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Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 991 records · Page 55Linked to original sources
PubMed1990

Free radicals, antioxidant enzymes, and carcinogenesis.

Free radicals are found to be involved in both initiation and promotion of multistage carcinogenesis. These highly reactive compounds can act as initiators and/or promoters, cause DNA damage, activate procarcinogens, and alter the cellular antioxidant defense system. Antioxidants, the free radical scavengers, however, are shown to be anticarcinogens. They function as the inhibitors at both initiation and promotion/transformation stage of carcinogenesis and protect cells against oxidative damage. Altered antioxidant enzymes were observed during carcinogenesis or in tumors. When compared to their appropriate normal cell counterparts, tumor cells are always low in manganese superoxide dismutase activity, usually low in copper and zinc superoxide dismutase activity and almost always low in catalase activity. Glutathione peroxidase and glutathione reductase activities are highly variable. In contrast, glutathione S-transferase 7-7 is increased in many tumor cells and in chemically induced preneoplastic rat hepatocyte nodules. Increased glucose-6-phosphate dehydrogenase activity is also found in many tumors. Comprehensive data on free radicals, antioxidant enzymes, and carcinogenesis are reviewed. The role of antioxidant enzymes in carcinogenesis is discussed.

Animals↗
PubMed1990

Daurisoline derivatives inhibit the ability of calmodulin to stimulate cyclic nucleotide phosphodiesterase activity.

Daurisoline alkaloid derivatives were found to be potent calmodulin (CaM) antagonists. The ability of daurisoline derivatives to attenuate the stimulatory effect on calmodulin activated cyclic nucleotides phosphodiesterase (CaM-PDE) was studied. These compounds did not inhibit the basal activity of this enzyme. The hydrophobicity of these compounds was related to their inhibitory potency. It is suggested that such drugs bind directly to calmodulin in a Ca2(+)-dependent fashion, as indicated by their ability to change calmodulin fluorescence.

Alkaloids↗
PubMed1990

Nucleotide sequence and deletion analysis of the polB gene of Escherichia coli.

The polB gene encodes DNA polymerase II in Escherichia coli. The nucleotide sequence shows an open reading frame of 2,304 nucleotides coding for a protein of 88 kD. The protein initiation signal is preceded by a lexA box lying 2 nucleotides from the termination signal of araD, and begins with GUG 75 nucleotides after the termination of araD. The polB gene and the araD gene are transcribed in the same direction. Initiation of protein synthesis was confirmed by peptide sequence. We have also demonstrated that the polB sequence is lacking in some strains. We conclude that DNA polymerase II is not a required protein in the cell. Sequence comparisons show that DNA polymerase II is an alpha-like DNA polymerase.

Amino Acid Sequence↗
PubMed1990

Biosynthesis of the Phytoalexin Pisatin : Isoflavone Reduction and Further Metabolism of the Product Sophorol by Extracts of Pisum sativum.

NADPH-dependent reduction of 2',7-dihydroxy-4',5'-methylenedioxyisoflavone to the isoflavanone sophorol, a proposed intermediate step in pisatin biosynthesis, was detected in extracts of Pisum sativum. This isoflavone reductase activity was inducible by treatment of pea seedlings with CuCl(2). The timing of induction coincided with that of the 6a-hydroxymaackiain 3-O-methyltransferase, which catalyzes the terminal biosynthetic step. Neither enzyme was light inducible. Further NADPH-dependent metabolism of sophorol by extracts of Cucl(2)-treated seedlings was also observed; three products were radiolabeled when [(3)H]sophorol was the substrate, one of which is tentatively identified as maackiain.

Journal Article↗
PubMed1990

Segmentation of coronary arteriograms by iterative ternary classification.

