PubMed Health⌕ Search

Biomedical subjects

W P Chen

Publications and source records attributed to W P Chen.

At least 19 recordsLinked to original sources
PubMed2006

Application of explicit process of care measurement to rheumatoid arthritis: Moving from evidence to practice.

OBJECTIVE: To construct quality measures with measurement validity and meaning for clinicians. METHODS: We conducted a prospective cohort study of rates of change in disease-modifying antirheumatic drug (DMARD) and/or systemic corticosteroid drug or dose for 568 patients with rheumatoid arthritis (RA) across 6,159 clinical encounters within 12 months to examine how changes in clinical specifications change adherence. RESULTS: Rates of DMARD change were sensitive to specifications regarding the intensity of disease activity (severe or moderate), duration of specified disease activity, and length of the observation period. Over 12 months, the proportions of 377 patients with severe disease activity observed for 1-month, 2-month, and 3-month time blocks who had a change in DMARD drug or dose were 36%, 57%, and 74%, respectively. Over 12 months, a change in DMARD drug or dose was observed for 44%, 50%, and 68% of 377 patients with severe disease within 3 months, 6 months, and 12 months, respectively, of the patient meeting criteria for severe disease activity. A change in DMARD drug or dose was observed for 21%, 23%, and 34% of 149 patients with moderate disease activity within 3, 6, and 12 months, respectively, of the patient meeting criteria for moderate disease activity. CONCLUSION: Rates of pharmacologic interventions for patients with moderate and severe RA disease activity vary substantially by intensity and duration of disease activity and by duration of period for observing change. Lack of precision in explicit process criteria could substantially mislead comparisons of quality of care across comparison groups.

Adrenal Cortex Hormones↗
PubMed2004

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets.

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5 +/- 0.5% of uncoated ones to 17.9 +/- 0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9-12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g. < or = 24 h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.

Alginates↗
PubMed2001

Evidence for a large-scale remnant of subducted lithosphere beneath Fiji.

We combine spatial variations of P- and S-wave speeds, 1000 fault plane solutions, and 6600 well-determined hypocenters to investigate the nature of subducted lithosphere and deep earthquakes beneath the Tonga back-arc. We show that perplexing patterns in seismicity and fault plane solutions can be accounted for by the juxtaposition of a steep-dipping Wadati-Benioff zone and a subhorizontal remnant of slab that is no longer attached to the actively subducting lithosphere. The detached slab may be from a previous episode of subduction along the fossil Vitiaz trench about 5 to 8 million years ago. The juxtaposition of slabs retains a large amount of subducted material in the transition zone of the mantle. Such a configuration, if common in the past, would allow the preservation of a primordial component in the lower mantle.

Journal Article↗
PubMed2001

Immune reponses in human mesangial cells regulated by emodin from Polygonum hypoleucum Ohwi.

In the hope of identifying agents of therapeutic value in glomerulonephritis from Chinese herbs, we found that methanolic extracts of Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) inhibit human mesangial cells proliferation activated with interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) previously. This study was designed to identify bioactive components from P. hypoleucum Ohwi and elucidate their action mechanisms. We tested four anthraquinones emodin, emodin 1-O-beta-D-glucoside (49A), physcion (62A), and physcion 1-O-beta-D-glucoside (50A) purified from P. hypoleucum Ohwi for their effects on human mesangial cell proliferation and cytokines production in vitro. On a percentage basis, emodin had the highest suppressing activity on the human mesangial cells proliferation activated by IL-1beta and IL-6. The IC50 of emodin on human mesangial cells proliferation were 17.9+/-1.2 microM. In contrast to 49A, 50A, and 62A, emodin also decreased IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha) production in human mesangial cells activated with IL-1beta and IL-6. The IC50 of emodin on IL-1beta, IL-6 and TNF-alpha production in activated human mesangial cells were 16.6+/-1.8 microM, 8.2+/-1.3 microM, and 9.5+/-1.6 microM, respectively. Moreover, IL-1beta and TNF-alpha mRNA expression in activated human mesangial cells was impaired by emodin. The intracellular free Ca2+ concentration ([Ca2+]i) in IL-1beta and IL-6 activated human mesangial cells was decreased by emodin. It is unlikely that cytotoxicity was involved because no cell deaths were observable. We hypothesize that the inhibitory mechanisms of emodin on activated human mesangial cells proliferation may be related to the impairments of gene expression and production of cytokines and [Ca2+]i in the cells.

