Biomedical subjects

Chih-Hung Chang

Publications and source records attributed to Chih-Hung Chang.

36 records · Page 2Linked to original sources

PubMed2005

Effects of econazole on Ca2+ levels in and the growth of human prostate cancer PC3 cells.

1. Econazole is used clinically as an antifungal drug with many different in vitro effects. However, the effects of econazole on prostate cancer cells are unknown. The effects of econazole on intracellular Ca2+ concentrations ([Ca2+]i) in and the proliferation of human PC3 prostate cancer cells was explored in the present study using fura-2 and tetrazolium as fluorescent dyes. 2. At a concentration of 0.1 micromol/L, econazole started to increase [Ca2+]i in a concentration-dependent manner. The econazole-induced increase in [Ca2+]i was reduced by 48% by removal of extracellular Ca2+, suggesting that the econazole-induced increase in [Ca2+]i was composed of extracellular Ca2+ influx and intracellular Ca2+. 3. This econazole-induced Ca2+ influx was via an L-type Ca2+ channel-like pathway. In Ca2+-free medium, 1 micromol/L thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a monophasic increase in [Ca2+]i, after which the effect of econazole to increase [Ca2+]i was substantially inhibited. Conversely, pretreatment with 5 micromol/L econazole to deplete intracellular Ca2+ stores totally prevented thapsigargin from releasing more Ca2+. 4. The phospholipase C (PLC) inhibitor U73122 (2 micromol/L) abolished the increase in [Ca2+]i induced by 10 micromol/L ATP (a Ca2+ mobilizer that needs inositol 1,4,5-trisphosphate). 5. Overnight incubation with 1-30 micromol/L econazole inhibited proliferation of PC3 cells in a concentration-dependent manner. 6. These findings suggest that, in PC3 cells, econazole increases [Ca2+]i by stimulating Ca2+ influx into cells and Ca2+ release from the endoplasmic reticulum via a PLC-independent mechanism. Econazole is cytotoxic at submicromolar concentrations.

Antineoplastic Agents↗

PubMed2005

Biosynthesis of silicon-germanium oxide nanocomposites by the marine diatom Nitzschia frustulum.

The biomineralization capacity of the photosynthetic marine diatom Nitzschia frustulum was harnessed to fabricate Si-Ge oxide nanocomposite materials. Germanium was incorporated into the diatom cell by a two-stage cultivation process. In stage 1, the N. frustulum cell suspension was grown up to cell density of 3 x 10(6) cells/mL in 0.35 mM silicic acid within a bubble-column photobioreactor. In stage 2, when all of the soluble silicon was consumed, 0.10 mM Ge(OH)4 or a mixture of 0.020 mM Ge(OH)4 and 0.25 mM Si(OH)4 were added to Si-starved cells. The cells assimilated soluble germanium by a surge uptake mechanism. The cell mass was thermally annealed in air at 800 degrees C for 6 h to oxidize carbonaceous materials. The thermally annealed cell biomass was characterized by TEM-EDS, FT-IR, and XRD. These measurements confirmed the formation nanostructured Ge-Si oxides composed of CaSiO3 and Ca3GeO5.

Calcium Compounds↗

PubMed2005

Defining higher order dimensions of self-reported health: further evidence for a two-dimensional structure.

We illustrate a method for understanding the extent to which a pool of fairly diverse health status questions can be examined for their dimensionality, by first fitting the data to a unidimensional measurement model, then examining item fit and residual factor analysis to determine the pattern of deviations from unidimensionality. We simultaneously administered five questionnaires to 1,714 people with cancer and HIV disease and combined all responses into one analysis. Item responses were cocalibrated onto one presumed underlying construct, often referred to as health-related quality of life (HRQOL). To identify significant, higher order substructures in the data, we then conducted a factor analysis of the data residuals, revealing two definable higher order dimensions: physical well-being and mental well-being. These results agree with other research and provide direction for further studies defining these dimensions within an item response theory (IRT) tradition.

