Biomedical subjects

J Y Chang

Publications and source records attributed to J Y Chang.

At least 91 records · Page 5Linked to original sources

PubMed1996

Herpes simplex virus gene expression in neurons: viral DNA synthesis is a critical regulatory event in the branch point between the lytic and latent pathways.

Herpes simplex virus establishes a latent infection in peripheral neurons. We examined viral gene expression in rat peripheral neurons in vitro and determined that viral gene expression is attenuated and delayed in these neurons compared with that in Vero cells. In addition, using pharmacologic and genetic blocks to viral DNA synthesis, we found that viral alpha and beta gene expression was upregulated by viral DNA synthesis. Although maximal gene expression in neurons requires viral DNA synthetic activity, activation of viral gene expression was seen even in the presence of herpes simplex virus DNA polymerase inhibitors, but not in the absence of the origin-binding protein. Initiation of viral DNA synthesis is apparently a key regulatory event in the balance between the lytic and latent pathways in peripheral neurons.

Animals↗

PubMed1996

Factor VIIa-tissue factor interactions: an evaluation using factor VII-factor IX chimeras.

Using molecular biological techniques, a series of factor VII-factor IX chimeric molecules were made for both kinetic and competition binding assays to tissue factor in order to understand the interaction between factor VIIa and tissue factor. The results of the binding studies indicated that the major interaction between factor VIIa and tissue factor. The results of the binding studies indicated that the major interaction between factor VIIa and tissue factor involved both the first epidermal growth factor-like (EGF1) and catalytic domains of factor VII. In addition, both the gamma-carboxyglutamic acid-containing (Gla) and EGF2 domains also play a minor role in binding to tissue factor. The Gla and EGF-2 domain might either impart structure to the rest of the molecule or contribute a relatively small amount of energy to direct binding.

Binding, Competitive↗

PubMed1996

Allogeneic bone marrow transplantation for fourteen patients with severe aplastic anemia.

BACKGROUND: Bone marrow transplantation (BMT) is the best curative approach for younger patients with severe aplastic anemia (SAA). Major obstacles to success of allogeneic BMT include graft-versus-host disease (GVHD), graft rejection and treatment related toxicities. Experience with 14 SAA patients who received BMT is reported here. METHODS: From December 1986 to May 1995, 14 patients with SAA were treated with BMT; 13 were allogeneic, and 1 was syngeneic. There were nine males and five females whose average age was 24.7 years (range 15-36 years). The median pretransplant disease duration was 93 days (range 7-610 days). Five patients were nontransfused before BMT. The pretransplant conditioning regimen consisted of 200 mg/kg cyclophosphamide (CY) intravenously, divided over four consecutive days, followed by 300 cGy total-body irradiation (TBI) on the day before BMT. Two untransfused, one transfused patient and one syngeneic transplant received CY only as preconditioning. For GVHD prophylaxis, the 13 patients were given a combination of cyclosporine and a short course of methotrexate. RESULTS: Of the 14 patients, 11 were still alive 10 to 90 months later, with functional engraftment; the median survival of 39 months. There were three deaths including one with primary graft failure with intracranial hemorrhage, and two with delayed graft rejection and sepsis. The patient who received syngeneic BMT developed late graft failure six months post-transplant, but was successfully treated with a second BMT. Acute GVHD occurred among 5 of the 13 engrafted patients, only one of whom was Grade III clinically. Chronic GVHD was observed in 2 out of 10 evaluable patients. CONCLUSIONS: The combination of CY and TBI is an effective, well-tolerated conditioning regimen for BMT in patients with SAA. The acute GVHD rate was low in our patients receiving cyclosporine. BMT is the treatment-of-choice for patients under the age of 40 with SAA, for those with human leucocyte antigen (HLA)-identical siblings or an identical twin and particularly for those patients who have not received transfusion.

Adolescent↗

PubMed1996

The effect of "chi-han (hot nature)" Chinese herbs on the secretion of IL-1 beta and TNF-alpha by mononuclear cells.

