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Hsieh CM, Yang NC, Yang AK, Tseng C. Abstract P1-12-17: Exercise and nutrition intervention on breast cancer survivors in Taiwan with BMI 25 or more to decrease BMI and maintain at an appropriate level -A preliminary report. Cancer Res 2019. [DOI: 10.1158/1538-7445.sabcs18-p1-12-17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
It has been reported that lifestyle changes after completion of breast cancer treatment may decrease recurrence rate. Lifestyle was formed since childhood, and modified and sustained throughout lifetime. Usually, lifestyle changes are difficult without specific motivation.
Materials and Methods
Breast cancer survivors, aged from 20 to 80 years old with stage I, II, III, who have received surgery and completed courses of chemotherapy within 4 years, were candidates for the study.
According to the American Athletic Association sports guidelines, aerobic, muscular and extension exercises are taught by a sports instructor to the participants, and the participants were asked to exercise at home, 150 minutes a week, 30 minutes each time. Participants were instructed to calculate the calories they needed (25 calories/kg/day). Food selection and diet plan must meet the calories they have calculated, and a diet log was recorded.
The study of one-year diet and exercise intervention study was designed. Group meeting was started at the beginning and then held every 3 months. Measurements of body weight, height, body fat, BMI, waist circumference, muscle mass, and basal metabolic rate were performed; WHO quality of life and brief pain inventory (BPI) were also collected.
Results
A total of 32 breast cancer survivors were recruited, and 20 participants had completed one-year follow-up. Two of the participants withdrew from the study due to personal reasons, and the remaining 18 were included in the statistical analysis.
Body weight, BMI, and body fat decreased after interventions in diet and exercise and reached a significant lower level (p-value = 0.001, 0.002 and 0.01, respectively). In the linear regression model, it could be seen that body weight has a negative correlation with time; the body weight and BMI gradually decreased during the one-year period (β= -0.327, p-value=0.005; β= - 0.362, p-value=0 .002, respectively). There was no statistically significant change in waist circumference, muscle mass and basal metabolic rate.
BPI at baseline, 17 reported among 20 participants (80%) and decreased to 11% (2/18) at after one-year follow-up.
In the quality of life questionnaire, after the score calculation, the single factor repeated measurement analysis (calculated under the statistical power α=0.05) was used. There was no significant difference and change between the scores after the interventional measures. In the bivariate regression analysis, it was also seen that QOL had not changed due to weight loss, and there was no correlation between the two.
Discussion
This study results demonstrated that lifestyle adjustment can be motivated, and lifestyle can be changed by exercise and diet intervention; however, statistically, quality of life did not change with weight loss.
Citation Format: Hsieh C-M, Yang N-C, Yang A-K, Tseng C. Exercise and nutrition intervention on breast cancer survivors in Taiwan with BMI 25 or more to decrease BMI and maintain at an appropriate level -A preliminary report [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-12-17.
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Affiliation(s)
- C-M Hsieh
- Taiwan Adventist Hospital, Taipei, Taiwan
| | - N-C Yang
- Taiwan Adventist Hospital, Taipei, Taiwan
| | - A-K Yang
- Taiwan Adventist Hospital, Taipei, Taiwan
| | - C Tseng
- Taiwan Adventist Hospital, Taipei, Taiwan
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Abstract
BACKGROUND We have previously proposed an equation derived from Fick's law and Lin's concept of effective blood concentration (EBC) to calculate the mixed venous blood concentration (MVBC) of isoflurane. Desflurane has a lower blood/air partition coefficient than isoflurane and, as such, promotes a faster induction and recovery from anesthesia. In this study, we investigated the application of the MVBC equation to predict the MVBC of desflurane. METHODS We maintained anesthesia with a fixed inspired concentration (CI) of desflurane (10%) during cardiac anesthesia in 11 patients. In order to measure the real concentrations of desflurane in mixed venous blood, pulmonary arterial blood samples were collected at different time points via a Swan-Ganz catheter for gas chromatographic-mass spectrometric determination. The relationship between the calculated concentrations and the actual blood sample concentrations of desflurane in mixed venous blood was investigated. Lin's EBC method was also used and the results were compared with those of MVBC. RESULTS The calculations from our derived MVBC equation and the actual blood concentrations showed a similar kinetic pattern; the concentration levels were approximately the same and correlated well (r = 0.89) during anesthesia. However, the EBC method failed to accurately estimate the actual blood concentrations. CONCLUSIONS The results demonstrate that our equation, but not the EBC method, may be useful for estimating pulmonary blood concentrations of desflurane. The clinical significance and the importance of the method merit further investigation.
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Affiliation(s)
- C C Wu
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan
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Ho WM, Hung WT, Wu CC, Shen CH, Yang NC, Hwang KL, Wong KC. Application of MVBC equation to predict mixed venous blood concentrations of sevoflurane in cardiac anaesthesia. Anaesthesia 2005; 60:882-6. [PMID: 16115250 DOI: 10.1111/j.1365-2044.2005.04280.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have proposed an equation for estimating the real-time mixed venous blood concentration (MVBC) of isoflurane in cardiac anaesthesia. However, information related to the application of our method to sevoflurane is lacking. We studied 12 patients undergoing cardiac surgery and anaesthetised with sevoflurane. At different time points, pulmonary arterial blood samples were collected for gas chromatography-mass spectrometry (GC-MS) to determine the real mixed venous concentrations of sevoflurane. The inspired and expired concentrations of sevoflurane, measured by a gas monitor, were used for the MVBC calculations. Using Bland-Altman analyses, we found that the calculated MVBCs accurately represent the actual concentrations of sevoflurane in pulmonary arterial blood, as shown by a near-zero percentage bias with a 0.14% precision between the two concentrations. The results demonstrated that our equation could be a useful method for estimating the pulmonary blood concentration of sevoflurane.