Adolescent↗

PubMed2005

Item response theory and its applications to patient-reported outcomes measurement.

This article provides an overview of item response theory (IRT) models and how they can be appropriately applied to patient-reported outcomes (PROs) measurement. Specifically, the following topics are discussed: (a) basics of IRT, (b) types of IRT models, (c) how IRT models have been applied to date, and (d) new directions in applying IRT to PRO measurements.

Health Services Research↗

PubMed2004

Cartilage tissue engineering on the surface of a novel gelatin-calcium-phosphate biphasic scaffold in a double-chamber bioreactor.

Tissue engineering is a new approach to articular cartilage repair; however, the integration of the engineered cartilage into the host subchondral bone is a major problem in osteochondral injury. The aim of the present work, therefore, was to make a tissue-engineered osteochondral construct from a novel biphasic scaffold in a newly designed double-chamber bioreactor. This bioreactor was designed to coculture chondrocytes and osteoblasts simultaneously. The aim of this study was to prove that engineered cartilage could be formed with the use of this biphasic scaffold. The scaffold was constructed from gelatin and a calcium-phosphate block made from calcined bovine bone. The cartilage part of the scaffold had a uniform pore size of about 180 microm and approximate porosity of 75%, with the trabecular pattern preserved in the bony part of the scaffold. The biphasic scaffolds were seeded with porcine chondrocytes and cultured in a double-chamber bioreactor for 2 or 4 weeks. The chondrocytes were homogeneously distributed in the gelatin part of the scaffold, and secretion of the extracellular matrix was demonstrated histologically. The chondrocytes retained their phenotype after 4 weeks of culture, as proven immunohistochemically. After 4 weeks of culture, hyaline-like cartilage with lacuna formation could be clearly seen in the gelatin scaffold on the surface of the calcium phosphate. The results show that this biphasic scaffold can support cartilage formation on a calcium-phosphate surface in a double-chamber bioreactor, and it seems reasonable to suggest that there is potential for further application in osteochondral tissue engineering.

Animals↗

PubMed2004

The talking touchscreen: a new approach to outcomes assessment in low literacy.

PURPOSE: Cancer patients who are deficient in literacy skills are particularly vulnerable to experiencing different outcomes due to disparities in care or barriers to care. Outcomes measurement in low literacy patients may provide new insight into problems previously undetected due to the challenges of completing paper-and-pencil forms. DESCRIPTION OF STUDY: A multimedia program was developed to provide a quality of life assessment platform that would be acceptable to patients with varying literacy skills and computer experience. One item at a time is presented on the computer touchscreen, accompanied by a recorded reading of the question. Various colors, fonts and graphic images are used to enhance visibility, and a small picture icon appears near each text element allowing patients to replay the sound as many times as they wish. Evaluation questions are presented to assess patient burden and preferences. RESULTS: An ethnically diverse group of 126 cancer patients with a range of literacy skills and computer experience reported that the 'talking touchscreen' (TT) was easy to use, and commented on the usefulness of the multimedia approach. CLINICAL IMPLICATIONS: The TT is a practical, user-friendly data acquisition method that provides greater opportunities to measure self-reported outcomes in patients with a range of literacy skills.

Adult↗

PubMed2003

Evaluation of the Functional Assessment of Cancer Therapy-General (FACT-G) Spanish Version 4 in South America: classic psychometric and item response theory analyses.

