Biomedical subjects

S H Chen

Publications and source records attributed to S H Chen.

At least 19 recordsLinked to original sources

PubMed1996

Combination suicide and cytokine gene therapy for hepatic metastases of colon carcinoma: sustained antitumor immunity prolongs animal survival.

The effectiveness of combination therapy using a suicide gene and cytokine genes for the treatment of metastatic colon carcinoma in the mouse liver was investigated. Pre-established hepatic tumors treated with a recombinant adenoviral vector containing the herpes simplex virus thymidine kinase gene(tk) exhibited substantial regression, although all treated animals suffered from subsequent relapses. Although cotreatment with a mouse interleukin 2 (mIL-2)-containing adenoviral vector induced an effective antitumor immune response, the immunity waned with time, and the treated animals eventually succumbed to hepatic tumor relapse or distant metastases. In this study, mouse granulocyte macrophage colony-stimulating factor (mGM-CSF) gene was tested for its ability to further enhance and prolong the antitumoral cellular immunity. A fraction of the animals treated with tk + mIL-2 + mGM-CSF developed long-term antitumor immunity and survived for more than 4 months without recurrence. This long-term antitumor immunity could be enhanced further by subsequent "vaccination" with mIL-2-expressing parental tumor cells. The results indicate that local expression of GM-CSF in the hepatic tumors and prolonged mIL-2 expression are necessary to generate persistent antitumor immunity that is essential for the prevention of tumor recurrence and long-term animal survival.

Animals↗

PubMed1996

Combination gene therapy for oral cancer in a murine model.

Combination therapy involving adenovirus-mediated transfer of the genes for herpes thymidine kinase (tk) and murine interleukin 2 (mIL-2) was used to treat head and neck cancer in C3H/HeJ mice. Tumors were generated by transcutaneous injection of 5 X 10(5) murine squamous carcinoma cells into the floor of the mouth of these syngeneic mice. After 1 week, recombinant adenoviral vectors containing both therapeutic and control genes in various combinations were injected directly into the established tumors, and subsequently all mice were administered ganciclovir twice daily (25 mg/kg) for 6 days. Animals receiving either tk alone or tk + mIL-2 demonstrated significant tumor regression compared to mIL-2 alone or control vector-treated mice (P < 0.008). Mice receiving both tk + mIL-2, however, also demonstrated a significantly greater regression of tumors compared to those treated with tk alone (P<0.008), indicating a synergistic effect of the combination gene therapy. This synergism was confirmed in survival studies because tk + mIL-2 treated mice showed increased survivals (P=0.0002). Clinical and microscopic exam of regional surrounding tissues and distant organs showed no evidence of cytotoxicity for representative animals in each experimental group. These results suggest that combination tk and mIL-2 gene therapy may provide a powerful new modality for the treatment of head and neck cancer.

Adenoviridae↗

PubMed1996

In vivo gene therapy of ovarian cancer by adenovirus-mediated thymidine kinase gene transduction and ganciclovir administration.

Efficacy and toxicity of adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene followed by administration of ganciclovir were studied in vivo. A human epithelial ovarian cancer animal model was established in nude mice using the serous ovarian adenocarcinoma cell line Ov-ca-2774. Intraperitoneal (ip) injection of 1 x 10(8) Ov-ca-2774 cells resulted in tumor growth and formation of malignant ascites in all 15 animals. In a prospective randomized experimental design mice were treated 1, 3, or 7 days after ip injection of 1 x 10(8) cells with ip injection of 2 x 10(8), 6.7 x 10(8), or 2 x 10(9) pfu ADV.RSV-TK followed by administration of ganciclovir (10 microgram /ml, ip, bid) for 6 consecutive days. End points were survival and toxicity. Mice treated with GCV or HSV-TK alone died from 14.4 +/- 1.7 to 19.5 +/- 3.5 days after treatment as did untreated controls. No toxicity of ADV.RSV-TK was found up to 2 x 10(9) pfu (2 x 10(11) particles). The mice with the highest tumor burden treated with the lowest viral dose lived significantly longer than controls (P < 0.05). Median survival in all other groups of mice treated with ADV.RSV-TK plus GCV was even longer (P < 0.01). Treatment benefit was dependent on ADV/RSV-TK dose and tumor burden. Adenovirus-mediated thymidine kinase gene therapy is a realistic approach to ovarian cancer treatment that warrants investigation in the clinical setting.

Adenoviridae↗

PubMed1996

Early cytokine synthesis in the excised mouse cornea.

