53 results on '"Pan, S. S."'
Search Results
2. [Effect of Dendrobium nobile Lindl. alkaloids on myocardial lipid metabolism during cardiopulmonary bypass ischemia-reperfusion in dogs].
- Author
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Pan SS, Liang GY, Yang XL, Xiao RH, Ke XX, Zhang DS, Wang LP, Zhang CJ, and Zhao L
- Subjects
- Alkaloids, Animals, Cardiopulmonary Bypass, Dendrobium, Dogs, Female, Male, Myocardium, Lipid Metabolism
- Abstract
Objective: To explore the effects and mechanisms of Dendrobium nobile Lindl. alkaloids (DNLA) on myocardial lipid metabolism during ischemia-reperfusion in dogs undergoing cardiopulmonary bypass (CPB). Methods: Twenty-four healthy hybrid dogs, half male and half female, were randomly divided into sham group, model group, solvent control group and treatment group (DNLA, 6 mg/kg) ( n= 6), all of which were established with CPB. Except for the sham group, the aorta of the other groups was occluded for 60 min and then reopened. The uptake rate of free fatty acids, the concentration of long-chain acyl coenzyme A (LCACoA), mRNA and protein expression of fatty acid translocase enzyme/CD36 (FAT/CD36) in myocardial tissue and the cardiac function indexes were measured at 4 time points: before cardiopulmonary bypass (T1), 15 min (T2), 60 min (T3), and 90 min (T4) after reperfusion in each group. Results: Before CPB, there were no statistically significant differences in the uptake rate of free fatty acids, the concentration of LCACoA and mRNA expression of FAT/CD36 in myocardial tissue in each group ( P> 0.05). After the opening of the aorta, the above indexes in model group [(35.8±4.7)%, (8.55±1.51) nmol/g, 3.23±0.68] and treatment group [(27.4±2.7)%, (6.10±1.38) nmol/g, 2.20±0.56] were higher than those in sham group [(19.6±3.9)%, (4.16±0.81)nmol/g, 1.19±0.52], which were the highest at T2, and then gradually decreased (all P< 0.05). Compared with the model group, the increase of above indicators in the treatment group was significantly lower at T2 (all P< 0.05). Before CPB, there was no statistically significant differences in cardiac function indexes [left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and±dp/dtmax] among the groups ( P> 0.05). After the aorta was opened, the above indexes in model group [(76.5±9.1) mmHg, (31.1±2.9) mmHg, (1.2±0.4) mmHg/ms, (-0.9±0.1) mmHg/ms] and treatment group [(92.9±8.7) mmHg, (25.3±3.6) mmHg, (1.8±0.4) mmHg/ms, (-1.3±0.1) mmHg/ms] were lower than those in sham group [(165.5±12.9) mmHg, (6.5±0.5) mmHg, (3.3±0.6) mmHg/ms, (-2.9±0.3) mmHg/ms] (all P< 0.05), but the impairment degree of cardiac function indicators in treatment group was significantly lower than that those in model group (all P< 0.05). Conclusion: During CPB in dogs, DNLA can inhibit the abnormal expression of FAT/CD36, decrease the uptake of free fatty acids, and reduce the abnormal accumulation of LCACoA in myocardium,thereby alleviating the myocardial injury after ischemia-reperfusion.
- Published
- 2020
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3. MiR-202-5p suppressed cell proliferation, migration and invasion in ovarian cancer via regulating HOXB2.
- Author
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Yu HY and Pan SS
- Subjects
- Cell Movement, Cell Proliferation, Cells, Cultured, Epithelial-Mesenchymal Transition genetics, Female, Humans, MicroRNAs genetics, Ovarian Neoplasms pathology, Homeodomain Proteins metabolism, MicroRNAs metabolism, Ovarian Neoplasms metabolism, Transcription Factors metabolism
- Abstract
Objective: Ovarian cancer (OC) is still the third leading cause of death in reproductive system malignancies. In OC, the biological function of microRNA-202-5p (miR-202-5p) is unknown. Our current research mainly focuses on miR-202-5p in the OC progression., Patients and Methods: MiR-202-5p was determined to be down-regulated in OC by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Cell counting kit-8 (CCK-8) assay and colony formation assay were recruited to access the ability of miR-202-5p on cell proliferation. Cell migration and invasion were determined by transwell assay and Matrigel assay. Dual-Luciferase reporter assay was recruited, and it validated that HOXB2 was a downstream target of miR-202-5p. Epithelial-mesenchymal transition (EMT) hallmark genes and HOXB2 expression level were examined by Western blotting., Results: MiR-202-5p was down-expressed in OC. Receiver operating characteristic (ROC) curve indicated that miR-202-5p was positively related to HOXB2. MiR-202-5p over-expression led to a higher 5-year survival rate. Up-regulated miR-202-5p inhibited cell proliferation and metastasis in vitro. HOXB2 was a downstream target of miR-202-5p., Conclusions: We verified that miR-202-5p suppressed cell proliferation, migration, and invasion in OC via regulating HOXB2. Our findings provide new insights into the underlying mechanism of OC progression and may be useful in finding biomarkers and therapeutic targets of OC.
- Published
- 2020
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4. TRIM24 aggravates the progression of ovarian cancer through negatively regulating FOXM1 level.
- Author
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Zhou HE, Pan SS, and Han H
- Subjects
- Aged, Carrier Proteins genetics, Cell Line, Tumor, Cell Movement genetics, Cell Proliferation genetics, Disease Progression, Down-Regulation, Female, Forkhead Box Protein M1 genetics, Gene Silencing, Humans, Kaplan-Meier Estimate, Middle Aged, Ovarian Neoplasms genetics, Up-Regulation, Carrier Proteins metabolism, Forkhead Box Protein M1 metabolism, Gene Expression Regulation, Neoplastic, Ovarian Neoplasms metabolism
- Abstract
Objective: This study aims to uncover the biological functions of the feedback loop tripartite motif-containing 24 (TRIM24)/Forkhead Box M1 (FOXM1) in the pathological progression of ovarian cancer (OC) and the underlying mechanism., Patients and Methods: The expression levels of TRIM24 and FOXM1 in OC tissues and cells were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The potential correlation between TRIM24 level and clinical indexes of OC patients was analyzed. The Kaplan-Meier curves were depicted for evaluating the prognostic potentials of TRIM24 and FOXM1 in OC patients. The regulatory effects of TRIM24 and FOXM1 on proliferative, migratory, and invasive capacities of SKOV3 and OVCAR3 cells were assessed through functional experiments. The rescue experiments were performed to clarify the feedback loop TRIM24/FOXM1 in influencing the progression of OC., Results: TRIM24 was upregulated in OC tissues and cells. The high level of TRIM24 was linked to higher rates of lymphatic and distant metastasis and worse survival in OC patients. The silence of TRIM24 attenuated proliferative, migratory, and invasive capacities of SKOV3 and OVCAR3 cells. FOXM1 level was negatively regulated by TRIM24, which was downregulated in OC. The low level of FOXM1 predicted worse survival in OC patients. Besides, the rescue experiments demonstrated that the feedback loop TRIM24/FOXM1 aggravated the malignant progression of OC., Conclusions: TRIM24 is upregulated in OC tissues, and closely linked to the occurrence of lymphatic and distant metastasis. Through negatively regulating FOXM1 level, TRIM24 aggravates the progression of OC.
- Published
- 2019
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5. MiR-195-5p inhibits the cell migration and invasion of cervical carcinoma through suppressing ARL2.
- Author
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Pan SS, Zhou HE, Yu HY, and Xu LH
- Subjects
- Adult, Cell Line, Tumor, Down-Regulation, Female, GTP-Binding Proteins genetics, Humans, MicroRNAs genetics, Neoplasm Invasiveness, Uterine Cervical Neoplasms genetics, Uterine Cervical Neoplasms pathology, Cell Movement genetics, GTP-Binding Proteins antagonists & inhibitors, Gene Expression Regulation, Neoplastic, MicroRNAs metabolism, Uterine Cervical Neoplasms metabolism
- Abstract
Objective: MicroRNAs (miRNAs) have great effects on the progression of cervical cancer (CC). This study aimed to investigate the role of miR-195-5p in CC and to explain the regulatory mechanism between ARL2 and miR-195-5p., Patients and Methods: Quantitative Real-Time-Polymerase Chain Reaction (qRT-PCR) was used to detect miR-195-5p levels in CC tissues and cell lines. Transwell assays for cell migration and invasion were also performed. A luciferase reporter assay was used to detect the direct target of miR-195-5p. The protein levels of ARL2 were measured by Western blot analysis., Results: In CC tissues and cell lines, miR-195-5p expression was decreased. Downregulation of miR-195-5p was associated with higher FIGO stage, deep stromal invasion, and lymph node metastasis. Moreover, over-expression of miR-195-5p inhibited cell migration and invasion in CC. Furthermore, it was observed that miR-195-5p directly targeted ARL2, which affected the suppressive effect of miR-195-5p in CC., Conclusions: MiR-195-5p inhibited cell migration and invasion in CC by suppressing ARL2 expression. The miR-195/ARL2 axis may provide a pathway for cell metastasis in CC.
- Published
- 2019
- Full Text
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6. [Occupational activity disorders of extremely severe mass burn patients in recovery period after injury: a cross-sectional survey].