BACKGROUND: The FACT-G has gone through many validation studies. However, little research has been conducted in South American Spanish speaking patients. The present study aimed to evaluate the FACT-G Spanish Version 4 in Uruguayan cancer patients. METHODS: The data analyzed were collected from 309 patients, with various tumor sites, at different stages of disease and receiving different treatments. RESULTS: Reliability was evaluated using Cronbach's coefficient alpha and showed high internal consistency for each of the subscales and its total scale (range =.78 -.91) of the FACT-G. The FACT-G total score also showed significant mean differences among known groups (performance status, in vs. outpatients) when tested by ANOVA and t-test. When the tumor stage (Local and Regional vs. Metastatic disease) was used as a clinical anchor, the FACT-G total score, the Physical Well-being (PWB), and Functional Well-being (FWB) subscale scores showed mean differences, ranging from 5 to 10 points in a scale from 0-108 (effect sizes = 0.30-0.60). Item response theory (IRT)-based evaluation using mean square fit statistics (.60-1.4) criteria showed that only two items misfit: "Estoy satisfecho(a) con mi vida sexual" (I am satisfied with my sex life) and "Estoy satisfecho(a) de cómo estoy enfrentando mi enfermedad" (I am satisfied with how I am coping with my illness). CONCLUSION: The results indicated that, using both traditional and IRT approaches, the Spanish FACT-G has good reliability and validity to be used as a QOL instrument among Uruguayan cancer patients.

Adult↗

PubMed2003

Gelatin-chondroitin-hyaluronan tri-copolymer scaffold for cartilage tissue engineering.

The mechanism by which the cell synthesizes and secretes extracellular matrix (ECM) and is, in turn, regulated by the ECM is termed dynamic reciprocity. The aim of the present work was to produce a gelatin/chondoitin-6-sulfate/hyaluronan tri-copolymer to mimic natural cartilage matrix for use as a scaffold for cartilage tissue engineering. The scaffold produced had a uniform pore size of about 180 microm and adequate porosity of 75%. Porcine chondrocytes were seeded onto the tri-copolymer scaffold and cultured in Petri dishes or spinner flasks for 2, 3, 4, or 5 weeks. Chondrocytes were uniformly distributed in the scaffold in the spinner flask cultures, but less so in the Petri dish cultures. Secretion of ECM was found under histology examination. In spinner flask cultures, chondrocytes retained their phenotype for at least 5 weeks, as shown immunohistochemically, and synthesized type II collagen. These results show that gelatin/chondroitin sulfate/hyaluronan tri-copolymer has potential for use as a cartilage tissue engineering scaffold.

Animals↗

PubMed2003

The Washington Psychosocial Seizure Inventory (WPSI): psychometric evaluation and future applications.

The Washington Psychosocial Seizure Inventory (WPSI) clinical scales were developed via an empirical item selection approach and have been used widely to measure aspects of psychosocial functioning of patients with epilepsy. However, these empirically derived clinical scales have not been assessed psychometrically using a modern item response theory-based model. The goals of this study were to: (1) evaluate how items in each clinical scale performed in such a way as to represent the underlying constructs being measured; and (2) derive a shorter version while maintaining measurement precision. WPSI item response data from 145 adults with epilepsy collected for an evaluation study of an intervention to pact negative attributional style in epilepsy were used. The dichotomous Rasch model suitable for the true-false response choices was used to analyse each clinical scale separately. Most items within each scale fit the measurement model well, with very few exceptions. All items, therefore, were retained. A method, based on computerised adaptive testing (CAT), is offered for shortening the WPSI using a psychosocial outcomes item bank derived from the study. Individuals' specific levels of functioning are used to derive measures of their psychosocial functioning with a minimum number of items.

Adaptation, Psychological↗

PubMed2003

Should symptoms be scaled for intensity, frequency, or both?

OBJECTIVE: This study evaluated the comparability of two 5-point symptom self-report rating scales: Intensity (from "not at all" to "very much") and Frequency (from "none of the time" to "all of the time"). Questions from the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue 13-item scale was examined. METHODS: Data from 161 patients (60 cancer, 51 stroke, 50 HIV) were calibrated separately to fit an item response theory-based rating scale model (RSM). The RSM specifies intersection parameters (step thresholds) between two adjacent response categories and the item location parameter that reflects the probability that a problem will be endorsed. Along with patient fatigue scores ("measures"), the spread of the step thresholds and between-threshold ranges were examined. The item locations were also examined for differential item functioning. RESULTS: There was no mean raw score difference between intensity and frequency rating scales (37.2 vs. 36.4, p = n.s.). The high correlation (r = .86, p < .001) between the intensity versus frequency scores indicated their essential equivalence. However, frequency step thresholds covered more of the fatigue measurement continuum and were more equidistant, and therefore reduced floor and ceiling effects. SIGNIFICANCE OF RESULTS: These two scaling methods produce essentially equivalent fatigue estimates; it is difficult to justify assessing both. The frequency response scaling may be preferable in that it provides fuller coverage of the fatigue continuum, including slightly better differentiation of people with relatively little fatigue, and a small group of the most fatigued patients. Intensity response scaling offers slightly more precision among the patients with significant fatigue.