Corneas excised from normal BALB/c mice and incubated in vitro were analyzed for the production of "early-warning" cytokines via reverse transcription-polymerase chain reaction and ELISA. It was found that the trauma of excision stimulated rapid IL-1 alpha synthesis, with peak protein accumulation occurring at 6 h, whereas IL-6 synthesis was maximal at 18 h. Neither IL-1 beta protein nor message was detected at any point, and TNF-alpha synthesis never increased above constituted levels. Antibody neutralization of endogenous IL-1 alpha blocked IL-6 synthesis. Addition of exogenous IL-1 alpha induced IL-1 alpha and IL-6 synthesis in vitro. Inoculation of IL-1 alpha into the cornea induced IL-6 synthesis in vivo. Addition of IL-1 alpha could stimulate IL-1R, IL-1 alpha, and IL-6 mRNA synthesis in the epithelial, stromal, and endothelial components of the cornea. However, protein production was readily detected only in the epithelial layer. We concluded that mechanical trauma to the mouse cornea triggers the enhanced synthesis of IL-1 alpha and IL-1R, which in turn results in the production of IL-6 and more IL-1 alpha. That corneal excision did not stimulate the synthesis of IL-1 beta or TNF-alpha indicates that there is a selective induction of early cytokine expression in this specialized tissue.

Animals↗

PubMed1996

Gastric metaplasia of regenerating duodenal mucosa and deformity of duodenal bulb: a correlative study.

The correlation between the presence and degree of gastric metaplasia of regenerating duodenal mucosa and the deformity of duodenal bulb was studied. Based on the endoscopically morphological patterns of bulb, the duodenal ulcers were divided into three types: type I, with a normal-shaped bulb; type II, with mildly deformed bulb; and type III, with a markedly deformed bulb. A total of 159 patients with active duodenal ulcers were scheduled to be treated with H2-receptor antagonists. Of these patients, 124 proved to have a healed duodenal ulcer 4 weeks after initial treatment upon follow-up endoscopic examinations. Two biopsies were taken from the centre of the ulcer scar when the ulcer was found to be healed for light microscopic study. Histologically, the degree of gastric metaplasia was divided into three grades: grades 0, 1 and 2. The results show that a healed duodenal ulcer with a normal-shaped bulb is not frequently accompanied by gastric metaplasia. However, a healed ulcer with a markedly deformed bulb has a high incidence and degree of gastric metaplasia, which may be easily colonized by Helicobacter pylori and thus develop an environment of easy recurrence. Therefore, a cycle of healing and recurrence may exist in patients with a duodenal ulcer and a markedly deformed bulb. Eradication of H. pylori may be the best way to break this cycle.

Adult↗

PubMed1996

Neutrophil-mediated suppression of virus replication after herpes simplex virus type 1 infection of the murine cornea.

Herpes simplex virus type 1 (HSV-1) infection of the murine cornea induces the rapid infiltration of neutrophils. We investigated whether these cells could influence virus replication. BALB/c mice treated with monoclonal antibody (MAb) RB6-8C5 experienced a profound depletion of neutrophils in the bloodstream, spleen, and cornea. In these animals, virus titers in the eye were significantly higher than those in the immunoglobulin G-treated controls at 3 days postinfection. By day 9, virus was no longer detectable in the controls, whereas titers of 10(3) to 10(6) PFU were still present in the neutrophil-depleted hosts. Furthermore, virus spread more readily to the skin and brains of MAb RB6-8C5-treated animals, rendering them significantly more susceptible to HSV-1-induced blepharitis and encephalitis. Only 25% of the treated animals survived, whereas all of the controls lived. Although MAb RB6-8C5 treatment did not alter the CD4+ T-cell, B-cell, natural killer cell, or macrophage populations, the CD8+ T-cell population was partially reduced. Therefore, the experiments were repeated in severe combined immunodeficiency mice, which lack CD8+ T cells. Again virus growth was found to be significantly elevated in the eyes, trigeminal ganglia, and brains of the MAb RB6-8C5-treated hosts. These results strongly indicate that in both immunocompetent and immunodeficient mice, neutrophils play a significant role in helping to control the replication and spread of HSV-1 after corneal infection.

