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Biomedical subjects

S C Kao

Publications and source records attributed to S C Kao.

At least 19 recordsLinked to original sources

Welded tracheal stent removal in a child under cardiopulmonary bypass.

Metallic tracheal stents have been used in the treatment of paediatric tracheomalacia for more than a decade. We describe a case in which critical airway obstruction occurred during removal of a welded tracheal stent using a rigid bronchoscope under general anaesthesia. Life-saving cardiopulmonary bypass was instituted urgently, and the welded stent was then removed successfully by directly opening the trachea.

Airway Obstruction↗

beta-Amyloid stimulation of microglia and monocytes results in TNFalpha-dependent expression of inducible nitric oxide synthase and neuronal apoptosis.

Reactive microglia associated with the beta-amyloid plaques in Alzheimer's disease (AD) brains initiate a sequence of inflammatory events integral to the disease process. We have observed that fibrillar beta-amyloid peptides activate a tyrosine kinase-based signaling response in primary mouse microglia and the human monocytic cell line, THP-1, resulting in production of neurotoxic secretory products, proinflammatory cytokines, and reactive oxygen species. We report that most of the amyloid-induced tyrosine kinase activity was stimulated after activation of Src family members such as Lyn. However, transduction of the signaling response required for increased production of the cytokines TNFalpha and IL1-beta was mediated by the nonreceptor tyrosine kinase, Syk. Additionally, beta-amyloid stimulated an NFkappaB-dependent pathway in parallel that was required for cytokine production. Importantly, TNFalpha generated by the monocytes and microglia was responsible for the majority of the neuorotoxic activity secreted by these cells after beta-amyloid stimulation but must act in concert with other factors elaborated by microglia to elicit neuronal death. Moreover, we observed that the neuronal loss was apoptotic in nature and involved increased neuronal expression of inducible nitric oxide synthase and subsequent peroxynitrite production. Selective inhibitors of inducible nitric oxide synthase effectively protected cells from toxicity associated with the microglial and monocytic secretory products. This study demonstrates a functional linkage between beta-amyloid-dependent activation of microglia and several characteristic markers of neuronal death occurring in Alzheimer's disease brains.

Alzheimer Disease↗

Presence of Epstein-Barr virus latent membrane protein 1 gene in the nasopharyngeal swabs from patients with nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is the most common head and neck malignancy in southeastern China and Taiwan. Early detection of the local disease followed immediately by proper treatment is essential to increase the cure and survival rates. Because every NPC tumor cell carries Epstein-Barr Virus (EBV) genomes, detection of EBV genomic DNA such as latent membrane protein 1 gene (LMP1) might indicate the presence of NPC. We developed a simple and noninvasive technique of nasopharyngeal swabbing to acquire nasopharyngeal cells for detecting the presence of EBV genome. The aim of this study was to investigate the feasibility and reliability of this technique. METHODS: We collected nasopharyngeal cells by means of a nasopharyngeal swabbing technique and detected the presence of EBV LMP1 with polymerase chain reaction (PCR). Thirty-eight swab specimens were obtained from patients with NPC who were newly diagnosed or were just beginning radiotherapy. Two groups of control subjects were recruited, including 20 patients with other head and neck cancers and eight family members of the NPC patients. An additional group of 65 NPC patients were enrolled in the course of regular follow-up after definitive radiotherapy. RESULTS: All of the samples yielded sufficient DNA for PCR amplification. Thirty-six of 38 NPC swab samples were positive for EBV LMP1, and all the control subjects had swab sample results negative for EBV. All five patients with suspected local recurrence exhibited positive EBV test results. CONCLUSIONS: Demonstration of EBV LMP1 in the nasopharyngeal swab specimens detected NPC with a sensitivity of 94.7% and specificity of 100%. This study confirms the reliability and feasibility of nasopharyngeal swab in the predicting and screening of NPC.

Base Sequence↗

Visual acuity and contrast sensitivity in different types of posterior capsule opacification.

