[Care of amebic hepatic abscess].
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Female↗
Biomedical subjects
Z X Chen
Publications and source records attributed to Z X Chen.
A novel bioactive delta lactone FD-211. Taxonomy, isolation and characterization.
During our screening program for natural product drugs effective against multidrug-resistant mammalian cells, we have discovered a new delta lactone FD-211 from the fermantation broth of Myceliophthora lutea TF-0409. FD-211 had a broad spectrum activity against cultured tumor cell lines, including adriamycin-resistant HL-60 cells.
Animals↗
Bassiatin, a new platelet aggregation inhibitor produced by Beauveria bassiana K-717.
A new platelet aggregation inhibitor, bassiatin, was isolated from the cultured broth of Beauveria bassiana which had been isolated from a soil sample collected in Yunnan province, China. The structure of bassiatin was determined to be (3S, 6R)-4-methyl-6-(1-methylethyl)-3-phenylmethyl-1, 4-perhydrooxazine-2,5-dione by NMR analysis, X-ray crystallographic analysis and chemical synthesis. Bassiatin inhibited ADP-induced aggregation of rabbit platelets with the IC50 being 1.9 x 10(-4) M.
Animals↗
[Effect of wu lin powder and its ingredients on atrial natriuretic factor level in mice].
Wu Lin powder (WLP) is a prescription that causes urination to remove dampness. In order to elucidate its mechanism of action, the effect of WLP on atrial natriuretic factor (ANF) was observed. The results showed that the level of ANF was significantly higher in the plasma of mice after giving WLP as well as giving Alisma orientalis or Cinnamomum cassia orally, compared with control, P < 0.05, 0.01 and 0.001 respectively. The effect was most evident at 45 minute after giving WLP (P < 0.05). It is suggested that ANF might play an important role in therapeutic action of WLP.
Animals↗
Specific inhibition of hepatitis b virus gene expression by an antisense oligonucleotide in vitro.
It was previously shown that a number of antisense oligonucleotides against hepatitis B virus (HBV) mRNAs were highly effective in inhibition of HBV gene expression (Yao et al., 1995). Here, using radioisotope techniques, we report a specific inhibition of HBV surface antigen (HBsAg) production in vitro by 2.2.15 cells (Hep-G2 cells transfected with HBV genome) by the antisense oligonucleotide 15-S-asON, a 15-mer phosphorothioate analogue complementary to the cap site of the SPII promoter of HBV mRNA, at a concentration of 2-5 mumol/l. After 24 and 48 hrs of incubation of cells with 15-S-asON, the intracellular concentration of the latter rose to 69.4 and 75.8 nmol/l, respectively, and the HBsAg level assayed by ELISA was reduced by 50.0% and 70.6%, respectively. These results were checked by use of the radioimmunoprecipitation method: 2.2.15 cells exposed to 15-S-asON and labelled with [35S]-methionine for 48 hrs showed a decrease of the HBsAg level by 81.26% but almost none of the total proteins. No cytotoxicity of the 15-S-asON was observed with regard to the cell morphology and growth. These results indicate that the tested antisense oligonucleotide specifically inhibits the HBV gene expression.
Cell Line↗
Tributyrin: a prodrug of butyric acid for potential clinical application in differentiation therapy.
Butyric acid (BA) induces cytodifferentiation in vitro of a wide variety of neoplastic cells. The potential clinical utility of BA is limited by the apparent difficulty of achieving effective concentrations because of its rapid metabolism and short plasma half-life. In this study we addressed two approaches that may achieve effective concentrations of BA in vivo. One strategy is to use BA derivatives as prodrugs that can be metabolized to yield effective BA concentrations in vivo over a sustained period of time. Another strategy is to define agents that are synergistic with BA so that the desired effect can be achieved at lower concentrations of BA. In this study monobutyrin (MB) and tributyrin (TB) were studied in vitro for their effects on inducing differentiation of human myeloid leukemia HL60 cells and murine erythroleukemia cells. On a molar basis TB was about 4-fold more potent than either BA or MB for inducing differentiation of HL60 cells. BA, MB, or TB induced erythroid differentiation of murine erythroleukemia cells. On a molar basis TB was 3- to 4-fold more potent than BA, whereas MB was much less potent than BA. Combinations of all-trans-retinoic acid with either BA, MB, or TB induced myeloid differentiation of HL60 cells synergistically. We saw marked reductions in the doses of each agent that were needed in combination to achieve the same effect as single agents. For example, 130 microM TB, 110 nM all-trans-retinoic acid, and a combination of 13 microM TB plus 13 nM all-trans-retinoic acid all induced half-maximal differentiation of HL60 cells. Our results suggest that the readily available TB may be an effective prodrug of BA and may be useful either as a sole agent or in combination with other agents for cytodifferentiation therapy of human malignancies.