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Affiliation(s)
- W-M Ho
- Department of Anaesthesia, Taichung Veterans General Hospital and Chung Shan Medical University, Taichung, Taiwan.
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Yang NC, Wang HF, Hwang KL, Ho WM. A Novel Method for Determining the Blood/Gas Partition Coefficients of Inhalation Anesthetics to Calculate the Percentage of Loss at Different Temperatures. J Anal Toxicol 2004; 28:122-7. [PMID: 15068566 DOI: 10.1093/jat/28.2.122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The loss by blood/gas (lambda) partition of inhalation anesthetics can be estimated by an equation for the percentage of loss. However, because lambdas of inhalation anesthetics at different temperatures have not been fully determined so far, the percentage of loss at varying temperature in various headspace volumes cannot be estimated. Therefore, a novel method was developed for the determination of inhalation anesthetic lambda, in this study. The method was precise, with a relative standard deviation of less than 5%. The average of lambda from seven distinct blood samples at 4 degrees C, 25 degrees C, and 37 degrees C were determined as 6.68, 2.04, and 1.32 of isoflurane; 3.47, 1.10, and 0.65 of sevoflurane; and 2.31, 0.75, and 0.46 of desflurane, respectively. In addition, increasing temperature was found to decrease lambda profoundly by a secondary order mechanism. Using the obtained value of lambda, the percentage of loss of isoflurane, sevoflurane, and desflurane were then predicted using a 5-mL vacuum tube as a collecting container for an example. In conclusion, a novel method was developed here for lambda determination, and lambdas of isoflurane, sevoflurane, and desflurane at various temperatures were given for estimating the loss resulting from liquid/gas partitioning.
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Affiliation(s)
- N C Yang
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan
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Yang NC, Hwang KL, Shen CH, Wang HF, Ho WM. Simultaneous determination of fluorinated inhalation anesthetics in blood by gas chromatography-mass spectrometry combined with a headspace autosampler. J Chromatogr B Biomed Sci Appl 2001; 759:307-18. [PMID: 11499484 DOI: 10.1016/s0378-4347(01)00239-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Although the fluorinated inhalation anesthetics, including desflurane, sevoflurane, isoflurane, enflurane, and halothane are commonly used, fatal cases resulting from their abuse or misuse have been reported. To date, gas chromatography (GC) equipped with different kinds of detectors has been utilized to analyze inhalation anesthetics. However, none of them can detect desflurane reliably or analyze all five common anesthetics simultaneously. The purpose of the present work is to further modify the previously developed headspace (HS) GC-MS method for blood isoflurane determination to analyze and distinguish five common clinical inhalation anesthetics, simultaneously. The modified HS-GC-MS method adopts a 60 m x 0.25 mm I.D., 0.25 microm film thickness DB-5 capillary column along with an adequate GC temperature program, which gives the five inhalation anesthetics, including isoflurane and its isomer, enflurane, a high resolution. The method also takes both the volatility and the influence of the top space on the obtained concentration into consideration and therefore keeps the sample loss acceptable even for analyzing the highly volatile desflurane. Within a certain concentration range of the calibration standard (about 20-300 microg/ml), this method shows a good linearity with correlation coefficients greater than 0.999. In addition, both within- and between-run precision and accuracy results meet the validation requirements as well as the tested results of practical blood samples of desflurane. In summary, this is a reliable analytical method to simultaneously determine the concentration of five common inhalation anesthetics in blood. Such a method is very practical for both clinical and occupational monitoring, as well as for analytical toxicology.
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Affiliation(s)
- N C Yang
- Department of Anesthesiology, Taichung Veterans General Hospital, Taiwan
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6
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Yang NC, Jeng KC, Ho WM, Chou SJ, Hu ML. DHEA inhibits cell growth and induces apoptosis in BV-2 cells and the effects are inversely associated with glucose concentration in the medium. J Steroid Biochem Mol Biol 2000; 75:159-66. [PMID: 11226832 DOI: 10.1016/s0960-0760(00)00180-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dehydroepiandrosterone (DHEA), a major steroid secreted by the adrenal gland which decreases with age after adolescence, is available as a nutritional supplement. DHEA is known to have antiproliferative effects but the mechanism is unclear. In this study using BV-2 cells, a murine microglial cell line, we investigated the effect of DHEA on cell viability and the interaction between DHEA and glucose concentrations in the medium. We showed that DHEA inhibited cell viability and G6PD activity in a dose-dependent manner and that the effect of DHEA on cell viability was inversely associated with glucose concentrations in the medium, i.e. lowered glucose strongly enhanced the inhibition of cell viability by DHEA. DHEA inhibited cell growth by causing cell cycle arrest primarily in the G0--G1 phase, and the effect was more pronounced at zero glucose (no glucose added, G0) than high glucose (4.5 mg/ml of the medium, G4.5). Glucose deprivation also enhanced apoptosis induced by DHEA. At G4.5, DHEA did not induce formation of DNA ladder until it reached 200 microM. However, at G0, 100 microM DHEA was able to induce apoptosis, as evidenced by the formation of DNA ladder, elevation of histone-associated DNA fragmentation and increase in cells positively stained with annexin V-FITC and annexin V-FITC/propidium iodide. The interactions between DHEA and glucose support the contention that DHEA exerts its antiproliferative effects through alteration of glucose metabolism, possibly by inhibition of G6PD activity leading to decreased supply of ribose-5-phosphate for synthesis of DNA and RNA. Although DHEA is only antiproliferative at pharmacological levels, our results indicate that its antiproliferative effect can be enhanced by limiting the supply of glucose such as by energy restriction. In addition, the present study shows that glucose concentration is an important factor to consider when studying the antiproliferative and toxicological effects of DHEA.