A segmentation algorithm for extracting arterial structures in coronary angiograms is presented. The algorithm mimics the process of interactive interpretation in human vision by iteratively implementing a ternary classification and learning process. Two gray-scale thresholds are computed to define three pixel classes: artery, background, and undecided. Then, two new thresholds for undecided pixels are computed using statistics conditioned upon the current classification. The threshold adaptation is governed by a learning algorithm based on the line and consistency measurements around each pixel. The process converges and results in a binary image. The performance of this algorithm on human coronary arteriograms was compared qualitatively to that of a relaxation algorithm and of a scattering based algorithm. Quantitative comparison was also made possible with computer generated images, which were obtained with the help of a model of the imaging chain and a process of interactive visualization of the modeled data. The iterative ternary classifier showed the best performance over a broad range of image quality. The study also demonstrated the use of visualization and user interaction in model building and algorithm development.

Algorithms↗
PubMed1990

The importance of surgery as the first step in multimodality treatment of small cell bronchial carcinoma. The ISC Lung Cancer Study Group.

For patients with small cell lung cancer (SCLC) in their early stages (TNM I, II), surgery for cure was used to eliminate the primary tumour and its regional lymph-nodes followed by intermittent chemotherapy and radiotherapy within the first six postoperative months. After the pathohistological examination of the operation-specimen a two-arm-randomization was performed: standard chemotherapy (1000 mg/m2 cyclophosphamide, 50 mg/m2 doxorubicin, 1.4 mg/m2 vincristine) compared with sequential chemotherapy using three different drug-combinations (A: 1500 mg/m2 cyclophosphamide, 100 mg/m2 lomustine, 15 mg/m2 methotrexate; B: 1000 mg/m2 cyclophosphamide, 40 mg/m2 doxorubicin, 1 mg/m2 vincristine; C: 5 x 1.6 g/m2 ifosfamide plus mesna, 5 x 120 mg/m2 etopside). Thereafter disease-free patients only received prophylactic cranial irradiation (PCI: administering 3600 TD Gy/18 fractions) according to the protocols of the International Society of Chemotherapy Studies I and II. Preliminary evaluations in March 1990 of 170 patients from 24 cooperating departments for thoracic surgery showed that the projected life-table four-year-survival rate of 63 patients with SCLC at pTNM-stage I was 61%, of 54 patients at pTNM-stage II was 35%, of 13 patients at stage pT3, 4 NO, 1 MO was 59% and of 40 patients at stage pT N2 MO was 35%. The indication for surgery is emphasized for pTNM-stages I + II. For N2-lesions surgery would not be recommended in general, but the survival rate seems to indicate that this treatment was not detrimental, being rather more favourable compared with chemotherapy or radiotherapy alone. The continuation and enlargement of these studies seem not only justified, but emphatically indicated.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Detection of HPV-16 DNA in cervical carcinoma by paraffin section in situ hybridization.

Thirty-eight cervical carcinomas and 1 cervical condyloma were examined for the presence of human papillomavirus (HPV) type 16 DNA using 3H-dCTP-labelled HPV-16 DNA probe in paraffin section in situ hybridization and 32P-dCTP-labelled probe in dot blot hybridization (Tm-17). The results showed an HPV-16 DNA positive rate in our series of about 74.4% (29/39) as determined by paraffin section in situ hybridization and about 71.8% (28/29) by dot blot hybridization. There was no significant difference between the two methods. We thus confirmed that paraffin section in situ hybridization is an informative, reliable, and sensitive method for the diagnosis of cervical HPV infection.

Condylomata Acuminata↗
PubMed1990

[Effect of human semen and vaginal bacteria culture fluid on induction of cervical cancer in mice].

The effect of human semen and culture fluid of bacteria (SB) isolated from the cervix of carcinoma patients on the induction of cervical carcinoma by 20-methylcholanthrene (MCA) in mice was studied. It was found that cervical carcinoma could be induced by SB with an induction rate of 12%. That by MCA alone was 11.8% whereas the SB positive for inducing EB virus EA in Raji cells used in combination with MCA gave an induction rate of 54.2%. The experimental results indicated that SB was both carcinogenic and tumor promoting. The possible mechanism of action of SB is discussed.

Animals↗
PubMed1990

[The physiologic disposition and pharmacokinetics of guaiacol acetylsalicylate in rats].

