Metastatic Kaposi's sarcoma presenting as acute appendicitis.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
M S Baker
Publications and source records attributed to M S Baker.
The effect of pH on the conversion of superoxide to hydroxyl free radicals.
The conversion of superoxide (O-.2) to the hydroxyl (HO.) free radical by superoxide-driven Fenton reactions was measured by the formation of hydroxylated derivatives from benzoate. Among a range of catalysts required for the conversion, the Fe3+EDTA complex was the most effective. The effect of superoxide dismutase and catalase indicated that O-.2 and H2O2 were essential reactants, while the formation of authentic HO. was confirmed by the inhibiting capacities of formate, t-butanol, and mannitol. The conversion of O-.2 to HO. was tested over a broad pH range, and was found to be highest at pH 4.8 whether Fe3+EDTA or free Fe3+ were used as the catalysts. When Fe3+EDTA was used at the optimum pH, every HO. produced required 3.7 O-.2 radicals, close to the theoretical limit of one HO. from every three O-.2 radicals generated.
Catalysis↗
Reaction of dATP with N-methyl-N-nitrosourea in vitro.
Extensive methylation was found upon reaction of N-methyl-N-nitrosourea with dATP. The products of this reaction were purified by repeated anion exchange column chromatography and were found to consist of adenine deoxyribonucleotides methylated on the base moiety, terminal phosphate, or both. Products methylated on the adenine ring were identified by co-migration of acid-hydrolyzed samples with authentic standards on reverse phase high pressure liquid chromatography. Products methylated on the sugar phosphate moiety were identified by digestion with snake venom phosphodiesterase, alkaline phosphatase, or both followed by polyethyleneimine cellulose thin layer chromatography. The results demonstrate production of gamma-phosphate-methyldATP, beta-phosphate-methyl-dADP, 1-methyldATP, and gamma-phosphate-methyl-1-methyldATP as well as the relatively unstable products 3-methyldATP and gamma-phosphate-methyl-3-methyl-dATP. The identities and amounts of products formed during this reaction in vitro are consistent with our finding that cellular deoxyribonucleotide pools are a significant target for N-methyl-N-nitrosourea (Topal, M. D., and Baker, M. S. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 2211-2215).
Chromatography, High Pressure Liquid↗
DNA precursors in chemical mutagenesis: a novel application of DNA sequencing.
Recently, we have shown that deoxyribonucleoside residues in the cellular DNA precursor pool are generally more susceptible to methylation than are residues within the DNA duplex. The N-1 position of adenosine, for example, was found to be at least 13,000 times more susceptible to methylation by N-methyl-N-nitrosourea (MNU) than the same site in the DNA. These results suggest that potential sites for alkylation in the double-strand duplex are relatively inaccessible to direct alkylation in vivo. Many of these sites are probably protected from alkylation not only by their position in the interstices of the DNA helix, but also by further in vivo 'packaging' of the DNA in chromatin. We have now used DNA sequencing to demonstrate the incorporation properties of products of the reaction of MNU with dATP and of deoxy-N4-hydroxycytidine triphosphate during DNA replication in vitro by phage T4 DNA polymerase and the 'Klenow' fragment of Escherichia coli pol I. The results suggest that DNA precursor nucleotides due to their greater availability for alkylation, may offer routes for the introduction of alkylated residues into double-stranded DNA.
Alkylation↗
DNA precursor pool: a significant target for N-methyl-N-nitrosourea in C3H/10T1/2 clone 8 cells.
Synchronized C3H/10T1/2 clone 8 cells were treated in vitro with a nontoxic dose of N-methyl-N-nitrosourea during their S phase. Chromatographic isolation of the deoxyribonucleotide DNA precursor pool and measurement of the precursor content per cell showed that a nucleic acid residue in the precursor pool is 190-13,000 times more susceptible to methylation than a residue in the DNA duplex, depending on the site of methylation. This conclusion comes from measurements indicating that, for example, the N-1 position of adenine in dATP is 6.3 times more methylated than the same position in the DNA, even though the adenine content of the pool is only a fraction (0.0005) of the adenine content of the DNA helix. The comparative susceptibility between pool and DNA was found to vary with the site of methylation in the order the N-1 position of adenine greater than phosphate greater than the N-3 position of adenine greater than the O6 position of guanine greater than the N-7 position of guanine. The significance of these results for chemical mutagenesis and carcinogenesis is discussed.
Adenine↗
Indications for exploring the retroperitoneal space.
The retroperitoneal space is an area that deserves consideration in patients with serious bleeding problems. This area should be explored in all patients with a history of previous reconstructive vascular surgery of the abdominal aorta and iliac vessels and who subsequently present with gastrointestinal hemorrhage. It should also be considered for exploration in patients presenting with serious bleeding problems when the bleeding site cannot be identified and the area in which blood is accumulating cannot be detected. We present three cases in which early adequate exploration of the retroperitoneal space would have been beneficial to the patients.
Aged↗
Diagnosis and treatment of aortoenteric fistulae: case reports.
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Aortic Diseases↗
TA in brief psychotherapy with college students.
