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Guan-Yu Chen

Publications and source records attributed to Guan-Yu Chen.

8 recordsLinked to original sources
PubMed2005

Highly efficient red-electrophosphorescent devices based on polyfluorene copolymers containing charge-transporting pendant units.

We have systematically examined the photoluminescence (PL) and electroluminescence (EL) behavior of blends comprising two efficient red phosphors doped, respectively, into the blue-emitting polyfluorene derivatives PF-TPA-OXD and PF-OXD. The host polymers, which contain both hole- and electron-transporting or merely electron-transporting side chains, are capable of facilitating charge injection and transport. After determining the HOMO and LUMO energy levels of these materials, we were able to match the dopant with its most suitable host to achieve the direct formation and confinement of an exciton at the dopant. This configuration also leads to a reduction in the electrical excitation of the host polymer, which in turn decreases the degree of exciton loss arising from nonradiative decay of the host triplet. Using this approach, we were able to realize the production of high-performance red-electrophosphorescent devices. For Os(fppz)-doped devices, we obtain a balanced charge recombination in conjunction with higher current and luminance when using PF-TPA-OXD as the host matrix; this device reached a maximum external quantum efficiency of 8.37% with a peak brightness of 16 720 cd/m2. The absence of charge-transporting pendant units, i.e., the device fabricated from poly[9,9-dioctylfluorene-2,7-diyl] (POF), led, however, to relatively poor electroluminescence characteristics (5.81% and 2144 cd/m2).

Journal Article↗
PubMed2005

Narrow-band UVB treatment of vitiligo in Chinese.

Narrow-band ultraviolet B (NBUVB) phototherapy has recently been reported to be an effective and safe treatment modality for vitiligo. In the present report, we evaluated the efficacy and safety of NBUVB therapy for vitiligo in Chinese patients. Seventy-two vitiligo patients treated from 2000 to 2003, were included retrospectively (male: female=33:39, mean age: 38.5). Among them, 61 were non-segmental type and 11 the segmental type. Treatments were given two to three times a week for a maximum period of one year with an initial dose of 0.2 J/cm2 and a 0-20% increment each session (mean accumulation dose: 155.3 J/cm2). Computer image analysis by Supervise classification was used to estimate the area of vitiligo involvement before and after treatment. An excellent response (75-100% area of repigmentation) was obtained in 9 patients (12.5%) and a good response (50-75%) in 24 (33.3%), a moderate response (25-50%) in 20 (27.8%), and a poor response (0-25%) in 19 (26.4%). In summary, 45.8% of our patients had more than 50% repigmentation. Burns were a side effect in 5 patients (7%) and transient erythema with itching or xerosis was noted in 5 patients (7%). These results indicate that NBUVB phototherapy is an effective and safe treatment choice for generalized vitiligo.

Adult↗
PubMed2005

Mild cutaneous manifestation in two young women with extraordinary hyperandrogenemia.

Hyperandrogenism with hyperandrogenemia should be considered in those with severe acne of sudden onset or conspicuous male-pattern baldness with hairline recession, although the majority of female patients with acne or androgenetic alopecia possess no endocrine disorder. Herein we describe on the contrary 2 young women with primary amenorrhea displaying prominent hyperandrogenemia but subtle cutaneous manifestation. The first one presenting vertical alopecia had an elevated level of serum dehydroepiandrosterone sulfate (>800 microg/dl) and was suspected to be a case of late-onset, non-classical adrenal hyperplasia. The second case with mild acne had a soaring serum level of total testosterone >9,000 ng/dl derived from an androgen-secreting adrenal adenoma overexpressing steroidogenic acute regulatory protein, P450 side-chain cleavage enzyme and aromatase. A careful patient history and a complete physical examination are mandatory in each individual female case with acne or alopecia. The possibility of adrenal tumor should be explored in patients with escalated circulating testosterone.

Acne Vulgaris↗
PubMed2004

Patients with a large prostate show a higher prevalence of androgenetic alopecia.

