Biomedical subjects

H C Liu

Publications and source records attributed to H C Liu.

At least 73 records · Page 4Linked to original sources

PubMed2000

Theoretical study of temperature elevation at muscle/bone interface during ultrasound hyperthermia.

This paper examines the distributions of the SAR (specific absorption rate) ratio and temperature elevation when an ultrasound beam propagates through the interface of muscle and bone. This interface is regarded as a flat boundary to partition the energy of the ultrasound beam, and the analytical solution of temperature distribution is based on the steady-state bio-heat transfer equation. The parameters considered are the incident angle of ultrasound beam, the ultrasound frequency, the acoustic attenuation coefficients of refracted longitudinal and shear waves in bone, and the blood perfusion in muscle. The results show that the peak of the SAR ratio is always at the interface of muscle and bone, while the peak of temperature is located in the bone region beyond the interface. A muscle with lower perfusion or a bone with higher acoustic attenuation results in the shifting of the temperature peak closer to the interface. It is more difficult to heat a higher perfused muscle in front of a bone using a lower frequency ultrasound since the temperature elevation for bone relative to muscle is greater.

Acoustics↗

PubMed2000

Polymorphisms of the parkin gene in sporadic Parkinson's disease among Chinese in Taiwan.

The role of genetics in Parkinson's disease (PD), previously controversial, is now documented by several studies. A major breakthrough has been the discovery of two single-gene defects in familial PD. A single base pair change at position 209 from G to A (G209A) in the fourth exon of the alpha-synuclein gene has been identified in cases of autosomal dominant familial PD. Mutations in the Parkin gene can induce autosomal recessive juvenile parkinsonism. A polymorphism of R/W366 in the Parkin gene was found to be associated with a protective factor for sporadic PD. We surveyed the polymorphisms of the Parkin gene, including S/N167, R/W366 and V/L380, in 92 cases of sporadic PD and 98 nonaffected individuals in Taiwanese Chinese. The allele frequencies of these polymorphisms are not significantly different between PD and nonaffected controls. We conclude that polymorphisms of the Parkin gene, S/N167, R/W366, V/L380, are not genetic factors for sporadic PD among Chinese in Taiwan.

Aged↗

PubMed2000

The synergistic effect of thrombopoietin in erythropoiesis and myelopoiesis from human bone marrow cells.

We sought to determine whether recombinant human thrombopoietin (TPO) acts synergistically with recombinant human erythropoietin (EPO) and/or recombinant human interleukin-3 (IL-3) on erythroid burst formation and granulocyte-macrophage colony formation from human bone marrow (BM). BM cells were from 5 adults and 15 children who underwent bone marrow examination because of a clinical suspicion of malignancy; their bone marrows as well as the complete blood counts were normal and were cultured in a methylcellulose system. TPO has a synergistic effect with EPO or EPO + IL-3 on erythropoiesis of human BM, as the addition of TPO to EPO significantly gave rise to more erythroid bursts (p = 0.0001) and the addition of TPO to EPO + IL-3 might give rise to more erythroid bursts (p = 0.05). TPO also has a synergistic effect with recombinant human granulocyte colony-stimulating factor (G-CSF) on myelopoiesis of human BM, since the addition of TPO to G-CSF gave rise to significantly more granulocyte-macrophage colonies (p = 0. 0001). Besides its well-known significant role in megakaryopoiesis, TPO also has synergistic effects on erythropoiesis and myelopoiesis.

Adolescent↗

PubMed2000

A model to study antioxidant regulation of endotoxemia-modulated neonatal granulopoiesis and granulocyte apoptosis.

