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Chih-Chao Yang

Publications and source records attributed to Chih-Chao Yang.

16 recordsLinked to original sources
PubMed2006

Fabrication of a polymeric vertical microlens with the dip method.

We have investigated a process based on the dip method to fabricate a polymeric vertical microlens (PVM). After the primary dip step, the PVM is formed by hanging the liquid SU-8 on a wall in virtue of the strong adhesive force and liquid cohesion. The microlens is then baked and exposed in ultraviolet light to further cross-link the negative photoresist SU-8 to enhance thermal stability and reliability. According to the experimental results, the radius of curvature of the fabricated vertical microlens varies from 120.8 to 34.2 microm, which relates to the dip depth or the thickness of the dipped pool. To characterize the PVM, an edge-emitting laser diode (lambda=1.31 microm) is then bonded onto the optical bench and a detector is utilized to observe the beam divergence with and without the lens insertion. Compared with an angle of 40.8 degrees without the microlens, the beam passing through a suitable PVM shows a vertical far-field angle of 3.32 degrees. Furthermore, the lens efficiency, approximately 83.4%, is also specified by the measurements.

Journal Article↗
PubMed2006

The spectrum of WRN mutations in Werner syndrome patients.

The International Registry of Werner syndrome (www.wernersyndrome.org) has been providing molecular diagnosis of the Werner syndrome (WS) for the past decade. The present communication summarizes, from among 99 WS subjects, the spectrum of 50 distinct mutations discovered by our group and by others since the WRN gene (also called RECQL2 or REQ3) was first cloned in 1996; 25 of these have not previously been published. All WRN mutations reported thus far have resulted in the elimination of the nuclear localization signal at the C-terminus of the protein, precluding functional interactions in the nucleus; thus, all could be classified as null mutations. We now report two new mutations in the N-terminus that result in instability of the WRN protein. Clinical data confirm that the most penetrant phenotype is bilateral ocular cataracts. Other cardinal signs were seen in more than 95% of the cases. The median age of death, previously reported to be in the range of 46-48 years, is 54 years. Lymphoblastoid cell lines (LCLs) have been cryopreserved from the majority of our index cases, including material from nuclear pedigrees. These, as well as inducible and complemented hTERT (catalytic subunit of human telomerase) immortalized skin fibroblast cell lines are available to qualified investigators.

Adult↗
PubMed2006

Identification of forty-five novel and twenty-three known NF1 mutations in Chinese patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1), characterized by skin neurofibromas and an excess of café-au-lait spots, is due to mutations in the neurofibromin (NF1) gene. Identifying the genetic defect in individuals with the disease represents a significant challenge because the gene is extremely large with a high incidence of sporadic mutations across the entire gene ranging from single nucleotide substitutes to large deletions. In the present study, we have used a combination of techniques (heteroduplex analysis, sequencing, loss of heterozygosity and quantification of gene dosage) to define the genetic defect in 68 individuals from a cohort of 107 NF1 Taiwanese patients of Chinese origin. Fifty-eight were initially identified using heteroduplex analytical techniques and confirmed by sequence analysis. A further five were identified by direct sequence analysis alone. The reminders were shown to carry large deletions in the NF1 gene by demonstrating loss of heterozygosity that was confirmed by gene dosage measurements using quantitative-PCR techniques. Mis-sense, non-sense, frame-shift or splice-site mutations were identified across the entire gene of which the majority (45/68) were novel in nature. The detection rate with the various analytical techniques and the types of mutation detected are consistent with published data involving both individuals and large cohort studies from other ethnic backgrounds.

Adolescent↗
PubMed2006

Multiple sclerosis with childhood onset: report of 21 cases in Taiwan.