The effect of "chi-han (hot nature)" Chinese herbs on the secretion of the cytokines IL-1 beta and TNF-alpha was investigated by studying the in vitro effect of the "hot nature" Chinese herbs Radix aconiti, Evodia rutaecarpa, Zingiberis rhizoma, and Cortex cinnamomi. An ethanolic extract of each of these Chinese medicinal herbs was added to human peripheral mononuclear cell culture medium and allowed to react for various specified lengths of time. The culture medium supernatants were collected and tested for their cytokine levels at specified time intervals. We found different reaction patterns of cytokine secretion among these "hot nature" Chinese herbs. Radix aconiti extract showed an augmentative effect on the secretion of cytokines IL-1 beta and TNF-alpha with 20% to 50% concentrations of the pure herbal extract, especially when the reaction time was 18 or 24 hours. Evodia rutaecarpa extract showed a biphasic effect on the secretion of IL-1 beta and TNF-alpha when the reaction time was 18 or 24 hours. The secretion of cytokines was stimulated by low concentrations of the herbal extract, but inhibited by higher concentrations of the extract. Zingiberis rhizoma extract also showed a biphasic effect on the secretion of cytokine IL-1 beta when the reaction time was 18 or 24 hours. As for Cortex cinnamomi extract, no significant augmentative effect on cytokine secretion was found in our study. In consideration of the pyrogenic property of cytokines, it would appear that "hot nature" Chinese herbs can be further divided into different subgroups with minute differences based on their different effects on cytokine secretion.

Dose-Response Relationship, Drug↗

PubMed1996

Examination of pericardial effusions by cytology and immunocytochemistry.

BACKGROUND: Cytologic examination of pericardial effusions (PE) has been uncommonly reported in the literature. Fewer reports have studied the role of immunocytochemistry in diagnosis of PE. We described our experience, according to cytologic examination and immunocyto-chemical staining of PE. METHODS: Over a four-year period, 50 PE specimens from 36 patients were examined cytologically by Wright-Giemsa stain and/or Papanicolaou stain, at Tri-Service General Hospital. Immunocytochemical stainings were further performed to ensure the cell nature. RESULTS: Eighteen of these patients had benign etiologies; the others suffered from malignant diseases. Sixteen cases, including eight benign and eight malignant, received pericardial biopsy for comparison. Commonly encountered cells in PE with any kind of etiology included neutrophils, lymphocytes macrophages and mesothelial cells. Cancer cells were additionally seen in malignant PE, but not in all cases with cancers. Furthermore, reactive mesothelial cells and macrophages were sometimes not easily distinguished from cancer cells, and reactive lymphocytes frequently mimicked hematopoietic malignancies. Further, the nature of small round tumor cells can hardly be ensured by morphologic examination only. Immunocytochemical studies were successfully used to solve these dilemmas in some suspicious cases. CONCLUSIONS: This study showed that cytology together with clinical information and immunocytochemistry can achieve excellent sensitivity and specificity in identification of malignant PE. The use of immunocytochemistry can even ensure the nature of certain cancers such as small cell carcinoma and B cell lymphoma.

Adult↗

PubMed1995

The properties of scrambled hirudins.

Scrambled hirudins serve as relevant folding intermediates during in vitro renaturation of the reduced/denatured hirudin. Eleven species of scrambled hirudins were isolated and structurally identified. Their properties, including their relative stability and the kinetics of their consolidation (disulfide reshuffling) to attain the native structure, have been investigated and are reported here.

Chromatography, High Pressure Liquid↗

PubMed1995

The roles of factor VII's structural domains in tissue factor binding.

Factor VIIa binds to tissue factor in one of the initial steps of blood clotting. In order to determine the role of the various domains of the factor VII molecule in this interaction, we made several chimeric factor VII proteins using recombinant DNA techniques. The molecules have factor IX domains substituted into factor VII and vice versa. The domains exchanged were the 4-carboxyglutamic acid plus aromatic stack domain (gla), the first epidermal growth factor-like domain (Egf-1), the second epidermal growth factor-like domain (Egf-2), and the catalytic domain. Using tissue factor-coated microtiter wells, competition binding studies with 125I-labeled factor VIIa indicated factor VIIa's Kd is 4.2 nM. Employing the same microtiter plate assay, koff and kon were determined and yielded a Kd of 1.5 nM. The results of competitive binding experiments and activation assays using chimeric proteins indicated the interaction between factor VIIa and tissue factor involves direct contact between tissue factor and factor VIIa's Egf-1 domain and catalytic domain. On the other hand, the gla and Egf-2 domains, while necessary for optimal binding, may merely impart structure to the rest of the molecule. However, either one or both of the latter domains might contribute a relatively small amount of energy to direct binding.