Animals↗

PubMed1995

The Wiskott-Aldrich syndrome and X-linked congenital thrombocytopenia are caused by mutations of the same gene.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, small platelets, eczema, recurrent infections, and immunodeficiency. Besides the classic WAS phenotype, there is a group of patients with congenital X-linked thrombocytopenia (XLT) who have small platelets but only transient eczema, if any, and minimal immune deficiency. Because the gene responsible for WAS has been sequenced, it was possible to correlate the WAS phenotypes with WAS gene mutations. Using a fingerprinting screening technique, we determined the approximate location of the mutation in 13 unrelated WAS patients with mild to severe clinical symptoms. Direct sequence analysis of cDNA and genomic DNA obtained from patient-derived cell lines showed 12 unique mutations distributed throughout the WAS gene, including insertions, deletions, and point mutations resulting in amino acid substitutions, termination, exon skipping, or splicing defects. Of 4 unrelated patients with the XLT phenotype, 3 had missense mutations affecting exon 2 and 1 had a splice-site mutation affecting exon 9. Patients with classic WAS had more complex mutations, resulting in termination codons, frameshift, and early termination. These findings provide direct evidence that XLT and WAS are caused by mutations of the same gene and suggest that severe clinical phenotypes are associated with complex mutations.

Base Sequence↗

PubMed1995

Conformation of the propeptide domain of factor IX.

The propeptide domain in the precursor forms of blood clotting proteins contains the recognition sequences for gamma-carboxylase. In hemophilia B, several point mutations in this propeptide domain are responsible for the inherited disease. A peptide containing the propeptide sequence of factor IX was synthesized by solid phase methods. Two dimensional 1H-NMR and CD studies indicate that this peptide motif adopts an alpha-helical structure in a 40% trifluoroethanol-containing aqueous solution. The results suggest that the amphipathic alpha-helix within the propeptide domain of factor IX could create a recognition surface for gamma-carboxylase. The influences of mutations and their relationship with the alpha-helical structure are discussed.

1-Carboxyglutamic Acid↗

PubMed1995

Adenovirus-mediated gene therapy for experimental spinal cord tumors: tumoricidal efficacy and functional outcome.

We evaluated the efficacy of adenoviral-mediated gene therapy of experimental spinal cord tumors and the functional outcome after this treatment. Spinal cord tumors were generated in the thoracic region of the spinal cord in Fischer 344 rats by stereotaxic intramedullary injection of 1 x 10(4) 9L gliosarcoma cells. Seven days after tumor cell injection, a replication-defective adenoviral vector carrying the herpes simplex virus thymidine kinase gene (ADV-tk) or a control adenoviral vector carrying the beta-galactosidase gene (ADV-beta gal) was injected into the tumors. Beginning 12 h later the animals were treated with the antiviral drug ganciclovir (GCV; 50 mg/kg) or saline twice a day for 6 days. The neurological performance of the animals was assessed during and following treatment. Eighteen days after tumor cell injection, all of the control animals had paraplegia and large tumors. In contrast, no tumors were detected in animals treated with ADV-tk and GCV. In long-term studies, two of the 5 animals treated with ADV-tk and GCV remained tumor-free and remained neurologically intact at 6 months whereas all animals in the control groups became paraplegic within 18 days.

Animals↗

PubMed1995

Synthesis and biological evaluation of novel C-4 aziridine-bearing paclitaxel (taxol) analogs.

Three novel C-4 aziridine-bearing paclitaxel analogs, 3-5, have been synthesized during the course of our continuing effort at C-4 modification. The key step in the synthesis is the aziridine ring formation at the C-4 position via an intramolecular Mitsunobu reaction. The syntheses and the biological evaluation of these C-4 aziridine-containing derivatives are herein discussed.

Aziridines↗

PubMed1995

Combination gene therapy for liver metastasis of colon carcinoma in vivo.

The efficacy of combination therapy with a "suicide gene" and a cytokine gene to treat metastatic colon carcinoma in the liver was investigated. Tumor in the liver was generated by intrahepatic injection of a colon carcinoma cell line (MCA-26) in syngeneic BALB/c mice. Recombinant adenoviral vectors containing various control and therapeutic genes were injected directly into the solid tumors, followed by treatment with ganciclovir. While the tumors continued to grow in all animals treated with a control vector or a mouse interleukin 2 vector, those treated with a herpes simplex virus thymidine kinase vector, with or without the coadministration of the mouse interleukin 2 vector, exhibited dramatic necrosis and regression. However, only animals treated with both vectors developed an effective systemic antitumoral immunity against challenges of tumorigenic doses of parental tumor cells inoculated at distant sites. The antitumoral immunity was associated with the presence of MCA-26 tumor-specific cytolytic CD8+ T lymphocytes. The results suggest that combination suicide and cytokine gene therapy in vivo can be a powerful approach for treatment of metastatic colon carcinoma in the liver.

Adenoviridae↗

PubMed1995

Adenovirus-mediated gene therapy for human head and neck squamous cell cancer in a nude mouse model.

Adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene followed by ganciclovir administration was used to treat human head and neck cancer in nude mice. Tumors were generated by transcutaneous needle injection of 6 x 10(6) human squamous carcinoma cells into the floor of the mouth. After 14 days, 10(10) particles of a replication-defective recombinant adenovirus containing the herpes simplex virus thymidine kinase gene (ADV/RSV-tk) were injected directly into the tumors. The mice subsequently received ganciclovir injections for six consecutive days and were sacrificed at 21 days post tumor cell implantation. Clinical response to the treatment was assessed by computer-imaged morphometric analysis of cross sectional area of nonnecrotic tumor and mitotic activity, which were used for the calculation of a tumor index. The median tumor index value of the treatment group was 280- to 2400-fold smaller than controls which did not receive the therapeutic gene (P < 0.001-0.016), and three-quarters of the treatment group had tumor index values that were indicative of near total tumor regression. Survival studies show that 50% of the ADV/RSV-tk-treated mice are free of tumor at 160 days post adenovirus injection, while all controls died or required sacrifice within 43 days. These results demonstrate that clinically effective in vivo treatment of human squamous cell cancer can be achieved using adenovirus-mediated gene therapy.

Adenoviridae↗

PubMed1995

Role of granulocyte colony-stimulating factor as adjunct therapy for septicemia in children with acute leukemia.

The granulocyte colony-stimulating factor (G-CSF) has been shown to accelerate recovery from severe neutropenia and to decrease the incidence of documented infections after intensive chemotherapy in cancer patients. However, the routine prophylactic use of G-CSF is expensive. This study was conducted to determine the role of G-CSF as adjunct therapy for septicemia following neutropenia caused by chemotherapy in children with acute leukemia. Fifty consecutive episodes of septicemia were studied involving 34 episodes of Gram-negative, 7 episodes of Gram-positive, 5 episodes of polymicrobial bacterial septicemia, one episode of fungemia, and 3 episodes of disseminated fungal infection. In the first 25 episodes, G-CSF was not used (group A). For the next 16 episodes, G-CSF 200 micrograms per square meter per day subcutaneously was given immediately after the septicemia was documented until the absolute neutrophil count was maintained at more than 1,500 per cubic millimeter (group B). Thereafter, G-CSF at the same dose as that of group B was prophylactically used in all the children who received high-dose cytosine arabinoside-containing regimens. Nine episodes of septicemia occurred (group C). The incidences of mortality per episode of septicemia in groups A, B, and C were 12.0% (3/25), 12.5% (2/16) and 0% (0/9), respectively. Statistically, there was no difference between the three groups overall and in pair-wise comparisons (all P > 0.5). The durations of G-CSF administration in group B ranged from 6 to 26 days with a median of 12 days and the durations of G-CSF administration in group C ranged from 10 to 23 days with a median of 19 days. With or without G-CSF, there may be no significant difference in the mortality of septicemia following neutropenia caused by chemotherapy in children with acute leukemia.

Acinetobacter Infections↗

PubMed1995

Treatment of platelet alloimmunization with intravenous immunoglobulin in a child with aplastic anemia.

A 9-year-old girl with severe refractory aplastic anemia had become refractory to platelet transfusion due to platelet alloimmunization. As a result, a huge right parieto-temporo-occipital cerebral hematoma and a subarachnoid hemorrhage subsequently occurred. Intravenous immunoglobulin (IVIG) (Green Cross, Taiwan) at a dose of 0.4 g/kg/day for 5 days, followed by another 3 doses during the following 5 days, and combined with large-dose platelet transfusions effectively controlled the bleeding by elevating the platelet count to above 100 x 10(3)/mm3. The patient soon recovered with only a mild sequela. Two months later, because of multiple caries and a periodontal abscess, dental extraction needed to be performed. IVIG (0.4 g/kg/day x 6 days) enabled surgery to proceed by elevating the platelet count to above 55 x 10(3)/mm3, and no bleeding complications occurred during or after the procedure. The potential benefit of high-dose IVIG in modulating platelet alloimmunization is a result of increasing the survival of transfused platelets. Thus, this therapy is recommended when patients with platelet alloimmunization have critical bleeding episodes or undergo surgical procedures.

Anemia, Aplastic↗

PubMed1995

Gene expression of markers associated with proliferation and differentiation in human keratinocytes cultured from epidermis and from buccal mucosa.