Neonates with septicemia tend to develop granulocytopenia, which may, in part, be due to septic mediators such as oxygen free radicals and tumor necrosis factor alpha (TNF-alpha). Granulocytopenia may be caused by a decrease in granulocyte growth and/or an increase in granulocyte destruction. In the present study, we investigated antioxidant regulation of endotoxin-modulated neonatal granulopoiesis and granulocyte apoptosis. Using human umbilical cord blood (HUCB), we found that simulating endotoxemia in vitro elicited significant superoxide production within a few minutes. Endotoxin exposure suppressed colony-forming unit-granulocyte and monocyte formation in a dose-dependent fashion. Addition of antioxidants such as N-acetyl-cysteine could reverse the endotoxin suppression of colony-forming unit-granulocyte and monocyte formation (13 +/- 5 versus 75 +/- 5 colony-forming units/mL). Spontaneous in vitro granulocyte apoptosis in 6 h, as reflected by phosphatidylserine expression on the cell surface, was higher in granulocytes from HUCB than in those from adult blood (10.8 +/- 1.0% versus 5.6 +/- 1.2%). The addition of endotoxin or IL-8 to the cells in the in vitro model did not promote granulocyte apoptosis, but TNF-alpha, a major mediator of the effects of endotoxin, significantly induced granulocyte apoptosis in HUCB (control versus TNF-alpha: 8.9 +/- 1.2% versus 35.9 +/- 2.9%). Addition of the antioxidant N-acetyl-cysteine effectively blocked TNF-alpha-induced granulocyte apoptosis as demonstrated by DNA fragmentation. Results from these studies indicate that oxygen radicals are directly involved in endotoxin suppression of granulopoiesis, and indirectly promote granulocyte apoptosis, presumably through TNF-alpha-mediated action. Thus, under certain conditions, modulation of oxygen radical production in the blood may benefit neonates with granulocytopenia.

Acetylcysteine↗

PubMed2000

Burkitt's lymphoma presenting with jaw lesions.

We report an unusual case of Burkitt's lymphoma (BL) presenting with jaw lesions in a 14-year-old Chinese boy. The patient presented initially with mobile teeth in all 4 jaw quadrants, with corresponding radiographic detection of alveolar bone crest destruction and periapical bone resorption in the absence of clinically detectable jaw tumors. Moreover, radiographs taken only 17 days later showed clearly distinguishable signs of more extensive alveolar bone destruction compared with the initial radiographs.

Adolescent↗

PubMed2000

Disposition of olanzapine in Chinese schizophrenic patients.

The disposition of olanzapine was evaluated in 21 male chronic schizophrenic patients. A single 10 mg dose of olanzapine was administered and blood sampling performed over the following 120 hours. The mean (+/- SD) oral clearance and elimination half-life of olanzapine were 51.5+/-61.6 l/h and 30.9+/-4.3 hours, respectively. A wide interpatient variability was found. Compared to the population norms, no significant differences were observed between different populations and Chinese patients in olanzapine disposition.

Adult↗

PubMed2000

Right-sided pleural effusion in spontaneous esophageal perforation.

Spontaneous esophageal perforation (Boerhaave's syndrome) is a rare clinical entity in which overindulgence in a large meal precedes vomiting and chest pain. Early diagnosis and aggressive management are keys to minimizing the morbidity and mortality. We report an unusual presentation of this already uncommon occurrence in a 33-year-old female. She presented to the Emergency Department with severe chest pain following vomiting with hematemesis after a large meal. The initial chest radiograph showed up nothing in particular. Dyspnea developed two days later, and a right-sided pleural effusion was seen on chest x-ray. Panendoscopy was highly suggestive of Boerhaave's syndrome. She underwent emergency operation. After three months of hospital care, she was discharged in relatively good condition. This case of right-sided pleural effusion extends the reported description of Boerhaave's syndrome.

Adult↗

PubMed2000

Kleine-Levin syndrome and psychosis: observation from an unusual case.

OBJECTIVE: This study evaluated the possible pathologic relation between Kleine-Levin syndrome (KLS) and mood disorders. BACKGROUND: A 28-year-old man with a remote history of KLS had the sudden onset of a manic episode with psychotic features after the end of hypersomnolence. METHOD: The patient received an extensive laboratory examination, including single photon emission computed tomography and magnetic resonance imaging. RESULTS: Single photon emission computed tomography showed decreased tracer perfusion in the basal ganglion, hypothalamus, and right frontotemporal region. Magnetic resonance imaging revealed a cystic lesion in the pineal region. CONCLUSIONS: Hypothalamic dysfunction has been described in KLS and mood disorders, but pineal gland dysfunction has been mentioned only rarely. The clinical and neuroimaging findings suggest the need for further study of KLS.