Binding, Competitive↗

PubMed1995

Size of hirudin sequence required to fold into an active core domain.

The active core domain of hirudin contains three native disulfides (Cys6-Cys14,Cys16-Cys28, and Cys22-Cys39) and 49 amino acid residues (Hir1-49). This compact structure folds spontaneously, and its folding pathway has been elucidated recently [Chatrenet and Chang (1993) J. Biol. Chem. 268, 20988-20996]. The folding mechanisms of Hir1-35 and Hir1-43 were investigated in order to determine the minimum structural elements required to fold into this active core structure. Hir1-35 includes two native disulfides (Cys6-Cys14 and Cys16-Cys28) and an extra Cys22. When reduced/denatured Hir1-35 was allowed to fold, it folded into a collection of equilibrated 2-disulfide isomers. At least eight fractions of the 2-disulfide species have been observed. Structural analysis revealed that out of the 10 possible disulfide pairings, only five were detected to exist in the 2-disulfide isomers, and all have their half-cystines separated by less than 8-10 amino acid residues. One of the native disulfides, Cys16-Cys28, has not been found in any of those 2-disulfide species. On the other hand, the C-terminal extension of an octapeptide permitted reduced/denaturated Hir1-43 to fold into a defined active structure possessing the three native disulfides. These results also demonstrate that the folding mechanism of Hir1-35 resembles what occurs during the early stage of Hir1-43 (and Hir1-49) folding, which involves a process of nonspecific packing of unfolded polypeptide chains.

Amino Acid Sequence↗

PubMed1995

The effect of Chinese medicinal herb Zingiberis rhizoma extract on cytokine secretion by human peripheral blood mononuclear cells.

The ethanolic extract of the Chinese medicinal herb Zingiberis rhizoma, the rhizome of Zingiber officinale Roscoe (Zingiberaceae), was found to show biphasic effects on secretion of cytokines by human peripheral blood mononuclear cells in vitro. In this study, the augmentative effect of Zingiberis rhizoma extract on cytokine secretion was shown to be time dependent. No significant secretion of cytokine was noted when the reaction time was 1 or 3 h. Secretion of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the mononuclear cells was markedly increased in the presence of a low concentration of Zingiberis rhizoma extract, varying from 10-30 mg/ml, when the reaction time was 18 or 24 h. A higher concentration of the herbal extract did not show similar or stronger augmentative effect as did low concentration of the herbal extract.

Cytokines↗

PubMed1995

The disulfide structures of scrambled hirudins.

Scrambled hirudins consist of a collection of equilibrated isomers and serve as essential folding intermediates during the in vitro renaturation of hirudin (Chatrenet, B., and Chang, J.-Y. (1993) J. Biol. Chem. 268, 20988-20996). Ten fractions of scrambled hirudins have been isolated. Their disulfide structures were deduced from the analysis of thermolysin-digested peptides by amino acid sequencing and mass spectrometry. The results reveal 9 fractions of pure scrambled species, and, together, 11 species of scrambled structures have been identified. About all possible disulfide isomers of hirudin have been found to exist. The three native disulfides, Cys6-Cys14, Cys16-Cys28, and Cys22-Cys39, are detected in five different scrambled species and constitute 18% of the total disulfide bonds found in scrambled hirudins.

Amino Acid Sequence↗

PubMed1995

The disulfide folding pathway of human epidermal growth factor.

