Biomedical subjects

Wei-Liang Chen

Publications and source records attributed to Wei-Liang Chen.

15 recordsLinked to original sources

PubMed2006

Recurrent ameloblastoma of the anterior skull base: three cases treated by radical resections.

INTRODUCTION: Recurrent ameloblastomas rarely present in the anterior skull base but are, common following inadequate excision. PATIENTS AND METHODS: Three patients are presented with ameloblastoma in the anterior skull base including frontotemporal fossa and pterygomaxillary fossa recurring following multiple enucleations, segmental mandibulectomy, or partial maxillectomy. The recurrences were found 3-4 years following the primary operations. All 3 patients were treated by radical dissection. RESULTS: Microscopically one case was a mixed follicular and plexiform, two cases were of a follicular type. All patients healed without serious complications. CONCLUSION: Ameloblastomas in these regions have a greater recurrence potential even when treated by radical dissection.

Adult↗

PubMed2006

Investigating mechanisms of collagen thermal denaturation by high resolution second-harmonic generation imaging.

We apply the technique of second-harmonic generation (SHG) microscopy to obtain large area submicron resolution image of Type I collagen from rat tail tendon as it is heated from 40 degrees C to 70 degrees C for 0-180 min. The change in the collagen structure as reflected in its SHG image is observed at length scales from submicron to hundreds of microns. We observed that heating the tendon below the temperature of 54 degrees C does not produce any change in the averaged SHG intensity. At the heating temperature of 54 degrees C and above, we find that increasing the heating temperature and time leads to decreasing SHG intensity. As the tendon is heated above 54 degrees C, the regions where the SHG signal vanish and form a tiger-tail like pattern. In addition, a decrease in the SHG signal occurs uniformly throughout the tendon. By comparing the relative SHG intensities in small and large areas, we found that the denaturation process responsible for forming the tiger-tail like pattern occurs at a higher rate than the global denaturation process occurring throughout the tendon. We also measured the fibril spacing and found that it remains constant at 1.61 +/- 0.04 micron for all heating temperature and times. The constant fibril density shows that the global denaturation process occurs at a length scale smaller than the size of the fibril. Our results show that second-harmonic generation microscopy is effective in monitoring the thermal damage to collagen and has potential applications in biomedicine.

Animals↗

PubMed2006

Effects of different immersion media in multiphoton imaging of the epithelium and dermis of human skin.

In this work, we compared the performance of objectives with similar numerical aperture of 0.75 but different immersion media of air, water, glycerin, and oil in the imaging of human skin epithelium and dermis. In general, we found that the oil immersion objective recorded the strongest intensity at the same mechanical depth. We also characterized the focal shifts and found that with decreasing refractive index, the focal shift becomes increasingly more negative (for both the epithelium and dermis). In imaging the dermis, we estimated the image resolution at the depths of 18.8 and 30.2 microm, and found that the image resolution were comparable at these depths under the four types of immersion conditions. Our results demonstrate that by changing the immersion media, the main microscopic imaging effects are the recorded axial intensities and the focal shifts. The effects on the image resolution are negligible.

Dermis↗

PubMed2006

A novel heterozygous missense mutation 377T > C (V126A) of TGIF gene in a family segregated with holoprosencephaly and moyamoya disease.

OBJECTIVES: To identify whether any mutations of candidate genes including SHH, ZIC2, SIX3, and TGIF exist in a Taiwanese family segregated with holoprosencephaly (HPE) and moyamoya disease. METHODS: Genotypes of the candidate genes SHH, ZIC2, SIX3, and TGIF were determined in the family members who were available for analysis by sequencing. In addition, genomic regions of another 50 unrelated Taiwanese (100 chromosomes) were studied to verify whether the nucleotide changes we found were mutations or polymorphisms. RESULTS: A novel missense mutation 377T > C and two polymorphisms (420A > G and 487C > T) in the TGIF gene were identified. No mutations in SHH, ZIC2 and SIX3 were found. The mother of the three HPE fetuses was found to be afflicted with moyamoya disease. A brief review of the mutations as well as polymorphisms reported in the TGIF gene up to 2005 is given. CONCLUSION: Molecular diagnosis can help genetic counseling in HPE, which is a heterogeneous disorder with its phenotypic and genotypic spectrum highly widened and variable. The possible association between TGIF mutation and moyamoya disease noted in our study also appeared to be novel.

