PubMed Health⌕ Search

Biomedical subjects

C Chi

Publications and source records attributed to C Chi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Estrogen receptors and glucocorticoid receptors in human well-differentiated thyroid cancer.

Previously, we and others have found that the prognosis of patients with well differentiated thyroid cancer is related to patient age and gender. In this study, we examined estrogen and glucocorticoid receptors in thyroid cancers and adjacent non-neoplastic thyroid tissues from 31 Chinese patients. Our results indicate that the level of estrogen and glucocorticoid receptors in thyroid cancer tissues was similar to that in non-neoplastic thyroid tissues. Significant higher estrogen and glucocorticoid receptor levels were found in thyroid cancers from men than women. There was no difference in estrogen receptor levels from thyroid cancer in women less than or older than 45. However, the level of glucocorticoid receptor in thyroid cancer from women less than 45 years old was significantly higher than that of women older than 45. Estrogen or glucocorticoid receptor levels did not correlate with tumor invasiveness. The pathobiological role of glucocorticoid receptors in thyroid cancer is not known but may be involved in changes in circadian rhythm of thyroid tumors.

Journal Article↗
PubMed1997

Effects of mycobacteria on regulation of apoptosis in mononuclear phagocytes.

Since apoptosis is observed in tuberculous granulomata, we investigated the molecular mechanisms underlying the apoptotic pathway in an in vitro model of mycobacterial infection of mononuclear phagocytes. We postulated that Mycobacterium tuberculosis could trigger the apoptotic pathway in macrophages, resulting in death of the microorganism by modulating the expression of bcl-2, bax, bcl-xL, and bcl-xS. We found that the mRNA of bcl-2, an inhibitor of apoptosis, was downregulated in peripheral blood monocytes (PBM) between 2 and 6 h following infection with M. bovis BCG or induction with heat-killed M. tuberculosis H37Ra. Western analysis showed a downregulation of the Bcl-2 protein, with a half-life of 24 h. At the same time points, there was no change in the expression of Bax or Bcl-xS, inducers of apoptosis, but Bcl-xL, another inhibitor of apoptosis, was minimally upregulated by BCG. To determine if apoptosis could be a mechanism for growth inhibition in vivo, we obtained alveolar macrophages by bronchoalveolar lavage from involved sites in patients with active pulmonary tuberculosis. Using the TUNEL (terminal deoxynucleotidyltransferase mediated nick end labeling) technique, we observed significantly more apoptosis in involved segments of five tuberculosis patients (14.8 +/- 1.9%) than in those of normal controls (<1%, P = 0.02) or in uninvolved segments (4.3 +/- 0.9%, P < 0.05). We conclude that apoptosis of mononuclear phagocytes induced by M. tuberculosis occurs in vivo and that in an in vitro model of mycobacterial infection, apoptosis may be mediated by downregulation of Bcl-2.

Apoptosis↗
PubMed1997

GM-CSF gene expression is normal but protein release is absent in a patient with pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by an excessive accumulation of surfactant lipids and proteins in the alveolar space. In mice with a homozygous deletion of granulocyte macrophage-colony stimulating factor (GM-CSF), their phenotype mimics PAP. To evaluate whether the knockout mouse model mimics human disease, we evaluated GM-CSF expression in alveolar macrophages from a patient with PAP. We performed multiple whole lung lavages on a patient with PAP, and cultured BAL cells in the presence or absence of LPS. In contrast to the GM-CSF knockout mouse, human BAL cells from a patient with PAP expressed mRNA for GM-CSF following LPS stimulation. However, similar to the knockout mouse, GM-CSF protein release from BAL cells was undetectable with or without LPS. BAL cells from normal human controls released GM-CSF in abundance after LPS stimulation. In BAL cells from the patient with PAP, neutralization of interleukin-10 (IL-10) by anti-IL-10 antibody, resulted in enhanced GM-CSF production. Thus, alveolar macrophages from a PAP lung have deficient GM-CSF production analogous to the GM-CSF knockout mice; in contrast, human cells from a PAP lung have an intact GM-CSF gene. This case report illustrates an important difference between the knockout mouse model of PAP and the human disease.

Adult↗
PubMed1997

Utilization of Chinese medicine in Taiwan.