Human epidermal growth factor (EGF) contains three disulfides and 53 amino acids. Reduced/denatured EGF refolds spontaneously in vitro to acquire its native structure. The mechanism of this folding process has been elucidated by structural analysis of both acid and iodoacetate trapped intermediates. The results reveal that the folding is accompanied by a sequential flow of unfolded EGF (0-disulfide) through three groups of folding intermediates, namely 1-disulfide, 2-disulfide, and 3-disulfide (scrambled) EGF isomers, to reach the native structure. Equilibrium occurs among isomers of each class of disulfide species, and the composition of intermediates appears to be highly heterogeneous. Together, at least 27 fractions of folding intermediates have been identified, but there exist only limited numbers of well populated species which constitute more than 80% of the total intermediates found during EGF folding. Six species of such well populated intermediates have been isolated, which included two 1-S-S, two 2-S-S, and two 3-S-S scrambled species. Their disulfide structures have been identified here. Both 1-S-S isomers are found to contain non-native disulfides. One of the 2-S-S species consists of two non-native disulfides and the other admits two native disulfides. Among the six disulfides of the two scrambled species, only one is native. Together, native disulfides constitute 25% of the total disulfides found in these six well populated intermediates. These results contrast sharply to those observed with bovine pancreatic trypsin inhibitor, which has shown that well populated folding intermediates consist of exclusively native disulfides (Weissman, J. S., and Kim, P. S. (1991) Science 253, 1386-1393). We propose that well populated folding intermediates, regardless of whether they contain native or non-native disulfides, do not necessarily represent the productive species and specify the folding pathway. Furthermore, conditions influencing the efficiency of EGF folding have been investigated. It is demonstrated here that under optimized compositions of redox agents, including the use of cysteine/cystine and protein disulfide isomerase, the in vitro folding of EGF could be achieved quantitatively within 1 min.

Amino Acid Sequence↗

PubMed1995

Differential expression of the human metastasis adhesion molecule CD44V in normal and carcinomatous stomach mucosa of Chinese subjects.

BACKGROUND: CD44 is a cell surface adhesion molecule involved in cell-cell and cell-matrix interactions. Tumor cells transfected to overexpress the isoform CD44V readily gain access to lymph nodes and form distant metastases. METHODS: Monoclonal antibodies directed at epitopes common to known CD44 isoforms were used to investigate CD44V expression in 30 normal gastric mucosa tissues, 64 different gastric adenocarcinomas, 20 metastatic adenocarcinoma lymph nodes and 4 established gastric carcinoma cell lines. In addition, CD44V gene expression in six gastric adenocarcinoma tissues and four gastric cancer cell lines were investigated by northern blotting. RESULTS: Immunohistochemistry screening of 30 subjects with normal gastric mucosa did not reveal expression of CD44 variants. Areas of intestinal metaplasia, a precancerous lesion, were stained with antibodies against either V5- or V6-containing isoforms of CD44. Tubular and signet-ring cell types of adenocarcinoma were strongly positive for epitopes encoded by CD44 variants containing exons V5 (41/49 and 10/10, respectively). Some tubular type adenocarcinomas (15/49) also expressed CD44 variants containing the V6 epitope. Tumor differentiation was closely related to CD44 V5 expression (P < 0.001). In addition, 18 of 20 gastric adenocarcinomas metastatic to lymph nodes expressed the V5 epitope of CD44 and 4 of 20 expressed the V6 epitope. Analysis of four established gastric adenocarcinoma cell lines revealed that two had moderate to strong expression of exons V5 and V6 of CD44. An antibody directed against CD44 variants containing exons V8 to V10 strongly stained all gastric adenocarcinoma cell lines. Northern blotting demonstrated that all four tumor cell lines and six gastric carcinoma mucosa tissues expressed CD44V. CONCLUSIONS: Generation of CD44 splice variants may be closely linked with gastric carcinoma tumorigenesis and differentiation. In addition, expression of CD44 variants containing exons V5 and V6 may be used as an indicator of evolving gastric cancer.

Adenocarcinoma↗

PubMed1995

T cell receptor-mediated Ca2+ signaling: release and influx are independent events linked to different Ca2+ entry pathways in the plasma membrane.