Calcium↗
PubMed2001

The underlying diseases and follow-up in Taiwanese children screened by urinalysis.

To date, the underlying diseases and follow-up of Taiwanese children screened by urinalysis have not been reported. The grading of urine abnormalities varied from grade A (microscopic hematuria only), grade B (light proteinuria only), grade C (light proteinuria and microscopic hematuria) to grade D (heavy proteinuria). From January 1991 to August 1998, 630 students, aged 6-15 years and with positive urinary screening, were admitted to our hospital for further evaluation. Of these, 573 students had confirmed abnormal findings, 298 were boys, 275 were girls, and 294 students received a renal biopsy and have had regular follow-up visits. This study was designed to retrospectively elucidate: (1) the relationship between grading of urine abnormality and underlying disease; (2) the relationships among hypertension, grading of urine abnormality, and underlying disease; (3) the underlying disease of low serum C3 level; and (4) to determine whether urinary screening progressively decreased the number of students with end-stage renal disease (ESRD) annually. The results show that glomerular nephritis (GN) is still one of the major causes of urinary abnormalities. The most-important secondary GN was systemic lupus erythematosus (SLE) with lupus nephritis. One-quarter of the patients fulfilled at least four of the revised American Rheumatology Association (ARA) criteria for SLE at first administration, while the others who fulfilled only two to three of the revised ARA criteria had gradually developing signs and symptoms of SLE at follow-up. The percentage of SLE patients amongst anti-nuclear antibody (ANA) positive children was 72%. Membranoproliferative GN is very rare. The distribution of hypertension was 8.2% in grade A, 10.7% in grade B, 9.7% in grade C, and 28.9% in grade D urinary abnormality. There were statistical differences between grade D and either grade A or B or C (P<0.05). Lower serum C3 levels were found only in a minority of patients, including those with SLE. In this series, focal segmental glomerular sclerosis (FSGS) and active class IV lupus nephritis patients were found early enough to receive methylprednisolone pulse plus cyclosporine A therapy. To date there have been only 2 cases (5%) of FSGS with impaired renal function, and none of the lupus nephritis patients are in the predialysis stage. In conclusion, GN is still the major cause of urinary screening abnormality. ANA study is indicated in all Chinese students with abnormal urinary screening. The correlations between the severity of proteinuria and hypertension showed more-severe proteinuria in patients with nephritis as well as in those with hypertension.

Adolescent↗
PubMed2001

Stress distribution of the foot during mid-stance to push-off in barefoot gait: a 3-D finite element analysis.

OBJECTIVE: To quantify stress distribution of the foot during mid-stance to push-off in barefoot gait using 3-D finite element analysis. DESIGN: To simulate the foot structure and facilitate later consideration of footwear. Finite element model was generated and loading condition simulating barefoot gait during mid-stance to push-off was used to quantify the stress distributions. BACKGROUND: A computational model can provide overall stress distributions of the foot subject to various loading conditions. METHODS: A preliminary 3-D finite element foot model was generated based on the computed tomography data of a male subject and the bone and soft tissue structures were modeled. Analysis was performed for loading condition simulating barefoot gait during mid-stance to push-off. RESULTS: The peak plantar pressure ranged from 374 to 1003 kPa and the peak von Mises stress in the bone ranged from 2.12 to 6.91 MPa at different instants. The plantar pressure patterns were similar to measurement result from previous literature. CONCLUSIONS: The present study provides a preliminary computational model that is capable of estimating the overall plantar pressure and bone stress distributions. It can also provide quantitative analysis for normal and pathological foot motion. RELEVANCE: This model can identify areas of increased pressure and correlate the pressure with foot pathology. Potential applications can be found in the study of foot deformities, footwear, surgical interventions. It may assist pre-treatment planning, design of pedorthotic appliances, and predict the treatment effect of foot orthosis.