This article examines the use of Chinese medicine in Taiwan. Based on a national sample survey, the authors investigated how Chinese medicine is being used and factors that are associated with its use among the Taiwanese. Results of the study suggest that Chinese medicine use among this population depends on health conditions, and that having a regular source of care for Chinese medicine as well as a preference for Chinese medicine are two predictors for its use. Policies on the integration of Chinese medicine or other traditional medicine into the modern healthcare system are recommended.

Adolescent↗
PubMed1996

The practice of Chinese medicine in Taiwan.

This paper examines the practice of Chinese medicine in Taiwan. Using a national sample survey of Chinese medicine physicians, supplemented by another national survey of Chinese medicine hospitals and government records, the authors study the education and training background of Chinese medicine physicians, their mode of practice, their productivity measured by patient visits, and the practice characteristics of Chinese medicine hospitals. Moreover, the authors investigate the relationship between the resource input, the public health insurance contract, and the number of patient visits Chinese medicine physicians provided. Results of this study are used to make several recommendations on the appropriate way of integrating the practice of Chinese medicine into the modern health care system. Many of these recommendations may also be applicable to other countries that are contemplating integrating traditional or alternative medicine into their health care systems.

Adult↗
PubMed1996

Increased release of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha by bronchoalveolar cells lavaged from involved sites in pulmonary tuberculosis.

Mycobacterium tuberculosis and its components have been shown to stimulate mononuclear phagocytes in vitro to release interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6). Animal models of tuberculosis (TB) also demonstrate the presence of cytokines in granulomas. We hypothesized that bronchoalveolar lavage (BAL) cells from patients with pulmonary TB would have increased spontaneous release of IL-1 beta, IL-6, and TNF-alpha and would have a concomitant alveolitis. We performed BAL on 26 patients with active TB and on six normal volunteers. BAL fluid from radiographically involved and uninvolved sites was evaluated separately for cell types and the spontaneous release of cytokines. The alveolar inflammation in involved sites was characterized by an increase in lymphocytes (miliary TB, 38 +/- 10%; involved sites, 22 +/- 4%; uninvolved sites, 13 +/- 2%; normal, 5 +/- 2%) and neutrophils (involved sites, 21 +/- 7%; uninvolved sites, 3 +/- 2%). There was a significant increase in the spontaneous release of IL-1 beta (501 +/- 280 pg/ml), TNF-alpha (782 +/- 165 pg/ml), and IL-6 (473 +/- 157 pg/ml) from involved sites of TB patients that was 5- to 20-fold greater than uninvolved sites, normal controls, or miliary TB. Northern analysis revealed increased gene expression of IL-1 beta, TNF-alpha, and IL-6 from the involved sites from two patients with TB compared with two negative controls. We conclude that BAL cells, especially alveolar macrophages, are activated in the alveolar inflammation of active TB and spontaneously release increased quantities of IL-1 beta, IL-6, and TNF-alpha, and that these cytokines are likely to be involved in directing granuloma formation and control of M. tuberculosis infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Integrating traditional medicine into modern health care systems: examining the role of Chinese medicine in Taiwan.

Since the World Health Organization officially promoted traditional medicine in developing countries in 1978, there have been increasing interests among developing countries in integrating traditional medicine into a national health care system. Most of these policies, however, tend to be the policy of coexistence instead of integration. This paper focuses on the rationale, strategies, and process of integrating traditional medicine into a modern health care system by using the experience of Chinese medicine in Taiwan as an example. After briefly describing the changing roles of Chinese medicine in Taiwan, the author critically reviews the government policies and regulations on Chinese medicine. Research findings and government statistics on the demand and supply of Chinese medicine are also described to provide some insights for developing recommendations for an appropriate integration policy. To effectively integrate traditional medicine into a modern health care system, this paper suggests that such integration should begin at the grass roots level, that is with the training of physicians and practitioners. A successful, integrated health care system would facilitate more efficient use of domestic medical resources, and enhance self-sufficiency in health development for resource poor countries. Integrating traditional medicine into a modern health care system, moreover, can benefit industrialized nations as well. After recommending several strategies for integration, the author proposes a further development of a unified medical system as the final stage of full integration. This unified medical system should be an inclusive medical system, which could help countries to expand the available medical resources.

