PubMed Health⌕ Search

Biomedical subjects

J Chiang

Publications and source records attributed to J Chiang.

At least 19 recordsLinked to original sources
PubMed2006

A referent bone mineral density database for Chinese American women.

INTRODUCTION: While osteoporosis is common among women of Chinese descent, a readily available bone mineral density (BMD) referent database for Chinese American women does not exist. Fracture risk among this population is currently assessed using a Caucasian reference as well as diagnostic criteria for osteoporosis developed for postmenopausal Caucasian women. Many studies indicate that there are important racial differences in skeletal health and fracture risk, an observation that makes the application of Caucasian data to all groups problematical. This study was undertaken to establish a BMD referent database in Chinese American women and to compare it with a Caucasian female database. It is expected that a race-specific database will be useful in the assessment of bone health for Chinese American women. METHODS: Healthy Chinese American women (n=359), ages 20-90, were recruited. Along with dual-energy X-ray absorptiometry (DXA) of the total hip and lumbar spine, demographic, medical, familial, nutritional, and behavioral data were obtained. The mean and standard deviation for BMD at each site was calculated for each 10-year age group and compared to mean BMD values for Caucasian women supplied as found in the Hologic DXA instrument. Osteoporosis diagnosis rates for this cohort, calculated with the Caucasian and newly established Chinese American BMD referent values, were compared with each other. RESULTS: Compared with Caucasian women, Chinese American women have significantly lower BMD at the lumbar spine, total hip, and femoral neck across a wide spectrum of age groups. As a consequence, more than one-half of Chinese American women>or=50 years of age, who would be characterized as osteoporotic using a Caucasian referent, would not be diagnosed as such if a Chinese American referent were utilized. CONCLUSION: Chinese American reference BMD values are significantly lower than those for Caucasian women. Future studies relating Chinese American BMD values to fracture risk are necessary in order to determine if ethnic database-derived T-scores would be more predictive of fracture risk and to develop meaningful diagnostic criteria for this population.

Absorptiometry, Photon↗
PubMed2006

Effect of a periodized exercise training and active recovery program on antitumor activity and development of dendritic cells.

AIM: Dendritic cells (DCs) are potent antigen-presenting cells that promote antitumor immunity in vivo when pulsed with tumor antigen. No studies have indicated that exercise training affects DC function. The purpose of this study was to investigate the effect of a 5-week periodized exercise training and active recovery program on the development of DCs, and to test their effect on the antitumor immunity of mononuclear cells (MNC) from blood and spleen against human leukemic U937 and murine lymphoma Yac-1 cells, respectively. METHODS: Male Fisher 344 rats were divided into 2 groups: exercise and non-exercise group. The training protocol consisted of running on a motor-driven treadmill 6 days a week for consecutive 5 weeks, during which the running time, treadmill speed, and incline gradient were increased weekly. Active recovery parameters were set at 30% of the intensity of the previous day. RESULTS: DC numbers increased significantly (P<0.05) in the exercise group compared to controls, but there were no significant changes in the expression of surface antigens CD80 and CD86. In exercise group MNC-conditioned medium (CM) prepared with 50 microg/mL phytohemagglutinin (PHA) significantly inhibited proliferation of U937 cells, and splenocyte-CM with PHA at 20 and 40 microg/mL significantly inhibited proliferation of YAC-1 cells greater than control group. CONCLUSIONS: The 5-week periodized exercise training with active recovery promotes the number of DCs and enhances the activity of DCs against tumor cells.

Animals↗
PubMed2002

Approaching healthy body mass index norms for children and adolescents from health-related physical fitness.