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system. However, the clinical features of childhood-onset multiple sclerosis in Asia have been rarely reported. This report presents our experience in 21 patients with multiple sclerosis (15 females, 6 males, mean age 12.4 +/- 4.5 years) in Taiwan with the onset age before 18. The most common presenting symptoms were limb weakness (62%) and visual disturbance (43%). Poly-symptomatic presentations were found in 16 (76%) patients. Magnetic resonance imaging demonstrated basal ganglion involvement in 33.3% of the patients. Neuroimaging and neurophysiologic evaluations revealed optic nerve involvement in 13 (62%) patients. Only one child had the optico-spinal form. Eighteen (86%) patients had a relapsing remission course, whereas three (14%) patients had secondary progressive course. Three (14%) patients initially diagnosed with acute disseminated encephalomyelitis developed multiple sclerosis after 4 months, 2 years, and 6 years, respectively. In conclusion, childhood multiple sclerosis in Taiwan is frequently poly-symptomatic, and is characterized by a higher ratio of optic nerve and basal ganglion involvement. However, the optico-spinal form of multiple sclerosis occurs rarely in children in Taiwan. Our experience suggests that the chance of relapsing should not be overlooked in patients presenting with clinical and neuroimaging findings suggestive of acute disseminated encephalomyelitis.

Adolescent↗
PubMed2006

Homozygous SLC25A13 mutation in a Taiwanese patient with adult-onset citrullinemia complicated with steatosis and hepatocellular carcinoma.

Citrullinemia is a metabolic disorder characterized by elevated plasma concentrations of citrulline and ammonia. Adult-onset citrullinemia (type II, CTLN2) has been attributed to citrin deficiency caused by mutations in the SLC25A13 gene. CTLN2 is associated with a high incidence of hepatocellular carcinoma (HCC) in Japanese. We report a 48-year-old Taiwanese man with citrullinemia, who was in good health until the age of 34 when he had repeated episodes of consciousness disturbance. Hyperammonia (201 micromol/L) was found during an episode of coma. Liver function and electrolyte levels were normal at that time. Serologic markers of viral hepatitis B and C were negative. Analysis of genomic DNA extracted from peripheral blood leukocytes showed homozygous 851del4 mutation in exon 9 of the SLC25A13 gene on chromosome 7q21.3. Fourteen years after disease onset, at the age of 48, he was admitted due to an episode of coma. Abdominal sonography and computed tomography showed a 2.5 cm tumor in the left lobe of the liver, without evidence of liver cirrhosis. Wedge resection of the tumor was performed and grade 2 HCC was diagnosed. The nontumor part of the resected specimen showed chronic persistent hepatitis with moderate steatosis. The results in this case support that both citrin deficiency and steatohepatitis may contribute to hepatocarcinogenesis.

Biopsy, Fine-Needle↗
PubMed2006

Hypercalcemia in the emergency department.

BACKGROUND: Severe hypercalcemia can be life-threatening. However, its incidence and the underlying causes in the emergency department (ED) have not been determined. In the present study, we investigated these issues and the impacts on renal function and patients' survival. METHODS: We performed a retrospective study to analyze the patients with hypercalcemia in the ED for 1 year. Serum total calcium level greater than 10.3 mg/dL was defined as hypercalcemia. RESULTS: During the study period, 321 of 4293 patients (7.5%) were found to have hypercalcemia (serum calcium 11.7 +/- 1.6 mg/dL). Most of them had mild hypercalcemia (calcium level < 12.0 g/dL, 70.7%). Malignancy (36.4%) and uremia (32.4%) were the most common underlying causes. Normal renal function was observed in only 75 (23.4%) of all patients with hypercalcemia. The total mortality rate was 23.1%, and death was associated with male gender, higher calcium level, lower hemoglobin, and malignancy (all P < 0.05). Logistic analysis found that serum calcium and hemoglobin levels were independent risk factors for mortality. CONCLUSIONS: Severe hypercalcemia is frequently and life-threatening in the ED. Therefore routine determination of serum calcium level is recommended, and immediate therapy should be initiated to treat the patients at high risk.

Adult↗
PubMed2006

Levamisole-induced multifocal inflammatory leukoencephalopathy: clinical characteristics, outcome, and impact of treatment in 31 patients.