In this study, we showed that cross-linking CD3 molecules on the T cell surface resulted in Ca2+ release from the intracellular stores followed by a sustained Ca2+ influx. Inhibition of release with TMB-8 did not block the influx. However, inhibition of phospholipase C activity suppressed both Ca2+ release and influx. Once activated, the influx pathway remained open in the absence of further hydrolysis of PIP2. Thapsigargin, a microsomal Ca(2+)-ATPase inhibitor, stimulated Ca2+ entry into the cells by a mechanism other than emptying Ca2+ stores. In addition, Ca2+ entry into the Ca(2+)-depleted cells was stimulated by low basal level of cytosolic Ca2+, not by the emptying of intracellular Ca2+ stores. Both the Ca2+ release and influx were dependent on high and low concentrations of extracellular Ca2+. At low concentrations, Mn2+ entered the cell through the Ca2+ influx pathway and quenched the sustained phase of fluorescence; whereas, at higher Mn2+ concentration both the transient and the sustained phases of fluorescence were quenched. Moreover, Ca2+ release was inhibited by low concentrations of Ni2+, La3+, and EGTA, while Ca2+ influx was inhibited by high concentrations. Thus, in T cells Ca2+ influx occurs independently of IP3-dependent Ca2+ release. However, some other PIP2 hydrolysis-dependent event was involved in prolonged activation of Ca2+ influx. Extracellular Ca2+ influenced Ca2+ release and influx through the action of two plasma membrane Ca2+ entry pathways with different pharmacological and biochemical properties.

Animals↗

PubMed1995

Epstein-Barr virus-associated gastric adenocarcinoma in Taiwan.

Fifty-five gastric carcinoma tumors from Chinese patients in Taiwan, including 40 tubular type (one lymphoepthelioma-like carcinoma subtype), eight signet ring cell type, one papillary type, and six mucinous type gastric carcinomas, were investigated for the presence of Epstein-Barr virus (EBV) transcripts by in situ hybridization using fluorescein-conjugated EBV oligonucleotides for EBERs (Epstein-Barr virus early RNAs) expression and the polymerase chain reaction for viral DNA. Epstein-Barr virus was detected in six of 55 lesions (11%), a significantly lower proportion than has been observed in a North American series. Epstein-Barr virus involvement was more common among male patients. Epstein-Barr virus DNA and its EBERs were specifically present within gastric carcinoma and adjacent dysplastic cells but were absent in surrounding lymphocytes and normal gastric mucosa. Epstein-Barr virus DNA and EBERs were found in one sample of lymphoepithelioma-like carcinoma (LELC) and five specimens of typical gastric adenocarcinoma. Among the EBV-positive gastric adenocarcinomas, four were tubular type of varied differentiation and one was signet ring cell type. Furthermore, we evaluated the expression of the latent membrane protein (LMP) with monoclonal antibodies. We found that LMP was expressed in two EBV-positive samples. In addition, the presence of the EBV receptor was studied by probing samples with CD21 monoclonal antibody. Epstein-Barr virus receptor was not detected in any sample. Southern blot analysis indicated single clonal proliferation of tumor cells. These findings confirm and extend the results of Shibata et al. They also indicate that EBV infection might be related to oncogenesis not only in rare gastric cancers that resemble nasopharyngeal lymphoepithelioma but also in typical gastric adenocarcinoma.

Adenocarcinoma↗

PubMed1995

The effect of Evodia rutaecarpa extract on cytokine secretion by human mononuclear cells in vitro.

The effect of Evodia rutaecarpa extract on cytokine secretion by human mononuclear cells in vitro was investigated. Evodia rutaecarpa extract of various concentrations in mononuclear cell culture medium showed biphasic effects on the secretion of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and granulocyte-macrophage colony stimulating factor (GM-CSF) by the mononuclear cells. Generally speaking, a low to medium level of Evodia rutaecarpa extract, in concentrations ranging from 10% to 30%, showed significant stimulating effects on the secretion of IL-1 beta, IL-6, TNF-alpha and GM-CSF. On the other hand, high level of Evodia rutaecarpa extract, with concentration more than 40%, lost its stimulating effects. Moreover, reaction time affected the stimulating effects of Evodia rutaecarpa extract on cytokine secretion by mononuclear cells. Mononuclear cell culture medium containing Evodia rutaecarpa extract that was allowed to react for 18 or 24 hours showed significantly better stimulating effects than that reacted for 1 or 3 hours.

