Search PubMed⌕ Search

Biomedical subjects

Y Chang

Publications and source records attributed to Y Chang.

At least 235 records · Page 13Linked to original sources
PubMed1996

Clinical and experimental studies on the treatment of senile constipation with shenshen wan.

From August 1988 through February 1991, we have successfully treated 400 cases of senile constipation with self-made Shenshen Wan with a total effective rate of 98%. A group of patients taking Maren Wan served as controls. Clinical practice has proved that Shenshen Wan can not only relax the bowels, but also improve renal function. Furthermore, no side effects whatever were observed after a prolonged administration of the pills.

Aged↗
PubMed1995

Ceramide formation during heat shock: a potential mediator of alpha B-crystallin transcription.

Ceramide has been identified as a potential second messenger that may mediate cell differentiation and apoptosis after exposure to hormonal agonists such as 1 alpha, 25-dihydroxyvitamin D3, tumor necrosis factor alpha, or gamma-interferon. The secondary cellular events that follow ceramide generation remain undefined. We report that in NIH WT-3T3 cells, ceramide induces an enhancement of gene transcription of alpha B-crystallin, a small heat shock protein. The levels of alpha B-crystallin, as measured by Northern blot and immunoblot analyses, were increased by the addition of an exogenous short-chain ceramide, N-acetylsphingosine, or by increasing endogenous intracellular ceramide by inhibition of glucosylceramide synthase. Similar effects were not seen in the expression of the closely related gene, Hsp25. To ascertain whether ceramide-mediated gene transcription was a feature of the heat shock response, cell ceramide was measured in heat shocked cells and observed to be elevated 2-fold immediately upon the return of cells to 37 degrees C. Thus ceramide formed after heat shock treatment of 3T3 cells may mediate the transcription events associated with the cell stress response.

3T3 Cells↗
PubMed1995

Toward an optimal algorithm for ovarian cancer screening with longitudinal tumor markers.

Stored samples from women in the Stockholm screening study were reassayed for CA125II (Centocor, Malvern, PA) and OVX1. The postmenopausal women older than age 50 without ovarian cancer were randomly split into a training set to develop a screening test based on longitudinal marker levels and a second set to validate the test. The CA125II data from each woman is summarized by the slope and intercept from a linear regression of log(CA125II) on time since first sample. The slope versus the intercept for the training set and the ovarian cancer cases formed a bivariate scatter plot. A curve was drawn on the scatter plot that separated most of the women with ovarian cancer from all other women; it delineated a screening test. The specificity of this test was examined on the validation set with a specificity of 99.8%. Bayes' theorem was used to calculate the risk of ovarian cancer (ROC) based on the intercept, slope, and assay variability. It is important to account for assay variability because it can produce large slopes over short periods of time. The maximum risk, which identified 83% (5 of 6) of the ovarian cancers detected within a year of last assay, was applied as a test to the training set and confirmed a high specificity of 99.7%. With this specificity and sensitivity, the ROC algorithm using the CA125II assay has an estimated positive predictive value of 16%, substantially greater than the positive predictive value based on a single assay. Further study is planned to confirm the sensitivity of this approach.

Aged↗
PubMed1995

In vitro establishment and characterization of two acquired immunodeficiency syndrome-related lymphoma cell lines (BC-1 and BC-2) containing Kaposi's sarcoma-associated herpesvirus-like (KSHV) DNA sequences.

Two unique DNA fragments were recently identified in over 90% of acquired immunodeficiency syndrome (AIDS)-related Kaposi's sarcoma tissues. Sequence analysis suggests that these fragments belong to a previously unidentified human herpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV). These fragments have also been identified in a subset of non-Hodgkin's lymphomas in human immunodeficiency virus-positive patients; specifically, in body cavity-based lymphomas (AIDS-BCBLs). We have established two cell lines derived from AIDS-BCBLs, BC-1 and BC-2, which retain the KSHV sequences, and have used them to further characterize this putative viral genome. In this report, we demonstrate that the KSHV sequences represent a portion of a much larger DNA molecule that is located predominantly in the nucleus of the infected cells. In situ hybridization of metaphase spreads made from both of these cell lines show these sequences in episomal structures. Their presence in the cells as large nuclear episomes supports previous sequence homology data suggesting that KSHV belongs to the herpesvirus family. These cell lines provide a continuous source of KSHV sequences. Thus, they represent an important tool for future studies of this recently described human herpesvirus that may be involved in the pathogenesis of Kaposi's sarcoma and some AIDS-related non-Hodgkin's lymphomas.