Adult↗
PubMed2001

[Effects of ANSON NANOTECH on the healing of cutaneous chronic wounds].

OBJECTIVE: To observe the effects of ANSON NANOTECH on the healing of cutaneous chronic wounds. METHODS: Thirty-four cases with 44 wounds were locally treated with ANSON NANOTECH in the wounds after debridement. Among them, there were 15 cases with traumatic ulcer (23 wounds), 9 cases with pressure ulcer(11 wounds), 5 cases with diabetes ulcer, and 5 cases with radiation ulcer. The healing time of wounds was used to evaluate the treatment results. RESULTS: The healing time in all of chronic wounds were accelerated. All wounds from trauma, diabetes and pressure were healed within 4 weeks and another 2 wounds from radiation injuries were healed over 4 weeks. The healing rate within 4 weeks was 95.5%. CONCLUSION: The results indicate that ANSON NANOTECH can accelerate the healing of chronic wounds. The mechanism probably include sterilization, improvement of local microcirculation, promotion of cell growth, and so on.

Adolescent↗
PubMed2000

Cutaneous nerve degeneration induced by acrylamide in mice.

Acrylamide is a neurotoxin producing distal axonopathy. Previous studies mainly focused on large-diameter motor and sensory nerves, and the influences of acrylamide neurotoxicity on small-diameter sensory nerves in the skin remained elusive. We investigated skin innervation in mice intoxicated by acrylamide. Small-diameter sensory nerves in the skin degenerated after acrylamide intoxication. Epidermal nerve swelling was the earliest sign of acrylamide intoxication, with 29.5+/-2.4% of swollen epidermal nerves in the initial stage (P<0.001). There was a trend of progressive loss of epidermal nerves with a significantly reduced epidermal nerve density in the late stage (P<0.003). In the mean time, degenerating dermal nerves exhibited a beaded appearance. These results suggest the scenario of small-diameter cutaneous nerve degeneration in acrylamide neurotoxicity: beginning with epidermal nerve terminal swelling in the initial stage and resultant epidermal nerve depletion in the late phase.

Acrylamide↗
PubMed2000

Taxol reduces cytosolic E-cadherin and beta-catenin levels in nasopharyngeal carcinoma cell line TW-039: cross-talk between the microtubule- and actin-based cytoskeletons.

Taxol affects microtubule dynamics by promoting microtubule assembly. To obtain a better insight into possible cross-talk between the microtubule- and actin-based cytoskeletons, we studied the short-term effects of Taxol treatment on the expression of actin and the E-cadherin/catenin complex in the nasopharyngeal carcinoma cell line TW-039 using immunofluorescence, immunoprecipitation, and immunoblotting methods. Morphologic changes in actin filaments, including ventral actin clumps and perijunctional actin blebs, were seen at Taxol concentrations > or =1 microM. Levels of detergent-soluble E-cadherin fell to 53% or 58% compared to controls in cells treated, respectively, with 1 or 5 microM Taxol, while levels of detergent-soluble beta-catenin fell to 76% or 74%. Levels of the detergent-soluble pool of alpha- and gamma-catenin and the detergent-insoluble pool of the E-cadherin/catenin complex were unchanged by Taxol treatment and no significant difference was seen in the levels of adenomatous polyposis coli or glycogen synthase-3beta or tyrosine phosphorylation patterns. These results suggest that modulation of microtubule dynamics by Taxol may have effects on the expression of actin and the cytosolic E-cadherin and beta-catenin in nasopharyngeal carcinoma cells through pathways not involving the phosphorylation of beta-catenin.