PURPOSE: To compare the visual acuity (VA) and contrast sensitivity in 2 types of posterior capsule opacification (PCO) in pseudophakic eyes before and after neodymium:YAG (Nd:YAG) capsulotomy and to evaluate vision test results after Nd:YAG capsulotomy. SETTING: Department of Ophthalmology, Taipei Veterans General Hospital, National Yang-Ming University, Taipei, Taiwan. METHODS: Fourteen eyes with fibrosis-type PCO and 15 eyes with Elschnig-pearl-type PCO were enrolled prospectively. Before and 1 week after Nd:YAG capsulotomy, VA and contrast sensitivity were assessed using the illiterate E version of the Bailey-Lovie chart and the Vistech VCTS 6000 chart, respectively. RESULTS: Before capsulotomy, the mean logMAR acuity in the group with Elschnig-pearl-type PCO was 0.47 +/- 0.32 (SD) and in the group with fibrosis-type PCO, 0.17 +/- 0.07. The difference between the 2 groups was significant (P =.002). After capsulotomy, there was no significant between-group difference (P >.05). Before capsulotomy, the contrast sensitivity was significantly worse (P <.01) at all spatial frequencies in the group with pearl-type PCO, especially at 6 cycles per degree. After capsulotomy, there was no significant between-group difference (P >.05) at any spatial frequency. CONCLUSIONS: After cataract surgery, patients with pearl-type PCO had lower VA and contrast sensitivity than those with fibrosis-type PCO. An Nd:YAG capsulotomy improved the VA and contrast sensitivity in patients with both types of PCO.

Aged↗

Molecular analysis of mucosa-associated lymphoid tissue (MALT) lymphoma of ocular adnexa.

Lymphomas of mucosa-associated lymphoid tissue (MALT) are a distinct subgroup of extranodal B-cell non-Hodgkin's lymphomas. Most studies have failed to demonstrate the clonal rearrangement of BCL-1, BCL-2 or c-MYC genes for MALT lymphomas. Further, alteration of the p53 gene is rarely demonstrated in low-grade MALT lymphomas, but can be detected in high-grade disease. Lymphomas of the ocular adnexa represent approximately eight percent of all extranodal lymphomas, most of which are MALT lymphomas, but few studies had explored the alterations of BCL-1, BCL-2, c-MYC and p53 genes specifically for ocular MALT lymphomas. We investigated the changes to BCL-1, BCL-2, c-MYC and p53 genes in these lymphomas for Taiwanese patients. Clonal rearrangement for immunoglobulin heavy-chain (IgH), BCL-1, BCL-2, c-MYC and p53 genes was examined for 16 cases of ocular MALT lymphoma. Restriction-length polymorphism and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) of the DNA, corresponding to exons 5 through 9, followed by DNA sequencing, were utilized to analyze the possible mutations of the p53 gene for these tumors. Thirteen of the cases revealed rearranged IgH genes using Southern blotting or PCR. No rearrangement of BCL-1, BCL-2, c-MYC or p53 genes was discovered, with point mutation of the p53 gene in one case. As for other types of MALT lymphomas, BCL-1, BCL-2 and c-MYC genes are not implicated in the pathogenesis of the ocular sub-group. Although alteration of the p53 gene is rare for low-grade ocular MALT lymphoma, its role in disease progression merits further research.

Adolescent↗

Involvement of focal adhesion kinase in hepatocyte growth factor-induced scatter of Madin-Darby canine kidney cells.

Focal adhesion kinase (FAK) has been implicated to play a critical role in integrin-mediated control of cell behavior. However, it is unclear whether FAK also participates in the regulation of growth factor-elicited cellular functions. In this study, we have demonstrated that although overexpression of FAK in Madin-Dardy canine kidney cells did not alter their growth property or ability to form tubules within collagen gel upon hepatocyte growth factor (HGF) stimulation, it apparently enhanced HGF-induced cell scattering. This enhancement was largely because of an increase in the third phase (i.e. cell migration) of cell scattering rather than the first two phases (i.e. cell spreading and cell-cell dissociation). Conversely, the expression of FAK-related nonkinase significantly ( approximately 60%) inhibited HGF-induced cell migration. Moreover, we have found that the effect of FAK on promoting HGF-induced cell motility was greatly dependent on cell-matrix interactions. We showed that HGF treatment selectively increased the expression of integrins alpha(2) and, to a lesser extent, alpha(3) in Madin-Dardy canine kidney cells and that a monoclonal antibody against integrin alpha(2) efficiently blocked HGF-enhanced cell migration on collagen. In our efforts to determine the mechanism by which FAK promotes HGF-induced cell migration, we found that FAK mutants deficient in phosphatidylinositol 3-kinase or p130(Cas) binding failed to promote HGF-induced cell migration. Interestingly, cells expressing a FAK mutant defective in Grb2 binding exhibited a rate of migration approximately 50% lower than that of cells expressing wild type FAK in response to HGF stimulation. Taken together, our results suggest a link between HGF-increased integrin expression, FAK activation, and enhanced cell motility and implicate a role for FAK in the facilitation of growth factor-induced cell motility.