Butyrates↗
Potential applications of cytodifferentiation therapy in hematologic malignancies.
Retinoids, including retinoic acid (RA), are naturally occurring and synthetic analogs of vitamin A that inhibit cell growth and induce cell differentiation in many experimental tumor models. Differentiation of the human myelogenous leukemia cell line HL-60 by RA led to the finding that cells from patients with acute promyelocytic leukemia (APL) are terminally differentiated by RA. One mechanism for the activity of RA in a variety of cell types involves the RA nuclear receptors (RA receptors [RARs] and retinoid X receptors), which have specific high-affinity binding sites for RA and some of its metabolites. Other mechanisms may also be involved in RA-induced differentiation. Recent studies suggest that RA acylation (retinoylation) may be involved in the RA induction of differentiation in leukemia cells. Combinations of RA with cyclic adenosine monophosphate (cAMP)-elevating agents led to synergistically induced differentiation of HL-60 cells. The lower doses of RA needed in combination therapy are unlikely to lead to RA resistance, a major limitation of RA therapy in APL. In vitro studies suggest that combinations of RA with either PGE or the butyric acid (BA) prodrug tributyrin (TB) may be useful in differentiation therapy for APL and other malignancies. This is a US government work. There are no restrictions on its use.
Antineoplastic Combined Chemotherapy Protocols↗
Pathological changes of oxytalan fibers in the human gingiva of chronic periodontitis.
The gingiva samples were obtained from 40 patients with chronic periodontitis after flap operation and 20 cases having healthy gingiva after ectopic wisdom tooth extraction. We investigated the oxytalan fibers by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results demonstrated that under normal conditions numerous oxytalan fibers were widely and evenly distributed throughout the periodontal tissues. There was marked degeneration of the oxytalan fibers in chronic peridontitis. The predominant features were disintegration, fragmentation or disappearance of the oxytalan fibers under the basement membrane. Around the blood vessels, the oxytalan fibers decreased in density with fragmentation of the fibers and sometimes they disappeared almost completely. These results indicated that degeneration and destruction of the oxytalan fibers were closely correlated with the chronic periodontitis process, leading to reduced function occlusion of teeth.
Adult↗
The present status in all-trans retinoic acid (ATRA) treatment for acute promyelocytic leukemia patients: further understanding and comprehensive strategy are required in the future.
All-trans retinoic acid (ATRA) has recently been recognized as the first line therapeutic agent in the treatment of patients with acute promyelocytic leukemia (APL). The extraordinary high remission rate achieved by ATRA in comparison with other chemotherapeutic agents suggested that ATRA differentiation induction therapy seemed superior to conventional chemotherapy for APL patients. However, after the great excitement aroused after the initial successes, we have to take stock and examine in detail several problems which have emerged preventing us from improving the clinical outcome in APL. Maintenance in order to prolong remission and prevention of or retreatment for the relapse are the major subjects of concern at present. Efforts should be made either to keep ATRA effective for APL patients or to resensitize the relapsing patients for repeated ATRA therapy. The administration of ATRA should be carefully adapted in accordance with the individual patient's condition. From both conceptual and practical points of view, ATRA differentiation therapy should be combined with chemotherapy, bone marrow transplantation and biomodifier treatment. Thus, a more comprehensive strategy must be planned and developed in the near future. Using molecular biological techniques, the diagnosis of APL can be more precisely made and the course of the disease more closely monitored. The central dogma, still to be revealed, is the relationship between APL pathogenesis, the chromosome translocation present with the relevant molecular alterations and the response to ATRA treatment. Current studies in all these above fields have provided us with a deeper understanding of the pathogenesis of APL and the physiological function and curative action of ATRA.(ABSTRACT TRUNCATED AT 250 WORDS)
Antineoplastic Combined Chemotherapy Protocols↗
[Zero-crossing derivative spectrophotometry for the determination of three components in paracetamol compound tablets].
