Biomedical subjects
Publications and source records attributed to D L Nelson.
We report the clinicopathologic findings in two cases of chondrosarcoma of the small bones of the hand arising from a preexisting solitary enchondroma. A critical review of the previously reported 18 cases shows that only one is actually well-documented.
The photolabile (diazomethyl)carbonyl function was introduced into the 8-position of 2-(N,N-di-n-propyl-amino)-1,2,3,4-tetrahydronaphthalene in three ways, resulting in the ether 8-[[(diazomethyl)carbonyl]methoxy]-2-(N,N-di-n-propylamino)-1,2,3,4- tetrahydronaphthalene (2), the ester 8-(diazoacetoxy)-2-(N,N-di-n-propyl-amino)-1,2,3,4- tetrahydronaphthalene (3), and the ketone 8-[(diazomethyl)carbonyl]-2-(N,N-di-n-propylamino)- 1,2,3,4-tetrahydronaphthalene (4). Specific binding of these compounds at the 5-hydroxytryptamine1A sites in rat brain membranes labeled with 1 nM [3H]-8-hydroxy-2-(N,N-di-n-propylamino)- 1,2,3,4-tetrahydronaphthalene (8-OH-DPAT) showed IC50 values of ca. 75, 125, and 25 nM, respectively, for the three compounds. Photolysis of methanolic solutions of 2-4 in the absence of receptor proteins lead in each case to an abundance of Wolff-rearranged products. In the case of ether 2, subsequent beta-elimination to 8-OH-DPAT removed this compound from serious consideration as a photoaffinity ligand. Ester 3 and ketone 4 were photolysed in vitro. Whereas ester 3 was ineffective in decreasing the specific binding of [3H]-8-OH-DPAT, ketone 4 decreased 40% of the specific binding of [3H]-8-OH-DPAT in the presence (but not the absence) of ultraviolet light. Thus this ketone emerges from these studies as a good candidate for a photoaffinity label for the 5-hydroxytrypatamine1A receptor.
Studying a familiar word activates its associates in long-term memory. In the present experiments we manipulated the number of associates activated by words studied in the presence of unrelated context words, meaningfully related context words, or in the absence of modifying context words. Memory was tested by either cued or free recall. The results showed that the number of directly activated associates can facilitate, have no effect, or disrupt recall for studied words. The direction and magnitude of the effects of number of activated associates is shown to be determined by the encoding/retrieval context. Implications for the distinction between episodic and semantic memory are discussed.
A state of T-cell activation, reflected by a marked degree of spontaneous proliferation in vitro, exists among patients with human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) but not in those with retroviral-induced adult T-cell leukemia (ATL). We wished to define the mechanism by which the immune activation of circulating cells from HAM/TSP is driven, thus gaining insight into the pathogenesis of this HTLV-I-associated disease. By using a modification of the polymerase chain reaction, we compared the levels of interleukin 2 (IL-2) and IL-2 receptor alpha chain (IL-2R alpha) mRNA expression to the transcription of the HTLV-I transactivator gene, pX, in peripheral blood mononuclear cells of HAM/TSP and ATL patients as well as seropositive carriers. Up-regulation of IL-2 and IL-2R alpha transcripts was detected in HAM/TSP and seropositive carriers that paralleled the coordinate mRNA expression of the pX transactivator. In addition, IL-2 and soluble IL-2R alpha serum levels in HAM/TSP and seropositive carriers were elevated. Despite markedly elevated levels of soluble IL-2R alpha in ATL, transcripts for IL-2 and pX were not demonstrable in the circulating cells. Finally, the marked degree of in vitro spontaneous proliferation present in HAM/TSP was profoundly inhibited by specific anti-IL-2R or anti-IL-2 blocking antibodies. Collectively, these results suggest that immune activation in HAM/TSP, in contrast to ATL, is virally driven by the transactivation and coordinate expression of IL-2 and IL-2R alpha. This deregulated autocrine process may contribute to the evolution of inflammatory nervous system damage in HAM/TSP.
Permeabilized, MgATP-reactivated cells of Paramecium (models) respond to cyclic AMP and cyclic GMP by increasing forward swimming speed. In association with the motile response, cyclic AMP and 8-bromo-cyclic GMP (8-Br-cyclic GMP) stimulated protein phosphorylation. Cyclic AMP addition to permeabilized cells reproducibly stimulated the phosphorylation of 10 proteins, ranging in molecular weight from 15 to 110K (K = 10(3) Mr). 8-Br-cyclic GMP, which selectively activates the cyclic GMP-dependent protein kinase of Paramecium, stimulated the phosphorylation of a subset of the proteins phosphorylated by cyclic AMP. Ca2+ addition caused backward swimming and stimulated the phosphorylation of four substrates, including a 25K target that may also be phosphorylated in response to cyclic nucleotide addition. Ba2+ and Sr2+ also induced backward swimming, but did not cause detectable phosphorylation. To identify ciliary targets of cyclic nucleotide-dependent protein kinase activity, permeabilized cells were deciliated following reactivation of motility with Mg-[gamma-32P]ATP in the presence or absence of cyclic nucleotide. Soluble proteins of the deciliation supernatant were enriched in 15 cyclic AMP-stimulated phosphoproteins, ranging in molecular weight from 15 to 95K. Most of the ciliary substrates were axonemal and could be released by high salt solution. A 29K protein that copurified in sucrose gradients with the 22S dynein, and a high molecular weight protein (greater than 300K) in the 19 S region were phosphorylated when cyclic AMP was added to permeabilized, motile cells. These data suggest that regulation of ciliary motility by cyclic AMP may include phosphorylation of dynein-associated proteins.