Cells, Cultured↗

PubMed1995

Diagnosis of disseminated candidiasis by fine needle aspiration of lymph node and by splenic imprint in a patient with acute promyelocytic leukemia.

Cytologic studies were done on fine needle aspirates of the lymph node and imprints of splenic biopsies from a patient with acute promyelocytic leukemia who was febrile while being treated with chemotherapy. Examination of the lymph node aspirates revealed pus and numerous pseudohyphae which were later identified as Candida tropicalis. When multiple nodular lesions were detected in the spleen by abdominal sonography and CT scan, needle biopsy of the spleen was done. Cytologic examination of touch imprints of the biopsy disclosed intracellular fungal blastospores. The patient was treated with and responded well to amphotericin B and 5-fluorocytosine. As a result of our experience with this patient we emphasize the importance of close incorporation of clinical information and diagnostic cytology. With such a cooperation, cytologic studies become a most useful method for diagnosis.

Adult↗

PubMed1995

Effects of indomethacin on lymphokine-activated killer cell activities in cancer patients.

Prostaglandin E2 (PGE2) is known to downregulate the generation of lymphokine-activated killer (LAK) cell activity. Indomethacin, an inhibitor of cyclooxygenase catalyzing the biosynthesis of PGE2, has been shown to augment LAK cell activities generated from peripheral blood mononuclear cells of normal healthy individuals. This study was undertaken to examine whether or not this augmentation is also a common phenomenon in cancer patients. LAK cell activities generated in the presence and the absence of indomethacin were examined in 15 normal healthy individuals and in 83 cancer patients. Paired data analysis revealed that indomethacin exhibited a significant augmentation of LAK activity generated from healthy individuals. Indomethacin enhanced LAK activity in patients with no distant metastases (TxNxM0); but depressed LAK activity in patients with distant metastases (TxNxM1). In patients without distant metastases, indomethacin showed an upregulating effect on LAK activity in those with an early T stage (T1-2NxM0), and no such effect was detected in those with a late T stage (T3-4NxM0). Indomethacin also significantly enhanced LAK cell generation in cancer patients with an ECOG performance status of 1, but significantly inhibited LAK cell generation in patients with a performance status of 4. These results indicated that indomethacin inhibited generation of LAK cell activity in cancer patients with a poor performance status or with distant metastatic disease, who normally would be the subjects of adoptive immunotherapy. Further, PGE2 production in cultured LAK cell medium was suppressed by indomethacin in all 20 cancer patients that were examined, suggesting that other yet to be identified factors or mechanisms may be responsible for the paradoxical effects of indomethacin on LAK cell activity.

Adjuvants, Immunologic↗

PubMed1995

Primary non-Hodgkin's lymphoma of the mediastinum: a clinicopathological report of six cases.

BACKGROUND: Primary mediastinal non-Hodgkin's lymphoma [NHL] predominates in young adult with diffuse large B-cell histologic characteristics, and favorable prognosis. Six patients with this disease were diagnosed and treated at the Tri-Service General hospital during the period of 1986 to 1991. METHODS: Pathology data were reviewed. All cases were classified according to the International Working Formulation. All specimens were studied immunohistologic for immunoglobulin kappa and lambda light chains, common leukocyte antigen (CLA), B cell marker (L26) and T cell marker (MT1 & UCHL1). All patients were treated with cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP) and adjuvant radiotherapy. RESULTS: Most of the patients were young adults with bulky disease in the anterior mediastinum. All presented with symptoms attributed to a rapidly growing mass. Four patients had superior vena cava syndromes. The histologic types were B-cell type lymphoma, including immunoblastic cell in two, and diffuse large cleaved cells in four patients. Three were in stage II and the others were in stage IV. Complete response was achieved in four patients and partial response in two, with an overall response rate of 100%. CONCLUSIONS: The results suggest that primary non-Hodgkin's non-lymphoblastic lymphoma commonly occurs in young adults and had an associated aggressive clinical course. In view of these results, observation have also suggested that intensive chemotherapy and bone marrow transplantation are needed for patients who relapse or fail to get complete remission.

Adult↗