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Biomedical subjects

C C Thompson

Publications and source records attributed to C C Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Postoperative pulmonary toxicity associated with mitomycin-C therapy.

As more patients survive cancer, and as more sophisticated multidrug antineoplastic protocols are developed, the chances of an anesthesiologist's coming into contact with patients who have been treated with such protocols are increasing. The anesthesiologist who must administer anesthesia to a patient who has had chemotherapy must be cognizant of the particular antineoplastic agents that have the potential for producing occult pulmonary dysfunction. Anesthetic management of these cases must be carefully planned and titrated to prevent further lung injury.

Adult↗
PubMed1991

Convergence of Ets- and notch-related structural motifs in a heteromeric DNA binding complex.

Analysis of the heteromeric DNA binding protein GABP has revealed the interaction of two distinct peptide sequence motifs normally associated with proteins located in different cellular compartments. The alpha subunit of GABP contains an 85-amino acid segment related to the Ets family of DNA binding proteins. The ETS domain of GABP alpha facilitates weak binding to DNA and, together with an adjacent segment of 37 amino acids, mediates stable interaction with GABP beta. The beta subunit of GABP contains four imperfect repeats of a sequence present in several transmembrane proteins including the product of the Notch gene of Drosophila melanogaster. These amino-terminal repeats of GABP beta mediate stable interaction with GABP alpha and, when complexed with GABP alpha, directly contact DNA. These observations provide evidence for a distinct biochemical role for the 33-amino acid repeats, and suggest that they may serve as a module for the generation of specific dimerization interfaces.

Animals↗
PubMed1991

Identification of Ets- and notch-related subunits in GA binding protein.

Recombinant cDNA clones that encode two distinct subunits of the transcription factor GA binding protein (GABP) have been isolated. The predicted amino acid sequence of one subunit, GABP alpha, exhibits similarity to the sequence of the product of the ets-1 protooncogene in a region known to encompass the Ets DNA binding domain. The sequence of the second subunit, GABP beta, contains four 33-amino acid repeats located close to the NH2-terminus of the subunit. The sequences of these repeats are similar to repeats in several transmembrane proteins, including Notch from Drosophila melanogaster and Glp-1 and Lin-12 from Caenorhabditis elegans. Avid, sequence-specific binding to DNA required the presence of both polypeptides, revealing a conceptual convergence of nuclear transforming proteins and membrane-anchored proteins implicated in developmentally regulated signal transduction processes.

Amino Acid Sequence↗
PubMed1991

Direct repeats as selective response elements for the thyroid hormone, retinoic acid, and vitamin D3 receptors.

We report here the identification of thyroid hormone response elements (TREs) that consist of a direct repeat, not a palindrome, of the half-sites. Unlike palindromic TREs, direct repeat TREs do not confer a retinoic acid response. The tandem TRE can be converted into a retinoic acid response element by increasing the spacing between the half-sites by 1 nucleotide, and the resulting retinoic acid response element is no longer a TRE. Decreasing the half-site spacing by 1 nucleotide converts the TRE to a vitamin D3 response element, while eliminating response to T3. These results correlate well with DNA-binding affinities of the thyroid hormone, retinoic acid, and vitamin D3 receptors. This study points to the general importance of tandem repeat hormone response elements and suggests a simple physiologic code exists in which half-site spacing plays a critical role in achieving selective hormonal response.

Animals↗
PubMed1991

Nucleotide pools and mutagenic effects of alkylating agents in wild-type and APRT-deficient Friend erythroleukaemia cells.

Wild-type Friend mouse erythroleukaemia cells (clone 707) were compared with adenine phosphoribosyltransferase (APRT)-deficient mutant subclones (707DAP8 and 707DAP10) for sensitivity to cell killing and mutagenesis by ethyl methanesulphonate (EMS) and methyl methanesulphonate (MMS). Cells were exposed to 0-300 micrograms/ml EMS and to 0-20 micrograms/ml MMS for a period of 16 h. A slight difference was found between wild-type cells and the two APRT-deficient subclones in terms of sensitivity to cell killing by both mutagens. The APRT-deficient subclones were, however, significantly more sensitive than wild-type cells to mutagenesis to 5-bromo-2-deoxyuridine resistance and 6-thioguanine resistance by EMS and MMS. The APRT-deficient subclones were found to have significantly decreased levels of dATP and dTTP nucleotides and decreased levels of all four ribonucleoside triphosphates (ATP, GTP, CTP and UTP) relative to wild-type cells. Wild-type Friend cells were found to have insignificant levels O6-methylguanine-DNA methyl transferase and it is suggested that the increased mutagen sensitivity of APRT-deficient cells may be due to imbalance of deoxyribonucleoside triphosphate pools during DNA excision-repair processes, or more probably due to deficiency of ATP for ATP-dependent DNA excision-repair enzymes.