Actins↗
PubMed2000

High-frequency interconversion of turbid and clear plaque strains of bacteriophage f1 and associated host cell death.

Under normal cultivation conditions, a mixture of turbid and clear plaques is often apparent in cultures of bacterial cells infected with filamentous bacteriophages. Beginning with a culture of wild-type filamentous phage f1, which itself produces turbid plaques, a clear plaque strain (c1) was isolated. From c1, the turbid plaque strain t1 was isolated; from t1, the clear plaque strain c2 was isolated; and from c2, the turbid plaque strain t2 was isolated. Each of these strains was generated with a frequency of approximately 1 x 10(-4). Although filamentous phages have been thought not to induce host cell death, both turbid and clear plaque strains of f1 killed host bacteria. Plating of bacterial cells 1 h after infection revealed that colonies produced by cells infected with either wild-type f1 or strain c2 were smaller than those derived from uninfected cells, and that colony formation by infected cells was reduced by 15% and 38%, respectively. The time course of bacterial growth revealed that, at 4 h after infection, the number of CFU per milliliter of culture of cells infected with wild-type f1 or with strain c2 was reduced by 27% and 95%, respectively, compared with that for uninfected cells. Microculture analysis also revealed that the percentages of nondividing cells in f1 or c2 infected were 19% and 52%, respectively, 4 h after infection with wild-type f1 or with strain c2; no such cells were detected in cultures of uninfected cells. Negative staining and electron microscopy showed that 20% and 61% of cells infected with wild-type f1 or with strain c2 were dead 4 h postinfection. Finally, although the rates of DNA synthesis were similar for infected and uninfected cells, the rates of RNA and protein synthesis were markedly reduced in infected cells.

Bacterial Proteins↗
PubMed1999

Age-dependent acrylamide neurotoxicity in mice: morphology, physiology, and function.

Acrylamide intoxication produces peripheral neuropathy characterized by weakness and ataxia in both humans and experimental animals. Previous studies on animals of different ages and species indicate that the longest and largest nerves are affected earlier with the major pathology in the terminal parts of axons, i.e., distal axonopathy. However, several issues have remained elusive; for example, what are the earliest pathological changes? An equally intriguing question is whether younger animals are more susceptible to acrylamide than older animals. To address these issues, we compared the vulnerability to acrylamide of 3- and 8-week-old mice. These mice were intoxicated with acrylamide in drinking water (400 ppm). The sequence of intoxication could be categorized into three stages. In the initial stage, there was no visible weakness or ataxia. The only noticeable changes were poor performance on the rota-rod test and swelling of motor nerve terminals. Obvious weakness and ataxia of hindlimbs developed gradually (here designated as the early stage). The weakness and ataxia progressed at variable speeds in mice of different ages, and eventually the forelimbs (quadriparesis) were affected in the late stage. Each stage appeared earlier in 3-week-old mice than in 8-week-old mice (7.1 +/- 1.1 vs 15.6 +/- 4.0 days, P < 0.01 for the early stage; and 15.3 +/- 2.1 vs 31.7 +/- 6.0 days, P < 0.01 for the late stage). The progression of neurological deficits was also faster in the younger mice (7.2 +/- 1.8 vs 16.3 +/- 4.2 days, P < 0.01). Pathological changes in the distal parts of motor nerves innervating hindfoot muscles were evaluated by combined cholinesterase histochemistry and immunocytochemistry for neuronal markers to demonstrate motor nerve terminals and neuromuscular junctions simultaneously. In the initial stage, there was axonal swelling in motor nerve terminals. As acrylamide intoxication continued, axonal swelling extended into junctional folds and into the intramuscular nerves, which resulted in Wallerian-like degeneration. Our results indicate that younger mice show a much higher susceptibility to acrylamide intoxication, and pathological changes precede neurological symptoms.

Acrylamide↗
PubMed1999

Blocking of cell proliferation, cytokines production and genes expression following administration of Chinese herbs in the human mesangial cells.