Base Sequence↗
PubMed1995

Characteristics of nonsmoking women in NHANES I and NHANES I epidemiologic follow-up study with exposure to spouses who smoke.

Few studies have examined the relation between passive smoking and dietary intake in a large population. This report examines the nutrition and behavioral characteristics of 3,896 nonsmoking women from the first National Health and Nutrition Examination Survey (NHANES I) population in relation to exposure to environmental tobacco smoke. The data indicate that nonsmoking women who were exposed to husbands who smoked were more likely to be older, have lower education, live in the city, and have other health behaviors that could increase their risk of lung cancer compared with nonsmoking women with husbands who did not smoke. The nonexposed women were more likely to take vitamin supplements, to not drink alcohol, and to consume higher levels of dietary vitamin A, vitamin C, and calcium. The exposed and nonexposed women showed no difference in the levels of fatty acid intake nor in the levels of several other foods from the food frequency list after correction for age. Many of the differences that the authors observed between the women who were exposed and nonexposed to passive smoking could affect the risk of cancer. Therefore, they recommend that future studies of nonsmokers examine the influence of both passive smoking and diet on the risk of disease rather than examine the influence of a single factor.

Adult↗
PubMed1995

Detection of herpesvirus-like DNA sequences in Kaposi's sarcoma in patients with and those without HIV infection.

BACKGROUND: Herpesvirus-like DNA sequences have recently been found in lesions from patients with Kaposi's sarcoma and the acquired immunodeficiency syndrome (AIDS). It is not known whether these sequences are also present in classic Kaposi's sarcoma or in the Kaposi's sarcoma that occurs in homosexual men who are seronegative for the human immunodeficiency virus (HIV). METHODS: We analyzed DNA in tissue samples from patients with AIDS-associated Kaposi's sarcoma, patients with classic Kaposi's sarcoma, and HIV-seronegative homosexual men with Kaposi's sarcoma. We also analyzed DNA in samples of uninvolved tissue from these patients and in control tissue from healthy subjects. All samples were tested blindly by polymerase chain reaction (PCR) with specific primers to amplify KS330(233), a herpesvirus-like DNA sequence. RESULTS: The KS330(233) PCR product was found in 20 of 21 tissue samples (95 percent) from the patients with Kaposi's sarcoma, including 10 of the 11 samples from the patients with AIDS-associated Kaposi's sarcoma, all 6 samples from the patients with classic Kaposi's sarcoma, and all 4 samples from the HIV-negative homosexual men with Kaposi's sarcoma. Only 1 of the 21 control samples (5 percent) was positive (odds ratio, 400; 95 percent confidence interval, 19 to 17,300). Of the 14 samples of uninvolved skin from the patients with Kaposi's sarcoma, 3 were positive for KS330(233). Representative PCR-product sequences were more than 98 percent identical for the three types of Kaposi's sarcoma, suggesting that all three are caused by the same agent. CONCLUSIONS: The same herpesvirus-like DNA sequences are present in AIDS-associated Kaposi's sarcoma, classic Kaposi's sarcoma, and the Kaposi's sarcoma that occurs in HIV-negative homosexual men. Therefore, this presumably new human herpesvirus is not solely an opportunistic infection in patients with AIDS, and the three forms of Kaposi's sarcoma may be caused by the same infectious agent.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Kaposi's sarcoma-associated herpesvirus-like DNA sequences in AIDS-related body-cavity-based lymphomas.

BACKGROUND: DNA fragments that appeared to belong to an unidentified human herpesvirus were recently found in more than 90 percent of Kaposi's sarcoma lesions associated with the acquired immunodeficiency syndrome (AIDS). These fragments were also found in 6 of 39 tissue samples without Kaposi's sarcoma, including 3 malignant lymphomas, from patients with AIDS, but not in samples from patients without AIDS. METHODS: We examined the DNA of 193 lymphomas from 42 patients with AIDS and 151 patients who did not have AIDS. We searched the DNA for sequences of Kaposi's sarcoma-associated herpesvirus (KSHV) by Southern blot hybridization, the polymerase chain reaction (PCR), or both. The PCR products in the positive samples were sequences and compared with the KSHV sequences in Kaposi's sarcoma tissues from patients with AIDS. RESULTS: KSHV sequences were identified in eight lymphomas in patients infected with the human immunodeficiency virus. All eight, and only these eight, were body-cavity-based lymphomas--that is, they were characterized by pleural, pericardial, or peritoneal lymphomatous effusions. All eight lymphomas also contained the Epstein-Barr viral genome. KSHV sequences were not found in the other 185 lymphomas. KSHV sequences were 40 to 80 times more abundant in the body-cavity-based lymphomas than in the Kaposi's sarcoma lesions. A high degree of conservation of KSHV sequences in Kaposi's sarcoma and in the eight lymphomas suggests the presence of the same agent in both lesions. CONCLUSIONS: The recently discovered KSHV DNA sequences occur in an unusual subgroup of AIDS-related B-cell lymphomas, but not in any other lymphoid neoplasm studied thus far. Our finding strongly suggests that a novel herpesvirus has a pathogenic role in AIDS-related body-cavity-based lymphomas.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Cell cycle arrest induced by an inhibitor of glucosylceramide synthase. Correlation with cyclin-dependent kinases.