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Affiliation(s)
- N C Yang
- Department of Food Science, National Chung-Hsing University, 250 Kuo-Kuang Road, 402 Taichung, Taiwan, ROC
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7
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Scherczinger CA, Hintz JL, Peck BJ, Adamowicz MS, Bourke MT, Coyle HM, Ladd C, Yang NC, Budowle B, Lee HC. Allele frequencies for the CODIS core STR loci in Connecticut populations. J Forensic Sci 2000; 45:938-40. [PMID: 10914605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- C A Scherczinger
- Connecticut State Police Forensic Science Laboratory, Meriden 06451, USA
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8
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Yang NC, Hwang KL, Hung DZ, Wuhh HH, Ho WM. Reliable gas chromatographic-mass spectrometric method combined with a headspace autosampler for isoflurane determination in blood. J Chromatogr B Biomed Sci Appl 2000; 742:277-82. [PMID: 10901132 DOI: 10.1016/s0378-4347(00)00168-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Isoflurane is a nonflammable, liquid, volatile inhalation anesthetic administered by vaporizing. Although it is now commonly used, fatal cases resulting from its abuse or misuse have been reported. A combined system of a gas chromatograph-mass spectrometer and a headspace autosampler is therefore proposed for the detection of blood isoflurane. This analytic method showed sharp and well separated peaks, and revealed a good linear relationship (r=0.9994) with a function of y = 7.3768x - 0.0222 at concentrations between 18.7 and 299.2 microg/ml. The limits of detection and quantitation of this method were 1.2 and 4.7 microg/ml, respectively. The within- and between-run precision for spiked samples, assessed by the coefficient of variations, ranged from 1.7 to 10.0% and from 4.1 to 12.8%, respectively. The within- and between-run accuracy, assessed by errors from theoretical values, were 2.2-7.8% and 2.4-9.6%, respectively. In addition, practical sample analysis showed a good applicability, with a within-run precision rate of 5.6 to 7.7% and a between-run precision rate of 5.2-10.6%. In summary, the present work presents a valid alternative for blood isoflurane analysis.
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Affiliation(s)
- N C Yang
- Department of Anesthesiology, Taichung Veterans General Hospital, Taiwan
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9
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Hwang KL, Kou SJ, Lu YM, Yang NC. Evaluation of the quality of surgical gloves among four different manufactures. Ann Occup Hyg 1999; 43:275-81. [PMID: 10432871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
A randomized trial was conducted to evaluate the quality of four different brands of surgical gloves in terms of the perforation rate, ventilation, fitness, allergic reaction, elasticity, thickness, powder, and satisfaction. Gloves of four different manufactures which were used by various medical centres were distributed to participants according to a computer-generated randomization table. A structured questionnaire was self-administered by volunteers immediately after the surgical procedure to gather the information from participants, including the demographic data, allergy history, length of use, and variables of quality measures. Two brands, A and D, were significantly inferior to the best manufacture among the four, B, in terms of the ventilation, elasticity, and thickness, odds ratios ranging from 6 to 24, p < 0.05. For the amount of corn starch powder and satisfaction, all three other brands were inferior to brand B, odds ratios ranging from 6 to 44, p < 0.05. Gloves worn longer than 2 hours had a slightly higher perforation rate post procedures (11.5% vs. 2.1%, p = 0.048). The rate of latex allergic reaction was not significantly different between surgeons (8.3%) and the others (6.7%). No difference of the allergic reaction rate was found between subjects with allergy history (7.7%) and those without the history (7.5%). The quality of surgical gloves differs from brand to brand. The government and institutions should take the responsibility of monitoring the quality of surgical gloves in order to provide a safer and more comfortable environment for the surgical personnel and patients.
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10
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Abstract
X-ray diffraction analysis at 1.5 A resolution has confirmed the helical conformation of a de novo designed 18-residue peptide. However, the crystal structure reveals the formation of continuous molecular layers of parallel-packed amphiphilic helices as a result of much more extensive helix-helix interactions than predicted. The crystal packing arrangement, by virtue of distinct antiparallel packing interactions, segregates the polar and apolar surfaces of the helices into discrete and well-defined interfacial regions. An extensive "ridges-into-grooves" interdigitation characterizes the hydrophobic interface, whereas an extensive network of salt bridges and hydrogen bonds dominates the corresponding hydrophilic interface.
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Affiliation(s)
- K S Taylor
- Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA
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11
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Kuo ML, Yang NC. Reversion of v-H-ras-transformed NIH 3T3 cells by apigenin through inhibiting mitogen activated protein kinase and its downstream oncogenes. Biochem Biophys Res Commun 1995; 212:767-75. [PMID: 7626110 DOI: 10.1006/bbrc.1995.2035] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Apigenin, a plant flavonoid, induced the reversion of transformed phenotypes of v-H-ras-transformed NIH 3T3 cells at a quite low concentration of 12.5 microM. In the present study, we have examined the components of this Ras-mediated signaling transduction to determine whether they were involved in the apigenin-induced reversion process. Interestingly, the consitutively activated mitogen activated protein kinase (MAPK) in the ras transformant was inhibited significantly and rapidly by 25 microM apigenin within 30 min, and this reduction continued for more than 4 h. Corroborating these observations, expression of the downstream oncogenes c-jun and c-fos was also dramatically reduced during the first 4 h of treatment. We found that the levels of ras protein and mRNA were not affected by 24 h of treatment with apigenin. These findings indicate that apigenin-induced reversion of v-H-ras-transformed NIH 3T3 cells may occur by inhibiting MAPK activity and its downstream oncogenes rather than by affecting the expression of the ras gene.