Levamisole (LEV) has been used as an immunomodulating medication in patients with recurrent aphthous ulcers and as an adjuvant for chemotherapy. LEV, with or without 5-fluorouracil (5-FU), induces multifocal inflammatory leukoencephalopathy (MIL). We identified 31 patients with LEV-induced MIL: 7 from our institution and 24 from a MEDLINE search. Twenty-one patients (67.7%) had been treated with a combination of LEV and 5-FU, while 10 patients had been treated with LEV alone. The onset of MIL was delayed in patients who took LEV and 5-FU in combination compared with the patients treated with LEV alone (11.7 +/- 3.7 vs. 4 +/- 2.5 wk, p < 0.001). Colon cancer (67.7%) was the most common indication for LEV administration. Gait ataxia occurred in 20 (64.5%) patients, and dysphagia was noted in 16 (51.6%) patients. Imaging studies revealed periventricular enhancement in 17 (54.8%) patients and supratentorial lesions in 16 (51.6%) patients. Cerebrospinal fluid studies showed lymphocytic pleocytosis in 10 of 21 (47.6%) patients. Early diagnosis of MIL and discontinuation of LEV is essential, yielding good recovery in most cases. Treatment with corticosteroids and/or intravenous immunoglobulin may be needed for this serious inflammatory encephalopathy. Twenty-nine patients exhibited improved clinical status and imaging findings after initial steroid or immunoglobulin treatment. Plasmapheresis may be an alternative regimen for patients with steroid resistance.

Adult↗
PubMed2005

IgM-anticardiolipin antibody and vascular access thrombosis in chronic hemodialysis patients.

AIM: Vascular access failure is a major cause of morbidity in chronic hemodialysis (HD) patients. Elevated immunoglobulin-M anticardiolipin antibody (IgM-aCL) titer is associated with stenosis of vascular access in HD patients. The clinical significance of elevated IgM-aCL titer relative to recurrent vascular access thrombosis (VAT) in patients with HD is less clear. However, little information has been available until now about the clinical influence of elevated IgM-aCL titer with recurrent VAT in HD patients from Western countries, and no report exists for Taiwan. This study attempted to determine whether elevated IgM-aCL titer was associated with recurrent VAT in HD patients. METHODS: This study enrolled 483 patients undergoing HD. IgM-aCL titer and hepatitis C marker were measured for all subjects. RESULTS: Elevated IgM-aCL titer was present in 17.4% (84/483) of patients. There was no association recurrent VAT between elevated and normal IgM-aCL titers (P=0.90). Presence of hepatitis C had significant differences between elevated and normal IgM-aCL titers (P=0.027). CONCLUSIONS: We found no significant differences in recurrent VAT between elevated and normal IgM-aCL titer in chronic HD patients. Our results suggest recurrent VAT of synthetic or native fistula may not be caused by elevated IgM-aCL titer in these patients. Presence of hepatitis C may be a cofactor.

Antibodies, Anticardiolipin↗
PubMed2005

[Diagnosis of multiple sclerosis].

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system. The disorder displays marked clinical heterogeneity. In certain cases, making diagnosis can be challenging. Diagnosis of MS has become more important in the era of treatments that change the natural history of the disease. Several general diagnostic principles are useful to guide the diagnostic approach to MS. Clinically, MS requires neurological problems associated with objective abnormalities. Certain basic principles, first outlined by Schumacher et al. (1965) are still pertinent. Poser et al. (1983) have further modified the criteria using data derived from clinical evaluation and laboratory studies, including cerebrospinal fluid analysis, evoked potentials, and imaging studies. Poser criteria have long been familial for most neurologists. The most recent addition to our diagnostic armamentarium are the McDonald criteria (2001), which are the first attempt to incorporate standardized MRI criteria into the MS diagnostic process. The most innovative use of MRI to support an MS diagnosis is dissemination of demyelination can be demonstrated by MRI alone, in the absence of any new clinical attacks. Diagnosing MS by such sensitive MRI criteria will occur more quickly than waiting for a second clinical event. This has added some sensitivity, some controversy, and a lot of confusion. The application of the new criteria on Asian MS patients remains to be validated. Each of the criteria will be discussed, with major emphasis on the McDonald criteria.