In an attempt to define the basis for sphingolipid regulation of cell proliferation, we studied the effects of glucosylceramide (GlcCer) synthase inhibition by threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) on NIH 3T3 cells overexpressing insulin-like growth factor-1 (IGF-1) receptor. PDMP treatment resulted in a time-dependent decrease in GlcCer levels and an increase in cellular ceramide levels. PDMP abolished serum and IGF-1-stimulated cell proliferation, as measured by a reduction in [3H]thymidine incorporation, protein, and DNA levels. However it did not affect IGF-1-mediated early signaling events, including receptor tyrosine kinase, MAP kinase, and phosphatidylinositol 3-kinase activities. Two-color flow cytometry with propidium iodide and 5-bromo-2'-deoxyuridine monophosphate labeling revealed an arrest of the cell cycle at G1/S and G2/M transitions in an asynchronous population of cells. These changes were time dependent, with maximal effects seen by 12-24 h. Removal of PDMP from the cell medium resulted in reversal of the cell cycle changes, with cells re-entering the S phase. The cell cycle arrest at the G1/S and G2/M transitions was confirmed in cells synchronized by pretreatment with nocodazole, aphidicolin, or hydroxyurea, and released from blockade in the presence of PDMP. A decrease in the activities of two cyclin-dependent kinases, p34cdc2 kinase and cdk2 kinase, was observed with PDMP treatment. When cell ceramide levels were increased by N-acetylsphingosine, comparable changes in the cell cycle distribution were seen. However, sphingomyelinase treatment was without effect. Therefore, it appears that ceramide mediates in part the inhibitory effect of GlcCer synthase inhibition on IGF-1-induced cell proliferation in 3T3 cells. The rapid production of decreased cyclin-dependent kinase activities by PDMP suggests that one of the crucial sites of action of the inhibitor lies in this area.

3T3 Cells↗
PubMed1995

Distribution of medical insurance in China.

This paper investigates factors related to the distribution of medical insurance coverage in China, using information from an eight-province household survey of almost 16,000 individuals, conducted in 1989. Results of bivariate analyses show that medical insurance coverage, defined very broadly, varies considerably by individual and regional characteristics. Age, gender, education, occupation, employment sector, urbanization, level of industrial and commercial development, and province are all related to being insured or not. In addition, we find that the type of insurance program available to people varies by these same factors, and that the benefits provided by the seemingly uniform public and worker programs also vary, especially by province and degree of urban development. When the individual and regional variables are considered together in logistic regression analyses, the factors most strongly statistically related to the likelihood of being insured are where one works and where one lives. The distribution of insurance benefits in China appears to result in a pattern in which the rural and the poor, who are often at great risk of illness, are less likely to have medical insurance.

Adolescent↗
PubMed1995

Development of B cells in scid mice with immunoglobulin transgenes: implications for the control of V(D)J recombination.

The inability of scid pro-B cells to progress to the pre-B and B cell stages is believed to be caused by a defective recombinase activity that fails to resolve chromosomal breaks resulting from attempted V(D)J recombination. In support of this model, we report that certain immunoglobulin transgenes, specifically those which strongly inhibit endogenous VH-to-DJH and V kappa-to-J kappa rearrangement in wild-type mice, allow scid pro-B cells to progress to the pre-B and B cell stages. This rescue of scid B cell differentiation is associated with a dramatic reduction in expression of the recombination activation genes, RAG1 and RAG2, and with reduced transcription of the kappa locus.

Animals↗
PubMed1995

Benign prostatic hyperplasia specific health status measures in clinical research: how much change in the American Urological Association symptom index and the benign prostatic hyperplasia impact index is perceptible to patients?