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Affiliation(s)
- M L Kuo
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Republic of China
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12
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Kuo ML, Lin JK, Huang TS, Yang NC. Reversion of the transformed phenotypes of v-H-ras NIH3T3 cells by flavonoids through attenuating the content of phosphotyrosine. Cancer Lett 1994; 87:91-7. [PMID: 7525047 DOI: 10.1016/0304-3835(94)90414-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Fifteen flavonoids were employed to examine their effects on the morphological changes, foci formation in soft agar and cellular growth in v-H-ras-transformed NIH3T3 cells. The data presented here demonstrated that only three specific flavonoids--apigenin, kaempferol, and genistein--exhibited the reverting effect on the transformed phenotypes of ras-3T3 cells. For example, treatment with 25 microM of these flavonoids could effectively reverse the transformed morphology of ras-3T3 cells into flatter cells with contact inhibition. Colony formation in soft agar was decreased to 0.11%, 0.15%, and 0.35% by 25 microM apigenin, kaempferol, and genistein, respectively, as compared with control (0.92%). It was also found that the proliferation of ras-3T3 cells was significantly inhibited by these compounds in a dose-dependent manner. Finally, two biochemical parameters, the content of phosphotyrosine and cAMP, were examined to see whether affected by these compounds. The results showed the phosphotyrosine content in ras-3T3 cells was dramatically decreased by apigenin and kaempferol, but that was slightly reduced by genistein. By contrast, these three flavonoids all failed to significantly alter the level of cAMP within this transformant. Based on these observations, we suggest that some specific flavonoids are capable of reverting the transforming properties of v-H-ras transformed cells. The possible mechanism of this reversion is not mediated by activating the protein kinase A or its associated pathways, but rather inhibiting tyrosine kinases, subsequently leading to the blockage of p21ras-mediated signal transduction circuitry.
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Affiliation(s)
- M L Kuo
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, R.O.C
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13
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Abstract
Several signalling transduction modulators were used to examine their effects on the morphological changes, foci formation in soft agar and cellular growth in v-H-ras-transformed NIH 3T3 cells. The results from this study showed that specific tyrosine kinase inhibitors (genistein and tyrphostin 23) and cyclic AMP-elevating agents (forskolin and 3-isobutyl-1-methyl-xanthine) could effectively induce differential flat phenotype of v-H-ras transformant at micromolar concentrations. At the same dose range, both signalling modulators also caused a significant suppression of anchorage-independent and cellular growth in the same transformant. By contrast, compound inhibitors such as protein kinase C (staurosporin and H-7), phospholipase A2 (aristolochic acid), phospholipase C (neomycin sulfate) and cyclooxygenase (indomethacin) all did not alter the cellular morphology or foci formation in soft agar, although PKC inhibitors exhibited a slight inhibition on the cellular growth. Based on these observations, we propose that the alterations of protein kinase A or tyrosine kinase-associated signal pathways is necessary and the original cause of the transformation event, but that increase of the activities of protein kinase C, phospholipase C, phospholipase A2 or cyclooxygenase probably is an indirect result of the v-H-ras-mediated transformation.
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Affiliation(s)
- M L Kuo
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Republic of China
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14
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Locke BC, MacInnis JM, Qian S, Gordon JI, Li E, Fleming GR, Yang NC. Fluorescence studies of rat cellular retinol binding protein II produced in Escherichia coli: an analysis of four tryptophan substitution mutants. Biochemistry 1992; 31:2376-83. [PMID: 1540594 DOI: 10.1021/bi00123a024] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Rat intestinal cellular retinol binding protein II (CRBP II) is an abundant 134-residue protein that binds all-trans-retinol which contains 4 tryptophans in positions 9, 89, 107, and 110. Our ability to express CRBP II in Escherichia coli and to construct individual tryptophan substitution mutants by site-directed mutagenesis has provided a useful model system for studying the fluorescence of a multi-tryptophan protein. Each of the four mutant proteins binds all-trans-retinol with high affinity, although their affinities are less than that of the wild-type protein. Steady-state and time-resolved fluorescence analyses of these proteins indicate that W107 is at the hydrophobic binding site, W110 is in a polar environment, and the remaining two tryptophans are in a hydrophobic environment. Time-resolved fluorescence study indicates that excited-state energy transfer occurs from the hydrophobic tryptophans to W110. The Stern-Volmer analysis with acrylamide of these proteins reveals that static quenching occurs in the W9F mutant protein while others do not. The fluorescence of rat intestinal fatty acid binding protein (I-FABP), a related protein of known X-ray structure, was also studied for comparison. The results of these findings, coupled with those derived from NMR studies and molecular graphics, suggest that CRBP II undergoes minor structural changes in all of the mutant proteins. Since these effects may be cumulative on the protein structure and function, any conclusions derived from higher mutants in this family of proteins must be treated with caution.
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Affiliation(s)
- B C Locke
- Department of Chemistry, University of Chicago, Illinois 60637
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Leichner PK, Vriesendorp HM, Hawkins WG, Quadri SM, Yang NC, Stinson RL, Loudenslager DM, Frankel TL, Chen XY, Klein JL. Quantitative SPECT for indium-111-labeled antibodies in the livers of beagle dogs. J Nucl Med 1991; 32:1442-4. [PMID: 2066804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Results are presented for SPECT computations of liver volumes and 111In-labeled antibody activities in the livers of eight normal beagle dogs. Administered activities ranged from 1 to 2 mCi. SPECT studies were acquired 1 day postinjection using a rotating gamma camera system with elliptical orbits in a 360-degree rotation (128 views, 15 sec/view, 64 x 64 matrices). Uniformity-corrected images were reconstructed by use of the circular harmonic transform algorithm with computer software developed in-house. Liver volumes and activities were computed from transverse slices, 1 pixel (6.25 mm) in thickness. Comparison of SPECT and autopsy data demonstrated that absolute values of percent differences between measured and computed liver volumes ranged from 1.0% to 7.2%. Absolute values of percent differences between autopsy data and computed 111In activities in the liver ranged from 2.3% to 7.5%. These results suggest that quantitative SPECT has the potential of becoming an important tool in clinical trials for determining activities and localization volumes of radiolabeled antibodies directly from radionuclide images.
