Texas Medical Center

About: Texas Medical Center is a healthcare organization based out in Houston, Texas, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 2845 authors who have published 2394 publications receiving 79426 citations.

32P-postlabeling analysis of non-radioactive aromatic carcinogen — DNA adducts

Abstract: A newly developed enzymatic /sup 32/P-postlabeling method was applied to the analysis of DNA's containing non-radioactive arylamine, arylamide, and polycyclic aromatic hydrocarbon adducts. DNA reacted in vitro with N-hydroxy-2-amino-fluorene, N-acetoxy-2-acetylaminofluorene, and 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, respectively, as well as DNA preparations from the liver of rats treated with N-hydroxy-2-acetylaminofluorene and benzo(a)pyrene, respectively, were enzymatically digested to deoxyribonucleoside 3'-monophosphates, which were then converted to (5'-/sup 32/P)deoxyribonucleoside 3',5'-bisphosphates by T4 polynucleotide kinase-catalyzed (/sup 32/P)phosphate transfer from (gamma-/sup 32/P)ATP. The /sup 32/P-labeled nucleotides were resolved by anion-exchange t.l.c. on polyethyleneimine-cellulose and detected by autoradiography. Aromatic adduct nucleotides were found to be retained at the origin in aqueous electrolyte solutions, but to migrate as distinct spots in solvents containing 7-8.5 M urea. Advantage was taken of this observation to remove /sup 32/P-labeled normal DNA nucleotides from adduct nucleotides. This purification enabled the detection of a single adduct in 10(7)-10(8) normal nucleotides. The method appears applicable to the ultrasensitive detection of a large number of carcinogen--DNA adducts of diverse structure without requiring radioactive carcinogens or specific antibodies.

Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysial joint pain

Abstract: Study design A prospective audit. Objective To establish the efficacy of lumbar medial branch neurotomy under optimum conditions. Summary of background data Previous reports of the efficacy of lumbar medial branch neurotomy have been confounded by poor patient selection, inaccurate surgical technique, and inadequate assessment of outcome. Methods Fifteen patients with chronic low back pain whose pain was relieved by controlled, diagnostic medial branch blocks of the lumbar zygapophysial joints, underwent lumbar medial branch neurotomy. Before surgery, all were evaluated by visual analog scale and a variety of validated measures of pain, disability, and treatment satisfaction. Electromyography of the multifidus muscle was performed before and after surgery to ensure accuracy of the neurotomy. All outcome measures were repeated at 6 weeks, and 3, 6, and 12 months after surgery. Results Some 60% of the patients obtained at least 90% relief of pain at 12 months, and 87% obtained at least 60% relief. Relief was associated with denervation of the multifidus in those segments in which the medial branches had been coagulated. Prelesion electrical stimulation of the medial branch nerve with measurement of impedance was not associated with outcome. Conclusions Lumbar medial branch neurotomy is an effective means of reducing pain in patients carefully selected on the basis of controlled diagnostic blocks. Adequate coagulation of the target nerves can be achieved by carefully placing the electrode in correct position as judged radiologically. Electrical stimulation before lesioning is superfluous in assuring correct placement of the electrode.