Delivery of Health Care↗
PubMed1994

Studies on an artificial trypsin inhibitor peptide derived from the mung bean trypsin inhibitor: chemical synthesis, refolding, and crystallographic analysis of its complex with trypsin.

The active fragment with Lys at the reactive site of mung bean trypsin inhibitor (MBILF) is composed of two peptide chains, A1 of 26 residues and A2 of 9 residues linked via two disulfide bonds. In the present study, a peptide of 22 residue comprising the sequence of chain A1 from position 3 to 24 was synthesized by the solid-phase method. This synthetic peptide with six Cys residues contains a reactive site at position Lys11I-Ser12I (I denotes an inhibitor residue). Air oxidation and HPLC purification resulted in two antitrypsin active components, SPC1 and SPC2. Neither SPC1 nor SPC2 can stoichiometrically inhibit trypsin. The Ki values of SPC1 and SPC2 are 1.2 x 10(-7) and 4.0 x 10(-8) M, respectively. The complexes of SPC1 and SPC2 with bovine beta-trypsin (BTRY) were crystallized by ammonium sulphate precipitation at pH 6.4 and 6.0, respectively. The two crystals have the same crystal form with space group P2(1)2(1)2(1) and cell dimension of a = 63.2(2) A, b = 63.5(6) A, and c = 69.8(4) A. The crystal structure of one complex, SPC1-BTRY, was determined and refined at 2.2 A resolution to a final R-value of 19.2%. From the resulting electron density map, 9 residues of SPC1, from position 9I to 17I, were identified clearly and three-dimension atomic model of the 9-residue reactive loop formed by a disulfide bridge, Cys9I-Cys17I, was built. No electron density corresponding to the other 13 residues was observed in the present map.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1993

The 0.25-nm X-ray structure of the Bowman-Birk-type inhibitor from mung bean in ternary complex with porcine trypsin.

The structure of the Bowman-Birk-type inhibitor from mung bean Phaseolus aureus has been determined in ternary complex with porcine trypsin. The complex formed crystals of the trigonal space group P3(1)21 which diffracted to a resolution of 250 pm. Each of the two mung bean protease reactive sites is bound to trypsin according to the standard mechanism for serine proteinase inhibition. The binding loops thereby adopt the canonical conformation for the standard mechanism; however, the sub-van der Waals contact between the active-site serine O gamma (195) and the P1 carbonyl carbon of both loops is significantly smaller (210 pm) than hitherto observed, with continuous electron density connecting the two atoms. The inhibitor is formed by two double-stranded antiparallel beta-sheets, which are connected into a moderately twisted beta-sheet by a network of hydrogen bonds involving main-chain atoms and two water molecules. All contacts with neighbors in the crystal lattice occur between trypsin molecules. This apparently gives rise to an unusual form of disorder where the complexes pack in two orientations Ta:MaMb:Tb and Tb:MbMa:Ta (Ta, Tb = trypsin, Ma = mung bean loop I, Mb = mung bean loop II), such that the asymmetric unit consists of the ternary complex in two orientations, each with half occupancy. This is nearly equivalent to an asymmetric unit which has one trypsin molecule with full occupancy and one mung bean inhibitor with half occupancy and a crystallographic twofold symmetry axis through its center. Because of the approximate twofold symmetry of the inhibitor itself, however, the electron density was interpretable for most of the inhibitor (17 residues at the termini were not resolved) and shows evidence of its double orientation.

Animals↗
PubMed1991

[Distribution and activity regularities of medicinal Mojiang centipedes in Yunnan Province].

A study has been made on the distribution, living environment and behavior characteristics of medicinal Mojiang centipedes in Yunnan Province. The result has shown they are active between mid-March and late October every year. During this time, the temperature is 18-23 degrees C, moisture 75-85 percent, precipitation 50-280mm, sunshine 115-225 hours and evaporation 100-200mm.

Animals↗
PubMed1990

Signal averaging in real ear probe tube measurements.