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Affiliation(s)
- P K Leichner
- Radiation Oncology, Johns Hopkins Oncology Center, Baltimore, Maryland 21231
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16
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Hawkins WG, Yang NC, Leichner PK. Validation of the circular harmonic transform (CHT) algorithm for quantitative SPECT. J Nucl Med 1991; 32:141-50. [PMID: 1988620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The purpose of this study was to validate the use of the circular harmonic transform (CHT) algorithm for quantitative single-photon emission computed tomography (SPECT) with isotopes technetium-99m (99mTc) and indium-111 (111In) under clinically relevant conditions. Phantom studies were the principal tools used. Volumes of fillable organs within a tissue-equivalent anthropomorphic phantom were determined over a wide range (145-1960 ml) to within 6% by using a thresholding technique. Additionally, phantom studies with nonuniform activity distributions were made. These included a background of activity and hot as well as cold lesions. The hot lesion was computed to within 12% (111In) and 7.7% (99mTc), and contrast in the cold lesion was approximately 70% for both isotopes. The CHT algorithm incorporates the energy-distance relation (EDR) which minimizes the degrading effects of attenuation, scatter, collimator blur and poor statistics.
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Affiliation(s)
- W G Hawkins
- Johns Hopkins Oncology Center, Department of Radiation Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21231
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17
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Li E, Qian SJ, Yang NC, d'Avignon A, Gordon JI. 19F nuclear magnetic resonance studies of 6-fluorotryptophan-substituted rat cellular retinol binding protein II produced in Escherichia coli. An analysis of four tryptophan substitution mutants and their interactions with all-trans-retinol. J Biol Chem 1990; 265:11549-54. [PMID: 2195021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Rat cellular retinol binding protein (CRBP II) is a 134-amino acid intracellular protein synthesized in the polarized absorptive cells of the intestine. We have previously used 19F nuclear magnetic resonance (NMR) spectroscopy to survey the structural effects of ligand binding on the apoprotein. For these studies, all 4 Trp residues of rat CRBP II were efficiently labeled with 6-fluorotryptophan (6-F-Trp) by inducing its expression in a tryptophan auxotroph of Escherichia coli. Resonances corresponding to 2 of its Trp residues underwent large downfield shifts upon binding of all-trans-retinol and retinal, while resonances corresponding to the other 2 Trp residues underwent only minor perturbations in chemical shifts. To identify which Trp residues undergo changes in their environment upon ligand binding, we have constructed four CRBP II mutants where Trp9, Trp89, Trp107, or Trp110 have been replaced by another hydrophobic amino acid. By comparing the 19F NMR spectrum of each 6-F-Trp-labeled mutant with that of wild type 6-F-Trp CRBP II, we demonstrate that the 19F resonance corresponding to Trp107 undergoes the largest change in chemical shift upon ligand binding (2.0 ppm downfield). This is consistent with the position of this residue predicted from molecular modeling studies. The 19F resonance corresponding to Trp9 also undergoes a downfield change in chemical shift of 0.5 ppm associated with retinol binding even though it is predicted to be removed from the ligand binding site. By contrast, the resonances assigned to Trp89 and Trp110 undergo only minor perturbations in chemical shifts. These results have allowed us to identify residue-specific probes for evaluating the interactions of all-trans-retinol (and other retinoids) with this intracellular binding protein.
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Affiliation(s)
- E Li
- Department of Medicine, Washington University, St. Louis, Missouri 63110
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Li E, Quian SJ, Nader L, Yang NC, d'Avignon A, Sacchettini JC, Gordon JI. Nuclear magnetic resonance studies of 6-fluorotryptophan-substituted rat cellular retinol-binding protein II produced in Escherichia coli. Analysis of the apoprotein and the holoprotein containing bound all-trans-retinol and all-trans-retinal. J Biol Chem 1989; 264:17041-8. [PMID: 2676998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Rat cellular retinol-binding protein II (CRBP II) is a 15.6-kDa intestinal protein which binds all-trans-retinol and all-trans-retinal but not all-trans-retinoic acid. We have previously analyzed the interaction of Escherichia coli-derived rat apoCRBP II with several retinoids using fluorescence spectroscopic techniques. Interpretation of these experiments is complicated, because the protein has 4 tryptophan residues. To further investigate ligand-protein interactions, we have utilized 19F nuclear magnetic resonance (NMR) spectroscopy of CRBP II labeled at its 4 tryptophan residues with 6-fluorotryptophan. Efficient incorporation of 6-fluorotryptophan (93%) was achieved by growing a tryptophan auxotroph of E. coli harboring a prokaryotic expression vector with a full-length rat CRBP II cDNA on defined medium supplemented with the analog. Comparison of the 19F NMR spectra of 6-fluorotryptophan-substituted CRBP II with and without bound all-trans-retinol revealed that resonances corresponding to 2 tryptophan residues (designated WA and WB) undergo large downfield changes in chemical shifts (2.0 and 0.5 ppm, respectively) associated with ligand binding. In contrast, 19F resonances corresponding to two other tryptophan residues (WC and WD) undergo only minor perturbations in chemical shifts. The 19F NMR spectra of 6-fluorotryptophan-substituted CRBP II complexed with all-trans-retinal and all-trans-retinol were very similar, suggesting that the interactions of these two ligands with the protein are similar. Molecular model building, based on the crystalline structures of two homologous proteins was used to predict the positions of the 4 tryptophan residues of CRBP II and to make tentative resonance assignments. The fact that ligand binding produced residue-specific changes in the chemical shifts of resonances in CRBP II suggests that NMR analysis of isotopically labeled retinoid-binding proteins expressed in E. coli will provide an alternate, albeit it complementary, approach to fluorescence spectroscopy for examining the structural consequences of their association with ligand.