This paper describes the use of Transactional Analysis with university students in brief psychotherapy. In the clinical setting of a large university, Transactional Analysis was introduced as an alternative to crisis intervention and other mental health strategies. When Transactional Analysis was introduced as a treatment modality, it was also introduced to all the staff clinicians as an alternative therapeutic model and they were instructed in its basic theories. References are made to TA as a technique and a model which is advantageous for teaching adolescents and young adults in learning about themselves. The emphasis is away from the medical model with its focus on disease and placed instead on the learning model with its focus on solving problems in living. TA lends itself well to the developmental issues especially relevant to adolecents and young adults, i.e., autonomy, identity, and independence. In summary, the authors report results of a survey from the students treated within this framework which seem to support their thesis that TA in brief psychotherapy with university students is an effective learning and therapeutic tool.
Adolescent↗
Biliary clonorchiasis.
Parasitic infection of the biliary tree may be seen more frequently because of changing patterns in travel, and may come to the attention of the surgeon when obstruction or secondary bacterial infection occurs. In this case, intraoperative cholangiography indicated common duct abnormalities, and choledochotomy led to the diagnosis of Clonorchis sinensis. A recommendation is made to follow up patients with bilary parasite infections to determine the long-term sequelae.
Adult↗
Differing effects of isoleucine deficiency on the toxicity of MNNG for 10T1/2 and CHO cells.
Isoleucine deficiency sensitizes C3H 10T1/2 cells to the cytotoxic effects of MNNG. Synchrony of proliferation is not required for this effect since it occurs prior to full growth arrest and subsequent establishment of synchronous proliferation after refeeding in complete medium. Furthermore, confluence arrest of proliferation of 10T1/2 cells does not affect their cytotoxic response to MNNG, although they proliferate synchronously after replating at low density. In contrast, the toxicity of MNNG for CHO cells is not altered by isoleucine deficiency, even though these cells are readily synchronized by refeeding in complete medium after transient isoleucine deficiency.
Cell Count↗
Multiple carcinomas of the lung: case report.
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Adenocarcinoma↗
Recurrent aortoduodenal fistula.
We describe the second successful repair of a recurrent aortoduodenal fistula (ADF) occurring two years following insertion of the original prosthetic and 18 months following the repair of the first ADF. The recurrent ADF developed at the site of the previous repair, fistulizing between the sutured aorta and the duodenum closed by staples. Despite the admitted technical challenges of reoperation for a third or fourth time, as in the current case, these patients can be salvaged.
Aorta, Abdominal↗
Sump tube drainage as a source of bacterial contamination.
There is well documented evidence indicating in-appropriately high basal gastrins in patients with duodenal ulcer disease. After stimulation by protein meals, calcium infusion, and insulin-induced hypoglycemia there appears to be an exaggerated release of gastrin in patients with duodenal ulcers compared to control subjects. Vagotomy in general tends to increase serum gastrin by decreasing acid secretion and allowing less inhibition for antral gastrin release. This increase appears less with selective vagotomy and parietal cell vagotomy compared to truncal vagotomy, suggesting vagal inhibition of gastrin release outside the antrum. Antrectomy may decrease serum gastrins by removing a major source of the hormone. However, extra antral gastrin sources, if stimulated properly, may result in little postoperative change.
Calcium↗
Mutagenicity of cancer chemotherapeutic agents in the Salmonella/microsome test.
Seventeen cancer chemotherapeutic agents were tested for their ability to mutate Salmonella typhimurium tester strains in the Salmonella/microsome mutagenicity test. There was a high correlation between the mutagenicity and carcinogenicity of a given agent. Carcinogens positive in the test were Adriamycin, daunomycin, 1-propanol-3,3'-iminodimethanesulfonate, cyclophosphamide, isophosphamide, hycanthone, chlornaphazin, nitrogen mustard, uracil mustard, melphalan, and thio-tepa. Two carcinogesn, actinomycin D and bleomycin, were not detected as mutagens. The presumptive noncarcinogen, methotrexate, was negative in the test. Tilorone and 6-mercaptopurine, tentatively classified as noncarcinogens, were mutagenic. The carcinogenicity of cis-dichlorodiammineplatinum(II), which was positive in the test, has not been determined.
2-Naphthylamine↗
Atherosclerosis obliterans in healthy young adults.
A healthy young man developed unilateral claudication due to an isolated lesion of his external iliac artery, At operation, this was found to be obliterated by atherosclerotic change of long standing. No evidence of systemic disease was noted. A vascular reconstruction has allowed the patient to return to an active life style.
Adult↗
Infected aortic bifurcation grafts.
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Aortic Diseases↗
Cell cycle-specific oncogenic transformation of C3H/10T1/2 clone 8 mouse embryo cells by 1-beta-D-arabinofuranosylcytosine.
1-beta-Darabinofuranosylcytosine at concentrations ranging from 10(-3) to 10(-6) M induces oncogenic transformation in the C3H/10T1/2 clone 8 mouse embryo cell line. Cell lines derived from type III transformed foci grew in soft agarose and produced tumors in immunosuppressed syngeneic mice. With cells synchronized by postconfluent inhibition of growth or isoleucine deprivation, transformation was cell cycle dependent. Maximal transformation was seen in cells treated when in S phase, although some transformation was seen in cells treated in G1 phase of the cell cycle.
Animals↗