In this study, signal averaging measurements were performed using a broadband noise as the test signal in two acoustic environments typifying relatively noisy situations in which real ear probe tube measurements are made clinically. The minimum time-domain signal averaging required to reduce the degrading effects of background noise to levels acceptable for the production of valid real ear unaided responses (REURs) was established for three normal listeners at various signal-to-noise (S/N) ratios. Generally, averaging was not required at S/Ns of 20 dB or higher. Acceptable responses were obtained at S/Ns as low as -5 dB when the number of averages was increased to 256 and higher. The function derived from the data in the two acoustic environments was in good agreement with a theoretical rule. Findings suggest that averaging of only a few sweeps of the test signal is required to obtain reliable and valid real ear measurements, even in somewhat noisy test environments. With a knowledge of the levels of the test signal and the background noise, data from this study can be used to determine the requisite number of signal sweeps to be averaged in acquiring real ear responses in a minimum amount of time.

Acoustics↗
PubMed1981

Lanthanum and freeze fracture studies on the retinular cell junction in the compound eye of the housefly.

The retinular (R) cell junction between adjacent photoreceptor cells in the house-fly ommatidium was characterized by freeze fracture, thin section and tracer (lanthanum) studies. Focal tight junctions occur between cells, and some P face ridge-E face groove correspondences are present in this intramembranal area. When colloidal lanthanum was introduced into the extracellular space (ECS) of the peripheral retina of the housefly, this electron-dense tracer moved from the ECS (extra-ommatidial space), through the R-cell junctions and belt desmosomes, into the ommatidial cavity (OC = intrarhabdomal space) of each ommatidium. In the OC, lanthanum outlined a meshwork structure that pervaded this space. The evidence of this tracer movement suggests that there may be ionic continuity between the "traditional" ECS and the fluid bathing the individual rhabdomeres. The volume of the OC is calculated and we suggest that this space is part of the ECS. The functional implications of this postulate are considered in the light of: (1) the different functions of the peripheral and central cells; (2) the dissimilarity of rhabdomal membrane surface facing the OC compared to the "unmodified" plasma membrane of the photoreceptor cell facing the extra-ommatidial cavity; (3) the permeability properties of the R cell junction; and (4) the total ECS containing an ion store capable of sustaining current for the generator potential.

Animals↗
PubMed1981

The perineurium of the adult housefly: ultrastructure and permeability to lanthanum.

The ultrastructure of the perineurial cells of Musca overlying the first optic neuropile was examined by transmission electron microscopy. These cells are somewhat similar to those of other insects but cytoplasmic flanges seem to be absent, and mitochondria are relatively large and sinuous. The intercellular channel system on the lateral border of the cells is relatively spacious and highly meandering. Perineurial cells are joined by septate, gap, and tight junctions, hemidesmosomes, and desmosomes. Tight and septate junctions bond perineurial cells and glial cells. These data are evaluated on the basis of tracer studies with lanthanum. This material penetrates the extracellular space between perineurium and underlying glial and nerve cells, between epithelial glial cells and retinular axon terminals (capitate projections), and between the alpha-beta fiber pair in the optic cartridge (gnarls). If no damage occurs to the perineurial cells during tissue preparation, this passage of lanthanum to neuronal surfaces indicates that the blood brain barrier is incomplete in this restricted area. Supportive evidence for such permeance is based on electrophysiological data, considerations of membrane specializations in the optic neuropile, and Na+/K+ ratios of dipteran hemolymph.

Animals↗
PubMed1980

Membrane specializations in the first optic neuropil of the housefly, Musca domestica L. I. Junctions between neurons.