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Affiliation(s)
- E Li
- Department of Medicine, Washington University, St. Louis, Missouri 63110
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Li E, Quian SJ, Nader L, Yang NC, d'Avignon A, Sacchettini JC, Gordon JI. Nuclear Magnetic Resonance Studies of 6-Fluorotryptophan-substituted Rat Cellular Retinol-binding Protein II Produced in Escherichia coli. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)71456-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Levin MS, Locke B, Yang NC, Li E, Gordon JI. Comparison of the ligand binding properties of two homologous rat apocellular retinol-binding proteins expressed in Escherichia coli. J Biol Chem 1988; 263:17715-23. [PMID: 3053716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cellular retinol-binding protein (CRBP) and cellular retinol-binding protein II (CRBP II) are 132-residue cytosolic proteins which have 56% amino acid sequence identity and bind all-trans-retinol as their endogenous ligand. They belong to a family of cytoplasmic proteins which have evolved to bind distinct hydrophobic ligands. Their patterns of tissue-specific and developmental regulation are distinct. We have compared the ligand binding properties of rat apo-CRBP and apo-CRBP II that have been expressed in Escherichia coli. Several observations indicate that the E. coli-derived apoproteins are structurally similar to the native rat proteins: they co-migrate on isoelectric focusing gels; and when complexed with all-trans-retinol, their absorption and excitation/emission spectra are nearly identical to those of the authentic rat holoproteins. Comparative lifetime and acrylamide quenching studies suggest that there are differences in the conformations of apo-CRBP and apo-CRBP II. The interaction of E. coli-derived apo-CRBP and apo-CRBP II with a variety of retinoids was analyzed using spectroscopic techniques. Both apoproteins formed high affinity complexes with all-trans-retinol (K'd approximately 10 nM). In direct binding assays, all-trans-retinal bound to both apoproteins (K'd approximately 50 nM for CRBP; K'd approximately 90 nM for CRBP II). However, all-trans-retinal could displace all-trans-retinol bound to CRBP II but not to CRBP. These observations suggests that there is a specific yet distinct interaction between these two proteins and all-trans-retinal. Apo-CRBP and apo-CRBP II did not demonstrate significant binding to either retinoic acid or methyl retinoate, an uncharged derivative of all-trans-retinoic acid. This indicates that the carboxymethyl group of methyl retinoate cannot be sterically accommodated in their binding pockets and that failure to bind retinoic acid probably is not simply due to the negative charge of its C-15 carboxylate group. Finally, neither all-trans-retinol nor retinoic acid bound to E. coli-derived rat intestinal fatty acid-binding protein, a homologous protein whose tertiary structure is known. Together, the data suggest that these three family members have acquired unique functional capabilities.
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Affiliation(s)
- M S Levin
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
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Leichner PK, Yang NC, Frenkel TL, Loudenslager DM, Hawkins WG, Klein JL, Order SE. Dosimetry and treatment planning for 90Y-labeled antiferritin in hepatoma. Int J Radiat Oncol Biol Phys 1988; 14:1033-42. [PMID: 2834309 DOI: 10.1016/0360-3016(88)90029-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Radiation absorbed-dose estimates and treatment planning are reported for 11 patients with hepatoma who were administered 90Y-labeled polyclonal antiferritin IgG for therapy in a Phase 1-2 trial. Dosimetric studies included quantitation of the localization and clearance of 111In-labeled antiferritin IgG in tumor and normal tissues and computer-assisted tumor and normal liver volumetrics from X ray CT scans. For the group of patients studied, hepatoma volumes at the time of treatment ranged from 135 to 3442 cm3. Quantitative 111In antiferritin imaging prior to and following 600 or 900 cGy of external-beam irradiation of the primary tumor demonstrated that tumor uptake increased 1.1 to 5.8-fold (mean 2.8) following external beam. In contrast, changes in uptake of radiolabeled antiferritin in normal liver ranged from 0.35 to 2.1-fold (mean 0.93) after external irradiation. Administered activities of 90Y antiferritin ranged from 8 to 37 mCi and were dependent on tumor volume and tumor localization of radiolabeled antiferritin. Following external-beam irradiation, tumor dose rates achieved with 90Y antiferritin ranged from 10 to 20 cGy/hr and normal liver dose rates from 1.1 to 5.7 cGy/h. The corresponding absorbed dose in hepatomas ranged from 900 to 2150 cGy and in normal liver from 80 to 650 cGy. After external-beam irradiation, tumor and normal liver uptake of 90Y antiferritin was consistent with that of 131I antiferritin.