In the hope of identifying agents of therapeutic value in immuoglobulin A nephropathy (IgA-N), we tested crude methanol extracts of 15 Chinese herbs for their effect on human mesangial cell proliferation. The results indicated that 4 out of the 15 crude extracts inhibited human cells proliferation activated by IL-1beta and IL-6. The extracts and their median inhibitory concentrations were as follows (in microg/ml): Ludwiga octovalvis (MLS-052), 49.9 +/- 1.8; Rhus semialata (MLS-053), 31.2 +/- 1.6; Tabernaemontana divaricata (MLS-054), 50.0 +/- 2.1; Amepelopsis brevipedunculata (MLS-059), 42.9 +/- 1.1. These findings indicate that human mesangial cells were most sensitive to MLS-053 treatment. These herbs also decreased interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) production. Moreover, IL- 1beta mRNA expression was inhibited by Rhus semialata (R. semialata; MLS-053). It is unlikely that cytotoxicity was involved, because no cell deaths were observable. We hypothesize that the inhibitory mechanisms of these Chinese herbs may be related to the impairments of gene expression and production of cytokines in human mesangial cells. Plans are underway for the isolation of pure compounds from these Chinese herbs and the elucidation of their mechanisms of action.

Cell Division↗
PubMed1999

Inhibition of activated human mesangial cell proliferation by the natural product of Cordyceps sinensis (H1-A): an implication for treatment of IgA mesangial nephropathy.

Cordyceps sinensis (CS) is a parasitic fungus that has been used as a Chinese medicine for a long time in the treatment of nephritis. Today, the hypothesis about the pathogenesis of immunoglobulin A nephropathy (IgAN) is that nephritogenic IgA immune complexes (IgAIC) go to the kidney to stimulate resting mesangial cells to release cytokines and growth factors. These cytokines and growth factors cause mesangial cell proliferation and release matrix, chemical mediators that lead to the glomerular injury. However, nephritogenic IgAIC in humans is still unknown. To solve this problem previously, we established an in vitro model that showed that cultured human mesangial cells (HMC) stimulated with interleukin-1 (IL-1) plus IL-6 can cause mesangial cell proliferation, increasing production of chemical mediators and superoxide anion. An in vivo model also proved that this culture medium may lead to renal injury with hematuria and proteinuria. Therefore, to fractionate the crude components that can be used in the treatment of patients with IgAN, we cultured HMC, and then an HMC activating model with HMC incubated with IL-1 and IL-6 was established. We fractionated the crude methanolic extracts from fruiting bodies of CS with the use of this in vitro inhibition of HMC activation model as our assay method. In brief, the fruiting bodies were extracted by silica gel column chromatography. One out of 6 column fractions, F-2, significantly inhibited the HMC activation by IL-1 plus IL-6. The acute toxicity test with male Institute of Cancer Research mice showed no liver toxicity or mutagenicity. Then we established an IgAN animal model with R36A (Pneumococcal C-polysaccharide purified from Streptococcus pneumoniae) as antigen and anti-R36A IgA monoclonal antibody to form nephritogenic IgA-IC, which can induce hematuria and proteinuria in mice with IgA deposition in the mesangial area. The mice in the IgAN model fed with 1% F-2 in diet had significant reduction of hematuria and proteinuria together with histopathologic improvement. Therefore this fraction was then purified by silica gel column chromatography and high-performance liquid chromatography, which got a purified compound H1-A, which can suppress the activated HMC and alleviate IgAN (Berger's disease) with clinical and histologic improvement. These results give us a new regimen for the treatment of patients with IgAN in the future.

Adolescent↗
PubMed1999

The value of Ga-67 renal SPECT in diagnosing and monitoring complete and incomplete treatment in children with acute pyelonephritis.