Thin section and freeze-fracture replicas of the first optic neuropil (lamina ganglionaris) of the fly Musca were studied to determine the types, extent and location of membrane specializations between neurons. Five junctional types are found, exclusive of chemical synapses. These are gap, tight and septate junctions, close appositions between retinular (R) axons and capitate projections (in which an epithelial glial cell invaginates into an R axon). Junctional types and their cellular associations follow: gap junctions, between lamina (L) interneurons, L1-L2; tight junctions, between L1-L2; L3-L4; L4-epithelial glial cell; and R7-R8. Septate junctions, between L1-L2, L3-L4, L3-beta, L4-beta, alpha-beta, and an unidentified fibre making septate junctions with L1 and L2. Close appositions are found between R axons in the distal portion of the optic cartridges of this neuropil prior to extensive R chemical synapses with L1, L2. These loci (seen in freeze-fracture replicas) have rhomboidal patches of hexagonally arrayed P face particles. Intermembranous clefts between R axons are about 50 A and are invariably electron lucent. These points of near contact between R terminals are probably the sites of low electrical resistance measured by Shaw (1979). Capitate projections are for the first time revealed in freeze fracture surfaces. Here epithelial glia send many, short, mushroom-shaped processes invaginating into R axons forming a tenacious structural bond. All four membrane leaflets (P and E faces of R axon and glial membrane) in the capitate projection possess particles in higher densities than in the surrounding nonspecialized regions. The known, general functions of each membrane specialization were correlated with the functional capacities of those lamina neurons possessing them in an effort to interpret better the integrative capacity of this neuropil. These data provide some fine structural bases for a putative 'blood-brain' barrier between lamina and haemolymph, between lamina and peripheral retina, and possibly between lamina and second optic neuropil.

Animals↗
PubMed1980

Membrane specializations in the first optic neuropil of the housefly, Musca domestica L. II. Junctions between glial cells.

Membrane specializations between the three types of glial cells in the first optic neuropil (lamina ganglionaris) of the housefly were determined from thin sections and freeze-fracture replicas. Three strata of glia cells are present in the lamina. A relatively thin layer of satellite glia covers the distal (perikaryal) rind of the lamina and these cells wrap retinular axons that enter the lamina. The central synaptic fields of the lamina neurons are enclosed by epithelial glia, while the proximal surface of the lamina is capped by marginal glial cells. Satellite glia bond to each other via desmosomes, septate and gap junctions. Freeze-fracture replicas show gap junctions as aggregations of E face particles and P face pits on the intramembranous surfaces. Parallel rows of P face particles are indicative of septate junctions. Angulated, intersecting, P face particle ridges are arranged in circumferential bands around retinular axons at the glia-axon interface. Thin section correlates of these junctions are presented. Epithelial glia are characterized by elaborate series of parallel membranes which appear to be suspended in the cytoplasm but may be the invaginated plasma membranes of a neighbouring glial cell. An intermembranous cleft of 40-50 A is noted and this area has an appreciable electron density which give the appearance of a gap junction. When cleaved, these membranes show plaques of particles on the P face. The marginal glial cells are relatively large and are joined by a newly discovered junction which is characterized (from freeze-fracture data) by numerous, undulating, uninterrupted, parallel P face ridges which sometimes become circular and form enclosures. In thin section, electron-dense material fills the membrane appositional areas and in tangential sections faint diffuse parallel striae are seen. This specialized cell contact may be a variant of a continuous junction although, based on fracture replicas, there are obvious similarities to tight junctions. These membranes specializations are related, in the three dimensions of the optic cartridges, to functions in a possible blood-eye barrier system.

Animals↗
PubMed1979

Membrane specializations in the peripheral retina of the housefly Musca domestica L.

Membrane specializations of the peripheral retina of the housefly (Musca domestica) are revealed in thin sections and freeze fracture/etch replicas. Septate junctions are abundant in corner areas of the pseudocone enclosure bonding: between homologous corneal pigment cells (CPC); between homologous large pigment cells (LPC); between CPC-LPC; between Semper cells (SC); between SC-CPC. Spot desmosomes are present between Semper cells. It is likely that septate junctions function as strengthening adhesions in this area. A new membrane specialization similar to a continuous junction was observed between retinular cells of the same or adjacent ommatidium. This junction has indistinct septa in the 115 A intermembrane cleft and is intermittent in character. When this junction is absent, the apposed cells gape apart. In freeze fracture studies, this junction is characterized by bridges composed of fused membrane particles and randomly arranged particles on the P face, and noncorresponding grooves on the E face. The ridges are elongate and roughly parallel and sometimes they form enclosures. Mitochondria line up along these junctions, often within 90 A of the unit membrane. This membrane specialization has characteristics of tight and continuous junctions. In line with previous findings, we suggest that this junction assists in retinular cell orientation, possibly in enforcing the ommatidial twist and in maintaining localized ionic concentration gradients between retinular cells.

Animals↗