- Author
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Shi JJ, Shen AM, Sun Y, Li YJ, Wang SN, Pan SS, Li Z, and Jiao L
- Subjects
- Burns complications, Child, Cross-Sectional Studies, Disability Evaluation, Explosions, Hospitalization, Humans, Surveys and Questionnaires, Accidents, Occupational, Activities of Daily Living, Aluminum toxicity, Blast Injuries, Burns therapy, Recovery of Function physiology
- Abstract
Objective: To observe the distribution of occupational activity disorders of extremely severe mass burn patients in recovery period after injury. Methods: From December 2014 to December 2015, 65 extremely severe burn patients conforming to the inclusion criteria involved in August 2 Kunshan factory aluminum dust explosion accident were admitted to Kunshan Rehabilitation Hospital. They received comprehensive rehabilitation treatment after burns, including wearing pressure clothes, ultrasound treatment, semiconductor laser and red light irradiation, motor function training, and so on. Over 2 years after injury, a cross-sectional survey was conducted on the patients' occupational activity disorders. Modified Barthel index (MBI) was used to assess the degree of activities of daily living (ADL) disorder of patients and to grade the independent level of completing each item of MBI, and then the independent level of patients completing self-care MBI items (bathing, dressing, grooming, eating, going to the toilet, urine control, and stool control) was compared with that of mobility items (going up and down stairs, bed and chair transfer, and walking). The Canadian Occupational Performance Measure (COPM) was used to assess the distribution of occupational activity disorders of patients. The distribution of the five most serious occupational activity disorders was counted, then the frequency and probability of which with frequency greater than or equal to 16 times were calculated. Data were processed with Pearson Chi-square test. Results: Over 2 years after injury, the MBI score of patients was (76±22) points, and the ADL of 83.08% (54/65) patients reached completely self-care or light ADL disorder level. The MBI items arranged according to the completing independent level of patients from high to low were urine control/stool control, walking, bed and chair transfer, going up and down stairs, going to the toilet, eating, grooming, dressing, and bathing. The independent level of patients completing self-care MBI items was lower than that of mobility items ( χ (2)=62.298, P <0.001). Over 2 years after injury, the five most serious occupational activity disorders in COPM dimension were mainly concentrated in the self-care dimension, accounting for 55.38% (180/325), followed by 22.46% (73/325) of production activities and 22.15% (72/325) of recreational activities, and the centrally distributed item was the personal self-care item under self-care dimension, accounting for 42.46% (138/325). Over 2 years after injury, the five most serious occupational activity disorders with frequency greater than or equal to 16 times were dressing and undressing, bathing, perineal cleaning, wearing pressure clothes, caring for children, visiting relatives and friends, 31, 25, 16, 17, 18, and 22 times respectively, with a probability of 47.69%, 38.46%, 24.62%, 26.15%, 27.69%, and 33.85% respectively. Conclusions: Over 2 years after injury, most of the patients with extremely severe burns caused by the aluminum dust explosion were completely or basically self-care in their daily life. The disorder of self-care ADL was more serious than that of mobility, and the disorder of individual self-care activity was still the most serious occupational activity disorder of patients in this stage. Clinical trial registration: Chinese clinical trial registry, ChiCTR-OOC-16009188.
- Published
- 2018
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7. Large Positive Thermal Expansion and Small Band Gap in Double-ReO 3 -Type Compound NaSbF 6 .
- Author
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Yang C, Qu BY, Pan SS, Zhang L, Zhang RR, Tong P, Xiao RC, Lin JC, Guo XG, Zhang K, Tong HY, Lu WJ, Wu Y, Lin S, Song WH, and Sun YP
- Abstract
Double-ReO
3 -type structure compound NaSbF6 undergoes a low-temperature rhombohedral to high-temperature cubic phase between 303 and 323 K, as revealed by temperature-dependent X-ray diffractions. Although many double-ReO3 -type fluorides exhibit either low thermal expansion or negative thermal expansion (NTE), NaSbF6 exhibits positive thermal expansion (PTE) with a large volumetric coefficient of thermal expansion, αv = 62 ppm/K, in its cubic phase. Raman spectroscopy reveals that the low-frequency transverse vibration of fluorine atoms is stiffened in NaSbF6 , compared with the typical NTE compound CaZrF6 with the same structure. The related weak contraction associated with the polyhedral rocking would be overcome by the notable elongation of the Na-F bond length on heating, thus leading to the large volumetric PTE. Unlike ScF3 and CaZrF6 which are insulators with a wide band gap, a relative small band gap of 3.76 eV was observed in NaSbF6 . The small band gap can be attributed to the hybridization between the Sb 5s and F 2p orbitals.- Published
- 2017
- Full Text
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8. The diagnostic value of high-resolution ultrasonography for the detection of anterior disc displacement of the temporomandibular joint: a meta-analysis employing the HSROC statistical model.
- Author
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Dong XY, He S, Zhu L, Dong TY, Pan SS, Tang LJ, and Zhu ZF
- Subjects
- Humans, Models, Statistical, Ultrasonography, Temporomandibular Joint Disc diagnostic imaging, Temporomandibular Joint Disorders diagnostic imaging
- Abstract
The study aimed to assess the diagnostic value of high-resolution ultrasonography (HR-US) in the detection of anterior disc displacement (ADD) of the temporomandibular joint. Relevant trials reported in MEDLINE, the Chinese National Knowledge Infrastructure Database, the Chinese Biomedical Literature Database, and Embase were identified. A manual search was also performed. The quality of retrieved data was evaluated using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria. Data were extracted and cross-checked, and a statistically rigorous meta-analysis was performed using a hierarchical summary receiver operating characteristic model (HSROC). The clinical utility of results was assessed using Fagan nomograms (Bayes theory). All data were evaluated using Stata software. A total 11 studies including 1096 subjects were included in the analysis; all reported the utility of HR-US for the diagnosis of ADD with reduction (ADDWR) and without reduction (ADDWoR). For ADDWR, the weighted sensitivity and specificity were 0.83 (95% confidence interval (CI) 0.78-0.88) and 0.85 (95% CI 0.76-0.92) respectively. The lambda value was 3.41 (95% CI 2.37-4.46) and the Fagan nomogram pre-test probability 58%, with a positive likelihood ratio (LR) of 6.01. The positive post-test probability was 89%, with a negative LR of 0.20. The negative post-test probability was 21%. The positive increase in diagnostic utility was 31% and the negative decrement in that value 37%. For ADDWoR, the weighted sensitivity and specificity values were 0.72 (95% CI 0.59-0.81) and 0.90 (95% CI 0.86-0.93), respectively. The lambda value was 3.69 (95% CI 2.39-4.99) and the Fagan nomogram pre-test probability 38%, with a positive LR of 7.00. The positive post-test probability was 82%, with a negative LR of 0.32. The negative post-test probability was 16%. The increase in diagnostic utility was 44% and the negative decrement in that value 22%. HR-US delivers acceptable performance when used to diagnose ADD, being superior for the detection of ADDWoR than ADDWR, and exhibiting a lower negative diagnostic value in the detection of ADDWoR than ADDWR. HR-US may serve as a new method for the rapid diagnosis of ADD. The method has the advantages of simplicity and low cost. Given the uncertainty in some of the estimated values, more high-quality studies are needed to assess that diagnostic efficacy., (Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2015
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9. Efficient removal of Cr(VI) from wastewater under sunlight by Fe(II)-doped TiO₂ spherical shell.
- Author
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Xu SC, Pan SS, Xu Y, Luo YY, Zhang YX, and Li GH
- Subjects
- Catalysis, Oxidation-Reduction, Photochemical Processes, Water Pollutants, Chemical chemistry, Chromium chemistry, Ferrous Compounds chemistry, Sunlight, Titanium chemistry, Wastewater chemistry
- Abstract
Fe(II)-doped TiO2 spherical shell catalyst was synthesized by one-pot hydrothermal method. The photocatalytic removal of Cr(VI) from plating wastewater under sunlight of the catalyst was demonstrated. It was found that the removal effectiveness of about 99.99% for initial Cr(VI) concentration of 102.3 ppm and 99.01% for 153.4 ppm under 3h sunlight irradiation is realized. The Fe(II) ions serve not only as reducing agents for reducing the Cr(VI) to Cr(III) but also as an intermedium of a two-step reduction, in which the TiO2 photoreduces the Fe(II) ions to Fe atoms firstly, and then the Fe atoms reduce the Cr(VI) to Cr(III). The improved photocatalytic activity of the catalyst is considered due to the synergistic effect of a multi reducing process by Fe(II) doping. The extended optical response and effectively utilization of sunlight of the special spherical-shell-like morphology also contribute to the enhanced photocatalytic activity., (Copyright © 2014 Elsevier B.V. All rights reserved.)
- Published
- 2015
- Full Text
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10. Recyclable magnetic photocatalysts of Fe2+/TiO2 hierarchical architecture with effective removal of Cr(VI) under UV light from water.
- Author
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Xu SC, Zhang YX, Pan SS, Ding HL, and Li GH
- Subjects
- Adsorption, Catalysis, Magnetic Fields, Nanotubes, Oxidation-Reduction, Photochemical Processes, Recycling, Chromium isolation & purification, Ferrous Compounds chemistry, Titanium chemistry, Ultraviolet Rays, Water Pollutants, Chemical isolation & purification, Water Purification methods
- Abstract
We report the synthesis and photocatalytic removal of Cr(VI) from water of hierarchical micro/nanostructured Fe(2+)/TiO(2) tubes. The TiO(2) tubes fabricated by a facile solvothermal approach show a three-level hierarchical architecture assembled from dense nanosheets nearly vertically standing on the surface of TiO(2) microtube. The nanosheets with a thickness of about 20 nm are composed of numerous TiO(2) nanocrystals with size in the range of 15-20 nm. Ferrous ions are doped into the hierarchical architecture by a reduction route. The Fe(2+)/TiO(2) catalyst demonstrates an effective removal of Cr(VI) from water under UV light and the removal effectiveness reaches 99.3% at the initial Cr(VI) concentration of 10 mg L(-1). The ferrous ion in the catalyst serves not as the photo-electron trap but as an intermedium of a two-step reduction. The TiO(2) photoreduces the Fe(2+) ions to Fe atoms firstly, then the Fe atoms reduce the Cr(VI) to Cr(III), and the later is removed by adsorption. The hierarchical architecture of the catalyst serves as a reactor for the photocatalytic reaction of Cr(VI) ions and an effective absorbent for the removal of Cr(III) ions. The catalyst can be easily magnetically separated from the wastewater after photocatalytic reaction and recycled after acid treatment., (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Published
- 2011
- Full Text
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11. Alterations of atrial natriuretic peptide in cardiomyocytes and plasma of rats after different intensity exercise.
- Author
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Pan SS
- Subjects
- Animals, Exercise Test, Immunohistochemistry, Male, Myocardium cytology, Rats, Rats, Sprague-Dawley, Time Factors, Atrial Natriuretic Factor blood, Atrial Natriuretic Factor metabolism, Myocardium chemistry, Myocytes, Cardiac chemistry, Physical Conditioning, Animal
- Abstract
To characterize the effect of long-term exercise training at different intensities on endocrine structure and function of the heart, plasma atrial natriuretic peptide (ANP) levels, expression of ANP in cardiomyocytes, and ultrastructure of cardiomyocytes were examined by radioimmunoassay, immunohistochemistry and transmission electron microscopy in Sprague-Dawley rats trained on a treadmill at different intensities for 8 weeks. The plasma ANP increased gradually with increasing exercise intensity. The immunoreactivity of ANP in cardiomyocytes increased in the moderate- and high-intensity exercise group and decreased in the exhaustive exercise group. The ANP electron-dense granules and the quantity and volume of mitochondria increased in moderate and high-intensity exercise group. The ANP electron dense granules decreased and the mitochondria tumefied in the exhaustive exercise group. The changes of plasma ANP have a tendency of increasing gradually with increase in exercise intensity. Moderate and high-intensity exercise increases ANP synthesis and storage in cardiomyocytes and induces adaptive changes in the ultrastructure of cardiomyocytes. The decrease of ANP immunoreactivity in cardiomyocytes after exhaustive exercise is probably the result of massive depletion and induces damaging changes in the ultrastructure of cardiomyocytes.
- Published
- 2008
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12. [Studies on the spectroscopic property of p-hydroxyphenol derivatives].