Chronic Disease↗

PubMed2003

Item banking to improve, shorten and computerize self-reported fatigue: an illustration of steps to create a core item bank from the FACIT-Fatigue Scale.

Fatigue is a common symptom among cancer patients and the general population. Due to its subjective nature, fatigue has been difficult to effectively and efficiently assess. Modern computerized adaptive testing (CAT) can enable precise assessment of fatigue using a small number of items from a fatigue item bank. CAT enables brief assessment by selecting questions from an item bank that provide the maximum amount of information given a person's previous responses. This article illustrates steps to prepare such an item bank, using 13 items from the Functional Assessment of Chronic Illness Therapy Fatigue Subscale (FACIT-F) as the basis. Samples included 1022 cancer patients and 1010 people from the general population. An Item Response Theory (IRT)-based rating scale model, a polytomous extension of the Rasch dichotomous model was utilized. Nine items demonstrating acceptable psychometric properties were selected and positioned on the fatigue continuum. The fatigue levels measured by these nine items along with their response categories covered 66.8% of the general population and 82.6% of the cancer patients. Although the operational CAT algorithms to handle polytomously scored items are still in progress, we illustrated how CAT may work by using nine core items to measure level of fatigue. Using this illustration, a fatigue measure comparable to its full-length 13-item scale administration was obtained using four items. The resulting item bank can serve as a core to which will be added a psychometrically sound and operational item bank covering the entire fatigue continuum.

Adult↗

PubMed2003

What are the most important symptom targets when treating advanced cancer? A survey of providers in the National Comprehensive Cancer Network (NCCN).

We derived a set of brief, clinically relevant symptom indices for assessing symptomatic response to chemotherapy for advanced bladder, brain, breast, colorectal, head and neck, hepatobiliary/pancreas, lung, ovarian, and prostate cancers. Questions were extracted from a multidimensional cancer quality of life (QOL) measurement system, the Functional Assessment of Cancer Therapy (FACT). Surveys of disease-related symptoms were presented to expert physicians and nurses at 17 National Comprehensive Cancer Network (NCCN) member institutions. In a two-step procedure, each expert narrowed the list to no more than five of the very most important to attend to when assessing the value of drug treatment for advanced disease. Symptoms endorsed at a frequency greater than chance probability were retained for the nine symptom indices. The resulting NCCN/FACT symptom indices are comprised of 6-15 items, depending on disease. Fatigue, pain, nausea, weight loss, worry about worsening condition, and contentment with current QOL were consistently selected by experts as priority symptoms across tumor sites. These nine tumor-specific symptom indices indicate the most important clinician-rated targets of chemotherapy for many advanced cancers. These results await validation in patient populations and examination of the extent to which changes in symptomatology translate into meaningful improvement to the patient.

Cancer Care Facilities↗

PubMed2002

Fatigue in cancer patients compared with fatigue in the general United States population.