PURPOSE: This study evaluated the utility of Ga-67 renal SPECT for diagnosing acute pyelonephritis (APN) in children and monitoring them. METHODS: Seventy-one children (ages 1 week to 12 years) who were thought clinically to have APN were included in the study. The disease was considered present if the patients had all of the following: fever (38.5 degrees C), pyuria (leukocyte counts/per high-power field > or = 10), and a positive result of a urinary culture or blood culture. Tc-99m DMSA, Ga-67 renal SPECT, and voiding cystourethrography were performed, with informed consent from the patients' parents, within 3 days after hospitalization. Three months after treatment, Tc-99m DMSA and Ga-67 renal SPECT were repeated in those patients who had abnormal results of the initial Ga-67 renal SPECT. RESULTS: In the diagnostic study, Ga-67 renal SPECT was superior to DMSA renal SPECT in detecting lesions (97% vs. 79%). Three children had false-negative results with Ga-67 renal SPECT. Seventeen kidneys were negative with Tc-99m DMSA but positive with Ga-67 renal SPECT. No patients had any Ga-67 uptake on post-therapy imaging. However, 32 of 107 kidneys (30%) had permanent renal scars. In these 107 kidneys, 78 (73%) were associated with high-grade vesicoureteral reflux (VUR; VUR grade > or = 3) and 29 (27%) with low-grade or no VUR. CONCLUSIONS: High-grade VUR tends to be associated more with APN than has been reported by others, probably because of an underestimation of APN by ultrasonography or DMSA. Ga-67 renal SPECT is sensitive and useful not only in diagnosis but also for monitoring and follow-up of children with clinical suspicion of APN, especially in those with equivocal results after DMSA renal SPECT studies.

Acute Disease↗
PubMed1999

Delayed irradiation effects on nasal epithelium in patients with nasopharyngeal carcinoma. An ultrastructural study.

The ostiomeatal complex is responsible for the clearance of most sinus secretions. To evaluate the delayed effects of irradiation. this study examined the infundibulum mucosa of 10 patients who developed sinusitis after receiving radiotherapy for nasopharyngeal carcinoma (NPC). Pathologic findings under the light microscope revealed an increased deposition of dense collagenous fibers in the lamina propria. The epithelial cells also transformed into a stratified arrangement and showed gradual reduction of cytoplasmic volume. Ultrastructural observations detected areas of ciliary loss, intercellular and intracellular vacuolation, and ciliary dysmorphism. Most of these pathologic findings were observed even in a patient 23 years after irradiation. The results presented herein suggest that radiotherapy may cause long-term damage to the nasal epithelium that may be responsible for the prolonged sinusitis of irradiated NPC patients.

Adult↗
PubMed1999

Intrarenal infusion of supernatant from cytokine-activated human mesangial cells may cause glomerular damage.

BACKGROUND: The pathogenesis of glomerular damage in glomerulonephritis (GN) is not fully understood. Several studies have suggested that reactive oxygen molecules play a role in renal disease. It is known that, during GN, mesangial cells are activated. In a previous study, we demonstrated that in vitro interleukin (IL)-1 plus IL-6 stimulated cultured human mesangial cell (HMC) activation to release free oxygen radicals. METHODS: In this study, we measured hydrogen peroxide (H2O2) and superoxide anion (O2-) levels after stimulation by IL-1 plus IL-6 in cultured HMCs. We then infused H2O2 directly into the left renal arteries of Sprague-Dawley rats. We also infused the culture supernatants of HMCs after stimulation by IL-1 plus IL-6 into the left renal arteries of rats. Two hours after stopping the infusion, the kidneys were removed and fixed using Carson's modified Millonig's buffer for electron microscopy. RESULTS: Both 100 microM H2O2 and supernatants of HMCs stimulated by IL-1 10 U/ml plus IL-6 1,000 U/ml caused similar glomerular damage, including blebbing and sloughing of endothelial cells, and denuded basement membrane in glomeruli. When 100 microM H2O2 or supernatants of cytokine-activated HMCs were infused into renal arteries, they caused hematuria and proteinuria. CONCLUSIONS: These results suggest that activated HMCs may secrete free radicals and cause glomerular damage.

Adolescent↗