- Author
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Wu FY, Fu MG, Pan SS, and Yang WP
- Subjects
- Biomarkers, Tumor urine, Catechols urine, Humans, Spectrometry, Fluorescence, Spectrophotometry, Ultraviolet, Biomarkers, Tumor chemistry, Catechols chemistry
- Abstract
In the paper, properties of p-hydroxyphenol derivatives are described. The results prove that p-hydroxyphenol derivatives with different function groups show different spectroscopic properties. Some methods will be proposed to analyze a series of p-hydroxyphenol derivatives in blood or urine so as to identify the cancer mark.
- Published
- 2001
13. C-terminal region amino acid substitutions contribute to catalytic differences between murine class alpha glutathione transferases mGSTA1-1 and mGSTA2-2 toward anti-diol epoxide isomers of benzo[c]phenanthrene.
- Author
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Pal A, Gu Y, Pan SS, Ji X, and Singh SV
- Subjects
- Animals, Catalysis, Enzyme Activation genetics, Glutathione chemistry, Glutathione genetics, Glutathione Transferase genetics, Isoenzymes genetics, Mice, Models, Molecular, Mutagenesis, Site-Directed, Peptide Fragments genetics, Recombinant Fusion Proteins chemistry, Recombinant Fusion Proteins genetics, Stereoisomerism, Structure-Activity Relationship, Amino Acid Substitution genetics, Carcinogens chemistry, Glutathione Transferase chemistry, Isoenzymes chemistry, Peptide Fragments chemistry, Phenanthrenes chemistry
- Abstract
The molecular basis for catalytic differences between structurally closely related murine class alpha glutathione (GSH) transferases mGSTA1-1 and mGSTA2-2 in the GSH conjugation of anti-diol epoxide isomers of benzo[c]phenanthrene (anti-B[c]PDE) was investigated. GSH conjugation of both (-)- and (+)-enantiomers of anti-B[c]PDE was observed in the presence of mGSTA1-1 (60 and 40% GSH conjugation, respectively), whereas mGSTA2-2 exhibited a preference for the (-)-anti-isomer (>97%). In addition, the specific activity of mGSTA2-2 toward the (-)-anti-B[c]PDE isomer was relatively higher than that of mGSTA1-1. The amino acid sequences of mGSTA1-1 and mGSTA2-2 differ at 10 positions that are distributed in three sections. Section I contains amino acid residues in positions 65 and 95; section II contains residues in positions 157, 162, and 169, and section III contains residues in positions 207, 213, 218, 221, and 222. Enzyme activity measurements with chimeras of mGSTA1-1 and mGSTA2-2 revealed that amino acid substitutions in section III account for their differential enantioselectivity and catalytic activity toward anti-B[c]PDE. Site-directed mutagenesis of amino acid residues in section III of mGSTA2-2 with corresponding residues of mGSTA1-1 followed by activity measurements of the wild type and mutated enzymes indicates that leucine 207 and phenylalanine 221 may be critical for the high catalytic activity of mGSTA2-2 toward (-)-anti-B[c]PDE. Molecular modeling studies demonstrated that the active site of mGSTA1-1 accommodates both enantiomers of anti-B[c]PDE, whereas the (-)-anti-isomer interacts more favorably with active site residues in mGSTA2-2. The results of this study clearly indicate that amino acid substitutions in the C-terminal region contribute to catalytic differences between mGSTA1-1 and mGSTA2-2 with respect to anti-B[c]PDE.
- Published
- 2001
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14. Two distinct 4-hydroxynonenal metabolizing glutathione S-transferase isozymes are differentially expressed in human tissues.
- Author
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Cheng JZ, Yang Y, Singh SP, Singhal SS, Awasthi S, Pan SS, Singh SV, Zimniak P, and Awasthi YC
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- Antibody Specificity, Blotting, Western, Brain enzymology, Brain Chemistry, Cell Line, Electrophoresis, Polyacrylamide Gel, Glutathione Transferase chemistry, Humans, Isoelectric Focusing, Isoenzymes chemistry, Isoenzymes metabolism, K562 Cells chemistry, K562 Cells enzymology, Liver chemistry, Liver enzymology, Male, Organ Specificity physiology, Pancreas chemistry, Pancreas enzymology, Substrate Specificity, Testis chemistry, Testis enzymology, Aldehydes metabolism, Glutathione Transferase metabolism
- Abstract
The two previously reported human glutathione S-transferase isozymes, hGST5.8 and hGSTA4-4, have been suggested to be similar because of their comparable activities toward 4-hydroxynonenal-GSH conjugation. Here, we demonstrate that hGST5.8 and hGSTA4-4 are distinct. Antibodies raised against hGSTA4-4 did not recognize hGST5.8, and antibodies raised against mouse GSTA4-4 that cross-react with hGST5.8 did not recognize hGSTA4-4. The pI value of hGSTA4-4 was found to be 8.4, as opposed to the pI value of 5.8 for hGST5.8. The two isozymes are differentially expressed in human tissues and there are significant differences in their kinetic properties. While both isozymes showed a strong expression in liver and testis, hGSTA4-4 was not detected in brain where hGST5.8 was present. In the pancreas, a strong expression of hGST5.8 was observed while hGSTA4-4 was barely detectable in this tissue., (Copyright 2001 Academic Press.)
- Published
- 2001
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15. Amino acid substitutions at positions 207 and 221 contribute to catalytic differences between murine glutathione S-transferase Al-1 and A2-2 toward (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene.
- Author
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Xia H, Gu Y, Pan SS, Ji X, and Singh SV
- Subjects
- Animals, Catalysis, Enzyme Activation genetics, Female, Glutathione Transferase chemistry, Glutathione Transferase genetics, Humans, Isoenzymes chemistry, Isoenzymes genetics, Kinetics, Mice, Mice, Inbred A, Models, Molecular, Mutagenesis, Site-Directed, Recombinant Proteins chemistry, Recombinant Proteins metabolism, Stereoisomerism, Amino Acid Substitution genetics, Benzopyrenes metabolism, Glutathione Transferase metabolism, Isoenzymes metabolism
- Abstract
We have previously identified a novel Alpha class murine glutathione (GSH) S-transferase isoenzyme (designated mGSTAl-2) which is exceptionally efficient in catalyzing the GSH conjugation of (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], the ultimate carcinogen of widespread environmental pollutant benzo[a]pyrene. Furthermore, we have demonstrated that the Al-type subunit of this isoenzyme is significantly more active toward (+)-anti-BPDE than the other subunit (mGSTA2). To establish the basis for catalytic differences between mGSTAl and mGSTA2, which differ in their primary structures by 10 amino acids [distributed in three sections (I-III) as clusters of two (residues 65 and 95), three (residues 157, 162, and 169), and five (residues 207, 213, 218, 221, and 222) amino acids], three chimeric enzymes were expressed and tested for their activity toward (+)-anti-BPDE. These studies revealed that amino acid substitution(s) in section III determined the high catalytic activity of mGSTAl. Molecular modeling studies suggested that amino acid substitutions at positions 207 and/or 221, but not at positions 213, 218, and 222, may be responsible for such a difference. To test this possibility, amino acids at positions 207 and 221 of mGSTAl were mutated with the equivalent residues of mGSTA2. Kinetic analysis of the wild type and the mutant enzymes revealed that both methionine-207 and isoleucine-221 are critical for higher activity of mGSTA1-1 toward (+)-anti-BPDE compared with that of mGSTA2-2.
- Published
- 1999
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16. A comparative study of the chemical stability of various mitomycin C solutions used in glaucoma filtering surgery.
- Author
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Francoeur AM, Assalian A, Lesk MR, Morin I, Tétreault F, Calleja K, Guttman A, Rauth M, and Pan SS
- Subjects
- Buffers, Chemotherapy, Adjuvant, Chromatography, High Pressure Liquid, Drug Stability, Drug Storage, Humans, Mitomycin standards, Mitomycin therapeutic use, Ophthalmic Solutions chemistry, Ophthalmic Solutions standards, Ophthalmic Solutions therapeutic use, Temperature, Filtering Surgery, Glaucoma therapy, Mitomycin chemistry
- Abstract
Objective: To determine the chemical stability of various mitomycin C (MMC) solutions used in glaucoma filtering surgery., Methods: A survey of the MMC solutions currently in use in 21 hospitals (11 in Canada, 10 in the United States) was conducted. A comparative study of the chemical stability of five different representative solutions was performed. The effects of buffer and storage variables on the chemical breakdown of MMC in the solutions were studied by means of high-performance liquid chromatography (HPLC)., Results: The survey revealed 33 different variations (including recipes and storage conditions) in the preparation of MMC solutions. Although the majority of the hospitals (15 of 21; 72%) were preparing stable solutions, six of the hospitals (28%) were preparing potentially unstable solutions. The stability of the solutions varied in a nonuniform manner when stored at different temperatures in different buffers., Conclusion: The lack of standardization and quality control of MMC solutions used in filtering surgery allows for the possibility of hospitals preparing unstable solutions.
- Published
- 1999
17. Cloning, expression, and biochemical characterization of a functionally novel alpha class glutathione S-transferase with exceptional activity in the glutathione conjugation of (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene.
- Author
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Xia H, Pan SS, Hu X, Srivastava SK, Pal A, and Singh SV
- Subjects
- Amino Acid Sequence, Animals, Cloning, Molecular, Escherichia coli, Female, Glutathione Transferase chemistry, Isoenzymes chemistry, Mice, Molecular Sequence Data, Peptide Mapping, 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide metabolism, Carcinogens metabolism, Glutathione metabolism, Glutathione Transferase genetics, Glutathione Transferase metabolism, Isoenzymes genetics, Isoenzymes metabolism
- Abstract
The present study describes cDNA cloning, expression, and kinetic characterization of the two subunits of a murine alpha-class glutathione (GSH) S-transferase (GST) isoenzyme (previously designated as GST 9.5), which, unlike other alpha-class mammalian GSTs, is exceptionally efficient in the GSH conjugation of (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene [(+)-anti-BPDE] [X. Hu, S. K. Srivastava, H. Xia, Y. C. Awasthi, and S. V. Singh (1996) J. Biol. Chem. 271, 32684-32688]. The cDNAs for both subunits of GST 9.5 (GST 9.5-1 and GST 9.5-2) were cloned by RT-PCR. The deduced amino acid sequences of GST 9.5-1 and GST 9.5-2 clones were identical to those of mGSTA1 and mGSTA2, respectively. Both these subunits were expressed in Escherichia coli to determine the relationships between recombinant mGSTA1-1 and mGSTA2-2 and corresponding subunits of tissue-isolated GST 9.5. The pI values of recombinant mGSTA1-1 and mGSTA2-2 (9.49 and 9.45, respectively) were similar to that of the tissue-isolated isoenzyme (pI 9.5). The reverse-phase HPLC elution profiles and immunological cross-reactivities of recombinant mGSTA1-1 and mGSTA2-2 were also similar to those of the corresponding subunits of tissue-isolated GST 9.5. The catalytic efficiency of recombinant mGSTA1-1 toward (+)-anti-BPDE, 131 mM-1.s-1, was approximately 9.5-to 655-fold higher compared with tissue-isolated mGSTP1-1, mGSTA3-3, mGSTM1-1, and mGSTA4-4. Moreover, the catalytic efficiency of mGSTA1-1 toward (+)-anti-BPDE was about 3.3-fold higher compared with recombinant mGSTA2-2. The mGSTA1 and/or mGSTA2 subunits were expressed to varying degrees in female A/J mouse tissues. For example, mGSTA1, but not mGSTA2, subunit expression was observed in the skin, which is a target organ for benzo(a)pyrene (BP)-induced cancer in mice. On the other hand, the expression of either mGSTA1 or mGSTA2 subunit could not be detected in the lung, which is another target organ for BP-induced cancer in mice. Interestingly, relatively large amounts of both mGSTA1 and mGSTA2 subunits were detected in the kidney. In conclusion, the results of the present study clearly indicate that the A1-type subunit of GST 9.5 is responsible for its exceptional catalytic efficiency in the GSH conjugation of (+)-anti-BPDE, which is the ultimate carcinogen of widespread environmental pollutant BP.