BACKGROUND: Although fatigue is a common symptom among cancer patients, it is also a common experience in the general, healthy population. Its universality has made it difficult to appreciate whether the fatigue experienced by patients with cancer is distinguishable from the fatigue experienced by the general population. Because the etiology of fatigue is multifactorial, it also has been difficult to appreciate fully the relative contribution of anemia to cancer-related fatigue. METHODS: To address this issue, responses to a brief, standardized set of 13 questions from the Functional Assessment of Chronic Illness Therapy (FACIT) Measurement System were compared across three groups: anemic cancer patients (n = 2369 patients), nonanemic cancer patients (n = 113 patients), and the general United States population (n = 1010 persons). RESULTS: Fatigue scores of the anemic cancer patients (at both baseline and upon completion of anemia therapy) were significantly worse compared with the scores of nonanemic cancer patients that, in turn, were worse compared with the scores of the general United States population (P < 0.001). Score distributions were quite distinct for these three groups. Within the group of anemic cancer patients, the degree of anemia (mild, moderate, or severe) also was predictive of the degree of fatigue (P < 0.001), although the distributions were not dramatically distinct. CONCLUSIONS: Although anemia is clearly a factor that contributes to the severity of disease-related fatigue among cancer patients, hemoglobin levels explain only part of the difference compared with fatigue among the general United States population. The distinct distributions of fatigue scores of anemic cancer patients compared with the general United States population and the substantial sample sizes of these two groups enabled a discriminant analysis approach that allowed the differentiation of anemic cancer patients from the general population with high sensitivity (0.92) and reasonable specificity (0.69). Thus, although fatigue is a symptom most anyone can relate to, the fatigue of cancer patients, particularly those who are anemic, is decidedly worse. Interventions targeting this common and life-disrupting symptom likely would be of considerable value to patients with cancer.

Anemia↗

PubMed2002

Advances in quality of life measurements in oncology patients.

Accurate assessment of the quality of life (QOL) of patients can provide important clinical information to physicians, especially in the area of oncology. Changes in QOL are important indicators of the impact of a new cytotoxic therapy, can affect a patient's willingness to continue treatment, and may aid in defining response in the absence of quantifiable endpoints such as tumor regression. Because QOL is becoming an increasingly important aspect in the management of patients with malignant disease, it is vital that the instruments used to measure QOL are reliable and accurate. Assessment of QOL involves a multidimensional approach that includes physical, functional, social, and emotional well-being, and the most comprehensive instruments measure at least three of these domains. Instruments to measure QOL can be generic (eg, the Nottingham Health Profile), targeted toward specific illnesses (eg, Functional Assessment of Cancer Therapy - Lung), or be a combination of generic and targeted. Two of the most widely used examples of the combination, or hybrid, instruments are the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 Items and the Functional Assessment of Chronic Illness Therapy. A consequence of the increasing international collaboration in clinical trials has been the growing necessity for instruments that are valid across languages and cultures. To assure the continuing reliability and validity of QOL instruments in this regard, item response theory can be applied. Techniques such as item response theory may be used in the future to construct QOL item banks containing large sets of validated questions that represent various levels of QOL domains. As QOL becomes increasingly important in understanding and approaching the overall management of cancer patients, the tools available to clinicians and researchers to assess QOL will continue to evolve. While the instruments currently available provide reliable and valid measurement, further improvements in precision and application are anticipated.

Cross-Cultural Comparison↗

PubMed2002

Muscle torques in total knee arthroplasty with subvastus and parapatellar approaches.

The current study was designed to compare muscle torques when using the subvastus and parapatellar approaches for unilateral total knee arthroplasty. Twelve female patients had unilateral total knee arthroplasty with the subvastus approach from January 1997 to June 1998. The historic control group consisted of 16 female patients who had unilateral total knee arthroplasty with the parapatellar approach from July 1994 to January 1997. Six and 12 months after surgery, a Cybex dynamometer was used to measure isometric and isokinetic muscle strength. Two parameters were used to compare the two approaches, the first parameter was the difference in peak torque between the surgically treated knee and the baseline value for the healthy knee, and the second parameter was the hamstring to quadriceps peak-torque ratio, again using the value for the healthy knee as baseline. The subvastus approach resulted in an initial higher peak torque in the quadriceps 6 months after surgery, but this difference became insignificant 12 months postoperative. Using the subvastus approach, the hamstring to quadriceps peak-torque ratio reached the normal range (0.50-0.80) sooner than was the case using the parapatellar approach. There is a phenomenon of cross adaptation of the untreated knee to the surgically treated knee, and knees operated on by the subvastus approach showed functional recovery at an earlier date than those operated on by the parapatellar approach.

