GCS score > 8), this new system was correlated to the GCS system well in grades 0 to 2. In cases of severe head injury, the prediction of outcome is better in our system because it is well correlated to dynamic change of intracranial hypertension, especially in cases with nonsurgical masses of grades 3 and 5. CONCLUSIONS: Our grading system is easy to use, and is well correlated to give an accurate prediction of outcome in cases with severe head injury based primarily on the results of an initial computed tomography scan, even without clinical information, and it should play a role in the classification of head injury.

Adolescent↗
PubMed1995

Unreamed interlocking nail versus external fixator for open type III tibia fractures.

We undertook a prospective study comparing the unreamed interlocking nail to Hoffmann external skeletal fixation (ESF) in the treatment of 36 consecutive patients with open type IIIA and IIIB tibia fractures. The choice of interlocking nail or Hoffmann ESF was randomized, ultimately producing four different patient groups: group 1, type IIIA fractures treated by interlocking nail; group 2, type IIIA fractures treated by ESF; group 3, type IIIB fractures with interlocking nail; and group 4, type IIIB fractures with ESF. The average length of follow-up was 20.5 months. The infection rate was highest in group 3 (3 of 8). The malrotation, malunion, and nonunion rates were highest in group 4 and lowest in group 1. These results suggest the unreamed interlocking nail is a good choice for the treatment of open type IIIA tibia fractures, but not recommended for the treatment of open type IIIB tibia fractures because of the high infection rate.

Adolescent↗
PubMed1995

Spinal intradural arteriovenous fistula: a case with an unusual presentation.

Spinal intradural arteriovenous fistula is a rare type of spinal vascular malformation. It is usually fed by the anterior spinal artery and causes episodic myelopathy in young adults. We present a pediatric patient with such a vascular malformation which was fed directly by a medullary artery. The clinical course, complete radiological study and the excellent outcome will be described in detail. This rare subtype of spinal vascular malformation will be discussed.

Aneurysm, Ruptured↗