Guaiacol acetylsalicylate (GASL) has been shown to possess significant anti-inflammatory, antipyretic and expectorant activities and has been used clinically in chronic bronchitis with fairly good results. In the present work, the absorption, distribution and excretion of metabolites of the drug were studied in rats using quantitative TLC scanning technique. GASL was shown to be unstable in rat gastrointestinal tract and guaiacol salicylate (GSLT) and salicylic acid (SLA) were found in plasma. The plasma SLA concentration-time curve obtained after oral administration of GASL to rats was shown to fit a one compartment open model with the following pharmacokinetic parameters: T1/2ka = 1.25 h, T1/2ke = 3.28 h, ka = 0.5554/h, ke = 0.2111/h, Tmax = 3.02 h, Cmax = 331.46 micrograms/ml, AUC = 2832.93 micrograms/ml.h The SLA concentration was found to be high in muscle, moderate in spleen, testicle, kidney, lung, plasma, heart and liver and low in brain. The GSLT concentration was found to be low in plasma and organs. Within 24 h following ig administration of GASL the total SLA excreted in urine and feces was 10.9 and 0.41 of the GASL dose, respectively.

Animals↗
PubMed1990

[Determination of water soluble silicon from herbal drugs].

This article has set up a method for silicon determination by ammonium molybdate-ferrous sulfate-sodium carbonate spectrophotometry. The method is simple, convenient, quick, effective and free of the influence of phosphate ion and reducing agents such as vitamin C and so on. By this method water soluble silicon has been determined in 38 herbal drugs.

Drugs, Chinese Herbal↗
PubMed1990

Investigation of anti-HCV in 391 serum samples in China.

391 serum samples from healthy blood donors, HBsAg positive blood donors and patients with different kinds of liver diseases in northern China were tested for anti-HCV by ELISA. Of the healthy donors, 4.6% (7/151) were anti-HCV positive; of the HBsAg positive donors, 32.4% (24/74) were positive; and of the liver disease patients, 5.4% (9/166) were positive. Among the 24 cases of HBV-HCV double infection, 10 were assayed for serum ALT level. 40% (4/10) of them were abnormal. The causes of the surprisingly high rate of HCV infection, both in healthy donors and in HBsAg positive donors, were discussed. This is the first report on the distribution of anti-HCV in certain population in China.

Adult↗
PubMed1990

[Anti-inflammatory effect of aconitines].

Aconitines are the total alkaloids isolated from the main root of Aconitum carmichaeli. They have marked suppressive effect on the swelling of rat's hind paw induced by injections of fresh egg protein, carrageenin, histamine and 5-HT, on the mouse's ear oedema induced by bimethylphenyl, on the exudate and proliferation of granulation tissue of granuloma pouch induced by croton oil, on the leukocyte migration and on the contents of PGE in the exudate of the swelling hind paw induced by injecting carrageenin. Aconitines have been found useful in inhibiting significantly such immune inflammations as reversible passive Arthus reaction, rat's delayed skin hypersensitivity and adjuvant arthritis. They have also a noticeable analgesic effect.

Aconitine↗
PubMed1990

Studies on the interaction of daurisoline alkaloid derivatives and calmodulin by fluorescence spectroscopy.

A new kind of bisbenzylisoquinoline compounds, daurisoline alkaloid derivatives, has been found to be very potent calmodulin antagonists. The fluorescence spectra of interaction between these derivatives and calmodulin have been studied. The experimental results showed that these derivatives could interact with calmodulin resulting in forming a complex and diminishing fluorescence intensity. The process was Ca2(+)-dependent. These derivatives can bind to calmodulin and result in conformational change of calmodulin. But the binding site of these derivatives on calmodulin may be different from that of trifluoperazine. These derivatives can not displace all Ca2+ on calmodulin like trifluoperazine can do. Their abilities of antagonizing calmodulin to stimulate calmodulin-dependent cyclic nucleotide phosphodiesterase and the affinities of binding to calmodulin were related to hydrophobicity of substituting groups in side chain of these derivatives. Increase in hydrophobicity of these substituting groups increased binding of the derivatives and generally increased the inhibition of calmodulin stimulation of calmodulin-dependent cyclic nucleotide phosphodiesterase.