- Published
- 1998
- Full Text
- View/download PDF
18. Differential induction of NAD(P)H:quinone oxidoreductase by anti-carcinogenic organosulfides from garlic.
- Author
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Singh SV, Pan SS, Srivastava SK, Xia H, Hu X, Zaren HA, and Orchard JL
- Subjects
- Animals, Benzo(a)pyrene pharmacology, Carcinogens pharmacology, Disulfides pharmacology, Enzyme Induction drug effects, Female, Lung enzymology, Mice, Propane analogs & derivatives, Propane pharmacology, Stomach enzymology, Structure-Activity Relationship, Allyl Compounds pharmacology, Anticarcinogenic Agents pharmacology, Garlic chemistry, NAD(P)H Dehydrogenase (Quinone) biosynthesis, Plants, Medicinal, Sulfides pharmacology
- Abstract
This study was undertaken to elucidate the mechanism of organ specificity and differential efficacy of garlic organosulfides (OSCs) [diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide (DATS), dipropyl sulfide (DPS) and dipropyl disulfide (DPDS)] in preventing benzo(a)pyrene (BP)-induced tumorigenesis in mice. The results of the present study reveal a good correlation between chemopreventive efficacies of garlic OSCs and their inductive effects on the expression of NAD(P)H:quinone oxidoreductase (NQO), an enzyme implicated in the detoxification of activated quinone metabolites of BP. Treatment of mice with DADS and DATS, which are potent inhibitors of BP-induced forestomach tumorigenesis, resulted in a statistically significant increase (2.4- and 1.5-fold, respectively) in forestomach NQO activity. In addition, DADS and DATS were much more potent inducers of forestomach NQO activity than DAS, which is a weak inhibitor of BP-induced forestomach tumorigenesis than the former compounds. Propyl-group containing OSCs (DPS and DPDS), which do not inhibit BP-induced tumorigenesis, did not affect forestomach NQO activity. Similar to forestomach, a good correlation was also observed between effects of these OSCs against BP-induced pulmonary tumorigenesis and their effects on NQO expression in the lung. For example, treatment of mice with DAS, which is a potent inhibitor of BP-induced pulmonary tumorigenesis, resulted in about 3.2-fold increase in pulmonary NQO activity. On the other hand, this activity was increased by about 1.5-fold upon DATS administration, which does not inhibit BP-induced cancer of the lung. In conclusion, our results suggest that induction of NQO may be important in anti-cancer effects of garlic OSCs.
- Published
- 1998
- Full Text
- View/download PDF
19. [The practice of postgraduate nursing and continuing education].
- Author
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Pan SS, Mei GP, and Xiao B
- Subjects
- Humans, Socialization, Education, Nursing, Continuing, Nursing Care standards, Students, Nursing
- Published
- 1997
20. Synthesis and antitumor evaluation of a highly potent cytotoxic DNA cross-linking polyamine analogue, 1,12-diaziridinyl-4,9-diazadodecane.
- Author
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Li Y, Eiseman JL, Sentz DL, Rogers FA, Pan SS, Hu LT, Egorin MJ, and Callery PS
- Subjects
- Animals, Antineoplastic Agents administration & dosage, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Aziridines administration & dosage, Aziridines chemistry, Cross-Linking Reagents pharmacology, Cross-Linking Reagents toxicity, Electrophoresis, Agar Gel, Female, Leukemia L1210 drug therapy, Mechlorethamine pharmacology, Melphalan pharmacology, Mice, Mice, Inbred Strains, Spermine administration & dosage, Spermine chemical synthesis, Spermine chemistry, Spermine pharmacology, Thiotepa pharmacology, Antineoplastic Agents chemical synthesis, Aziridines chemical synthesis, Aziridines pharmacology, Cross-Linking Reagents chemical synthesis, DNA drug effects, Spermine analogs & derivatives
- Abstract
A diaziridinylspermine analogue, 1,12-diaziridinyl-4,9-diazadodecane (NSC-667005), was synthesized as a bisalkylating agent with a polyamine backbone. DNA cross-linking was detected in the reaction of linearized pBR322 DNA with 1,12-diaziridinyl-4,9-diazadodecane at concentrations comparable with that required for cross-linking by two nitrogen mustard drugs, mechlorethamine and melphalan. A significant increase in life span of female CD2F1 mice bearing L1210 murine leukemia was observed after intravenous administration of 1,12-diaziridinyl-4,9-diazadodecane in doses of less than 2.7 mg/kg, given on days 1, 5, and 9 of treatment.
- Published
- 1996
- Full Text
- View/download PDF
21. [The application of computer assisted credit managing systems in nurses' postgraduate education and continuing education].
- Author
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Mei GP, Pan SS, and Huang JJ
- Subjects
- Accounting, Humans, Education, Nursing, Continuing economics, Education, Nursing, Graduate economics, Hospital Information Systems, Nursing Staff, Hospital education
- Published
- 1995
22. NAD(P)H:quinone oxidoreductase expression and mitomycin C resistance developed by human colon cancer HCT 116 cells.
- Author
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Pan SS, Forrest GL, Akman SA, and Hu LT
- Subjects
- Base Sequence, Blotting, Western, Colonic Neoplasms genetics, Drug Resistance, Escherichia coli enzymology, Humans, Indophenol analogs & derivatives, Indophenol metabolism, Molecular Sequence Data, Quinone Reductases analysis, Quinone Reductases genetics, RNA, Messenger analysis, Tumor Cells, Cultured, Colonic Neoplasms enzymology, DNA, Complementary genetics, DNA, Neoplasm genetics, Mitomycin metabolism, Quinone Reductases metabolism
- Abstract
An association between the resistance to mitomycin C (MMC) and a decrease of NAD(P)H:quinone oxidoreductase (NQO1) activity was reported for a MMC-resistant subline, HCT 116-R30A, derived from MMC-sensitive HCT 116 cells. Eight NQO1 cDNA clones were isolated from these two sublines by reverse transcription-PCR. Two clones, pDT9 from HCT 116 and pDT20 from HCT 116-R30A, are the full length of 274 amino acids. These two clones differ by a T to C substitution at nucleotide 464, which results in a replacement of arginine 139 by tryptophan in the enzyme. NQO1 of pDT9 and pDT20 was expressed in Escherichia coli, purified, and shown to have a protein subunit of M(r) 30,000. The change of amino acid 139 resulted in a shift of isoelectric pH from 9.5 to 8.35 and a 60% decrease of activity in reducing MMC. All of the other six clones differ from pDT9 by a deletion of exon 4. On Northern blot, we detected two mRNA species of NQO1 (1.2 and 2.7 kilobases) due to alternative polyadenylation in all sublines. MMC-resistant sublines showed 75-90% mRNA expression relative to HCT 116 cells. Reverse transcription-PCR amplification of cDNA fragment of nucleotide 298-617 revealed two full-length mRNAs in HCT 116 cells but only one full-length mRNA in HCT 116-R30A cells. An exon 4 deletion mRNA was detected in both sublines. The two full-length mRNAs may be from either alleles or chimeras of the same gene and the exon 4 deletion mRNA is a result of alternative splicing. On Western blot, we detected only one M(r) 30,000 protein in all sublines. A substantial decrease of this protein in MMC-resistant sublines (5% of HCT 116) explained the 95% decrease of their NQO1 activity. Transcriptional regulation and posttranscriptional modification may be responsible for the disparity of gene expression of NQO1 and the low concentration of NQO1 protein in MMC-resistant sublines. Reversal of MMC resistance and the recovery of NQO1 in two revertants further supports the hypothesis that cellular control of NQO1 can modulate the cytotoxicity of MMC.
- Published
- 1995
23. Design of a stabilized He-Ne laser by using a thin-film heater.
- Author
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Mio N, Ko MF, Ni WT, Pan SS, Araya A, Moriwaki S, and Tsubono K
- Abstract
Details concerning the design of the stabilization system for a He-Ne laser based on a two-mode method that uses a thin-film heater are discussed. The stability is evaluated by measuring the beat signal between two stabilized lasers; it is 1.1 × 10(-12), expressed in terms of the root Allan variance (τ = 35 s).
- Published
- 1993
- Full Text
- View/download PDF
24. Effect of pH on DNA alkylation by enzyme-activated mitomycin C and porfiromycin.
- Author
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Yu F and Pan SS
- Subjects
- Alkylation, Animals, Biotransformation, Cattle, Chromatography, High Pressure Liquid, Chromatography, Thin Layer, Hydrogen-Ion Concentration, Liver enzymology, NADPH-Ferrihemoprotein Reductase metabolism, Phosphodiesterase I, Phosphoric Diester Hydrolases metabolism, Rats, Xanthine Oxidase metabolism, DNA metabolism, DNA Adducts, Mitomycin metabolism, Porfiromycin metabolism
- Abstract
DNA adduct formation by enzyme-activated antibiotics, mitomycin C (MMC) or porfiromycin (PFM), at pH 7.6 or pH 6.0 under anaerobic conditions was analyzed by a 32P-postlabeling method. Antibiotic activation by rat liver NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and bovine milk xanthine oxidase (EC 1.2.3.2) produced similar results. Five 32P-labeled MMC adducts were separated by thin layer chromatography and high performance liquid chromatography from DNA alkylated at either pH. Four of the radioactive spots separated by thin layer chromatography were identified as two monofunctional monoadducts [1" alpha and 1" beta forms of N2-(2" beta,7"-diaminomitosen-1"-yl)-2'-deoxyguanylic acid], one bifunctional monoadduct [N2-(10"-decarbamoyl-2",7"-diaminomitosen-1" alpha-yl)-2'-deoxyguanylic acid], and one cross-linked adduct [N2-(2" beta,7"-diamino-10"-deoxyguanyl-N2-yl-mitosen- 1" alpha-yl)-2'-deoxyguanylic acid]. One minor radioactive spot was not identified. By comparing DNA alkylated at the two pH values, based on equal amounts of 32P radioactivity, similar amounts of cross-links were detected. However, the DNA showed different ratios of the alpha and beta isomers of the monofunctional monoadduct. Furthermore, the DNA alkylated at pH 6.0 showed more bifunctional monoadducts than did the DNA alkylated at pH 7.6. Analysis of alkylated DNA by enzyme-activated PFM showed a similar spectrum of DNA adduct formation. The effect of pH on the distribution of the five PFM-DNA adducts was similar to that observed for the five MMC-DNA adducts. The distribution of adducts in DNA alkylated at the same pH was similar irrespective of which enzyme activated MMC or PFM. The pH of the reaction during DNA and MMC interaction was the determining factor for the quantitative distribution of the adducts. This pH effect may be important for the cytotoxicity of MMC and PFM in tumor cells that have high levels of reductive enzymes with low optimal pH values.