PURPOSE: We assessed the relationship between changes in scores for the American Urological Association (AUA) symptom index and benign prostatic hyperplasia (BPH) impact index with patient global ratings of improvement in a large Veterans Affairs trial comparing different pharmacological therapies for BPH. MATERIALS AND METHODS: The primary analyses compared absolute score changes from baseline with global ratings of improvement at 13 weeks for 1,218 men. RESULTS: Subjects who rated themselves as being slightly improved had a mean decrease in AUA symptom index and BPH impact index scores of 3.1 and 0.4 points, respectively. However, the baseline scores strongly influenced this relationship. CONCLUSIONS: These data provide guidance for investigators using the AUA symptom index and BPH impact index as outcome measures.

Health Status↗
PubMed1995

The American Urological Association symptom index: does mode of administration affect its psychometric properties?

PURPOSE: We determine whether self-administration and interviewer administration of the American Urological Association (AUA) symptom index are equivalent. MATERIALS AND METHODS: The AUA symptom index was administered twice to 41 visually impaired or illiterate men. Men who were able were randomized to self-administration first and then interviewer administration (43) or the reverse (40). RESULTS: The scores in each group were reliable. However, because we could not reject a differential carryover effect, the nonsignificant test of mode effect in the crossover design may have been invalid. At time 1 there was no significant difference between group mean scores for randomized patients (p = 0.13). CONCLUSIONS: Although the AUA symptom index should be self-administered when possible, interviewer administration appears to be acceptable.

Aged↗
PubMed1995

Zinc is a mixed antagonist of homomeric rho 1 gamma-aminobutyric acid-activated channels.

The transition metal Zn2+ is differentially distributed in the central nervous system, where it is proposed to be a neuromodulator. One of the documented effects of Zn2+ is the antagonism of gamma-aminobutyric acid (GABA)-mediated synaptic inhibition. This antagonism is presumed to result from a direct interaction of Zn2+ with the GABA receptor/ionophore complex, although the characteristics of Zn2+ sensitivity are dependent on the particular GABA subunit combination. In this study, we examined the effects of Zn2+ on homomeric rho 1 GABA-activated channels expressed in Xenopus oocytes. Zn2+ was found to be a mixed antagonist of these recombinant rho 1 GABA receptors. The antagonism was predominantly competitive at low Zn2+ concentrations (< or = 100 microM), whereas at high Zn2+ concentrations (> 100 microM) a noncompetitive antagonism was apparent. Evidence is presented showing that the antagonism was not due to an interaction of GABA and Zn2+ in solution but, rather, resulted from interactions of these two ligands with the GABA-activated channel. A mechanism is proposed for Zn(2+)-mediated antagonism in which GABA and Zn2+ bind to distinct sites on the GABA complex. The apparent mixed antagonism may arise from different Ki values for the binding of Zn2+ to non-agonist-bound or agonist-bound receptors. However, two distinct Zn2+ binding sites, one competitive and one noncompetitive, could also give rise to the dual antagonism.

Animals↗
PubMed1994

Identification of herpesvirus-like DNA sequences in AIDS-associated Kaposi's sarcoma.

Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Effects of nerve segment supernatants on cultured Schwann cell proliferation and laminin production.

Mouse sciatic nerves were transected and 3 hr to 16 days later proximal segments were removed and homogenized. Supernatants of these segments or of normal sciatic nerves were added to Schwann cells maintained in Dulbecco's modified Eagle's medium (DMEM) + 15% fetal calf serum (FCS). After 6 days, Schwann cells were solubilized and the protein content was measured using a Bio-Rad (Melville, NY) protein assay. Samples containing the same amounts of protein were then applied to microtiter plates and the laminin content was determined by enzyme-linked immunosorbent assay (ELISA). Lysates of cultures treated with 24 hr proximal segment supernatants contained significantly higher levels of laminin than those prepared from other intervals, from distal segments, or from control nerves. Increased surface and cytoplasmic anti-laminin immunoreactivity also was found in Schwann cells treated with 24 hr supernatants. To identify the source(s) of this effect, proximal segments removed 24 hr after transection were bisected; supernatants were prepared from each half and tested. Significant increases in laminin production were produced by supernatants from both halves. When supernatants from proximal and distal halves were compared, the latter produced significantly higher laminin levels. Electron microscopic examination of both halves showed that distal halves contained sprouting neurites and growth cones ensheathed by Schwann cells which had a basal lamina and resembled those seen during development and regeneration. Proximal halves appeared normal. Schwann cell proliferation also was compared in supernatant-treated cultures by using a bromodeoxy-uridine (BrdU) ELISA. The 24 hr and 2 day supernatants increased Schwann cell proliferation significantly; 12 hr, 4 day, and 8 day supernatants produced smaller increases. Our observations suggest that axons undergoing early regenerative changes are one of several possible sources of substance(s) in our proximal segment supernatants which increased Schwann cell proliferation and laminin production.

Animals↗