Alkaloids↗
PubMed1990

[F3, a fractionated extract of Astragalus membranaceus, potentiates lymphokine-activated killer cell cytotoxicity generated by low-dose recombinant interleukin-2].

Success with rIL-2 immunotherapy of human cancer appears to depend on the administration of high doses which are frequently associated with excessive toxicity. Future use of rIL-2 will require certain modifications based on the use of lower doses of rIL-2 without significant loss of antitumor efficacy. The authors tested in vitro the possibility of potentiating the activity of rIL-2 in terms of LAK cell generation. The authors hypothesized that co-incubation of LAK cell precursors with a Chinese herbal extract (F3) of Astragalus membranaceus (an immune modulator currently under study in the authors' laboratory), along with a low concentration of rIL-2 would generate levels of LAK cell activity equivalent to those generated by high concentrations of rIL-2 alone. The authors found: (1) a 10-fold potentiation of rIL-2 activity manifested by tumor cell killing activity of 80% resulting from LAK cell generation with F3 plus 100 u/ml of rIL-2 versus 76% generated by 1000 u/ml of rIL-2 alone; (2) a significant reduction in the number of effector LAK cells required for equicytotoxic reaction following LAK cell generation with F3 plus rIL-2 compared to rIL-2 alone. The authors conclude that potentiation of antitumor activity mediated by rIL-2 in low concentrations is possible by the concomitant use of another immune modulator such as Astragalus membranaceus.

Astragalus propinquus↗
PubMed1990

[Treatment of rheumatoid arthritis with low doses of multi-glycosides of Tripterygium wilfordii].

Thirty two cases of rheumatoid arthritis were treated with multi-glycosides of Tripterygium wilfordii (T2) in a dosage of 30 mg daily for 12 weeks. Significant improvements in clinical and laboratory variables were observed. In comparison with the results of routine dose of T2 (60 mg per day) treatment, there was no significant difference to be seen between the two treatment plans. Meanwhile, symptom of rash and slightly alimentary canal lower incidences and milder manifestations of side effects of T2 were found in the patients of low dose group than in that of routine dose group. It is suggested that it is reasonable to choose the dose of 30 mg daily as the routine treatment for rheumatoid arthritis patients.

Adult↗
PubMed1989

Antioxidant enzyme activities in normal and transformed mouse liver cells.

Copper- and zinc-containing superoxide dismutase (CuZnSOD), manganese-containing superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPX, both Se-dependent and Se-independent), and glutathione reductase (GR) were measured in normal, nitrosoguanidine-transformed and SV40-transformed mouse liver cells in culture, as well as in mouse liver homogenates. Enzyme activities were compared on the basis of 3 different endpoints: per mg protein, per mg DNA, and per 10(6) cells. Except for GR, activity of all the measured anti-oxidant enzymes was much higher in vivo than in vitro. All of the anti-oxidant enzyme activities were lower in general in the 2 transformed cell lines than in the in vitro normal cell line, except Cu-ZnSOD, which showed little change. However, MnSOD was the only enzyme which showed lowered activity in both transformed cell lines, no matter what endpoint was used. This finding is in agreement with previous work showing lowered MnSOD activity in tumor cells.

Animals↗
PubMed1989

The role of ifosfamide and cyclophosphamide in the multi-modality treatment after surgery for cure for small-cell bronchial carcinomas (SCLC).

For the optimisation of the therapy for small cell bronchial carcinomas (SCLC), surgery is used to eliminate the primary tumor and its regional lymph nodes and chemo- and radiotherapy for the general treatment of micrometastasis. After patho-histological examination of the operation specimen, randomization for two arms is performed for a standard chemotherapy (CAV) or a sequential chemotherapy using three different drug combinations. Thereafter all disease-free patients receive prophylactic cranial irradiation (PCI). Preliminary evaluations in December 1987, of 112 patients from 19 cooperating departments show that the survival rate projected for 2 yr of 43 patients at stage pT1-3 N0 M0 is 76%, of 43 patients at stage pT1-3 N1 M0 it is 63% and of 26 patients at stage pT1-3 N2 M0 it is 38%.

Antineoplastic Combined Chemotherapy Protocols↗