- Published
- 1993
25. Enzymatic and pH modulation of mitomycin C-induced DNA damage in mitomycin C-resistant HCT 116 human colon cancer cells.
- Author
-
Pan SS, Yu F, and Hipsher C
- Subjects
- Biotransformation, Cell Death drug effects, Chemical Fractionation, Chromatography, Thin Layer, Colonic Neoplasms pathology, DNA, Neoplasm drug effects, Drug Resistance, Humans, Hydrogen-Ion Concentration, Microsomes, Tumor Cells, Cultured, Colonic Neoplasms metabolism, DNA metabolism, DNA Adducts, DNA Damage drug effects, DNA, Neoplasm metabolism, Mitomycin metabolism, Mitomycin toxicity, NAD(P)H Dehydrogenase (Quinone) metabolism
- Abstract
The effect of pH and oxygen on DNA alkylation by mitomycin C (MMC) was studied with cell fractions and intact cells. The cell lines used were the HCT 116 human colon cancer cell line and a MMC-resistant subline (HCT 116-R30A) that has 5% of the quinone reductase activity present in the parent cell line. Microsomal fractions of the two cell lines catalyzed MMC-DNA adduct formation only under anaerobic conditions with equal efficiency. However, the pH of the reaction controlled the production of four identified and two unidentified adducts. Soluble fractions from each cell source catalyzed MMC-DNA adduct formation under aerobic and anaerobic conditions similarly. At higher pH, limited DNA adducts were produced by MMC activated by soluble fractions from either cell source. At lower pH, more DNA adducts were obtained with MMC activated by the soluble fraction of HCT 116 cells than with that activated by the soluble fraction of HCT 116-R30A cells. Four of these adducts were identified as N2-(2" beta,7"-diaminomitosene-1" alpha-yl)-2'-deoxyguanylic acid, N2-(2" beta,7"-diaminomitosen-1" beta-yl)-2'-deoxyguanylic acid, N2-(10"-decarbamoyl-2",7"-diaminomitosen-1" alpha-yl)-2'-deoxyguanylic acid, and N2-(2" beta,7"-diamino-10"-deoxyguanyl-N2-yl-mitosen-1" alpha-yl)-2'- deoxyguanylic acid. Acidic intracellular pH enhanced the cytotoxicity of MMC for HCT 116 cells, decreasing the IC50 from 0.3 +/- 0.04 microM to 0.1 +/- 0.03 microM, but pH had limited effect on the cytotoxicity of MMC for HCT 116-R30A cells. When intracellular pH was decreased, interstrand DNA cross-linking by MMC increased to a greater extent in HCT 116 cells than in HCT 116-R30A cells. Only two DNA adducts, each at low intensity, were detected in HCT 116-R30A cells treated at pH 6.0 and 7.6 and in HCT 116 cells treated at pH 7.6. However, six radioactive spots were detected in HCT 116 cells treated at pH 6.0. Three of these adducts were identified. This is the first direct evidence that acidic intracellular pH enhances MMC-DNA adduct formation in tumor cells containing high quinone reductase activity. Results from this study further confirm that pH and not enzyme is the determining factor in the distribution of types of MMC-DNA adducts. This study also indicates that low intracellular pH enhances the activity of quinone reductase in reducing MMC, which is important for aerobic cytotoxicity of MMC against tumor cells with high concentration of quinone reductase.
- Published
- 1993
26. Alkylation of DNA with aziridine produced during the hydrolysis of N,N',N''-triethylenethiophosphoramide.
- Author
-
Musser SM, Pan SS, Egorin MJ, Kyle DJ, and Callery PS
- Subjects
- Alkylating Agents pharmacology, Aziridines pharmacology, Chromatography, High Pressure Liquid, DNA chemistry, Hydrogen-Ion Concentration, Hydrolysis, Magnetic Resonance Spectroscopy, Mass Spectrometry, Models, Molecular, Nucleosides chemistry, Spectrophotometry, Ultraviolet, Triethylenephosphoramide chemistry, Alkylating Agents chemistry, Aziridines chemistry, DNA drug effects, Thiotepa chemistry
- Abstract
A reaction pathway by which thiotepa (N,N',N''-triethylenethiophosphoramide) and tepa (N,N',N''-triethylenethiophosphoramide), its major metabolite in humans, alkylate and depurinate DNA involves hydrolysis to aziridine (ethylene imine), a highly reactive monofunctional alkylating agent. Hydrolytic cleavage of an N-P bond of thiotepa releases aziridine which reacts with DNA, resulting in depurination and formation of the stable N-7 adduct 7-(2-aminoethyl)guanine and an aminoethyl adduct of adenine. Chromatographically identical alkylated products were observed in the reaction of thiotepa and tepa with individual nucleosides. Adducts with deoxycytidine or thymidine were not detected. Aziridine was measured by HPLC after derivatization with 1,2-naphthoquinone 4-sulfate. On the basis of the identity of the DNA adducts and the rate of formation of aziridine by hydrolysis in vitro, thiotepa is concluded to be a lipophilic, stabilized form of aziridine which serves as a cell-penetrating carrier of aziridine.
- Published
- 1992
- Full Text
- View/download PDF
27. The role of NAD(P)H:quinone oxidoreductase in mitomycin C- and porfiromycin-resistant HCT 116 human colon-cancer cells.
- Author
-
Pan SS, Akman SA, Forrest GL, Hipsher C, and Johnson R
- Subjects
- 2,6-Dichloroindophenol metabolism, Carbon Radioisotopes, Cell Extracts, Cell Size physiology, Cell Survival drug effects, Cell Survival physiology, Colonic Neoplasms drug therapy, Colonic Neoplasms genetics, Drug Resistance, Drug Screening Assays, Antitumor, Humans, Intracellular Fluid metabolism, Microsomes metabolism, Mitomycin metabolism, NAD(P)H Dehydrogenase (Quinone) genetics, Oxidation-Reduction, Porfiromycin pharmacokinetics, RNA, Messenger genetics, Tissue Distribution, Transcription, Genetic genetics, Tumor Cells, Cultured drug effects, Vitamin K metabolism, Colonic Neoplasms enzymology, Mitomycin pharmacology, NAD(P)H Dehydrogenase (Quinone) physiology, Porfiromycin pharmacology
- Abstract
A mitomycin C (MMC)- and porfiromycin (PFM)-resistant subline of the HCT 116 human colon-cancer cell line was isolated after repeated exposure of HCT 116 cells to increasing concentrations of MMC under aerobic conditions. The MMC-resistant subline (designated HCT 116-R30A) was 5 times more resistant than the parent cells to MMC and PFM under aerobic conditions. Both the MMC-resistant cells and the parent HCT 116 cells accumulated similar amounts of PFM by passive diffusion, but levels of macromolecule-bound PFM were about 50% lower in the resistant cell line, implying a decrease in PFM reductive activation in the resistant cells. The finding that microsomes from either sensitive or resistant cells showed an equal ability to reduce MMC and PFM indicated that the activity of NADPH cytochrome P-450 reductase (EC 1.6.2.4) was not changed in the resistant subline. Soluble extracts of HCT 116 cells reduced MMC and PFM more effectively at pH 6.1, and NADH and NADPH were utilized equally well as electron donors under both aerobic and anaerobic conditions. These data suggest that quinone reductase (EC 1.6.99.2; DT-diaphorase) in soluble extracts is responsible for the reduction of MMC. Quinone reductase activities in soluble extracts of HCT 116-R30A cells for the reduction of dichlorophenol indophenol (DCPIP) and menadione-cytochrome c at optimal pHs were decreased by 95% as compared with those obtained in parent cells. However, the MMC-reducing activity of HCT 116-R30A soluble extracts was only 50% lower than that of the parent cell extracts. The kinetic constants (Km, Vmax) found for quinone reductase in the two cell lines with respect to the substrates DCPIP and menadione differed. Two species of mRNA for quinone reductase (2.7 and 1.2 kb) were detected in both cell lines, and there was no detectable difference between parent and resistant cells in the steady-state level of either of these mRNA species. Furthermore, incubation with the quinone reductase inhibitor dicoumarol rendered HCT 116 cells more resistant to MMC. Alteration of the quinone reductase activity in HCT 116-R30A cells appears to be the mechanism responsible for their resistance to MMC and PFM.
- Published
- 1992
- Full Text
- View/download PDF
28. Germ-cell deficient (gcd), an insertional mutation manifested as infertility in transgenic mice.
- Author
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Pellas TC, Ramachandran B, Duncan M, Pan SS, Marone M, and Chada K
- Subjects
- Animals, Female, Globins genetics, Heterozygote, Homozygote, Infertility pathology, Male, Mice, Mice, Transgenic, Ovary embryology, Ovary pathology, Restriction Mapping, Spermatogenesis, Testis embryology, Testis pathology, Germ Cells cytology, Infertility genetics
- Abstract
A genetic analysis is necessary to gain a greater understanding of the complex developmental processes in mammals. Toward this end, an insertional transgenic mouse mutant has been isolated that results in abnormal germ-cell development. This recessive mutation manifests as infertility in both males and females and is specific for the reproductive organs, since all other tissues examined were histologically normal. A developmental analysis of the gonadal tissues demonstrated that the germ cells were specifically depleted as early as day 11.5 of embryonic development, while the various somatic cells were apparently unaffected. Therefore, the mutated locus must play a critical role in the migration/proliferation of primordial germ cells to the genital ridges of developing embryos. In addition, females homozygous for the mutation could potentially be a valuable animal model of a human syndrome, premature ovarian failure. This mutation has been named germ-cell deficient, gcd.