Diagnosis, Differential↗
PubMed2004

Dysphagia as a manifestation of thyrotoxicosis: report of three cases and literature review.

Myopathy is frequently associated with thyrotoxicosis. Skeletal muscles are predominantly involved in thyrotoxic myopathy, but dysphagia is extremely rare. We report three cases of thyrotoxicosis with dysphagia and review of the literature of the past 30 years. Most of these patients had antecedent muscle weakness before the onset of dysphagia although some suffered from a sudden onset of bulbar palsy. Either a myopathic or neuropathic pattern was found on electromyography. The incidence of oropharyngeal dysphagia was higher than that of esophageal motility dysfunction. Aspiration pneumonia occurred more accompanied by oropharyngeal dysphagia. The swallowing disorder could be resolved completely within 3 weeks after treatment for thyrotoxicosis. In light of these clinical experiences, early intensive treatment that includes antithyroid agent, beta-blocker, and Lugol solution may be necessary.

Adult↗
PubMed2004

Expanded-spectrum beta-lactamase producing Klebsiella pneumoniae-related peritonitis in a patient on peritoneal dialysis.

While hospitalized for pneumonia with ventilator-dependent respiratory failure, a 45-year-old man on continuous ambulatory peritoneal dialysis (CAPD) had nosocomial peritonitis secondary to infection by expanded spectrum beta-lactamase producing Klebsiella pneumoniae (ESBL-Kp). He was treated successfully with a 3-week course of intraperitoneal (IP) flomoxef therapy without subsequent relapse, loss of peritoneal catheter, ultrafiltration failure, or dialysis inadequacy. The International Consensus Panel recommends IP ceftazidime as the treatment of choice for CAPD patients suffering Klebsiella species-related peritonitis. However, the most appropriate form of IP antibiotic therapy and the outcomes for expanded-spectrum beta-lactamase (ESBL)-producing bacteria-related peritonitis for CAPD patients have not been established yet. Further, the ability to correctly report minimal inhibitory concentrations (MICs) of ceftazidime for ESBL bacteria in the resistant range varies between laboratories, making the diagnosis of ESBL-Kp-related CAPD peritonitis more complex and difficult. Thus, it appears reasonable to suggest that its incidence is probably underestimated and its significance ignored. The authors suggest that a 3-week IP treatment with flomoxef, a synthesized oxacephem, with loading and maintenance doses of 250 and 125 mg/L, respectively, is effective and safe for ESBL-Kp-related peritonitis in these patients. ESBL producing bacterial infection should be considered as a possible cause of overt CAPD-related peritonitis. Early detection of ESBLB pathogens and institution of effective antibiotic treatment may improve the prognosis.

Bacterial Proteins↗
PubMed2003

Efficacy, safety, and tolerability of pramipexole in untreated and levodopa-treated patients with Parkinson's disease.

OBJECTIVE: To evaluate the efficacy and safety of the non-ergot dopamine agonist pramipexole in untreated and levodopa-treated Chinese patients with early or advanced Parkinson's disease. METHODS: This randomized, double-blind, placebo-controlled, parallel-group study, which was conducted in Hong Kong and Taiwan, comprised a screening period of at least 1 week, a dose-escalation period of 7 weeks, and a maintenance period of 8 weeks (total duration of treatment: 15 weeks). During the dose-escalation period, the dose of pramipexole (or number of placebo tablets) was escalated in a blinded fashion according to a predetermined schedule to the optimum tolerated dose of pramipexole, administered three times a day (minimum dose=0.375 mg/day; maximum dose=4.5 mg/day). This dose was then maintained for the duration of the maintenance period. Efficacy was primarily assessed by the Unified Parkinson's Disease Rating Scale (UPDRS). Safety and tolerability were evaluated by treatment-emergent adverse event reports, clinical laboratory test results (blood chemistry, hematology, and urinalysis), vital signs, and electrocardiograms. RESULTS: Pramipexole was significantly more effective than placebo in reducing the total scores of the UPDRS Part II, Part III, and Parts II and III combined. Approximately 70% of both the placebo- and pramipexole-treated patients evaluated in this analysis were on levodopa. Regardless of levodopa use, the mean UPDRS total scores showed a consistently greater improvement in pramipexole patients than in placebo patients. Mean scores for pramipexole patients not on levodopa showed a greater improvement than did pramipexole patients on levodopa. The mean improvement for the pramipexole/no levodopa group relative to the placebo/no levodopa group at week 15 was 10.93 points (i.e., -14.43 points minus -3.50 points). The mean improvement for the pramipexole/levodopa group relative to the placebo/levodopa group at week 15 was 9.04 points (i.e., -10.26 points minus -1.22 points). Pramipexole was also superior to placebo as measured by improvement in the modified Hoehn and Yahr Scale and a reduction in the number of "off" hours for patients on concomitant levodopa therapy. CONCLUSIONS: Pramipexole is an effective and well-tolerated therapy, with or without concomitant levodopa, for Chinese patients with Parkinson's disease.