Normal keratinocytes from epidermis and from buccal mucosa underwent dissimilar stages of differentiation in the same culture medium and responded differently to changes in the composition of the medium. Manifestations of these variations were examined in terms of the expression at the mRNA level (as measured by reverse transcriptase-polymerase chain reaction) of three regulatory genes (cdc2, c-myc, and p53) and five that encode structural proteins (keratins K5, K10 and K13, involucrin, and filaggrin), in three growth-medium formulations. The culture conditions enhanced or retarded maturation; the observed alterations in gene expression correlated with these changes. Except for the proliferation genes, the non-keratinizing buccal mucosa generally responded more weakly than the orthokeratotic epidermis to culture-medium supplementation favouring differentiation. Gene expression in cultured keratinocytes reflected their ability to differentiate in vivo; genes were expressed even when the corresponding protein was not seen in vitro. Although keratin K10 is not prevalent in the buccal mucosa nor keratin K13 in the epidermis, the genes for both were found to be expressed in both tissues.

Calcium↗

PubMed1995

RU486 inhibits ovulation, fertilization and early embryonic development in rabbits: in vivo and in vitro studies.

OBJECTIVE: To clarify the role of P in ovulation, fertilization, and early embryonic development using RU486, a potent P receptor blocker. DESIGN: Ovulatory efficiency, IVF, and early embryonic development were evaluated after RU486 administration in vivo and in vitro. SETTING: Research laboratory of a university hospital. PARTICIPANTS: Mature male and female New Zealand white rabbits. INTERVENTIONS: Animals were treated with RU486 or vehicle for 3 days before hCG-induced ovulation. Ovaries treated with hCG to induce ovulation were perfused for 6 hours in vitro with RU486 or vehicle. In vitro fertilization was performed in the presence or absence of RU486. MAIN OUTCOME MEASURES: The percentage of mature follicles ovulating (ovulatory efficiency) was determined after in vivo and in vitro treatment. Fertilization, morula, and blastocyst development were evaluated every 24 hours for 120 hours. RESULTS: RU486 significantly inhibited ovulation, fertilization, and early embryonic development. CONCLUSIONS: Progesterone plays a significant role in ovulation, fertilization, and preimplantation embryonic development.

Animals↗

PubMed1995

Crystal structure of 2-debenzoyl, 2-acetoxy paclitaxel (Taxol): conformation of the paclitaxel side-chain.

Crystals of the C2-acetate analog of paclitaxel, grown from a mixture of isopropyl alcohol and methanol, belong to the space group P2(1) with a = 9.058(3), b = 18.306(5), c = 15.043(1) Angstrum, beta = 97.09(1) degrees, Z = 2, V = 2475.1(9)Angstrum3, Dcalc = 1.269 gcm-3 and mu = 0.75 cm-1. The structure was determined by direct methods and refined to R(F) = 0.054 and wR(F) = 0.057 for 605 variables and 3496 observed reflections. The paclitaxel side chain possesses a conformation similar to that observed in the crystal structure of docetaxel (Taxotere). A three dimensional network of hydrogen bonds is formed through solvent molecules and stabilizes the crystal lattice.

Chemistry, Pharmaceutical↗

PubMed1995

Adenovirus-mediated gene therapy in an experimental model of breast cancer metastatic to the brain.

We investigated the therapeutic efficacy of adenovirus-mediated gene therapy to treat malignant mammary tumors in vitro and in vivo in the brain. A mammary adenocarcinoma cell line derived from Fischer rats (13762 MAT B III; MAT-B) was used. In vitro studies demonstrated that the MAT-B cells could be efficiently transduced with a replication-defective adenovirus (ADV) vector that carried the herpes simplex virus gene for thymidine kinase (ADV-tk), and that ADV-tk transduction rendered the MAT-B cells sensitive to killing, in a dose-dependent manner, with ganciclovir (GCV). An animal model of a mammary tumor metastatic to the brain was produced by injecting MAT-B cells into the caudate nucleus of Fischer rats. Seven days after MAT-B cell injection, when the tumors were approximately 5 mm2 in cross-sectional size, the tumors were injected with ADV-tk or a control adenovirus vector containing the beta-galactosidase (beta-Gal) gene (ADV-beta gal). After vector injection the animals were treated with GCV or with saline for 6 days. Sixteen days after tumor cell injection, the brains were examined histologically. The rats that were injected with ADV-beta gal and treated with GCV or saline, and those that were injected with ADV-tk and treated with saline had large tumors, whereas the rats that were injected with ADV-tk and treated with GCV had no visible tumor tissue at the site of tumor cell injection. In survival studies animals treated with ADV-tk+GCV survived a significantly longer time than animals treated with ADV-beta gal+GCV. Our results demonstrate that the recombinant adenoviral vector containing the tk gene confers GCV cytotoxic sensitivity to mammary tumor cells in vitro and in the brain, and suggest that this treatment strategy may be useful in treating somatic tumors that metastasize to the brain.

Adenocarcinoma↗