- Published
- 1991
- Full Text
- View/download PDF
29. Mechanisms for the modulation of alkylating activity by the quinone group in quinone alkylating agents.
- Author
-
Begleiter A, Leith MK, and Pan SS
- Subjects
- DNA metabolism, Dithiothreitol pharmacology, Oxidation-Reduction, Pyridines metabolism, Spectrum Analysis, Structure-Activity Relationship, Alkylating Agents pharmacology, Benzoquinones pharmacology
- Abstract
Previous studies have demonstrated that the quinone group may play an important role in modulating the alkylating activity of quinone alkylating agents. Introduction of a quinone moiety markedly increased the alkylating activity and cytotoxic activity of the model quinone alkylating agents benzoquinone mustard and benzoquinone dimustard. However, the cytotoxic and DNA-damaging activity of benzoquinone mustard was considerably greater than that of benzoquinone dimustard. In this study, we have investigated the role of the quinone group as a modulator of alkylating activity in these antitumor agents, using extracellular assays to eliminate differences due to cellular drug uptake and metabolism. Evidence was obtained that the alkylating activities of both benzoquinone mustard and benzoquinone dimustard were enhanced by reduction of the quinone group. In addition, when these agents were reduced, they displayed equal alkylating activity. This finding suggests that the difference in the activity of these agents in cells is not due to intrinsic differences in alkylating activities of the activated forms of these agents. Electrochemical studies revealed that benzoquinone dimustard has a lower redox potential than benzoquinone mustard and, thus, is less easily reduced. Inactivation and spectroscopic studies suggested that a major reason for the differences in activity between benzoquinone mustard and benzoquinone dimustard may be the rapid inactivation of the dimustard before its reduction. This effect may be enhanced by the lower redox potential of benzoquinone dimustard, compared with benzoquinone mustard. These findings support the hypothesis that the quinone group can modulate the alkylating activity of quinone alkylating agents; however, the mechanisms by which this modulation occurs may vary for different antitumor agents.
- Published
- 1991
30. Interaction of N,N',N''-triethylenethiophosphoramide and N,N',N''-triethylenephosphoramide with cellular DNA.
- Author
-
Cohen NA, Egorin MJ, Snyder SW, Ashar B, Wietharn BE, Pan SS, Ross DD, and Hilton J
- Subjects
- Animals, Aroclors pharmacology, Biotransformation, Cell Line, Chlorodiphenyl (54% Chlorine), DNA Repair drug effects, DNA Replication drug effects, DNA, Neoplasm isolation & purification, Humans, Kinetics, Leukemia L1210, Mice, Microsomes, Liver drug effects, Microsomes, Liver metabolism, Rats, Thiotepa metabolism, Triethylenephosphoramide metabolism, Cell Division drug effects, DNA Damage, DNA, Neoplasm drug effects, Thiotepa pharmacology, Triethylenephosphoramide pharmacology
- Abstract
The antineoplastic agents N,N',N''-triethylenethiophosphoramide (thioTEPA) and N,N',N''-triethylenephosphoramide (TEPA) were studied for their interaction with the DNA of L1210 cells in the presence and absence of rat hepatic microsomes and NADPH. Alkaline elution was used to study 3 types of DNA lesions. When L1210 cells were incubated with thioTEPA alone, or with thioTEPA in the presence of microsomes and NADPH, no single-strand breaks were detected. However, incubation of L1210 cells for 2 h with thioTEPA, at concentrations greater than or equal to 100 microM, caused a dose-dependent increase in interstrand cross-linking that reached a maximum by 2 h after drug exposure. In the presence of rat hepatic microsomes and NADPH, this cross-linking was eliminated, but a different DNA lesion, alkali-labile sites, was produced. These alkali-labile sites were partially reparable with maximum repair achieved by 2 h after removal of drug. ThioTEPA was greater than 85% consumed by the microsomal incubation conditions employed, and TEPA was the only product of the microsomal metabolism of thioTEPA. Alkaline elution studies of L1210 cells that had been incubated with TEPA, alone or in the presence of microsomes and NADPH, demonstrated an elution pattern identical to that produced by thioTEPA in the presence of microsomes and NADPH. Lymphoblastoid cell lines derived from patients with Fanconi's anemia were far more sensitive to thioTEPA and mechlorethamine hydrochloride than were lymphoblasts derived from normal humans, but this hypersensitivity was not noted with TEPA or bleomycin. This is consistent with the known hypersensitivity of cells from patients with Fanconi's anemia to agents that produce interstrand cross-links and with the alkaline elution studies described above. In contrast, lymphoblastoid cell lines derived from patients with ataxia telangiectasia were no more sensitive to thioTEPA than were lymphoblasts derived from normal humans but were far more sensitive to bleomycin. One of these cell lines proved hypersensitive to TEPA, whereas the other was no more sensitive to TEPA than were lymphoblasts from normal humans. Our data imply that thioTEPA produces interstrand cross-links but that TEPA, the primary metabolite of thioTEPA, produces DNA lesions that are alkali labile.
- Published
- 1991
31. Mitomycin antibiotic reductive potential and related pharmacological activities.
- Author
-
Pan SS and Gonzalez H
- Subjects
- Animals, Colonic Neoplasms drug therapy, Electrochemistry, Humans, Kinetics, Liver drug effects, Liver enzymology, Mitomycin, NADH Dehydrogenase metabolism, Oxidation-Reduction, Oxygen Consumption, Rats, Tumor Cells, Cultured, Xanthine Oxidase metabolism, Liver metabolism, Mitomycins pharmacology
- Abstract
Relationships of reductive potential, kinetics of enzymatic reduction, augmented oxygen consumption, and cytotoxicity were determined for seven clinically relevant mitomycin antibiotics. Potentials for one-electron reduction were obtained by cyclic voltammetry analysis in dimethyl sulfoxide with 0.1 M tetraethyl-ammonium perchlorate. These potentials were -0.55 V for N7-acetylmitomycin C, -0.61 V for mitomycin A, -0.75 V for N7-(p-hydroxyphenyl)mitomycin C, -0.79 V for N7-(dimethylamino-methylene)mitomycin C, -0.81 V for N7-(2-(4-nitrophenyldithio)-ethyl)-mitomycin C, -0.81 V for mitomycin C, and -0.89 V for porfiromycin. All seven antibiotics were reduced by xanthine oxidase and NADPH-cytochrome P450 reductase, but the rate of reduction varied for each antibiotic and each enzyme. The less negative the reductive potential of an antibiotic, the more easily that antibiotic was reduced enzymatically. These seven mitomycin antibiotics also augmented oxygen consumption by rat liver microsomes. As with their reduction by xanthine oxidase and NADPH-cytochrome P450 reductase, the less negative the reductive potential of an antibiotic, the more it augmented oxygen consumption. Cytotoxicity of each antibiotic was assessed by defining the IC50 against HCT 116 human colon carcinoma cells. A relationship between the reductive potential of these antibiotics and their cytotoxicity against HCT 116 cells was also observed.
- Published
- 1990
32. Cellular transport and accumulation of thiotepa.
- Author
-
Egorin MJ, Snyder SW, Pan SS, and Daly C
- Subjects
- Animals, Biological Transport, Birds, Cell Membrane Permeability drug effects, Erythrocytes drug effects, Erythrocytes metabolism, Half-Life, Humans, Leukemia L1210 metabolism, Mice, Tumor Cells, Cultured, Thiotepa pharmacokinetics
- Abstract
Because the transport and accumulation of N,N',N''-triethylenethiophosphoramide (thiotepa) by cells has not been characterized, these processes were investigated with [14C]thiotepa and cultured L1210 or freshly obtained human or avian RBCs. The octanol: phosphate-buffered saline (PBS) partition coefficient of thiotepa was 2.4 +/- 0.1 (n = 8). With this value, the permeability coefficient (Ps) for thiotepa was estimated to be between 2.8 x 10(-4) and 1.81 x 10(-3) cm/sec, and the half-life of accumulation of thiotepa by L1210 cells was estimated to be 0.063 to 0.40 seconds. Thiotepa accumulation by cells was measured after incubation of cells with [14C]thiotepa and subsequent harvesting of cells by centrifugation through silicone fluid. Thiotepa accumulation by L1210 cells was biphasic. The initial phase was rapid and essentially complete by 10 seconds. The amount of cell-associated 14C increased linearly with increasing extracellular concentrations of thiotepa or with increasing size of the cell pellet. The absolute amount of cell-associated 14C was consistent with that expected if the [14C]thiotepa had been evenly distributed in the incubation medium and a volume equal to that of the cell pellet had been sampled and counted. This rapid phase of thiotepa accumulation was not slowed when cells were incubated on ice. The second phase of [14C]thiotepa accumulation occurred at a rate much slower than that of the initial phase. This slower phase of drug accumulation was linear for at least 5 hours. The rate of 14C accumulation increased progressively over a range of extracellular thiotepa concentrations from 5 to 100 nmol/mL and could not be saturated under acceptable tissue culture conditions. The slower rate of 14C accumulation was ablated by incubating cells on ice and was reduced by 30% to 50% in the presence of 1mM of sodium azide or 2,4-dinitrophenol. The slow rate of accumulation of 14C reflected summation of a relatively stable or constant amount of exchangeable 14C and an amount of nonexchangeable 14C that increased linearly from almost undetectable levels at the start of the experiment to amounts equal to 64 +/- 11% of total cellular radioactivity after 5 hours. The initial association of [14C]thiotepa with both human and avian RBCs was also very rapid. Avian RBCs also exhibited a slow rate of 14C accumulation that was linear for at least 5 hours but that was 15% to 20% that of L1210 cells.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1990
33. Porfiromycin disposition in oxygen-modulated P388 cells.
- Author
-
Pan SS
- Subjects
- Aerobiosis, Animals, Carbon Radioisotopes, Cell Hypoxia, DNA metabolism, Dealkylation, Mice, Porfiromycin pharmacology, Tumor Cells, Cultured, Leukemia P388 metabolism, Oxygen pharmacology, Porfiromycin metabolism
- Abstract
The cytotoxicity, metabolism, and DNA alkylation of porfiromycin (PFM) under aerobic and hypoxic conditions were evaluated in P388 murine leukemia cells. Clonogenic assays showed that the IC50 value for a 1-h exposure to PFM was 4 microM for aerobic cells and 0.5 microM for hypoxic cells. After a 1-h exposure to concentrations of 1, 5, and 10 microM [14C]-PFM, the accumulation of total radioactivity in hypoxic cells was 10 to 20 times that in aerobic cells. The disposition of radioactivity in cells that had been treated for 1 h with 5 microM PFM under aerobic or hypoxic conditions showed that (a) under either condition, internal free-PFM concentration equalled the external drug concentration; (b) DNA-, RNA-, and protein-bound radioactivity were at least 10 times greater in hypoxic cells than in aerobic cells; and (c) known metabolites and unidentified radioactive products were also generated in greater amounts in hypoxic cells than in aerobic cells. Thus, the increased amounts of radioactivity accumulated by hypoxic P388 cells after exposure to [14C]-PFM resulted from the accumulation of nonexchangeable protein and nucleic-acid adducts and metabolites rather than free PFM. Determinations of DNA adducts formed in P388 cells revealed five possible adducts: (1) N2-(2'-deoxyguanosyl)-7-methylaminomitosene, (2) a second monofunctional PFM-guanine adduct, (3) a PFM cross-linked dinucleotide, (4) possibly a nucleoprotein-related adduct, and (5) an unknown. We conclude that the enhancement of PFM-induced cytotoxicity by hypoxia appears to be primarily due to increased alkylation of macromolecules.