The zero-order derivative absorption spectra of aspirin, paracetamol and caffeine are closely overlapping. In this paper, a zero-crossing derivative spectrophotometry combined with simultaneous equations is proposed for the determination of the three components in a mixture without the need of prior separation. Satisfactory results were obtained. The method is reproducible, accurate and rapid. Calculation is not complicated. This method could be applied to biological fluid analysis.
Acetaminophen↗
A clinical and experimental study on all-trans retinoic acid-treated acute promyelocytic leukemia patients.
Fifty patients with acute promyelocytic leukemia (APL) have been treated with all-trans retinoic acid (RA). In vitro induced differentiation of primarily cultured bone marrow cells from the patients, colony-forming unit granulocyte-macrophage (CFU-GM) and L-CFU colony-forming assays, and karyotype analysis were performed over the treatment course. The very high bone marrow complete remission (CR) rate (94%) suggested that all-trans RA was superior to conventional chemotherapeutic regimens for the treatment of APL. The leukemic clone was reduced by RA-induced terminal differentiation and loss of proliferation capacity of leukemic cells. Relapse after CR in about 40% of patients was the major reason for the failure of the RA treatment. Patients who relapsed after a chemotherapy-maintained CR could be effectively reinduced to second CR by RA. However, if relapse occurred after a CR maintained by both RA and chemotherapy, the sensitivity of newly emerged leukemic clones to RA was greatly reduced. Therefore, it is suggested that RA should be replaced by conventional chemotherapy as soon as CR is achieved. Laboratory studies proved valuable in selecting cases for RA therapy and in predicting therapeutic effects and prognosis.
Adolescent↗
Complementing amino acid substitutions within loop 6 of the alpha/beta-barrel active site influence the CO2/O2 specificity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase.
Photosynthesis-deficient mutant 45-3B of the green alga Chlamydomonas reinhardtii contains a chloroplast mutation that causes valine-331 to be replaced by alanine within the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. This amino acid substitution occurs in loop 6 of the alpha/beta-barrel active site, three residues distant from catalytic lysine-334. The mutation reduces the specific activity of the enzyme and also reduces its CO2/O2 specificity factor by 42%, but the amount of holoenzyme is unaffected. In a previous study, an intragenic-suppressor mutation, named S40-9D, was selected that causes threonine-342 to be replaced by isoleucine, thereby increasing the CO2/O2 specificity of the mutant enzyme by 36%. To determine which other residues might be able to complement the original mutation, nine additional genetically independent revertants have now been analyzed. Another intragenic suppressor, represented by mutation S61-2J, causes glycine-344 to be replaced by serine. This change increases the CO2/O2 specificity of the mutant enzyme by 25%. Of the revertants recovered and analyzed, the mutant enzyme was improved only due to true reversion or by intragenic suppression mediated by substitutions at residues 342 or 344. Changes in the physical properties of the two pairs of complementing substitutions indicate that steric effects within loop 6 are responsible for the observed changes in the CO2/O2 specificity of the enzyme.
Amino Acid Sequence↗
Antihypertensive effect of synthetic tetrandrine derivatives in SHR rats.
1. Effects of oral administration of synthetic tetrandrine (TD) derivatives (20 mg/kg per day) for 9 weeks on blood pressure, heart rate, plasma renin concentration (PRC) and vascular reactivities to pressor substances were studied in spontaneously hypertensive (SHR) rats. 2. 7-O-Ethyl fangchinolin (7-O-EFC) and 7-O-isopropyl fangchinolin (7-O-IFC) produced a significant and sustained reduction in blood pressure from the first week of administration. 7-O-EFC reduced heart rate when determined under restraint conditions, but not under unanesthetized, freely moving conditions. 3. TD derivatives produced no effect on PRC. 4. Pressor response to phenylephrine was reduced significantly whereas the response to angiotensin II was enhanced after prolonged administration of 7-O-EFC and 7-O-IFC. 5. These results demonstrate that TD derivatives are potential antihypertensive drugs, and that attenuation of the pressor response to phenylephrine may contribute at least in part to its antihypertensive effect.
Alkaloids↗
Stimulation of proteinase and amidase activities in Porphyromonas (Bacteroides) gingivalis by amino acids and dipeptides.