Adaptor Proteins, Signal Transducing↗

HOXB7 overexpression promotes differentiation of C3H10T1/2 cells to smooth muscle cells.

The presence of immature smooth muscle cells and ectopic tissues such as fully-formed bone in atherosclerotic lesions, may result from recapitulation of embryonic mechanisms in the artery wall. We hypothesized that expression of homeobox genes is triggered in atherogenesis and that these regulate proliferation and differentiation of multipotential progenitor cells along one or more specific lineages. We identified expression of the homeobox gene HOXB7 in clones of bovine aortic medial cells previously shown to be multipotent. HOXB7 was subsequently detected in human atherosclerotic plaques by RT-PCR and in situ hybridization. Expression was localized to areas adjacent to calcification and scattered in media and neointima, which may be reflective of a role in either osteoblastic or smooth muscle cell differentiation. To differentiate between these possibilities, we overexpressed HOXB7 in C3H10T1/2 cells, a multipotent cell line able to differentiate into vascular smooth muscle cells (SMC), as well as osteogenic and chondrogenic lineages. Results showed that overexpression of HOXB7 increased proliferation 3.5-fold, and induced an SMC-like cell morphology. In addition, expression of the early SMC markers calponin and SM22alpha increased 4-fold and 3-fold respectively by semi-quantitative RT-PCR. Expression of the intermediate SMC marker smooth muscle myosin heavy chain (SM-MHC) did not change. No increase in osteogenic or chondrogenic differentiation was detected, neither in the C3H10T1/2 cells nor in M2 cells, a bone marrow stromal cell line used to confirm this result. These findings suggest that HOXB7 plays a role in expansion of immature cell populations or dedifferentiation of mature cells.

Amino Acid Sequence↗

Prospective assessment of pituitary size and shape on MR imaging after suppressive hormonal therapy in central precocious puberty.

OBJECTIVE: The diagnostic significance of an enlarged pituitary gland regarding both shape and size parameters on MR imaging has previously been demonstrated in children with central precocious puberty. This study was designed to assess changes in these parameters following successful suppressive therapy of central precocious puberty with the gonadotropin-releasing hormone (GnRH) analogue. MATERIALS AND METHODS: Twelve girls (mean age 7.3 years) with central precocious puberty were prospectively enrolled in our study protocol. Sagittal and coronal MR images of the pituitary region were obtained in all patients before treatment and after at least 6 months of GnRH analogue therapy (mean 18.0 months). Parameters measured included pituitary gland height, length, width, sagittal cross-sectional area, and volume. RESULTS: All patients had excellent clinical response to treatment with arrest of secondary sexual development, normalization of serum estradiol levels, and complete obliteration of the LH response to diagnostic GnRH stimulation. No significant change occurred in any pituitary size or shape parameter following GnRH analogue therapy. CONCLUSION: Favorable clinical response to GnRH analogue therapy in central precocious puberty is not accompanied by significant a change in pituitary gland size and shape.

Antineoplastic Agents, Hormonal↗

Lack of mutations of BCL6 and BCL10 genes in mucosa-associated lymphoid tissue lymphomas of the orbital adnexa.