- Published
- 1990
- Full Text
- View/download PDF
34. DNA alkylation by enzyme-activated mitomycin C.
- Author
-
Pan SS, Iracki T, and Bachur NR
- Subjects
- Animals, Biotransformation, Cattle, Chromatography, Gel, Chromatography, High Pressure Liquid, Hydrogen-Ion Concentration, Kinetics, Mitomycin, NADPH-Ferrihemoprotein Reductase metabolism, Spectrum Analysis, Xanthine Oxidase metabolism, Alkylating Agents, DNA, Mitomycins antagonists & inhibitors, Mitomycins isolation & purification, Mitomycins metabolism
- Abstract
After anaerobic reductive activation by either NADPH cytochrome P-450 reductase (EC 1.6.2.4) or xanthine oxidase (EC 1.2.3.2), mitomycin C readily alkylated DNA. When the mitomycin C-alkylated DNA is digested by DNase, snake venom phosphodiasterase, and alkaline phosphatase, only partial release of the monofunctionally linked mitomycin C nucleotide adduct occurs. Cross-linked adducts are not released into dinucleotides but resist nuclease digestion and remain in oligonucleotides and insoluble precipitates. Kinetic analyses show that the nuclease-resistant fraction which is indicative of DNA cross-linking by mitomycin C takes place quite readily. This nuclease-resistant fraction is particularly significant when the amount of total bound mitomycin C is less than 15 mumol/mmol of DNA. The cross-linked mitomycin C product accounts for more than half of the total alkylation under all pH conditions tested. Our data suggest that particular DNA sites are available for DNA cross-linking by mitomycin C, and these sites are probably the preferred and immediate alkylating targets. Furthermore, DNA cross-links by mitomycin C are not the secondary product of monofunctional adducts. Activity of both flavoenzymes is pH dependent, hence, mitomycin C activation and the rate of DNA alkylation are pH dependent. At elevated mitomycin C alkylation of DNA, the highest amount of cross-linking occurs at neutral pH. High pressure liquid chromatographic separation of the nuclease-digested DNA detected one major and two less prominent mitomycin C adducts. These were verified to be mononucleotide mitosene types by UV spectra showing maximum absorbance at 312 and 250 nm. The major adduct was purified and identified as O6-(2'-deoxyguanosyl)-2,7-diaminomitosene by NMR, indicating that the O6 position of guanine is a preferred site in DNA for at least monofunctional linkage formation.
- Published
- 1986
35. Involvement of molybdenum and iron in the in vitro assembly of assimilatory nitrate reductase utilizing Neurospora mutant nit-1.
- Author
-
Lee KY, Pan SS, Erickson R, and Nason A
- Subjects
- Animals, Cations, Divalent, Cattle, Enzyme Induction, Hydrogen-Ion Concentration, Iron metabolism, Iron Radioisotopes, Liver enzymology, Milk enzymology, Molybdenum metabolism, Mutation, NADP, Neurospora drug effects, Neurospora crassa enzymology, Neurospora crassa metabolism, Nitrates pharmacology, Radioisotopes, Species Specificity, Xanthine Oxidase pharmacology, Iron pharmacology, Molybdenum pharmacology, Neurospora enzymology, Nitrate Reductases metabolism
- Published
- 1974
36. Reductive activation of mitomycin C and mitomycin C metabolites catalyzed by NADPH-cytochrome P-450 reductase and xanthine oxidase.
- Author
-
Pan SS, Andrews PA, Glover CJ, and Bachur NR
- Subjects
- Animals, Arsenates pharmacology, Cattle, Chromatography, High Pressure Liquid, Electron Spin Resonance Spectroscopy, Free Radicals, Hydrogen-Ion Concentration, Kinetics, Mitomycin, Phosphates pharmacology, Rats, Mitomycins metabolism, NADPH-Ferrihemoprotein Reductase metabolism, Xanthine Oxidase metabolism
- Abstract
Under anaerobic conditions and with proper electron donors, NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and xanthine oxidase (EC 1.2.3.2) similarly reductively metabolized mitomycin C. Reversed phase high performance liquid chromatography was used to separate, detect, and isolate several metabolites. Three metabolites were identified by mass spectrometry and thin layer chromatography as 1,2-cis- and trans-2,7-diamino-1-hydroxymitosene and 2,7-diaminomitosene. Three metabolites were phosphate-dependent, and two of them were identified to be 1,2-cis- and trans-2,7-diaminomitosene 1-phosphate. The amounts of the five identified metabolites generated during the reduction of mitomycin C varied with pH and nucleophile concentration. At pH 6.5, 2,7-diaminomitosene was essentially the only metabolite formed, whereas from pH 6.8 to 8.0, trans- and cis-2,7-diamino-1-hydroxymitosene increased in quantity as 2,7-diaminomitosene decreased. The disappearance of mitomycin C and the production of metabolites were enzyme and mitomycin C concentration-dependent. Substrate saturation was not reached for either enzyme up to 5 mM mitomycin C. Electron paramagnetic resonance studies demonstrated the formation of mitomycin C radical anion as an intermediate during enzymatic activation. Our results indicate that either enzyme catalyzed the initial activation of mitomycin C to a radical anion intermediate. Subsequent spontaneous reactions, including the elimination of methanol and the opening of the aziridine ring, generate one active center at C-1 which facilitates nucleophilic attack. Simultaneous generation of two reactive centers was not observed. All five primary metabolites were metabolized further by either flavoenzyme. The secondary metabolites exhibited similar changes in their absorbance spectra and were unlike the primary metabolites, suggesting that a second alkylating center other than C-1 was generated during secondary activation. We propose that secondary activation of monofunctionally bound mitomycin C is probably a main route for the bifunctional binding of mitomycin C to macromolecules and that the cytotoxic actions of mitomycin C result from multiple metabolic activations and reactions.
- Published
- 1984
37. [Professional morality of nurses in hospitals].
- Author
-
Pan SS
- Subjects
- Attitude of Health Personnel, Humans, Morals, Nurse-Patient Relations, Nursing Service, Hospital
- Published
- 1987
38. Liquid chromatography-thermospray mass spectrometry of DNA adducts formed with mitomycin C, porfiromycin and thiotepa.
- Author
-
Musser SM, Pan SS, and Callery PS
- Subjects
- Animals, Cattle, Chemical Phenomena, Chemistry, Chromatography, High Pressure Liquid methods, Hydrolysis, Mass Spectrometry methods, Mitomycin, Spectrophotometry, Ultraviolet, Thymus Gland metabolism, DNA analysis, Mitomycins analysis, Porfiromycin analysis, Thiotepa analysis
- Abstract
High-performance liquid chromatography (HPLC) and thermospray mass spectrometry were combined for the analysis of DNA adducts formed from the interaction of the anticancer drugs mitomycin C, porfiromycin and thiotepa with calf thymus DNA. The adducts formed from reaction of mitomycin C and porfiromycin with DNA were separated from unmodified nucleosides by HPLC on a C18 column and identified by thermospray mass spectrometry. Thiotepa DNA adducts readily depurinated from DNA and were chromatographed and identified by thermospray liquid chromatography-mass spectrometry as the modified bases without the ribose moiety attached. The utility of thermospray mass spectrometry for the identification of microgram quantities of nucleoside adducts and depurinated base adducts of these anticancer drugs was demonstrated.
- Published
- 1989
- Full Text
- View/download PDF
39. Xanthine oxidase catalyzed reductive cleavage of anthracycline antibiotics and free radical formation.
- Author
-
Pan SS and Bachur NR
- Subjects
- Catalysis, Drug Interactions, Electron Transport, Free Radicals, Hydrogen-Ion Concentration, Ions, NAD, NADP, Daunorubicin metabolism, Doxorubicin metabolism, Xanthine Oxidase metabolism
- Published
- 1980
40. Comparative flavoprotein catalysis of anthracycline antibiotic. Reductive cleavage and oxygen consumption.
- Author
-
Pan SS, Pedersen L, and Bachur NR
- Subjects
- Aclarubicin, Animals, Daunorubicin metabolism, Doxorubicin metabolism, In Vitro Techniques, Male, NAD metabolism, Naphthacenes, Oxidation-Reduction, Rats, Xanthine Oxidase metabolism, Antibiotics, Antineoplastic metabolism, Flavoproteins metabolism, Oxygen Consumption drug effects
- Published
- 1981
41. Mechanism of transport and intracellular binding of porfiromycin in HCT 116 human colon carcinoma cells.
- Author
-
Pan SS, Johnson R, Gonzalez H, and Thohan V
- Subjects
- Animals, Biological Transport, Biotransformation, Carbon Radioisotopes, Cell Line, Colonic Neoplasms, Erythrocytes metabolism, Humans, In Vitro Techniques, Kinetics, Microsomes, Liver metabolism, Porfiromycin blood, Rats, Mitomycins metabolism, Porfiromycin metabolism, Tumor Cells, Cultured metabolism
- Abstract
The mechanism of uptake and efflux of porfiromycin (PFM) by HCT 116 human colon carcinoma cells or freshly obtained human RBC was investigated. The time course of uptake of radioactivity upon exposure of HCT 116 cells to [14C]PFM showed one fast and one slow phase of linear increase. The initial phase of PFM uptake was not saturable with external drug concentrations from 2 to 100 microM. PFM accumulation was temperature dependent with a temperature coefficient (Q10 24-37 degrees C) of 2.3 +/- 0.3. PFM uptake was not affected either by individual inhibitors such as 1 mM 2,4-dinitrophenol, sodium azide, iodoacetic acid, ouabain, 0.02 mM oligomycin, p-hydroxylmercuribenzoate, 0.2 mM N-ethylmaleimide, or by combinations of inhibitors. PFM uptake did not demonstrate competitive inhibition by unlabeled PFM and mitomycin C. Efflux of cellular radioactivity was not affected by the above mentioned inhibitors or by verapamil, diltiazem, or trifluoperazine. Only aliphatic alcohols accelerated the initial influx rate. The RBC, however, only exhibited the initial fast accumulation of [14C]PFM, and all the 14C accumulated by RBC was exchangeable. These data demonstrate that the uptake and the efflux of PFM in HCT 116 cells and RBC comprise a passive diffusion process.