Current body mass index (BMI) norms for children and adolescents are developed from a reference population that includes obese and slim subjects. The validity of these norms is influenced by the observed secular increase in body weight and BMI. We hypothesized that the performance of children in health-related physical fitness tests would be negatively related to increased BMIs, and therefore fitness tests might be used as criteria for developing a more appropriate set of BMI norms. We evaluated the existing data from a nation-wide fitness survey for students in Taiwan (444 652 boys and 433 555 girls) to examine the relationship between BMI and fitness tests. The fitness tests used included: an 800/1600-m run/walk; a standing long jump; bent-leg curl-ups; and a sit-and-reach test. The BMI percentiles developed from the subgroup whose test scores were better than the 'poor' quartile in all four tests were compared with those of the whole population and linked to the adult criteria for overweight and obesity. The BMIs were significantly related to the results of fitness testing. A total of 43% of students had scores better than the poorest quartile in all of their tests. The upper BMI percentile curves of this fitter subgroup were lower than those of the total population. The 85th and 95th BMI percentile values of the fitter 18-year-old-students (23.7 and 25.5 kg m(-2) for boys; 22.6 and 24.6 kg m(-2) for girls) linked well with the adult cut-off points of 23 and 25 kg m(-2), which have been recommended as the Asian criteria for adult overweight and obesity. Hence, the BMI norms for children and adolescents could be created from selected subgroups that have better physical fitness. We expect that the new norms based on this approach will be used not only to assess the current status of obesity or overweight, but also to encourage activity and exercise.

Adolescent↗
PubMed2001

The in vivo dynamic response of the human spine to rapid lateral bend perturbation: effects of preload and step input magnitude.

STUDY DESIGN: A repeated measures design was used to determine the effects that combinations of two preloads and two added loads have on spine mechanics both before and during the response to the added load. OBJECTIVE: To investigate the effects of varying initial isometric and added step input load magnitudes on mechanical and electromyographic responses of the trunk during sudden loading that causes lateral bending moments. SUMMARY OF BACKGROUND DATA: Cocontractions of the antagonistic and agonistic muscles of the trunk are required for stability during loading of the spine. In several in vivo studies, it was observed that trunk muscle cocontraction serves a functional role before the application of unexpected or sudden loads. The response of agonistic and antagonistic trunk muscles to rapid lateral bend moments would provide further insight into the dynamic stability mechanisms of the spine. METHODS: In this study, 13 men maintained an upright standing posture while resisting the application of lateral bend moments produced by four different loading conditions comprising combinations of two preloads (5% or 15% of the maximum isometric lateral bend moment) and two added loads (20% or 30%). The preloading was used to develop different initial levels of trunk stiffness before the application of the added loads. The lateral bend moment and angular rotation of the trunk were measured, as well as the surface electromyogram amplitudes of the bilateral internal oblique, external oblique, rectus abdominus, lumbar erector spinae, and thoracic erector spinae muscles. Dependent measures were recorded during the steady state preload conditions, and peak values were recorded after the load was added. RESULTS: Higher added loads resulted in higher peak lateral bend rotations, and higher preloads resulted in lower rotations. The patterns of response were similar for the peak lateral bend moments and the electromyogram amplitudes from four of the five agonistic muscles. The thoracic erector spinae excepted, each of the other four muscles demonstrated larger responses in the agonistic muscles. However, all of the antagonistic muscles showed some increase in electromyogram activity in response to the added load. The thoracic erector spinae appeared to have the role of counteracting the flexor moments created by the abdominal muscles and the maintenance of spine stability. The agonistic external obliques and lumbar erector spinae had the largest responses to the added load. A comparison of the 35% loading conditions showed an increased response of the trunk to the 5% + 30% condition (with lower initial trunk stiffness), as compared with the 15% + 20% condition. CONCLUSIONS: The findings from this study show that higher levels of preactivation can serve to increase spine compression and trunk muscle stiffness, thereby attenuating the lateral displacements caused by rapid loading. Furthermore, antagonistic muscles were observed to respond rapidly to such perturbations with large increases in activation when preactivation and spine stability were low. The trunk muscles monitored all were larger, multisegmental muscles. The results from this study lend support to previous studies suggesting that the larger multisegmental muscles make a significant contribution to spinal stability.

Adult↗
PubMed2001

Identifying chromosomal fragile sites from a hierarchical-clustering point of view.

Identification of fragile sites is a way to investigate the genetic abnormalities that are the hallmark of cancer and play an important role in carcinogenesis. Manifestation of nonrandom breakage at a chromosome band is an essential criterion for determination of the fragility of the band. In this article, a new detection procedure is proposed. This new procedure takes the relationship of one site with the others into consideration and can be applied to tests of the randomness of breakpoints under either the proportional probability model (PPM) or the equiprobability model (EPM). The procedure can form a grouping structure that classifies all sites into several clusters. It is applied to identification of fragile sites for a real data set for Chinese patients with colorectal carcinoma for illustration of the proposed method.