Alkylating Agents↗
PubMed1989

Protein encoded by v-erbA functions as a thyroid-hormone receptor antagonist.

The thyroid-hormone receptor can, in the absence of its ligand, suppress activity of a responsive promoter. Addition of thyroid hormone, however, results in the stimulation of expression. The oncogenic derivative of the thyroid-hormone receptor, v-erbA, acts as a constitutive repressor and, when coexpressed with the receptor, blocks activation by thyroid hormone. Thus, v-erbA may be the first example of a dominant negative oncogene.

Animals↗
PubMed1989

Positional effect of cis/trans alpha globin gene deletions on the formation of "H" bodies.

Normal individuals have four alpha-globin genes, two on each member of the chromosome 16 pair (alpha alpha/alpha alpha). The alpha-thalassemia trait phenotype associated with deletions of two alpha-genes can be either on the same chromosome, the cis type (alpha alpha/--), or on opposite chromosomes, the trans type (alpha-/alpha-). Traditionally, the observation on vitally stained smears of occasional cells containing "H" bodies has been used as an important diagnostic criterion for alpha-thalassemia trait. These "H" bodies are thought to be precipitated beta tetramers because of the presence of excess beta-globin chains. Our study in patients with various alpha-genotypes indicates that normal subjects (alpha alpha/alpha alpha) and patients with silent alpha-thalassemia trait (alpha alpha/alpha-) generally have no "H" bodies. However, patients with the two-gene deletion of the cis type alpha-thalassemia (alpha alpha/--) show the occasional "H" body, and those with Hb "H" disease (alpha-/-- or alpha cs-/--) show many such bodies. On the other hand, patients with two-gene deletion of the trans type (alpha-/alpha-) do not show "H" bodies. The number of "H" bodies found does not appear to correlate directly with the degree of imbalance in alpha- and beta-chain production among the various alpha-genotypes examined. The chemical nature of "H" bodies is discussed, and an alternative hypothesis that embryonic zeta chains expressed in the cis type but not in the trans type of alpha-thalassemia are involved in the formation of "H" bodies is proposed.

Blotting, Southern↗
PubMed1989

Two kinetic methods to study the regulation of mammalian hexokinases.

Two new kinetic analyses for mammalian hexokinases are presented, which permit one to study the regulation of these enzymes by product inhibition. One method uses the pyruvate kinase-coupled assay and the other the glucose-6-phosphate dehydrogenase-coupled assay. Both methods give simple linear plots, which indicate that the magnesium-ATP complex overcomes the glucose 6-phosphate inhibition competitively, but by atypical kinetics. A new regulation coefficient (Kr) was defined and it was shown that, with both assay methods, the reciprocals of the slopes of the simple linear plots are proportional to Kr.[Mg.ATP].NADP, but not NAD, was found to be a powerful inhibitor of pig heart hexokinase.

Animals↗
PubMed1989

Trans-activation by thyroid hormone receptors: functional parallels with steroid hormone receptors.

The effects of thyroid hormones are mediated through nuclear receptor proteins that modulate the transcription of specific genes in target cells. We previously isolated cDNAs encoding two different mammalian thyroid hormone receptors, one from human placenta (hTR beta) and the other from rat brain (rTR alpha), and showed that their in vitro translation products bind thyroid hormones with the characteritistic affinities of the native thyroid hormone receptor. We now demonstrate that both of the cloned receptors activate transcription from a thyroid hormone-responsive promoter in a hormone-dependent manner, with rTR alpha eliciting a greater response than hTR beta. The putative functional domains of the thyroid hormone receptors were examined by creating chimeric thyroid hormone/glucocorticoid receptors, producing receptors with hybrid functional properties. These experiments support the proposal that the thyroid hormone receptors are composed of interchangeable functional domains, and indicate that the mechanism of hormone-inducible gene regulation has been conserved in steroid and thyroid hormone receptors.

Animals↗
PubMed1989

The interaction of anti 3.7 type quadruplicated alpha-globin genes and heterozygous beta-thalassemia.

Human alpha-globin gene mapping was carried out using a variety of restriction endonucleases (Bgl II, Bam HI, Hind III, Eco RI, Hpa I, Pvu II and Rsa I) on members of a family from El Salvador and a female from Hawaii, of Chinese descent, whose hematological and clinical parameters were those of beta-thalassemia intermedia. Southern blot DNA analysis showed that the beta-thalassemia intermedia patients from the above two families had the same anti 3.7 type quadruplicated alpha-genes on the one chromosome, and that they had the alpha genotype alpha 2, alpha 1 alpha 2, alpha 1 alpha 2, alpha 1/alpha 2, alpha 1. The alpha/beta globin synthesis ratios of the three affected Salvadoran patients were around 2.5, and the affected Hawaiian patient was 2.9. These ratios strongly suggest that the additional alpha-genes in the anti 3.7 type rearrangement are biologically active, thus accounting for the severity of the heterozygous beta-thalassemia observed among these patients.