- Published
- 1989
42. Effect of tungsten and vanadium on the in vitro assembly of assimilatory nitrate reductase utilizing Neurospora mutant nit-1.
- Author
-
Lee KY, Erickson R, Pan SS, Jones G, May F, and Nason A
- Subjects
- Cell-Free System, Culture Media, Enzyme Induction, Molybdenum antagonists & inhibitors, Molybdenum metabolism, Mutation, NADP, Neurospora crassa drug effects, Neurospora crassa enzymology, Neurospora crassa metabolism, Nitrates pharmacology, Radioisotopes, Species Specificity, Tungsten metabolism, Vanadium metabolism, Xanthine Oxidase pharmacology, Neurospora enzymology, Nitrate Reductases metabolism, Tungsten pharmacology, Vanadium pharmacology
- Published
- 1974
43. Planning for the facility of today and tomorrow.
- Author
-
Pan SS
- Subjects
- United States, Hospital Design and Construction, Hospital Planning
- Published
- 1984
44. [The length of digestive tract intubation under fibrogastroscopic guidance].
- Author
-
Pan SS
- Subjects
- Adolescent, Adult, Aged, Female, Fiber Optic Technology, Humans, Male, Middle Aged, Gastroscopy, Intubation, Gastrointestinal methods
- Published
- 1983
45. Automated microdensitometry and quantification of lipoproteins by agarose gel electrophoresis.
- Author
-
Wong RA, Banchero PG, Jensen LC, Pan SS, Adamson GL, and Lindgren FT
- Subjects
- Adult, Cholesterol blood, Female, Humans, Lipoproteins, HDL blood, Lipoproteins, LDL blood, Lipoproteins, VLDL blood, Male, Triglycerides blood, Computers, Densitometry methods, Electrophoresis methods, Electrophoresis, Agar Gel methods, Lipoproteins blood
- Abstract
A major obstacle in the application of quantitative microelectrophoresis has been tedious manipulations and calculations. To overcome these difficulties, we have developed an automatic system for the microdensitometry and calculations as part of a quantitative agarose gel electrophoresis facility. Results are internally standardized by serum cholesterol and/or triglyceride measurements. The hardware consists of a densitometer, an analog to digital converter, a cathode ray tube terminal, a teleprinter, and a small computer. A program in 4K words allows sample coding, electrophoretic scan display, indexing, and systematic identification of each peak. Data are acquired from scans of electrophoretic patterns of serum alone or in combination with the 1.006 gm/ml VLDL top and/or bottom preparative lipoprotein fractions. As many as 30 scans can be stored in 4K words of memory and then sent via high-speed telephone line to a larger computer for remote processing. The analysis corrects for baseline drifts and pre-beta asymmetry and will properly identify and quantify the amount of VLDL, LDL, and HDL with corrections for "sinking pre-beta" and "floating beta" in LDL and VLDL, respectively. Results are given in milligrams per 100 milliliter as well as percentile rank and standard deviation score ranking of each lipoprotein class as compared to an appropriate normal reference population. The latter data are in a form more meaningful to the physician and patient and provide a quantitative dimension to lipoprotein phenotyping.
- Published
- 1977
46. Cellular transport and accumulation of thiotepa in murine, human, and avian cells.
- Author
-
Egorin MJ, Snyder SW, Pan SS, and Daly C
- Subjects
- Animals, Biological Transport, Biotransformation, Cell Membrane Permeability, Humans, Kinetics, Leukemia L1210 metabolism, Mice, Temperature, Tumor Cells, Cultured, Thiotepa metabolism
- Abstract
Because the transport and accumulation of thiotepa by cells has not been characterized, these process were investigated with [14C]thiotepa and cultured L1210 or freshly obtained human or avian RBC. The octanol:phosphate buffered saline partition coefficient of thiotepa was 2.4 +/- 0.1 (n = 8). With this value, the permeability coefficient (P) for thiotepa was estimated to be between 2.8 X 10(-4) and 1.81 X 10(-3) cm/s and the half-life of accumulation of thiotepa by L1210 cells was estimated to be 0.063-0.40 s. Thiotepa accumulation by cells was measured after incubation of cell with [14C]thiotepa and subsequent harvesting of cells by centrifugation through silicone fluid. Thiotepa accumulation by L1210 cells was biphasic. The initial phase was rapid essentially complete by 10 s. The amount of cell-associated 14C increased linearly with increasing extracellular concentrations of thiotepa or with increasing size of the cell pellet. The absolute amount of cell-associated 14C was consistent with that expected if the [14C]thiotepa had been evenly distributed in the incubation medium and a volume equal to that of the cell pellet had been sampled and counted. This rapid phase of thiotepa accumulation was not slowed when cells were incubated on ice. The second phase of [14C]thiotepa accumulation occurred at a rate much slower than that of the initial phase. This slower phase of drug accumulation was linear for at least 5 h. The rate of 14C accumulation increased progressively over a range of extracellular thiotepa concentrations between 5 and 100 nmol/ml and could not be saturated under acceptable tissue culture conditions. The slower rate of 14C accumulation was ablated by incubation cells on ice and was reduced by 30-50% in the presence of 1 mM sodium azide or 2,4-dinitrophenol. The slow rate of accumulation of 14C reflected summation of a relatively stable or constant amount of exchangeable 14C an an amount of nonexchangeable 14C which increased linearly from almost undetectable levels at the start of the experiment to amounts approximately equal to those of exchangeable radioactivity after 5 h. The initial association of [14C]thiotepa with both human and avian RBCs was also very rapid. Avian RBCs also exhibited a slow rate of 14C accumulation which was linear for at least 5 h which was 15-20% that of L1210 cells. Human RBCs did not exhibit a slower rate of 14C accumulation and essentially all of the 14C associated with human RBCs was exchangeable for the 5 h duration of the experiment.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1989
47. Purification and characterization of homogeneous assimilatory reduced nicotinamide adenine dinucleotide phosphate-nitrate reductase from Neurospora crassa.
- Author
-
Pan SS and Nason A
- Subjects
- Copper analysis, Heme analysis, Iron analysis, Kinetics, Molybdenum analysis, NADP, Peptide Fragments analysis, Zinc analysis, Neurospora enzymology, Neurospora crassa enzymology, Nitrate Reductases isolation & purification, Nitrate Reductases metabolism
- Abstract
Neurospora crassa wild type STA4 NADPH-nitrate reductase (NADPH : nitrate oxidoreductase, EC 1.6.6.3) has been purified 5000-fold with an overall yield of 25--50%. The final purified enzyme contained 4 associated enzymatic activities: NADPH-nitrate reductase, FADH2-nitrate reductase, reduced methyl viologen-nitrate reductase and NADPH-cytochrome c reductase. Polyacrylamide gel electrophoresis yielded 1 major and 1 minor protein band and both bands exhibited NADPH-nitrate and reduced methyl viologen-nitrate reductase activities. SDS gel electrophoresis yielded 2 protein bands corresponding to molecular weights of 115 000 and 130 000. A single N-terminal amino acid (glutamic acid) was found and proteolytic mapping for the two separated subunits appeared similar. Purified NADPH-nitrate reductase contained 1 mol of molybdenum and 2 mol of cytochrome b557 per mol protein. Non-heme iron, zinc and copper were not detectable. It is proposed that the Neurospora assimilatory NADPH-nitrate reductase consists of 2 similar cytochrome b557-containing 4.5-S subunits linked together by one molybdenum cofactor. A revised electron flow scheme is presented. p-Hydroxymercuribenzoate inhibition was reversed by sulfhydryl reagents. Inhibitory pattern of p-hydroxymercuribenzoate and phenylglyoxal revealed accessible sulfhydryl and arginyl residue(s) as functional group(s) in the earlier part of electron transport chain as possibly the binding site of NADPH or FAD.
- Published
- 1978
- Full Text
- View/download PDF
48. [The Pont indices in a group of children with their permanent dentition].
- Author
-
Cocirlă E and Pan SS
- Subjects
- Adolescent, Child, Female, Humans, Jaw Relation Record, Male, Malocclusion diagnosis, Dental Occlusion
- Published
- 1975
49. Metabolites and DNA adduct formation from flavoenzyme-activated porfiromycin.
- Author
-
Pan SS and Iracki T
- Subjects
- Alkylating Agents, Chemical Phenomena, Chemistry, Chromatography, High Pressure Liquid, Magnetic Resonance Spectroscopy, Mass Spectrometry, Oxidation-Reduction, Spectrum Analysis, Structure-Activity Relationship, DNA, DNA Damage, Mitomycins, Porfiromycin analogs & derivatives
- Abstract
Porfiromycin was reductively metabolized by NADPH cytochrome P-450 reductase and xanthine oxidase under anaerobic conditions. The production of metabolites varied with the pH and the contents of the reaction buffer. In Tris buffer, two major metabolites were produced at pH 7.5 and above, whereas one major metabolite was produced at pH 6.5. The three major metabolites were separated and isolated by HPLC. Identification by californium-252 plasma desorption mass spectrometry showed that the two major metabolites from pH 7.5 were (trans) and (cis)-forms of 7-amino-1-hydroxyl-2-methylaminomitosene and the major metabolite from pH 6.5 was 7-amino-2-methylaminomitosene. All three major metabolites showed substitutions at the C-1 position. DNA was alkylated readily by enzyme-activated porfiromycin. Digestion of porfiromycin-alkylated DNA by DNase, snake venom phosphodiesterase, and alkaline phosphatase resulted in an insoluble nuclease-resistant fraction and a soluble fraction. The nuclease-resistant fraction reflected a high content of cross-linked adducts. Upon HPLC analysis, the solubilized fraction contained two monofunctionally linked porfiromycin adducts and a possibly cross-linked dinucleotide. The major adduct was isolated by HPLC and identified by NMR, as N2-(2'-deoxyguanosyl)-7-amino-2-methylaminomitosene. The N2 position of deoxyguanosine appeared as the major monofunctional alkylating site for DNA alkylation by porfiromycin. Thus, mitomycin C and porfiromycin (which differs from mitomycin C only by the addition of a methyl group to the aziridine nitrogen) share the same enzymatic activating mechanism that leads to the formation of the same types of metabolites and the same specificity of DNA alkylation.
- Published
- 1988
50. High density lipoprotein distribution. Resolution and determination of three major components in a normal population sample.
- Author
-
Anderson DW, Nichols AV, Pan SS, and Lindgren FT
- Subjects
- Adult, Aged, Female, Humans, Male, Middle Aged, Ultracentrifugation, Lipoproteins, HDL blood
- Published
- 1978
- Full Text
- View/download PDF
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