Chromosome Banding↗
PubMed2001

Basic fibroblast growth factor as a growth factor for SRV-2-infected simian retroperitoneal fibromatosis cells, an animal model for AIDS related Kaposi's sarcoma.

Basic fibroblast growth factor (bFGF) and vascular endothelial cell growth factor (VEGF) were demonstrated to be important factors sustaining the growth of Kaposi's sarcoma. RF cells were used to provide a model to study the pathogenesis of Kaposi's sarcoma. In this paper, we demonstrated that bFGF is present in the RF cells, cultured media, and tissues from monkey. The biological activities of bFGF on RF cells were also studied in vitro with serum-free media. The bFGF from serum-free-conditioned media is biologically active to stimulate RF cells in certain media condition. The mitogenic effect was abrogated by sheep neutralizing anti-bFGF antibody. Furthermore, the effect of antibody was reversed by the addition of exogenous bFGF. ELISA measurements indicating the growth potency of conditioned media correlated with the amount of bFGF in the conditioned media. The data from flow cytometry demonstrated the co-existence of SRV-2 and bFGF among RF cells and RF tissues. Immunohistochemical staining of RF tissue blocks for bFGF revealed that bFGF was present in the tumor and the presence of bFGF was not caused by the artifact of tissue culture. These results indicate that bFGF is an important growth factor to promote RF cell growth in vitro and RF tumor in vivo. Further studies are required to determine the relationship between the interaction of bFGF, SRV-2, and VEGF. This model also provides an adequate alternative to the model induced by simian immunodeficiency virus (SIV) to study the Kaposi's sarcoma.

Animals↗
PubMed2000

Implications of the X-Ray Variability for the Mass of MCG -6-30-15.

The bright Seyfert 1 galaxy MCG -6-30-15 shows large variability on a variety of timescales. We study the less, similar3 day timescale variability using a set of simultaneous archival observations that were obtained from the Rossi X-Ray Timing Explorer (RXTE) and the Advanced Satellite for Cosmology and Astrophysics (ASCA). The RXTE observations span nearly 106 s and indicate that the X-ray Fourier power spectral density has an rms variability of 16%, is flat from approximately 10-6 to 10-5 Hz, and then steepens into a power law proportional to f-alpha with alpha greater, similar1. A further steepening to alpha approximately 2 occurs between 10-4 and 10-3 Hz. The shape and rms amplitude are comparable to what has been observed in NGC 5548 and Cyg X-1, albeit with break frequencies that differ by a factor of 10-2 and 104, respectively. If the break frequencies are indicative of the central black hole mass, then this mass may be as low as 106 M middle dot in circle. An upper limit of approximately 2 ks for the relative lag between the 0.5-2 keV ASCA band compared to the 8-15 keV RXTE band was also found. Again by analogy with NGC 5548 and Cyg X-1, this limit is consistent with a relatively low central black hole mass.

Journal Article↗
PubMed2000

Applying workflow analysis tools to assess immunization delivery in outpatient primary care settings.

BACKGROUND: As health care organizations face increasing pressure to institute quality assurance activities, the already-underfunded community clinics that treat the poor and underserved are challenged to perform these activities within tight constraints of human and financial resources. With pediatric immunizations as a marker, a workflow observation tool was used to identify causal processes affecting immunization delivery. METHODS: Ten clinics and five private practices, located in areas designated as health professional shortage areas, participated in the study, gaining access to a tool that would have been unaffordable to them from the private sector. Trained observers followed families through the clinic, using a 127-item workflow observation form--the Observational Checklist of Patient Encounters (OCPE)--assessing discrete activities that families encountered during the checkin/pre-exam, exam, discharge, and billing processes. A convenience sampling of the targeted population--children younger than three years of age--included observations of scheduled acute, scheduled well-child, follow-up, and walk-in visits. In the feedback session, a summary of each clinic's immunization delivery patterns was presented, with an emphasis on the individual health center's operational issues. RESULTS: The workflow observation tool was used to identify operational errors affecting both clinical and fiscal processes in each of the clinics that had not been previously apparent to either clinic management or the quality improvement (QI) teams. DISCUSSION: Feedback addressed and encouraged process-oriented improvements in response to the workflow observations, which were incorporated into the clinics' QI procedures. Twelve of the 15 clinics have formed process action teams to address QI issues on an ongoing basis.