Adult↗

PubMed2006

[Expression and significance of inducible nitric oxide synthase and vascular endothelial growth factor in carcinogenesis of hamster cheek pouch].

BACKGROUND & OBJECTIVE: Inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor (VEGF) are related to carcinogenesis and development of tumors. This study was to explore the correlations of the expression of iNOS and VEGF to the angiogenesis in carcinogenesis of Golden hamster cheek pouch. METHODS: A total of 50 Golden hamsters were divided into 2 groups: 40 in experiment group, 10 in control group. DMBA was painted on the cheek pouches of the hamsters in experiment group, but not in control group. The hamsters in experiment group were killed at the 6th, 9th, 12th, and 16th weeks, respectively; 10 at each time. The hamsters in control group were killed at the 16th week. The expression of iNOS and VEGF and microvessel density (MVD) in carcinogenesis in the pouches of hamsters were detected by SABC immunohistochemistry; the level of nitric oxide (NO) was measured by spectrophotometry. RESULTS: Both iNOS and VEGF expression were negative in the pouches of the hamsters in control group, but they increased gradually from the 6th to 16th week in experiment group (P<0.05). The level of NO increased from the 6th to 16th week, too, and the difference between each 2 groups was significant (P<0.05). MVD was significantly higher in iNOS- and VEGF-positive group than in iNOS- and VEGF-negative group (P<0.05). CONCLUSIONS: NO plays an important role in the carcinogenesis of Golden hamster cheek pouch. iNOS and VEGF may exert interactions in tumor angiogenesis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2005

Anti-inflammatory mechanisms of phenanthroindolizidine alkaloids.

The molecular mechanisms for the anti-inflammatory activity of phenanthroindolizidine alkaloids were examined in an in vitro system mimicking acute inflammation by studying the suppression of lipopolysaccharide (LPS)/interferon-gamma (IFNgamma)-induced nitric oxide production in RAW264.7 cells. Two of the phenanthroindolizidine alkaloids, NSTP0G01 (tylophorine) and NSTP0G07 (ficuseptine-A), exhibited potent suppression of nitric oxide production and did not show significant cytotoxicity to the LPS/IFNgamma-stimulated RAW264.7 cells, in contrast to their respective cytotoxic effects on cancer cells. Tylophorine was studied further to investigate the responsible mechanisms. It was found to inhibit the induced protein levels of tumor necrosis factor-alpha, inducible nitric-oxide synthase (iNOS), and cyclooxygenase (COX)-II. It also inhibited the activation of murine iNOS and COX-II promoter activity. However, of the two common responsive elements of iNOS and COX-II promoters, nuclear factor-kappaB (NF-kappaB) and adaptor protein (AP)1, only AP1 activation was inhibited by tylophorine in the LPS/IFNgamma-stimulated RAW264.7 cells. Further studies showed that the tylophorine enhanced the phosphorylation of Akt and thus decreased the expression and phosphorylation levels of c-Jun protein, thereby causing the subsequent inhibition of AP1 activity. Furthermore, the tylophorine was able to block mitogen-activated protein/extracellular signal-regulated kinase kinase 1 activity and its downstream signaling activation of NF-kappaB and AP1. Thus, NSTP0G01 exerts its anti-inflammatory effects by inhibiting expression of the proinflammatory factors and related signaling pathways.

Adaptor Protein Complex 1↗

PubMed2005

Identification of anrF gene, a homology of admM of andrimid biosynthetic gene cluster related to the antagonistic activity of Enterobacter cloacae B8.

AIM: To identify the gene (s) related to the antagonistic activity of Enterobacter cloacae B8 and to elucidate its antagonistic mechanism. METHODS: Transposon-mediated mutagenesis and tagging method and cassette PCR-based chromosomal walking method were adopted to isolate the mutant strain(s) of B8 that lost the antagonistic activity and to clone DNA fragments around Tn5 insertion site. Sequence compiling and open reading frame (ORF) finding were done with DNAStar program and homologous sequence and conserved domain searches were performed with BlastN or BlastP programs at www.ncbi.nlm.nih.gov. To verify the gene involved in the antagonistic activity, complementation of a full-length clone of the anrF gene to the mutant B8F strain was used. RESULTS: A 3 321 bp contig around the Tn5 insertion site was obtained and an ORF of 2 634 bp in length designated as anrF gene encoding for a 877 aa polyketide synthase-like protein was identified. It had a homology of 83% at the nucleotide level and 79% ID/87% SIM at the protein level, to the admM gene of Pantoea agglomerans andrimid biosynthetic gene cluster (AY192157). The Tn5 was inserted at 2 420 bp of the gene corresponding to the COG3319 (the thioesterase domain of type I polyketide synthase) coding region on B8F. The antagonistic activity against Xanthomonas oryzae pv. oryzae was resumed with complementation of the full-length anrF gene to the mutant B8F. CONCLUSION: The anrF gene obtained is related to the antagonistic activity of B8, and the antagonistic substances produced by B8 are andrimid and/or its analogs.