Adult↗

PubMed2000

Delayed brachial plexus neurapraxia complicating malunion of the clavicle.

Delayed brachial plexus neurapraxia is a rare complication of midshaft clavicular fracture. The symptoms are variable and occur insidiously. Surgical decompression to release the compression of brachial plexus is the treatment of choice and usually has a good result. We report a patient whose brachial plexus was compressed by malunion of the clavicle. This patient had a good outcome after treatment with intramedullary nailing and Knowles pin fixation after corrective osteotomy without bone grafting.

Adult↗

PubMed2000

Squamous cell carcinoma of the right upper lung congenital tracheal bronchus.

Tracheal bronchus, directly arising from the abnormal tracheal wall, is a rare congenital anomaly of the airway. Lung cancer developing in a tracheal bronchus is even more rare. A 68-year-old man had a mass shadow over the right upper lung on chest radiography. Bronchoscopy revealed an abnormally displaced bronchus stemming from the right side of the tracheal wall, 2 cm above the carina. Arising from this tracheal bronchus was a tumor, a biopsy of which showed squamous cell carcinoma. During surgery, a bronchus arising from the right lateral wall of the trachea and supplying the apical segment of the right upper lobe was found. There was a tumor occluding the lumen of the tracheal bronchus, causing distal obstructive pneumonitis. The patient underwent right upper lobectomy with closure of the tracheal bronchus and radical lymph node dissection. The subsequent pathologic examination of the specimen revealed squamous cell carcinoma with surrounding pneumonitis. Bronchogenic cancers developing in a tracheal bronchus are rarely reported in the English language literature. Surgical resection appears to be the treatment of choice.

Bronchi↗

PubMed2000

Problem-based, small-group tutorial learning in clinical neurology for second-year medical students.

BACKGROUND: Problem-based learning (PBL) in small-group tutorials has been a trend in medical education. Chinese students are known to be reserved and passive; thus, they may not be adaptable to PBL. Neuroanatomy, important to clinical neurology, is difficult to learn. We incorporated clinical neurology with PBL, complementary to the traditional neuroanatomy curriculum, to evaluate the feasibility of PBL for Chinese students in Taiwan. METHODS: Forty-two second-year medical students and seven tutors participated in the clinical neurology PBL small-group tutorials. Twelve case reports were discussed weekly beginning in February, 1999. Each case was designed to meet the progressive curriculum of the neuroanatomy course. The tutors evaluated the students by the degree of their preparation, participation, key-point comprehension and interaction. All tutors and students filled out questionnaires at the end of each session. RESULTS: The majority of the students and tutors agreed that the case materials were clearly written. Ninety percent of the students agreed that the case materials matched the traditional content of neuroanatomy. Eighty-five percent of students and 71% of tutors were satisfied and found the class rewarding. Ninety-one percent of students and 74% of tutors were in favor of PBL being continued. CONCLUSIONS: This preliminary PBL, small-group tutorial learning in clinical neurology showed satisfactory results and was, indeed, complementary to a traditional neuroanatomy course. The students, as early as during the second year of their medical school education, were able to learn through the PBL. More integration of basic and clinical sciences by PBL may be considered in future curricula designs.

Education, Medical↗

PubMed1999

Association analysis of the 5-HT6 receptor polymorphism C267T in Alzheimer's disease.

Serotonergic dysfunction has been implicated in the pathogenesis of Alzheimer's disease (AD). This association study explores whether the serotonin 6 receptor (5-HT6) polymorphism (C267T) is a susceptibility factor for AD. Statistical analysis showed a significant difference in the genotype and gene frequencies between the AD group and the normal controls (P = 0.006; and P = 0.023, respectively). These findings indicate that the 267C allele of the 5-HT6 gene is a risk factor for AD.

Aged↗

PubMed1999

ApoE genotype in relation to AD and cholesterol: a study of 2,326 Chinese adults.