Age Factors↗
PubMed2000

Comparison of anti-leukemic immunity against U937 cells in endurance athletes versus sedentary controls.

To examine whether endurance athletes have higher anti-leukemic immunity than sedentary controls or not, we isolated peripheral blood mononuclear cells (MNC) from cyclists and sedentary controls to prepare conditioned media (CM) with various doses of phytohemagglutinin (PHA). The proliferation-inhibiting and differentiation-inducing activities of these PHA-MNC-CM on human leukemic U937 cells were investigated. Our results show that the growth inhibition activity of cyclists' PHA-MNC-CM were higher than that of controls. The dosage of PHA used to prepare MNC-CM to achieve about 90% growth inhibition was 5 microg/ml in the control group and was 2 microg/ml in the athletes group. The differentiation-inducing effects were evaluated by morphological scoring, superoxide production, and monocyte-associated antigen expression (CD14 and CD68). These three parameters all demonstrated the differentiation-inducing effect of MNC-CM increased with increasing dose of PHA. These effects were significantly greater in the athletic when compared to the sedentary control group at all doses of PHA. The levels of TNF-alpha and IFN-gamma PHA-MNC-CM increased in a PHA dose-dependent manner and were much higher in the athletic group when compared to the controls. We conclude that the capacity of endurance athletes to activate anti-leukemic immunity is significantly higher than that of sedentary controls.

Adult↗
PubMed1999

Testing the nonrandomness of chromosomal breakpoints using highest observed breakages.

To determine whether a chromosomal band is a fragile site rather than a spontaneous breakpoint, an essential step is to test the nonrandomness of breakage at the region. In this paper, the nonapplicability of the testing procedure introduced by Bohm et al. is discussed, and a new detection procedure is proposed. This new procedure considers the relations of one site with the others, and can be applied to tests of the nonrandomness of breakpoints under either the proportional probability model, or the equiprobability model. A data set for Chinese patients with colorectal carcinoma is analyzed as an illustration of the proposed method.

China↗
PubMed1999

The in vivo dynamic response of the spine to perturbations causing rapid flexion: effects of pre-load and step input magnitude.

OBJECTIVE: To evaluate the impact of muscle pre-activation levels and load magnitude on the response of the trunk to loading conditions causing rapid flexion. DESIGN: Eight male subjects were asked to maintain an upright standing posture while resisting the application of forward flexion moments produced by four different loading conditions consisting of combinations of two pre-loads (4% or 16% of the maximum extensor moment) and two added loads (12% or 24%). Pre-loading was used to develop different initial levels of trunk muscle activity prior to the application of the added loads. Of special interest were the two conditions that resulted in total final loads of 28%. BACKGROUND: Cocontraction of the antagonistic and agonistic muscles of the trunk are required to provide stability during normal physiological loading conditions. In several in vivo studies, levels of trunk muscle cocontraction have been observed prior to the application of unexpected or sudden loads. Forces from the abdominal muscles have been proposed to provide stability when extensor moments are generated. The response of trunk muscles to rapid flexor moments would provide further insight into the dynamic stability mechanisms of the spine. METHODS: Measurements were made of the trunk extensor moments, angular displacement of the trunk and unilateral surface EMG amplitudes of three abdominal and three trunk extensor muscles. Values were recorded during the isometric pre-load and for the maximum magnitude of each variable in response to the added load. RESULTS: Higher pre-loads resulted in lower flexion rotations of the spine and higher added loads caused larger rotations. With increasing magnitudes of final loads, a corresponding increase in trunk extensor moments and trunk muscle cocontraction was observed. The largest activations were observed in the lumbar erector spinae and thoracic erector spinae muscles, while smaller yet substantial EMG activity was observed in the internal oblique and external oblique. A comparison of the 28% loading conditions showed an increased response of the trunk to the [4 + 24] loading condition (with lower initial trunk stiffness) when compared to the [16 + 12] loading condition. CONCLUSIONS: Pre-activation of trunk extensor muscles can serve to reduce the flexion displacements caused by rapid loading. The abdominal oblique muscles, especially external oblique, will rapidly increase their activation levels in response to rapid loading. These changes are more pronounced when pre-activation levels are low, resulting in lower initial trunk stiffness and spine compression force. It is proposed that these factors will ultimately affect spine stability and the risk of injury. RELEVANCE: The results of this study provide insight into several mechanisms involved in the dynamic stability of the spine. Injuries can be caused by unexpected and rapid loading of the spine. A study of the mechanisms available to respond to such perturbations is important to an understanding of spine mechanics and the etiology of low back injury.