Knowledge regarding the molecular pathogenesis and progression of mucosa-associated lymphoid tissue (MALT) lymphomas of ocular adnexa is limited. Eleven cases of ocular MALT lymphoma were analyzed by clonal rearrangement of antigen receptor genes using Southern blot hybridization. Polymerase chain reaction-single stranded conformational polymorphism analysis and DNA sequencing was utilized to analyze the mutations of BCL6 and BCL10 genes. Clonal rearrangement of immunoglobulin heavy genes was found in all 11 patients. No point mutation was found in BCL6 or BCL10 genes in any of the samples analyzed. We suggest that mutations of BCL6 and BCL10 genes are rare in low-grade MALT lymphoma of ocular adnexa and are unlikely to be involved in the pathogenesis of the disease. But the role of alterations of both BCL6 and BCL10 genes in the disease progression of low-grade MALT lymphoma require additional study.

Adaptor Proteins, Signal Transducing↗

Results of intraoperative mitomycin C application in dacryocystorhinostomy.

AIMS: To evaluate the long term results of intraoperative mitomycin C application in dacryocystorhinostomy (DCR) surgery compared with results of the conventional procedure. METHODS: In this prospective randomised controlled study, a total of 88 eyes diagnosed with acquired nasolacrimal duct obstruction were randomly divided into a conventional DCR group and a mitomycin C group in which mitomycin C was used during DCR surgery. The surgical procedures in both groups were exactly the same, except that in the patients in the mitomycin C group, a piece of neurosurgical cottonoid soaked with 0.2 mg/ml mitomycin C was applied to the osteotomy site for 30 minutes. The results of the DCR surgeries were evaluated by objective findings such as irrigation and the height of tear meniscus and subjective symptoms by asking patients the condition of tearing improvement. RESULTS: Among the 44 eyes in the mitomycin C group, 95.5% of patients remained totally symptom free after 10 months of follow up; while in the conventional group, 70.5% of patients were reported to be symptom free and 18% of patients to have an improvement in their symptoms. There was a significant difference between these two groups. As far as objective findings were concerned, there were 41 eyes in the mitomycin C group classified as having a normal and one eye with moderate tear meniscus level, compared with 32 eyes and seven eyes, respectively, in the conventional group. There was also a significant difference between these two groups. The non-patency rate in the mitomycin C group is 4.5% compared with 11.4% in the conventional group. There were no complications such as abnormal nasal bleeding, mucosal necrosis, or infection except one patient with delayed wound healing. CONCLUSIONS: Intraoperative mitomycin C application is effective in increasing the success rate of DCR surgery in standard nasolacrimal duct obstruction, and no significant complications resulted from its use.

Dacryocystorhinostomy↗

Ectopic lacrimal gland cyst of the orbit.

Lacrimal duct cysts are not common. It is extremely rare when a lacrimal duct cyst and an ectopic lacrimal gland develop in the orbital cavity. A unique case of an ectopic lacrimal gland cyst of the orbit is presented. A 33-year-old man had a palpable mass above the inferior medial orbital rim for nearly two years. An ocular examination was normal except for a movable, firm mass found in the anterior nasal inferior orbit of the right eye. An echogram revealed a homogeneous, hypoechoic cystic mass. Computed tomography of the orbit showed a well-encapsulated lesion in the lower orbit of the right eye near the inferior rectus muscle, without bony erosion. A tense, thin-walled, clear fluid-filled cyst measuring 15 x 12 x 13 mm in size was completely enucleated without rupture by anterior orbitotomy. Pathologic examination disclosed a small nest of normal gland tissue surrounded by a cystic lesion lined with two layers of lacrimal duct epithelium cells. No recurrent signs were noticed during a 12-month period of follow-up.

Adult↗

Calcified schwannoma of the orbit and differential diagnosis of orbital calcification.

Calcified schwannoma of the orbit is rarely reported in the world literature. A 38-year-old Chinese male presented with a 5-year history of slow progressive left-sided axial proptosis. A smooth, retrobulbar and intracornal mass with central calcification and high internal reflectivity was found on computed tomography and sonographic study. From the clinical and radiologic features, the presumptive diagnosis of orbital cavernous hemangioma or meningioma was made and orbitotomy with tumor exicision was performed. Tumor excision revealed the rare diagnosis of calcified schwannoma. The differential diagnoses of a calcified orbital mass and the radiologic and clinical findings of the calcified schwannoma are described and discussed.