Base Sequence↗

PubMed2005

Solid breast masses: classification with computer-aided analysis of continuous US images obtained with probe compression.

PURPOSE: To prospectively evaluate the accuracy of continuous ultrasonographic (US) images obtained during probe compression and computer-aided analysis for classification of biopsy-proved (reference standard) benign and malignant breast tumors. MATERIALS AND METHODS: This study was approved by the local ethics committee, and informed consent was obtained from all included patients. Serial US images of 100 solid breast masses (60 benign and 40 malignant tumors) were obtained with US probe compression in 86 patients (mean age, 45 years; range, 20-67 years). After segmentation of tumor contours with the level-set method, three features of strain on tissue from probe compression--contour difference, shift distance, area difference--and one feature of shape--solidity-were computed. A maximum margin classifier was used to classify the tumors by using these four features. The Student t test and receiver operating characteristic curve analysis were used for statistical analysis. RESULTS: The mean values of contour difference, shift distance, area difference, and solidity were 3.52% +/- 2.12 (standard deviation), 2.62 +/- 1.31, 1.08% +/- 0.85, and 1.70 +/- 1.85 in malignant tumors and 9.72% +/- 4.54, 5.04 +/- 2.79, 3.17% +/- 2.86, and 0.53 +/- 0.63 in benign tumors, respectively. Differences with P < .001 were statistically significant for all four features. Area under the receiver operating characteristic curve (A(Z)) values for contour difference, shift distance, area difference, and solidity were 0.88, 0.85, 0.86, and 0.79, respectively. The A(Z) value of three features of strain was significantly higher than that of the feature of shape (P < .01). The accuracy, sensitivity, specificity, and positive and negative predictive values of US classifications that were based on values for these four features were 87.0% (87 of 100), 85% (34 of 40), 88% (53 of 60), 83% (34 of 41), and 90% (53 of 59), respectively, with an A(Z) value of 0.91. CONCLUSION: Continuous US images obtained with probe compression and computer-aided analysis can aid in classification of benign and malignant breast tumors.

Adult↗

PubMed2005

Clinical and magnetic resonance imaging manifestations of Holmes tremor.

Holmes tremor is a rare symptomatic slow tremor in the proximal parts of the limbs. It may be present at rest or maintenance of a posture, or during the movement of the affected limb. We describe herein three patients of Holmes tremor with possible etiologies of brainstem infarction and head injury. The intervals between the causal events and the appearance of tremor range from 1 month to 12 months. Magnetic resonance imaging studies reveal hypertrophy of the inferior olivary nucleus in all of the three patients, although only one of them has palatal myoclonus. The surface electromyographic recordings reveal characteristic slow oscillation with frequencies of 3.5 to 4.2 Hz. These features suggest that perturbation of the dentato-rubral-olivary circuitry may play a pivotal role for the generation of Holmes tremor. However, no tight correlation is observed between the presence of inferior olivary nuclear hypertrophy and the appearance of symptomatic palatal myoclonus in the current report.

Adult↗

PubMed2005

[An island pectoralis major myocutaneous flap for the reconstruction of tongue and floor of mouth].

OBJECTIVE: To evaluate an island pectoralis major myocutaneous flap for immediate reconstruction of the total tongue body and the floor of the mouth after radical resection of bilateral tongue carcinoma involved. METHODS: Form October 2000 to December 2002, seven patients with bilateral tongue carcinoma were selected to treat with salvage surgery, and an island pectoralis major myocutaneous flap were applied for immediate reconstruction of total body of tongue and floor of mouth. RESULTS: Six flaps survived well. Only one flap showed a partial necrosis, with no submandibular fistula, infection, and other complications. The reconstructed tongue and floor of mouth worked well. The speaking and swallowing functions were satisfactory after 2 approximately 16 months' follow-ups. Only one patient died of lung metastasis carcinoma in 9 months after the operation. CONCLUSIONS: The island pectoralis major myocutaneous flap could be an ideal selection for the immediate reconstruction of the total tongue body and the floor of mouth.

