Biomedical subjects
A Anderson
Publications and source records attributed to A Anderson.
European unity, inch by centimeter.
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Molecular biology. U.S. juggernaut overwhelms divided European elite.
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Neurobiology. Neuroscientists struggle to achieve a critical mass.
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Kinds of mutations induced by aflatoxin B1 in a shuttle vector replicating in human cells transiently expressing cytochrome P4501A2 cDNA.
Transient expression of rat liver cytochrome P450lA2 cDNA was combined with the use of a shuttle vector as a mutational target to determine the frequency and types of mutation caused by the conversion of aflatoxin B1 into genotoxic metabolites within human cells. Ad293 cells were first transfected with p91-lA2, a rat liver P450lA2 cDNA expression vector, or with p91-lA2(i) (a control vector that has the P450 cDNA in the inverted orientation) and incubated for 24 h to permit P450lA2 accumulation. Cells were then transfected with the pS189 shuttle-vector plasmid, which carries the Escherichia coli supF gene as a mutational target, and incubated for a further 24 h in the presence of aflatoxin B1 to permit promutagen activation and pS189 replication. In shuttle vectors replicated in p91-lA2-transfected cells, the supF point-mutation frequency increased with increasing concentration of aflatoxin B1. This frequency was nine to 23 times greater than the background point-mutation frequency obtained with aflatoxin B1-treated control (p91-lA2(i)-transfected) cells. The large majority of the aflatoxin B1-induced supF point mutations were base substitutions, mostly G:C----T:A transversions. This mutagenesis system permits the molecular analysis of mutations induced by specific P450/promutagen pairs in a shuttle vector replicating in human cells and will permit the investigation of host cell mechanisms involved in the generation of these mutations.
Vitamin E in the treatment of chemotherapy-induced mucositis.
PURPOSE: To determine the efficacy of vitamin E in the treatment of chemotherapy-induced mucositis in patients with malignancy. PATIENTS AND METHODS: A randomized, double-blind, placebo-controlled study was performed to evaluate the efficacy of topical vitamin E in the treatment of oral mucositis in patients receiving chemotherapy for various types of malignancy. A total of 18 patients, 17 of whom had solid tumors and one with acute leukemia, were included in this study. Lesions were observed daily prior to and 5 days after topical application of either vitamin E or placebo oil. RESULTS: Six of nine patients receiving vitamin E had complete resolution of their oral lesions. In eight of nine patients who received placebo, complete resolution of their oral lesions was not observed. This difference is statistically significant (p = 0.025 by Fisher's exact test). No toxicity was observed in this study. CONCLUSION: These results suggest that vitamin E may be an effective therapy in patients with chemotherapy-induced mucositis.
The detection of promutagen activation by extracts of cells expressing cytochrome P450IA2 cDNA: preincubation dramatically increases revertant yield in the Ames test.
Two slightly different protocols, the plate incorporation method and the preincubation method, are used in the Ames Salmonella mutagen test. Using a preincubation method, we recently demonstrated efficient activation of a number of food-derived promutagens by extracts of mammalian cells expressing cDNAs of rat-liver cytochrome P450IA2 and of a P450IA2-IA1 hybrid. We report here that, for 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 1-aminoanthracene and several other promutagens, preincubation dramatically increased the number of revertant colonies in the Ames test when extracts of cytochrome P450IA2-containing transfected cells or low concentrations of rat-liver extracts were used as the source of activating enzymes. At higher concentrations of rat-liver extract protein, the effect of preincubation was less pronounced. The effect of preincubation was not due to the low protein concentrations in the assays since increasing the total protein concentration did not abolish the requirement for preincubation for the detection of MeIQ activation at low concentrations of rat-liver extract. In experiments where P450IA2 synthesized in transfected cells in culture is used to study promutagen activation, the plate incorporation protocol may seriously underestimate the capacity of cell extracts to activate promutagens. Thus, interlaboratory comparisons become difficult and unnecessarily large quantities of cell extract protein may be needed to detect promutagen activation. Whenever Ames test assays are carried out under conditions where P450 concentration limits revertant yield, it would be prudent to examine both the preincubation and plate incorporation protocol.
Comparison and interaction of low dose felodipine and enalapril in the treatment of essential hypertension in elderly subjects.
The antihypertensive effect and tolerance of the combined low doses of felodipine and enalapril (5 + 5 mg daily) were compared with those of either drug at a higher dose level (10 mg daily). Our double-blind, three-way crossover study (balanced Latin square design) involved 36 elderly subjects (mean age 67 +/- 6 years) with essential hypertension. After a 4-week placebo run-in phase the subjects were randomized to the active treatment periods, starting with 5 mg felodipine plus 5 mg enalapril, 5 mg felodipine, or 5 mg enalapril daily for the first 4 weeks. The doses in the felodipine and enalapril periods were then doubled for another 2 weeks. All medication was given once daily in the morning, and blood pressure was measured 24 h after a previous dose. The supine blood pressure for subjects given placebo was 178/101 mm Hg. After 6 weeks' treatment systolic and diastolic supine blood pressures were significantly lower with 5 mg felodipine plus 5 mg enalapril (154/85 mg Hg) than with 10 mg felodipine (159/88 mm Hg) or with 10 mg enalapril (162/91 mm Hg), and the diastolic blood pressure was significantly lower with felodipine than with enalapril. At the end of the felodipine plus enalapril, felodipine, and enalapril treatment periods, 75, 69, and 56% of the subjects, respectively, had a supine diastolic blood pressure 90 mm Hg or less. The combination was tolerated better than either monotherapy. The most commonly reported adverse event was swollen ankles, which occurred in one, nine, and five subjects during felodipine plus enalapril, felodipine, and enalapril treatment, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Clinical efficacy of perindopril in hypertension.