Adult↗
PubMed2002

Preparation of controlled release ophthalmic drops, for glaucoma therapy using thermosensitive poly-N-isopropylacrylamide.

In this study, controlled release ophthalmic agents for glaucoma therapy were developed based on the thermosensitivity of poly-N-isopropylacrylamide (PNIPAAm). The clear solution of PNIPAAm was known to undergo phase transition when the temperature was raised from the room temperature to about 32 degrees C. The drug was entrapped in the tangled polymer chains or encapsulated within the crosslinked polymer hydrogel at room temperature, and released progressively after topical application (i.e., at a higher temperature). Linear PNIPAAm and crosslinked PNIAAm nanoparticles containing epinephrine were prepared. The drug release rate and cytotoxicity were investigated in vitro. Ophthalmic formulations based on either linear PNIPAAm or the mixture of linear PNIPAAm and crosslinked PNIPAAm nanoparticles were administered to rabbits and the intraocular pressure (IOP)-lowering effect was evaluated. The decreased pressure response of the formulation based on linear PNIPAAm lasted six-fold longer than that of the conventional eye drop. Furthermore, for formulation based on the mixture of linear PNIPAAm and crosslinked nanoparticles, the pressure-lowering effect lasted eight times longer. These results suggest the use of thermosensitive polymer solutions or hydrogels is potential in controlled release antiglaucoma ophthalmic drugs.

Acrylic Resins↗
PubMed2002

pipsqueak encodes a factor essential for sequence-specific targeting of a polycomb group protein complex.

The Polycomb (Pc) group (Pc-G) of repressors is essential for transcriptional silencing of homeotic genes that determine the axial development of metazoan animals. It is generally believed that the multimeric complexes formed by these proteins nucleate certain chromatin structures to silence promoter activity upon binding to Pc-G response elements (PRE). Little is known, however, about the molecular mechanism involved in sequence-specific binding of these complexes. Here, we show that an immunoaffinity-purified Pc protein complex contains a DNA binding activity specific to the (GA)n motif in a PRE from the bithoraxoid region. We found that this activity can be attributed primarily to the large protein isoform encoded by pipsqueak (psq) instead of to the well-characterized GAGA factor. The functional relevance of psq to the silencing mechanism is strongly supported by its synergistic interactions with a subset of Pc-G that cause misexpression of homeotic genes.

Animals↗
PubMedDate not supplied

Schwartz-Jampel syndrome: report of one case.

We report a case of Schwartz-Jampel syndrome in a 2-year-9-month-old Taiwanese girl and her clinical response to treatment. She had a history of generalized muscle stiffness and hypertrophy since birth. Clinical and electromyographic myotonia were noted. Other clinical features included short stature, unusual facial appearance, ophthalmoplegia, elbow joint contractures, and developmental hip dysplasia. Muscle stiffness and myotonia improved after infusion of lidocaine. She then received oral mexiletine and the symptoms significantly improved.

Child, Preschool↗