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Affiliation(s)
- P K Leichner
- Department of Radiation Oncology, Johns Hopkins Medical Institutions, Baltimore, MD 21205
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Hawkins WG, Leichner PK, Yang NC. The circular harmonic transform for SPECT reconstruction and boundary conditions on the Fourier transform of the sinogram. IEEE Trans Med Imaging 1988; 7:135-138. [PMID: 18230462 DOI: 10.1109/42.3940] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The circular harmonic transform (CHT) solution of the exponential Randon transform (ERT) is applied to single-photon emission computed tomography (SPECT) for uniform attenuation within a convex boundary. An important special case also considered is the linear (unattenuated) Radon transform (LRT). The solution is on the form of an orthogonal function expansion matched to projections that are in parallel-ray geometry. This property allows for efficient and accurate processing of the projections with fast Fourier transform (FFT) without interpolation or beam matching. The algorithm is optimized by the use of boundary conditions on the 2-D Fourier transform of the sinogram. These boundary conditions imply that the signal energy of the sinogram is concentrated in well-defined sectors in transform space. The angle defining the sectors depends in a direct way on the radius of the field view. These results are also obtained for fan-beam geometry and the linear Radon transform (the Fourier-Chebyshev transform of the sinogram) to demonstrate that the boundary conditions are a more general property of the Radon transform and a not a property unique to rectangular coordinates.
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Li E, Locke B, Yang NC, Ong DE, Gordon JI. Characterization of rat cellular retinol-binding protein II expressed in Escherichia coli. J Biol Chem 1987; 262:13773-9. [PMID: 3308883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Rat cellular retinol-binding protein II (CRBP II) is a small (15.6 kDa) intracellular protein that binds all-trans-retinol. In the adult rat, expression of the CRBP II gene is essentially limited to the small intestinal lining cells (enterocytes), suggesting that CRBP II may be uniquely adapted for intestinal metabolism of newly absorbed retinol. Functional and structural analysis of this protein has been hampered by difficulties in freeing rat intestinal CRBP II from its ligand without denaturation. To circumvent this problem, we have obtained efficient expression of rat apoCRBP II in Escherichia coli. The purified E. coli-derived apoprotein, when complexed with all-trans-retinol, demonstrates fluorescence excitation-emission spectra and absorption spectra indistinguishable from that of CRBP II-retinol isolated from rat intestine. Quantitative ligand binding studies were performed by monitoring either the fluorescence of bound retinol or the quenching of protein fluorescence. They revealed that E. coli-derived CRBP II binds retinol tightly (the apparent dissociation constant is estimated to be 10(-7)-10(-8) M), with a stoichiometry of 1:1. Fluorescence quenching studies used acrylamide as a probe for the exposure of the 4 tryptophan residues to solvent. The results indicate that although there is heterogeneity in the exposure of these 4 tryptophan residues to solvent, they are situated in a relatively nonpolar environment. These studies suggest that E. coli-derived apoCRBP II will serve as a useful model for studying retinol-protein interactions.
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Affiliation(s)
- E Li
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
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Li E, Locke B, Yang NC, Ong DE, Gordon JI. Characterization of rat cellular retinol-binding protein II expressed in Escherichia coli. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)76493-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
A new method is introduced in which the total photon interaction cross sections per electron of human tissues are used to define effective atomic numbers for blood, bone, brain, fat, heart, kidney, liver, lung, muscle, ovary, pancreas, spleen, and water. These effective atomic numbers are equal within 4% from 10 to 200 keV in each soft tissue, whereas for bones of different chemical compositions the variation ranges from 2.86% to 5.03%. This effective atomic number definition is less energy dependent than a previous definition based on the total photon interaction cross section per atom averaged over all elements in the tissue, from which the computed effective atomic numbers varied by as much as 50% (in bone) as a function of photon energy over the energy range from 10 to 200 keV.
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Affiliation(s)
- N C Yang
- Johns Hopkins Hospital, Department of Radiation Oncology, Baltimore, Maryland 21205
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Yang NC, Leichner PK, Fishman EK, Siegelman SS, Frenkel TL, Wallace JR, Loudenslager DM, Hawkins WG, Order SE. CT volumetrics of primary liver cancers. J Comput Assist Tomogr 1986; 10:621-8. [PMID: 3016045 DOI: 10.1097/00004728-198607000-00015] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A new computer algorithm is described for liver and tumor volume determinations for patients with hepatoma and primary hepatic cholangiocarcinoma. The algorithm is based on global histograms of CT numbers of the liver and primary liver cancers. The algorithm includes computer-assisted definition of the liver boundary in each CT slice. Liver and tumor volumes of 10 patients calculated by the histogram method were compared with volumes obtained from CT slices that were manually contoured by experienced observers. A correlation coefficient of 0.995 was determined for these two methods of volume computations. Mean values of the differences in volumes obtained by the two methods were 6.7 and 8.0% for the liver and tumor, respectively. The computer algorithm was tested on CT scans for an additional 46 patients by highlighting regions corresponding to normal liver and tumor tissues in each CT slice and determined to be accurate by experienced observers. The computer software is being used clinically to assess tumor response in a new treatment program for primary liver cancers that includes radiolabeled antibodies.
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Abstract
Carcinogenic 9-anthryloxirane binds covalently to calf thymus DNA and poly(dA-dT). Application of the technique for DNA sequence determination shows that acid cleavage of the modified DNA frees approximately half of the anthryl groups from the DNA. HPLC analysis indicates that an adenine adduct and the glycol derived from 9-anthryloxirane are the major acid-labile products. Spectroscopic analyses establish that the adenine adduct is the N-3 adduct of 9-anthryloxirane to adenine. Similar analyses of modified poly(dA-dT) indicate that the binding of 9-anthryloxirane takes place selectively at the N-3 position of adenine. The significance of this finding is briefly discussed.