1. Perindopril's effectiveness in mild to moderate hypertension was evaluated in three studies. 2. Perindopril was more effective than sodium restriction in reducing blood pressure, and the effects were additive. 3. Perindopril was as effective as atenolol in reducing blood pressure, and was well tolerated. 4. Perindopril lowered blood pressure to the same extent as enalapril at peak drug levels but had a greater effect at the trough level of the drugs. 5. Perindopril is an effective antihypertensive agent with an acceptable side-effect profile in people with hypertension.
Immunopathology of chronic experimental histoplasmic choroiditis in the primate.
A nonhuman primate model of ocular histoplasmosis was developed that enabled the authors to define the choroidal cellular immunopathology of both the acute and chronic phases of experimental histoplasmic choroiditis. Anti-human monoclonal antibodies were used to identify the inflammatory cell subsets and to calculate their relative percentages in the choroidal inflammatory lesions. Comparison of the acute (less than or equal to 65 days) and chronic (greater than or equal to 1 yr) phases suggested possible variations in the evolution of these lesions, resulting in the development of immunopathologically distinct chronic lesions. In this model, these late lesions could be differentiated by the presence or absence of dense lymphocytic foci, comprised predominantly of mature B-lymphocytes, located within the more diffuse inflammatory cell background. The chronic lesions containing these B-cell foci had significantly higher percentages of both mature B-cells (P less than 0.0001) and helper-inducer T-cells (P less than 0.05) than did the chronic lesions without B-cell foci. The increase in helper-inducer T-cells in the chronic lesions with B-cell foci resulted in a higher mean helper-suppressor T-cell ratio (mu = 0.60) than that seen in lesions lacking foci (mu = 0.33). These findings suggest that, even in the same eye, individual chronic histoplasmic choroidal lesions, which clinically resemble "histo spots" in humans, may have different immunopotentials.
Cellular proto-oncogene expression following exposure of mice to gamma rays.
Many studies have shown the importance of altered cellular proto-oncogene expression in contributing to changes in cell survival, cell transformation, and cell cycle progression. In these experiments we examined the effects of total-body exposure of BCF1 mice to gamma rays (3 Gy) in modulating expression of cellular oncogenes in both gut and liver tissues. We selected specific cellular oncogenes (c-fos, c-myc, c-src, and c-H-ras), based on their normal expression in liver and gut tissues from untreated mice. As early as 5 min following whole-body exposure of BCF1 mice to gamma rays we detected induction of mRNA specific for c-src and c-H-ras in both liver and gut tissues. Accumulation of c-fos-RNA was slightly decreased in gut but was unaffected in liver tissue from irradiated mice relative to untreated controls. Accumulation of c-myc mRNA was unaffected in all tissues examined. These experiments document that modulation of cellular proto-oncogene expression can occur as an early event in tissues following irradiation and suggest that this modulation may play a role in radiation-induced cellular changes.
Hemodynamic comparisons of enalapril and felodipine and their combination.
Thirty-six patients (33 male, 3 female) with a mean age of 67 years and a diastolic blood pressure between 95 and 115 mm Hg, after a four-week placebo run-in period entered a double-blind crossover study comparing felodipine 5 and 10 mg with enalapril 5 and 10 mg and their combination (enalapril 5 mg + felodipine 5 mg). Combined therapy caused a fall in blood pressure of 24/16 mm Hg at trough level that was greater than the falls with the higher doses of monotherapy. The fall with felodipine was greater than with enalapril. Similar patients responded to felodipine and enalapril but more patients achieved blood pressure control with felodipine. When patients not controlled with enalapril 5 mg had felodipine 5 mg or enalapril 5 mg added, felodipine was more effective at lowering blood pressure than the increase in enalapril dosage. A similar effect occurred in those not controlled with felodipine 5 mg. Adverse effects occurred in 22 patients on felodipine, 14 patients on enalapril and 8 on combined therapy. The lipoprotein profile was not altered significantly. Glomerular filtration rates as assessed by 24-hour creatinine clearance were 90 ml/min at randomization, 125 ml/min on felodipine, 108 ml/min on enalapril and 120 ml/min on the combination. Felodipine and enalapril in low doses are effective antihypertensive agents in elderly people. Felodipine monotherapy is more effective than enalapril monotherapy but a greater blood pressure lowering effect can be obtained with the combination of low doses of enalapril and felodipine. This has the advantage that the number of side effects is less.
Funding in Europe: how the big three cope.
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Collagen: a new probe into prehistoric diet.
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A window on life in the Bronze Age. The remains of a 4000-year-old man may shed light on the racial structure and culture of early Europe.
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Networks for thinking in cliques?
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A unique lab design fits the British to a tea.
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Effect of the calmodulin inhibitor trifluoperazine on phosphorylation of P-glycoprotein and topoisomerase II: relationship to modulation of subcellular distribution, DNA damage and cytotoxicity of doxorubicin in multidrug resistant L1210 mouse leukemia cells.
The results from the present study using the sensitive and progressively DOX resistant L1210 model system demonstrated that the effects of TFP are not due to redistribution of DOX to the nucleus, and modulation of cytotoxicity is related to effects on DOX-induced DNA strand breaks. Although TFP affects phosphorylation of PGP and TOPO II (R2 greater than R1), the comparable DNA strand breaks at lower DOX levels with TFP in the resistant sublines suggest that modulation of TOPO II function related to drug-induced DNA damage by calmodulin-mediated events may be an important mode of action.