Adult↗
PubMed1999

Acquired pseudocholinesterase deficiency after high-dose cyclophosphamide.

Succinylcholine, a depolarizing neuromuscular blocking agent used in anesthesia is hydrolyzed in the plasma by the enzyme pseudocholinesterase (PSC). Conditions associated with reduced PSC activity lead to sustained action of succinylcholine and result in prolonged apnea. Cyclophosphamide is an inhibitor of PSC and its suppressive effect may be dose-dependent. We report a case of severe PSC deficiency after high-dose cyclophosphamide at 7 g/m2. The patient received succinylcholine during anesthesia 9 h after chemotherapy and developed prolonged apnea. This case highlights the potential risk of drug-induced PSC deficiency and cautions the use of depolarizing muscular relaxants soon after high-dose cyclophosphamide.

Adrenal Gland Neoplasms↗
PubMed1997

Aortic smooth muscle cells interact with tenascin-C through its fibrinogen-like domain.

The extracellular matrix protein tenascin-C is a multidomain protein that regulates cell adhesion. We used two different smooth muscle cell subtypes derived from adult and newborn rat aorta to investigate the interaction of tenascin-C or its various domains with these cells using an adhesion assay. Newborn cells were three times more adherent to tenascin-C than adult cells. Tenascin C-adhering cells remained round, whereas they spread rapidly on a fibronectin substrate. Adhesion assays showed the interaction between tenascin-C and newborn cells to be predominantly RGD-independent. Mg2+ increased newborn cell adhesion to tenascin-C in a concentration-dependent manner, whereas Ca2+ had no effect. To analyze the structure-function relationships of different domains of tenascin-C, we used recombinant full-length fibronectin-like and fibrinogen-like domains and various subdomains corresponding to the alternatively spliced regions of tenascin-C. The cells adhered to the fibrinogen-like domain but not to the fibronectin-like domain or its subdomains. As with the intact tenascin-C molecule, adherent cells remained round, and the Mg2+, but not Ca2+, promoted this interaction. The interaction of cells with the fibrinogen-like region was further mapped to a 30-amino acid peptide located near the carboxyl-terminal part of the tenascin-C molecule. The same 30-amino acid peptide was active in promoting cell migration. Our results provide a basis for understanding the mechanism of interaction of tenascin-C with smooth muscle cells and a framework for isolating membrane binding sites that mediate the cellular responses to this molecule.

Amino Acid Sequence↗
PubMed1997

Low serum HDL-cholesterol is associated with raised tumor necrosis factor-alpha during ENL reactions.

The concentrations of serum lipids and tumor necrosis factor (TNF) were measured in leprosy patients across the spectrum of the disease and in erythema nodosum leprosum (ENL) patients at the onset of the reaction and after the reaction had clinically subsided. Lepromatous/borderline lepromatous (LL/BL) patients had significantly higher serum triglyceride and lower HDL-cholesterol levels; there was no such change in the tuberculoid/borderline tuberculoid (TT/BT) patients. The household contacts (HC) of the LL/BL patients also had significantly lower serum HDL levels. ENL patients during the acute phase of the reaction had significantly lower total, LDL-, HDL-cholesterol levels compared to the stable LL/BL patients, and these changes were reversible to pre-ENL levels after the reaction had subsided. Serum TNF levels were significantly higher in household contacts and in LL/BL patients but were not statistically different in TT/BT patients. Serum TNF levels were also significantly higher during the acute phase of ENL, and declined after the clinical remission of the reaction to levels comparable with those of LL/BL patients. There was a significant negative correlation between serum TNF and HDL-cholesterol levels during and after ENL reaction. However, there was no such correlation between TNF and total or LDL-cholesterol levels in ENL patients. Our results suggest that the changes in HDL-cholesterol metabolism are a specific part of the host response to lepromatous leprosy and to the ENL reaction and may be mediated by increased TNF production.