Adult↗

Requirement of phosphatidylinositol 3-kinase in focal adhesion kinase-promoted cell migration.

We have previously shown that overexpression of focal adhesion kinase (FAK) in Chinese hamster ovary (CHO) cells promoted their migration on fibronectin. This effect was dependent on the phosphorylation of FAK at Tyr-397. This residue was known to serve as a binding site for both Src and phosphatidylinositol 3-kinase (PI3K), implying that either one or both are required for FAK to promote cell migration. In this study, we have examined the role of PI3K in FAK-promoted cell migration. We have demonstrated that the PI3K inhibitors, wortmannin and LY294002, were able to inhibit FAK-promoted migration in a dose-dependent manner. Furthermore, a FAK mutant capable of binding Src but not PI3K was generated by a substitution of Asp residue 395 with Ala. When overexpressed in CHO cells, this differential binding mutant failed to promote cell migration although its association with Src was retained. Together, these results strongly suggest that PI3K binding is required for FAK to promote cell migration and that the binding of Src and p130(Cas) to FAK may not be sufficient for this event.

Amino Acid Sequence↗

A survey of post-discharge side effects of conscious sedation using chloral hydrate in pediatric CT and MR imaging.

BACKGROUND: Limited information is available on post-discharge side effects of chloral hydrate sedation in pediatric imaging. OBJECTIVE: To prospectively study the post-discharge side effects of chloral hydrate sedation in pediatric CT and MR imaging. MATERIALS AND METHODS: A total of 119 children undergoing CT and MRI were sedated using chloral hydrate with 89 % success (mean initial dose, 72 mg/kg body weight) and 98 % success after augmentation (mean total, 78 mg/kg body weight). The frequency of each post-discharge side effect was correlated with other side effects and 12 patient/technical parameters. RESULTS: The survey was completed in 80 children. Sleepiness lasted for > 4 h in 28 %. Unsteadiness occurred in 68 % and hyperactivity in 29 %. Appetite became poor in 14 % and vomiting occurred in 15 %. Normal activity was resumed after > 4 h in 54 %. Sleep deprivation did not result in increased success or earlier onset of sedation and might be associated with hyperactivity. A higher dose did not result in an increased success rate or earlier onset of sedation within the dose range used in this study. CONCLUSION: Data on the post-discharge side effects of chloral hydrate sedation will be useful to radiologists, technologists, and nurses explaining to parents about sedation using this agent.

Child↗

Delayed-onset of Pseudomonas infection in a hydroxyapatite orbital implant: a case report.

Hydroxyapatite (HA) orbital implant, a multiple porous coralloid-like material, is frequently used in orbital reconstruction after enucleation or evisceration surgery. HA implants contain multiple interconnected pores in which rich fibrovascular tissue ingrowth could theoretically help to resist infection. Infection of hydroxyapatite implants are rare. Most HA implant infections occur before complete vascularization. We present this first case in Taiwan of delayed-onset Pseudomonas infection five years after receiving the HA implant. There was not much improvement after intensive medications, so removal of the implant was finally performed. The pathology study disclosed diffuse inflammatory cell infiltration in the whole implant with a necrotic central core. Rich fibrovascular ingrowth was also noted. Once a porous HA implant is infected, the infection is difficult to control and becomes more severe due to the dead space of the interconnected pores. Removal of the implant seems to be the only successful treatment modality.

Adult↗

The use of rectus abdominis sheath for wrapping of the hydroxyapatite orbital implants.

Because of the decreasing availability of whole eye donation, the source of banked sclera is becoming less available. We used autogenous Rectus abdominis sheath (RAS) as an alternative to banked sclera in wrapping the hydroxyapatite (HA)orbital implant. Five anophthalmic patients were included in this study from July 1994 to December 1997. Identical surgical methods were used in every case. The average follow-up time was 18.4 months. The motility associated with sheath-wrapped HA implants was excellent and good vascular ingrowth was found in each patient during peg drilling. The complications are minimal in all the cases. Use of RAS as wrapping material for HA orbital implant has promising results. The RAS served as a practical substitute for banked donor sclera.

Abdominal Muscles↗