OBJECTIVE: To calculate the frequencies of apolipoprotein E (apoE) alleles in a large Chinese community sample and to compare the serum cholesterol levels of epsilon2, epsilon3, and epsilon4 carriers. BACKGROUND: In comparison with Western populations, a lower frequency of the apoE epsilon4 allele among the Chinese has been proposed as one factor for the lower prevalence of AD found in Chinese populations, but there are insufficient Chinese data on epsilon4 frequency that are based on large community samples. In addition, although Western studies have repeatedly found a lower cholesterol level in epsilon2 carriers and a higher cholesterol level in epsilon4 carriers in comparison with epsilon3 homozygotes, two Chinese studies have yielded inconsistent findings between them. METHODS: During the incidence phase of an epidemiologic survey of several neurologic disorders in a Chinese community, the authors took blood samples from 2,326 participants to determine the apoE genotypes and to measure cholesterol levels. RESULTS: The allelic frequencies of epsilon2, epsilon3, and epsilon4 were 11.8%, 76.4%, and 11.8% among 17 AD patients, and 7.8%, 84.1%, and 8.1% for the entire sample. The mean cholesterol level of the epsilon2 carriers was significantly lower, and that of the epsilon4 carriers significantly higher, than that of the epsilon3 homozygotes. CONCLUSIONS: The obtained epsilon4 rate of 8.1% is lower than most of the Western findings, and this may account in part for the lower prevalence of AD found among the Chinese. The associations between the apoE genotype and serum cholesterol level are similar between Chinese and white populations.

Aged↗

PubMed1999

Transcriptional regulation of mouse delta-opioid receptor gene.

Three major types of opioid receptors, mu (MOR), delta (DOR), and kappa (KOR), have been cloned and characterized. Each opioid receptor exhibits a distinct pharmacological profile as well as a distinct pattern of temporal and spatial expression in the brain, suggesting the critical role of transcription regulatory elements and their associated factors. Here, we report the identification of a minimum core promoter, in the 5'-flanking region of the mouse DOR gene, containing an E box and a GC box that are crucial for DOR promoter activity in NS20Y cells, a DOR-expressing mouse neuronal cell line. In vitro protein-DNA binding assays and in vivo transient transfection assays indicated that members of both the upstream stimulatory factor and Sp families of transcription factors bound to and trans-activated the DOR promoter via the E box and GC box, respectively. Furthermore, functional and physical interactions between these factors were critical for the basal as well as maximum promoter activity of the DOR gene. Thus, the distinct developmental emergence and brain regional distribution of the delta opioid receptor appear to be controlled, at least in part, by these two regulatory elements and their associated factors.

Animals↗

PubMed1999

No association of alpha-2 macroglobulin gene five-nucleotide deletion with AD in Taiwan Chinese.

The alpha-2 macroglobulin five-nucleotide deletion (A2M-2) allele frequency was not significantly higher in the AD group than the control group (0.062 versus 0.101, p > 0.1). The odds ratio for AD in individuals with the A2M-2 allele was 0.582 (95% CI, 0.25 to 1.40). These results do not support the association between A2M-2 and AD in the Chinese population, although the allele frequency of A2M-2 is lower than that found in the Caucasian population. Therefore, A2M-2 might not be a significant risk factor of AD among Taiwan Chinese.

Aged↗

PubMed1999

The influence of hydroxyapatite particles on osteoclast cell activities.

Aseptic loosening after total joint arthroplasty is a major problem in orthopedic surgery. Small particles from material wear have been reported as the main cause of implant failure. For this reason, investigation into possible wear particles from the materials used in the implant may lead to longevity after arthroplasty. Hydroxyapatite (HA) has been extensively investigated and reported as an excellent biomaterial with excellent biocompatibility. In this study, we used an in vitro osteoblast/osteoclast model to test the biocompatibility of various-sized HA particles. Primary osteoclasts/osteoblasts were co-cultured with different-sized HA particles (0.5-3.0 microm, 37-53 microm, 177-205 microm, and 420-841 microm) for 3 h, 1 day, 3 days, and 7 days. Cellular responses to the HA particles were evaluated by changes in cell counts and the secretion of transforming growth factor (TGF-beta1), alkaline phosphatase (ALP), tumor necrosis factor (TNF-alpha), prostaglandin (PGE2), and lactate dehydrogenase (LDH) in the supernatant of the culture media. The results showed that osteoblasts/osteoclasts co-cultured with HA particles smaller than 53 microm undergo the most significant changes. Cellular counts significantly decreased, and the changes were more obvious in the osteoblast population. There also was a significant decrease in TGF-beta1 concentration and a significant increase in PGE2 and LDH concentration, but there were no changes in the TNF-alpha or ALP titer. It can be concluded that larger HA particles may be quite compatible with bone cells while smaller-sized HA particles can both activate the osteoclasts and decrease the cell population of the osteoblasts. Justification for the additional expense incurred with the use of hydroxyapatite in primary total hip arthroplasty should be further evaluated.