Adolescent↗
PubMed1996

Ca(2+)-permeable AMPA/kainate and NMDA channels: high rate of Ca2+ influx underlies potent induction of injury.

Neurodegeneration may occur secondary to glutamate-triggered Ca2+ influx through any of three routes: NMDA channels, voltage-sensitive Ca2+ channels (VSCC), and Ca(2+)-permeable AMPA/kainate channels (Ca-A/K). This study aims to examine Ca2+ ion dynamics in the generation of excitotoxic injury by correlating the relative amounts of 45Ca2+ that flow into cortical neurons through each of these routes over a 10 min epoch ("10 min Ca2+ loads;" a measure of influx rate), with resultant levels of intracellular free Ca2+ ([Ca2+]) and subsequent injury. Neurons possessing Ca-A/K make up a small subset (approximately 13%) of cortical neurons in culture, which can be identified by a histochemical stain based on kainate-stimulated Co2+ uptake (Co2+ (+) neurons) and which are unusually vulnerable to AMPA/kainate receptor-mediated injury. Initial studies using brief kainate exposures (to selectively destroy Co2+ (+) neurons) along with kainate-triggered 45Ca2+ influx measurements suggested that kainate causes rapid Ca2+ influx into Co2+ (+) neurons (comparable to that caused by NMDA). Influx through both Ca-A/K and NMDA channels increased proportionately with extracellular Ca2+, suggesting that these channels have high Ca2+ permeability. When cultures were subjected to exposures that gave similar 10 min Ca2+ loads through different routes, comparable levels of injury were observed, suggesting that net intracellular Ca2+ accumulation is a critical determinant of injury. However, the relationship between [Ca2+]i and influx was less direct: although exposures that gave the lowest or highest 10 min Ca2+ loads showed correspondingly lower or higher mean [Ca2+]i responses, there appears to be a wide range of exposures over which individual neuronal differences and sequestration/buffering mechanisms obscure [Ca2+]i as a reflection of influx rate.

Animals↗
PubMed1996

Psoas sheath chemical neurolysis for management of intractable leg pain from metastatic liposarcoma.

CASE REPORT: A 56-year-old man with widely metastatic liposarcoma, after left Tower extremity amputation, complained of severe right lower extremity pain. Trials of systemic opioids had resulted in poor pain control while introducing intolerable dose-limiting side effects. METHODS AND RESULTS: Initial inpatient management consisted of a lumbar epidural infusion of a dilute local anesthetic and preservative-free morphine. This provided satisfactory relief but was discontinued because of recrudescence of phantom limb pain. A lumbar epidural infusion of preservative-free morphine sulfate was associated with poor pain relief, central nervous system (CNS) side effects, and severe urinary retention resulting in acute renal failure. A repeated trial of parental opioids provided marginal pain relief with persistent CNS side effects. Chemical neurolysis of the lumbar plexus was performed with 10 ml of 10% aqueous phenol injected into the psoas muscle sheath. The pain gradually resolved over a 2-day period without apparent side effects. Motor function was preserved, pain was resolved, and as systemic opioids were reduced, cognitive function and overall well-being were improved.

Amputation, Surgical↗
PubMed1996

Food intake and dosage level, but not tablet vs solution dosage form, affect the absorption of metformin HCl in man.

The pharmacokinetics of four single-dose treatments of the metformin administered orally (as the HCl salt) were compared in 24 healthy subjects: 500 mg and 850 mg tablets and 850 mg solution fasting and 850 mg tablet with food. Solution and tablet formulations are bioequivalent. Bioavailability of a 500 mg tablet is 14% greater than that of an 850 mg tablet. Compared with the fasting state, bioavailability is 24% lower, and the peak concentration delayed about 37 min when an 850 mg tablet is administered with food.

Adult↗