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Stevenson KA, Yen SF, Yang NC, Boykin DW, Wilson WD. A substituent constant analysis of the interaction of substituted naphthalene monoimides with DNA. J Med Chem 1984; 27:1677-82. [PMID: 6502597 DOI: 10.1021/jm00378a026] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In a continuing analysis of substituent effects in intercalator-DNA interactions, an unsubstituted naphthalene monoimide, with a 3-(dimethylamino)propyl group on the imide nitrogen has been prepared along with 3- and 4-nitro- and 3- and 4-amino-substituted derivatives. These derivatives allow an evaluation of the importance of the Hammett substituent constant and of the substituent position on the binding of naphthalene monoimides to DNA. Viscosity and spectrophotometric analyses indicate that all five compounds bind to DNA by intercalation. The 4-nitro compound gives a smaller viscosity increase and binds only approximately one-third as strongly as the 3-nitro derivative. It is postulated that this difference is due to the significant angle that the 4-nitro group makes with the intercalated monoimide ring system. The 3-NO2 group can assume a coplanar configuration with the monoimide ring system, allowing more favorable interactions with DNA base pairs, larger viscosity increases, and stronger binding to DNA. The binding constants of the 3-substituted monoimides are in the order 2 greater than 4 greater than 1 and, thus, do not follow a substituent constant pattern. The Tm values from thermal melting of DNA, on the other hand, are in the order 2 greater than 1 greater than 4, suggesting that the enthalpy contributions are significantly different for the binding of the three compounds to DNA. van't Hoff plots support this finding and indicate that both enthalpy and entropy contribute significantly to the binding free energy of 1 and 2 while the binding of 4 is primarily an enthalpic process. Plots of Tm and 65 degrees C log K values as a function of substituent constant for 1, 2, and 4 are linear. CPK model building studies suggest that 4 can form a hydrogen bond with the 5' diester oxygen of the sugar-phosphate backbone of DNA in an intercalation complex. This would lead to more favorable energetics of binding but a loss of mobility and/or available binding configurations with a resulting enthalpy-entropy compensation in the binding free energy of 4. This series of compounds dramatically illustrates the steric and hydrogen bonding complexity that can arise in attempts to design drugs to favorably interact with a DNA intercalation site as a potential bioreceptor.
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Agarwal KL, Hrinyo TP, Yang NC. Interaction of (+/-)-7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene with relaxed circular pBR322 DNA. Biochem Biophys Res Commun 1983; 114:14-9. [PMID: 6309162 DOI: 10.1016/0006-291x(83)91587-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The interaction of (+/-)-BPDE (1) with DNA at neutral pH was investigated by the application of relaxed circular pBR322 DNA. (+/-)-BPDE causes a rapid positive supercoiling of this DNA followed by a slower spontaneous relaxation. The results indicate that there are two clearly discernible types of chemical interactions between 1 and DNA, a rapid intercalative covalent binding and a slower strand breakage. The implications of these findings are discussed.
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Yang NC, Hrinyo TP, Petrich JW, Yang DD. Base sequence selectivity in binding of aromatic hydrocarbons with synthetic polynucleotides. Biochem Biophys Res Commun 1983; 114:8-13. [PMID: 6882433 DOI: 10.1016/0006-291x(83)91586-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The interactions between DOBP (3) and calf thymus DNA as well as four synthetic polynucleotides, poly(dA-dT), polydA:polydT, poly(dG-dC), and polydG:polydC, were investigated by spectroscopic techniques. It was found that the binding of 3 with poly(dA-dT) is favored appreciably over other synthetic polynucleotides and DNA. The results suggest that the initial association of carcinogenic BPDE (2) with DNA may take place preferentially at certain specific base sequences in DNA.
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Abstract
The photochemistry of thymidylyl-(3' leads to 5')- deoxycytidine (dTpdC) was studied as a model system of adjacent thymine and cytosine bases in DNA. Acetophenonesensitized irradiation causes the cytosine moiety in dTpdC to react with the thymine moiety intramolecularly. Three unstable photoproducts are formed initially which are converted into three isomeric dinucleoside phosphates of thymine-uracil cyclobutane photodimer in a ratio of 4.2:2.2:1. Under the same irradiation condition thymidylyl-(3' leads to 5')-thymidine (dTpdT) yields two products in a ratio of 6:1. The structures of these products are established by chemical and spectroscopic methods. The major product in these reactions has been identified as the stereoisomer which has the same anti,anti relationship between the pyrimidine rings and the deoxyribose group as in the parent dinucleoside phosphates. The efficiency of the intramolecular dimerization of dTpdC is about one-third that of dTpdT. The results suggest that the cytosine base in DNA may be converted to a uracil base via photodimerization with an adjacent pyrimidine base, hydrolysis, and photoreactivation.
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Liu FT, Yang NC. Photochemistry of cytosine derivatives. 2. Photohydration of cytosine derivatives. Proton magnetic resonance study on the chemical structure and property of photohydrates. Biochemistry 1978; 17:4877-85. [PMID: 718862 DOI: 10.1021/bi00616a004] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Photohydrates of cytidine and cytidylic acids have been definitively characterized to be isomeric 6-hydroxy-5,6-dihydrocytosine derivatives. It has also been demonstrated by nuclear magnetic resonance spectroscopy that (1) the stereochemistry of photohydration is random, (2) the C5-H trans to the C6-OH undergoes a rapid selective exchange in the presence of proton acids, and (3) the dehydration of photohydrates is a trans-elimination. The mechanism of these processes is discussed.
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Drinkwater NR, Miller JA, Miller EC, Yang NC. Covalent intercalative binding to DNA in relation to the mutagenicity of hydrocarbon epoxides and N-acetoxy-2-acetylaminofluorene. Cancer Res 1978; 38:3247-55. [PMID: 356963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Yang NC, Ng LK, Neoh SB, Leonov D. A spectrofluorimetric investigation of calf thymus DNA modified by BP diolepoxide and 1-pyrenyloxirane. Biochem Biophys Res Commun 1978; 82:929-34. [PMID: 567984 DOI: 10.1016/0006-291x(78)90872-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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