DNA↗
PubMed1987

Identification of a novel thyroid hormone receptor expressed in the mammalian central nervous system.

A complementary DNA clone derived from rat brain messenger RNA has been isolated on the basis of homology to the human thyroid hormone receptor gene. Expression of this complementary DNA produces a high-affinity binding protein for thyroid hormones. Sequence analysis and the mapping of this gene to a distinct human genetic locus indicate the existence of multiple human thyroid hormone receptors. Messenger RNA from this gene is expressed in a tissue-specific fashion with highest levels in the central nervous system.

Amino Acid Sequence↗
PubMed1984

Sequence of the bacteriophage SP01 gene coding for transcription factor 1, a viral homologue of the bacterial type II DNA-binding proteins.

The Bacillus subtilis phage SP01, whose DNA contains 5-hydroxymethyluracil (hmUra) in place of thymine, codes for an abundant, small, basic protein called TF1. TF1 binds preferentially to hydroxymethyluracil-containing DNA and thereby selectively inhibits transcription of such DNA in vitro. The gene for TF1 has been sequenced. We find that this viral protein is a homologue of the ubiquitous bacterial type II DNA-binding proteins. The three-dimensional structure of one of these bacterial proteins has recently been determined. We are able to discern common as well as distinctive features in the amino acid sequence and the three-dimensional structure of the homologous viral protein.

Amino Acid Sequence↗
PubMed1982

Purpuric oral and cutaneous lesions in a case of drug-induced thrombocytopenia.

This case, from all appearances, seems to constitute a case of secondary thrombocytopenia caused by drugs. Whether the etiology is one of over-dosage achieved when the two drugs, propranolol and disulfiram, were used in combination, or the interaction of the two drugs, or a response to disulfiram is difficult to state definitely. The use of propranolol alone does not seem to be the triggering factor because the patient resumed use of the drug without ill effect. Either an overdosage, exceeding a triggering threshold, was achieved in the combined usage of these two potentially purpuric drugs, or a reaction to disulfiram occurred subsequent to prior sensitizing exposure to this drug. The case does point out that the practitioner, whether dental or medical, should take a careful drug history--particularly in cases of purpura but also in other conditions, such as xerostomia, lichenoid reactions, and burning mouth or tongue. A copy of a current Physician's Desk Reference should be available in every dental or medical office.

Disulfiram↗
PubMed1980

Oral manifestations of the congenital insensitivity-to-pain syndrome.

The congenital insensitivity-to-pain syndrome is a sensory syndrome in which pain is impaired. It has been variably classified under a variety of terms, on occasion leading to some confusion. The condition is present at birth. The patient is usually, but not always, normal with respect to intelligence, development, and psychological adjustments. Other sensory perceptions are normal. Traumatic lesions as a result of self-mutilative acts are not uncommon, especially at an early age. The condition may not be apparent clinically until the time of initial tooth eruption. As the primary teeth erupt, the patient acquires the necessary apparatus for self-infliction of wounds to oral structures, skin, and fingernails. A case of congenital indifference to pain is presented, with clinical documentation of tooth-related problems occurring over a 2-year period and of the steps taken to correct or minimize the traumatic effects of chewing.

Humans↗
PubMed1979

Test-retest gains in WAIS scores after four retest intervals.

Administered the WAIS to 76 male college students on two occasions with a retest interval of either 1 week, 1 month, 2 months, or 4 months. Essentially all Verbal, Performance, and Full Scale IQs increased significantly on the retest. Increases in Verbal IQ for the four time intervals were 4.7, 1.8, 2.3, and .8 IQ points, respectively; the latter was the only nonsignificant gain found. The Performance IQ increased by 11.4, 9.8, 8.7, and 8.0 points for each subsequent time period, and the Full Scale IQ increased by 8.0, 5.7, 5.4, and 4.2 points for each respective time period. Test-retest correlations for the four intervals ranged from .91 to .72 for the Verbal IQ, .87 to .79 for the Performance IQ, and .94 to .74 for the Full Scale IQ. The results were pitted against similar test-retest studies, and clinical and research implications were discussed.

Humans↗
PubMed1978

Molecular complexing ability of quinoline and its simple derivatives.

Electron donor-acceptor complexes for a group of quinolines and naphthalenes with 9-(dicyanomethylene)-2,4,7-trinitrofluorene in 1,2-dichloroethane were studied by optical absorption methods. Association constants, molar absorptivities, and charge-transfer transition energies were evaluated for each system, together with theoretically calcualted orbital energies and complex geometries. In contrast to the association constants and structures reported for N-heterocycle-halogen complexes, these studies indicate that, with a moderately large pi-electron acceptor, quinolines function as pi-rather then n-(lone-pair) donors. These results support intercalation models for drug-receptor interactions involving the quinoline moiety.

Chemical Phenomena↗