Adult↗

PubMed2005

[Expression of cyclooxygenase-2 and inducible nitric oxide synthase in tongue hyperplasia and tongue squamous cell carcinoma].

BACKGROUND & OBJECTIVE: Recently, it has been recognized that both cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) produce important endogenous factors of human tumor progression. However, the biological significance of the adnormal expression of COX-2 and iNOS in tongue squamous cell carcinoma remains unclear. This study was to investigate the expression of COX-2 and iNOS in tongue squamous cell carcinoma and precancerous lesions, and analyze their interrelation. METHODS: The expression of COX-2 and iNOS in 59 specimens of tongue squamous cell carcinoma (SCC), 45 specimens of hyperplasia (22 cases of mild hyperplasia, 20 cases of moderate hyperplasia, and 3 cases of severe hyperplasia), and 36 specimens of pericancerous normal epithelium was detected by SP immunohistochemistry. RESULTS: The positive rates of COX-2 were 8.3% in normal epithelium, 4.5% in mild hyperplasia, 5.0% in moderate hyperplasia, 0 in severe hyperplasia, and 45.8% in SCC, respectively; those of iNOS were 44.4% in normal epithelium, 72.7% in mild hyperplasia, 80.0% in moderate hyperplasia, 100% in severe hyperplasia, and 98.3% in SCC, respectively. The positive rates of COX-2 and iNOS were significantly higher in SCC than in normal epithelium (P < 0.001); the positive rate of iNOS was also significantly higher in hyperplasia than in normal epithelium (P < 0.001). The overexpression of COX-2 and iNOS was positively correlated with pathologic grade of the lesions (r = 0.418, P < 0.001; r = 0.607, P < 0.001). COX-2 expression was positively correlated with iNOS expression (r = 0.245, P < 0.001). CONCLUSOIN: The overexpression of COX-2 and iNOS is closely related to the carcinogenesis of the tongue.

Adult↗

PubMed2004

[Modification for primary tongue reconstruction with free forearm flap after radical operation of tongue carcinoma].

BACKGROUND & OBJECTIVE: Radical operation of tongue carcinoma causes hemi-tongue defective, which seriously affected the quality of life in these patients. The primary tongue reconstruction guaranteed the healing of the surgical incision at early stage. This may help to recover swallowing and speaking of the patients. However, the vascular crisis happened in the free flap proved to be an obstacle to the extensive application in the tongue reconstruction. This paper illustrated some modifications in the application of the free forearm flap, which may ensure the success in operation. METHODS: Some methods like skin flap design, preparation and vascular anastomosis were modified in the application among the 32 tongue carcinoma patients. RESULTS: The surgical incisions of the oral cavity and neck healed up, with no salivary fistula, chylorrhea, submandibular fistula, infection and other complications. After the operations, 6 flaps developed vascular crisis, and 5 flaps were successfully salvaged, meanwhile, one case failed, which resulted in the flap abandonment. The total successful transplantation rate reached 96.9%. The reconstructed tongue recovered, and the speaking as well as swallowing functions re-obtained. CONCLUSION: The modified methods of tongue reconstruction with free forearm flap improve the clinical effects of reconstructed tongue.

Adult↗

PubMed2003

Metallic stenting for treatment of central venous obstruction in hemodialysis patients.