Androgenetic alopecia (AGA) and benign prostatic hyperplasia (BPH) are both androgen-dependent disorders, displaying in situ high levels of dihydrotestosterone with a good therapeutic response to finasteride. Embryological development of both the hair follicle and the prostate depends on mesenchymal-epithelial interaction, which is influenced by the expression of type 2 5alpha-reductase. The aim of this study was to elucidate the association between the size of the prostate gland and the prevalence and severity of AGA. A total of 46 patients age between 56 and 87 years were retrospectively recruited. They fulfilling the clinical diagnosis of BPH defined as (1) prostate volume > 30 cm3, measured by transrectal ultrasound, (2) maximal urine flow rate < 15 ml/s and mean urine flow rate < 10 ml/s, and (3) prostate serum albumin < 10 ng/ml. The control group comprised 34 patients aged between 49 and 81 years with urogenital infection, cystitis or urolithiasis. The expression and severity of AGA were evaluated by dermatologists using modified Norwood/Hamilton classification. Patients with a prostate volume > 30 cm3 had a higher prevalence of AGA than patients with a smaller prostate (< 30 cm3) (83.3% vs 61.3%; P < 0.05). The prostate size, however, did not correlate with the severity of AGA in either group or in the whole patient group. The prevalence of AGA was not significantly different in patients with or without BPH (85.7% vs 70.6%). The prostate was slightly larger among patients with AGA than among those without AGA (mean+/-SD 42.7+/-17.4 vs 35.4+/-14.9 cm3), but this was not statistically significant. There was no significant correlation between the age of onset of AGA and the development of BPH. Our results suggest that a larger prostate is associated with a higher prevalence of AGA. It remains to be seen if long-term use of finasteride in AGA patients will prophylactically lower the incidence of BPH.

Aged↗
PubMedDate not supplied

Combination of massive mucinosis, dermatomyositis, pyoderma gangrenosum-like ulcer, bullae and fatal intestinal vasculopathy in a young female.

Cutaneous mucinosis secondary to autoimmune collagen vascular disease is well recognized, but manifestation as cellulitis-like massive cutaneous mucinosis preceding dermatomyositis is unusual. Here we report a 21-year-old Taiwanese woman with a large, rapid onset, painful erythematous, edematous plaque, which histopathologically revealed septal panniculitis with fat necrosis and massive mucin deposition. Incapacitated muscle weakness of proximal extremities, generalized edema, heliotrope erythema, and Gottron's papules developed in a short period of time with high titers of serum muscle enzyme. Serological titers of ANA, anti-dsDNA, anti-ENA panels, and erythrocyte sedimentation rate, however, all showed unremarkable results. Diagnosis of dermatomyositis was confirmed by electromyographic findings of myopathy. As the disease progressed, large, deep cutaneous ulceration and vesiculobullous lesions also developed. In spite of aggressive treatment, the patient died 9 months after the disease onset, probably due to the complication of gastrointestinal ischemia and perforation.

Adult↗
PubMedDate not supplied

Higher body mass index is a significant risk factor for acne formation in schoolchildren.

Obesity is frequently accompanied by peripheral hyperandrogenism, which may be associated with increased sebum production and the development of severe acne. Body mass index (BMI) is one of the most accurate ways to measure and determine obesity. The aim of the present study was to study the correlation between obesity and the point prevalence and patterns of acne in schoolchildren. A total of 3,274 children (aged 6-11 years) from Magong Township were examined by two board-certified dermatologists. The acne prevalence was 7.3%, with more girls affected than boys (ratio = 1.5). Comedones were more commonly observed than inflammatory acne (10.4% vs. 6.9%). The mean of BMI in non-acne students (18.2 +/- 3.4) was significantly lower than that in acne subjects (19.5 +/- 3.7), without gender difference. Overall schoolchildren with a BMI < 18.5 had less prevalence rate of acne, especially the inflammatory lesions, while those with a BMI-for-age > or = 95% had a significantly higher rate of acne development.

Acne Vulgaris↗