Proteolytic enzymes from the organism Porphyromonas gingivalis are believed to be involved in the development of periodontitis. Studies on both crude extracts and purified trypsinlike enzymes from this organism indicate that substantial stimulation of both amidase and proteinase activities can be obtained during incubation with glycine-containing compounds. We postulate that P. gingivalis may have developed this unusual property to take advantage of the glycine-rich environment which occurs during the periodontitis-associated degradation of gingival collagen. The finding of such a stimulation in crevicular fluids from discrete periodontal sites has been correlated with the presence of P. gingivalis and could be utilized for the early detection of infection by this organism during the onset of periodontitis.
Amidohydrolases↗
[Effect of colchicine on rat neuromuscular transmission].
The function of the microtubules (MTs) beneath the postsynaptic membrane was studied in the isolated non-uniform stretched muscle preparation of rat diaphragm with the use of colchicine. After exposure to this drug, the amplitude of miniature endplate potential (MEPP), the mean quantal contents and mean amplitude of endplate potentials (EPPs) elicited by 10 Hz and 50 Hz stimulation and the amplitude of acetylcholine potentials (AChP) were decreased significantly, but the frequency of MEPP, membrane potential and the time course of EPP and AChP remained unchanged. These results indicate that colchicine suppresses the responses of acetylcholine receptors (AChR). No such effects were observed with colchicine's isomer lumicolchicine. It is suggested that the MTs beneath the postsynaptic membrane may be involved in the responsive process of AChR.
Animals↗
Serum-free culture system for L-CFU assay on acute non-lymphocytic leukemia cases.
A completely serum-free culture system for L-CFU assay in vitro on 5 cases of acute non-lymphocytic leukemia (ANLL) is reported. Several agents were tested for the requirement of L-CFU assay in order to substitute the animal or human serum in the conventional culture medium. The results showed that fraction V of bovine serum albumin (2 x 10(-4) mol/L), iron saturated human transferrin (400 micrograms/ml), insulin (1 U/ml), and cholesterol (20 micrograms/ml) were indispensible components for the growth of ANLL L-CFU. Colonies of larger size could be obtained by adding 2-mercaptoethanol. HTB9-CM as the source of growth stimulating factor was used in all experiments. This method is useful for the study of L-CFU proliferation regulated by the human hemopoietic growth factors and the standardization of L-CFU assay.
Adult↗
[Expression of protooncogenes c-myb and c-myc during the hexamethylene bisacetamide (HMBA)-induced commitment to terminal differentiation of murine erythroleukemia cells].
Modulation of a number of protooncogene expression occurs during differentiation of eukaryotes. Changes in expression of c-myb and c-myc during the HMBA-induced terminal differentiation of murine erythroleukemia cells were characterized by an early decrease (within 4 hrs), followed by the recovery of c-myc mRNA by 10 hrs, and the retention of suppression of c-myb expression for the rest of the induction period. Two MELC variants were used to further define the relationship between the differentiation and the protooncogene expression. R1 was a MELC variant completely resistant to HMBA, and R1 (VCR), a vincristine resistant R1, became inducible by HMBA again. The cell differentiation and the c-myb and c-myc expression were determined on R1 or R1 (VCR) cultured with HMBA respectively. The results demonstrated that the c-myc mRNA increased and remained relatively high as the cells grew to a saturated density regardless of the induction of differentiation. The R1 (VCR) cultured with HMBA displayed an early decrease in c-myb mRNA and a subsequent suppression of its expression, while the R1 cultured with HMBA showed a stable level of c-myb mRNA. These results suggest that the c-myb expression, rather than c-myc expression, is closely related to the HMBA-induced terminal differentiation.
Acetamides↗
Suppressive effect of high energy shock waves on tumor cells.
Suppressive effect on tumor cells of high energy shock waves (HESW) has aroused the interest of physicians in recent years. We assessed experimentally the cytotoxic effects of HESW on tumor cells both in vitro and in vivo and determined whether a Chinese domestic lithotriptor is capable of generating effective HESW, which has the potential to break tumor cells, reduce cell viability, retard cell growth, delay doubling time, impair cell attachment and cell clonogenicity. In nude rats, HESW was able to delay tumor growth and reduce tumor size without evidence of metastasis. The nature of HESW in the induction of cell damage and its clinical application need to be further investigated.
Animals↗