Alkaline Phosphatase↗

PubMed1999

Ossification of the posterior longitudinal ligament of the spine. A case-control risk factor study.

STUDY DESIGN: A case-control study. OBJECTIVES: To determine the risk factors for ossification of the posterior longitudinal ligament (OPLL) of the spine. SUMMARY OF BACKGROUND DATA: Previous epidemiologic studies conducted in Japan showed consuming vegetable protein and salt was a risk factor for OPLL. Dietary habits of the Taiwanese and Japanese people are similar. Whether the similar dietary habits play an important role in the high prevalence of OPLL in Taiwan was of interest. METHODS: A case-control study was conducted in a tertiary teaching hospital. The study included 98 consecutive cervical spine patients with OPLL, with 98 age-matched patients with cervical spondylosis serving as control subjects. Radiologic examinations, clinical interviews, physical examinations, and risk factor questionnaires were administered to all the participants. RESULTS: Compared with incidence in the control patients, the frequency of the ossification of the anterior longitudinal ligaments was significantly higher in OPLL patients with OPLL (31% vs. 19%; P = 0.049), but there was no difference in incidence of ossification of the ligamentum flavum (13.3% vs. 16.3%; P = 0.546). More OPLL patients preferred a high-salt diet (OPLL/CS, no:somewhat:yes = 23/38:18/25:57/35;, X2 for trend = 6.3; P = 0.001) and pickled foods (OPLL/CS, no:somewhat:yes = 39/56:11/11:48/31; X2 for trend = 6.7; P = 0.0099). Fewer patients with OPLL consumed meat daily (63% vs. 79%; P = 0.018). High-salt diet (odds ratio = 2.62) and daily meat intake (odds ratio = 0.39) showed persistent association with OPLL in a multivariate logistic regression. CONCLUSIONS: The similar dietary habits, particularly a high-salt and low meat intakes, may partially explain the high prevalence of OPLL in Taiwan and Japan. Modifying dietary habits may help prevent this disease, especially in those high-risk populations.

Aged↗

PubMed1999

Bone defect healing enhanced by ultrasound stimulation: an in vitro tissue culture model.

Ultrasound has many medical applications. Previous animal and clinical studies have clearly shown a positive effect of ultrasound on the rate of osseous repair. The present in vitro study was designed to elucidate the specific response of bony tissue to ultrasound treatment. Bilateral femora were obtained from 36 mature male Wistar rats. A bone defect was created at the center of each distal metaphysis. The femora were maintained for either 7 or 14 days in in vitro tissue culture and received 15 min of ultrasound stimulation or a sham exposure. The ultrasound intensity used was either 320 or 770 mW/cm2. Healing of the bone defect was evaluated by histomorphological examination and by analysis for the synthesis and secretion of prostaglandin E2. The results showed that ultrasound stimulation can accelerate both defect healing and trabecular bone regeneration. All experimental femoral defects treated with ultrasound healed faster than the untreated cortical defects, but only the defects receiving 770 mW/cm2 reached a level that was significantly different. The healing rate for the 320-mW/cm2 stimulated defects was intermediate between that of the 770-mW/cm2 and sham-exposed defects. With ultrasound stimulation, prostaglandin E2 secretion by the experimental femora decreased significantly. Changes in the prostaglandin synthesis and concentration were found to correspond to changes in the amount of trabecular regeneration and to acceleration of bone healing. This highly controlled and well-studied model of ultrasound stimulation of bone healing in vitro can be used to further examine the biological mechanisms involved.

Animals↗