BACKGROUND: Central venous obstruction is a serious and common complication in hemodialysis patients. The recurrence rate is high after balloon dilation, while surgical repair is hazardous in these chronically ill patients. The aim of this study was to evaluate the efficacy of primary Wallstent placement for treatment of hemodialysis-related central venous obstructions. METHODS: Eighteen hemodialysis patients with symptomatic shunt dysfunction and arm swelling due to subclavian (n = 3) or innominate (n = 15) venous obstructions were treated at Kaohsiung Veterans General Hospital with primary Wallstent placement from November 1998 to August 2001. Technical success and complications were reported. Primary and secondary patency rates of stent and hemodialysis access were calculated by survival analysis with Kaplan-Meier method. RESULTS: A total of twenty-five Wallstents were deployed for central venous stenosis (n = 18) and occlusion (n = 7) in these 18 hemodialysis patients. The initial technical success rate was 100%. Fourteen episodes of re-obstruction developed during the observation period. Of them, seven episodes occurred within the stent, four episodes outside of but abutting to the peripheral end of the stent, and another three episodes of re-obstruction were attributed to delayed shortening of the Wallstent. Six of the 14 episodes were treated percutaneously with angioplasty alone, while seven episodes necessitated additional stent placement. No stent migration or other complications were encountered. Primary patency rates of stent and hemodialysis access at 3, 6, 12 and 18 months were 100 and 89%, 73 and 68%, 49 and 42%, and 16 and 0%, respectively. Secondary patency rates of stent and hemodialysis access each were both 100% after 3 months, 93 and 100% after 6 months, 85 and 91% after 12 months and, 68 and 72% after 24 months. CONCLUSIONS: Wallstents are safe to deploy, with excellent technical success for hemodialysis-related central venous obstructions. The Wallstent provides continued use of a hemodialysis access for a substantial period. However, repeated interventions may be necessary to maintain the patency.

Aged↗

PubMedDate not supplied

Magnetic resonance imaging and diffusion-weighted images of cystic meningioma: correlating with histopathology.

BACKGROUND AND PURPOSE: Cystic meningiomas are quite rare, accounting for between 2% and 4% of all intracranial meningiomas. To better understand all the types of cystic meningiomas with magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) and histopathology, we attempted to correlate the MRI and DWI features of cystic meningiomas with the histopathological findings. METHODS: We collected 15 cases of cystic meningiomas diagnosed between 1993 and 2000 (5 men and 10 women, 41-80 years old). Fifteen patients had conventional MRI and 14 patients had CT scan. DWI was also performed in three patients. Apparent diffusion coefficient (ADC) images were also done. In the classification of cystic meningiomas, we adopted Worthington's classification, which divides cystic meningiomas into five groups. RESULTS: Tumor resection was performed in all patients. Tumor locations were as follows: convexity (10), falx (2), pterion (2) and lateral ventricle (1). Regarding the types of cystic lesion, type I (3), type II (3), type III (3), type IV (1) and type V (5) were found. Histopathologically, there were six atypical, four meningothelial, two malignant, one fibroblastic, one angiomatous and one transitional. Intratumoral cystic meningiomas were more common in atypical types. Peritumoral cystic meningiomas were more common in meningothelial and atypical types. The cystic portion of the three cystic meningiomas was hypointense or mildly hyperintense on DWI. ADC ratio (ADCR) of DWI for cyst part of two type I cystic meningiomas was 1.25 and 0.82; for cyst part of one type III was 4.04. CONCLUSIONS: It is important to recognize the neuroimaging features of the cystic meningiomas. Conventional MRI and DWI may play an important role in the preoperative radiological evaluation and the recognition of these types of cysts for proper surgical treatment.

Adult↗

PubMedDate not supplied

Prediction of heat-induced collagen shrinkage by use of second harmonic generation microscopy.

Collagen shrinkage associated with denaturation from thermal treatment has a number of important clinical applications. However, individualized treatment is hindered by the lack of reliable noninvasive methods to monitor the process of collagen denaturation. We investigate the serial changes of collagen denaturation from thermal treatment of rat tail tendons at 58 degrees C by use of second harmonic generation (SHG) microscopy. We find that rat tail tendon shrinks progressively from 0 to 9 min of thermal treatment, and remains unchanged in length upon further thermal treatment. The SHG intensity also decreases from 0 to 9 min of thermal treatment and becomes barely detectable from further thermal treatment. Collagen shrinkage and the SHG intensity are well correlated in a linear model. In addition, SHG imaging reveals a tiger-tail-like pattern of collagen denaturation. The bands of denatured collagen progressively widen from increased thermal treatment and completely replace the adjacent bands of normal collagen after 9 min of thermal treatment. Our results show that collagen denaturation in rat tail tendon from thermal treatment is inhomogeneous, and that SHG intensity can be used to predict the degree of thermally induced collagen shrinkage. With additional development, this approach has the potential to be used in biomedical applications.

Animals↗