Adult↗

PubMed2002

Real-time clinical application of quality-of-life assessment in advanced lung cancer.

In the management of advanced non-small-cell lung cancer (NSCLC), quality of life (QOL) is a very important consideration when determining therapy. However, clinicians and patients generally make their treatment decisions based upon informal appraisal of QOL rather than formal assessment. Previously, we showed that Functional Assessment of Cancer Therapy-Lung (FACT-L) data were highly prognostic of survival in advanced NSCLC, suggesting the potential value of FACT-L scores for treatment decision making. A key barrier is the impracticality and burden of real-time administration and scoring of paper forms in the clinic. Handheld and touch screen computer administration and scoring can address that barrier. This pilot study assessed the feasibility of using computer technology to aid in the collection and interpretation of QOL and selected clinical data in real time, reducing human effort. The technology was found to be acceptable to patients and staff and feasible within the clinical setting. Integrating formal QOL assessment into treatment decision making in a clinical oncology setting requires further evaluation.

Journal Article↗

PubMed2002

A brief assessment of concerns associated with genetic testing for cancer: the Multidimensional Impact of Cancer Risk Assessment (MICRA) questionnaire.

The Multidimensional Impact of Cancer Risk Assessment (MICRA) is a new tool to measure the specific impact of result disclosure after genetic testing. The authors compared its performance with that of questionnaires measuring general and cancer-specific distress. Participants (158 women) responded 1 month after they received genetic test results. The women were divided into 4 standard clinical test result groups: BRCA1/2 positive, BRCA1/2 negative, panel negative, and true negative. Factor analysis supported the formation of 3 subscales: Distress (6 items, alpha = .86), Uncertainty (9 items, alpha = .77), and Positive Experiences (4 items, alpha = .75). All 3 MICRA subscales differentiated participants who were BRCA1/2 positive from the other 3 groups. MICRA thus helps identify subgroups of vulnerable genetic testing participants.

Adult↗

PubMedDate not supplied

Who's caring for whom? Differing perspectives between seriously ill patients and their family caregivers.

Although clinicians and researchers often rely on family members 'reports of a wide range of dying patients' symptoms and care preferences, available data indicate divergences between the two. We used a national sample to analyze patient-caregiver pairs to explore areas of concordance and nonconcordance about physical symptoms, communication with physicians, caregiving needs, and future fears. We also assessed whether identifiable patient or caregiver characteristics were associated with nonconcordance. Our data were from a national, random sample of 988 terminally ill patients, of whom 893 had caregivers who were also interviewed. Frequencies and types of nonconcordance were computed for patient-caregiver pairs. Bivariate associations between patient and caregiver reports on each item were tested. Logistic and conditional logistic regression analyses assessed multiple predictors of nonconcordance for each item. Primary diagnoses included cancer (51.1 percent), heart disease (17. 7 percent), chronic obstructive pulmonary disease (10. 7 percent), and other diseases (20.5 percent). The proportion of concordant reports among pairs of patients and caregivers ranged from 53 percent to 66 percent. Among pairs showing nonconcordant responses, caregivers reported higher levels of pain and disability than patients, lower caregiving needs, and different fears about the future. Few demographic or clinical predictors were associated with nonconcordance. Concordance between patients 'and their caregivers' responses ranged widely, and there were important areas of nonconcordant responses. When responses differed, patients were more likely to express concern about domains that might impose on caregivers, while caregivers were more likely to express concern about patients 'physical suffering. Consistent sociodemographic or clinical predictors of nonconcordant responses were not found. These data suggest important ways that patient and caregiver reports of the same experience vary.

Adult↗