The purpose of these experiments was to determine whether retrieval access in cued recall can be selectively restricted to a single domain of encoding when information has been encoded within two domains as different as word sound and word meaning. In Experiment 1, the subjects studied pairs of rhyming words differing in rhyme set size under verbal-repetition or interactive-imagery instructions. Recall was cued with study-context rhymes, with extralist rhymes, or with extralist associates. The results indicated that rhyme set size and instructional effects were found no matter how recall was cued, indicating that both domains of encoding were always accessed. In Experiment 2, potential effects of study time and overt naming of the test cues were explored. These results indicated that both domains of encoding were accessed, except when long study times were available and subjects did not have to name the rhyme test cues. Rhyme set-size effects were eliminated under these conditions, suggesting that selective access to encoded meaning is possible in cued recall. Retrieval access in this task appears to be more controlled by domains of encoding than by information directly available in the cue, and access to encoded information can be restricted to a single domain.
Occupational therapists frequently use their knowledge of occupation to add meaning and purpose to therapeutic tasks. This study investigated the effects of an attempt to add meaning to a particular occupational situation--a design copy task. Added meaning was given to the design copy task through the use of stimulus figures that were representational of familiar objects--an arrow, a house, and a face. The control condition consisted of three nonrepresentational figures composed of the same geometric shapes, in the same locations on the paper as the representational figures, but combined differently. The order of presentation was controlled for. The study used 30 elderly subjects (22 women and 8 men) from six nursing homes. The accuracy of the drawings was measured by a blind rater using graph overlays and predetermined rules of scoring. A two-way analysis of variance with one repeated measure (Order X Type of Figure) indicated significant differences at the .01 level between the representational and nonrepresentational figures. This study demonstrates how added meaning can enhance performance on a visuomotor task in a vulnerable population.
Many studies have documented the effectiveness of verbally elicited imagery in the enhancement of motor skills in young, nondisabled populations. The present study examined the effects of verbally elicited imagery in the encouragement of two exercises (i.e., reaching up to pick apples and reaching down to pick up coins) in elderly women. The subjects were 27 women between 62 and 96 years of age who were selected from a nursing home, a residential retirement home, and a foster care home. All of the subjects received imagery as well as control conditions, but in a counterbalanced fashion. The Wilcoxon matched-pairs signed rank tests indicated that the imagery condition elicited significantly more repetitions of the reaching-up exercise than did the control condition (z = 2.25, p [one-tailed] = .012). The results in the reaching-down exercise were generally in the same direction but difficult to interpret statistically. The results are discussed in terms of other recent research investigating ways to add purpose to therapeutic exercise through occupation. Clinicians are urged to explore the advantages and disadvantages of imagery-based occupations in treatment.
We expressed the human midsized neurofilament subunit (NF-M) using genomic DNA in mouse L cells and showed that it is transcribed and translated into a protein capable of assembly into the cytoskeleton and of forming a filamentous network that colocalizes with the endogenous vimentin filaments. Moreover, human NF-M expressed in L cells is phosphorylated at sites within the multiphosphorylation repeat (MPR), i.e., the major sites of phosphorylation of NF-M in vivo. We also expressed a genomic construct lacking the MPR domain in the native molecule and showed that this MPR(-) protein also was expressed and formed a filamentous network despite diminished incorporation of radiolabeled phosphate. Two major conclusions emerged from the work described in this paper: human NF-M is translated, assembled, and phosphorylated at physiological sites without the need of any other specific neuronal proteins; phosphorylation sites other than the MPR are present within NF-M which may play a role in synthesis, assembly, and degradation of NF protein in humans.
To examine the pathogenesis of type 1 (reversal) reactions in leprosy, we studied cellular and soluble immunologic components of skin lesions in 10 patients with reactions, 24 active patients without reactions, and 33 control patients whose leprosy had been treated and cured. Cells and Tac-peptide levels were obtained from fluid aspirated from blisters induced by suction directly over representative skin lesions. During reversal reactions: a) the lesions contained an increased number and percentage of CD4+ (T-helper) cells; b) Tac-peptide levels were elevated in half of the lesions; c) the increases in Tac peptide and CD4+ cells were directly correlated; and d) systemic administration of corticosteroids appeared to cause a reduction in the intralesional CD4+ cell population. These findings were localized to the skin, and do not represent simple filtration of these components from the peripheral blood. We conclude that spontaneous lymphocyte activation in situ, primarily of CD4+ cells, is an important feature of reversal reactions, and may be an intermittent or cyclic phenomenon during the reaction. Findings in active patients without reactions are consistent with the hypothesis that differing states of immunologic equilibrium have been established in different portions of the leprosy spectrum. In reversal reactions we may, therefore, be examining immunologic processes set in motion when a pre-existing equilibrium has been upset by spontaneous, natural events. The mechanism of such spontaneous changes in immunity in leprosy is of considerable interest, not only to understand the reaction, but also to examine the underlying determinants of delayed-type hypersensitivity and cell-mediated immunity in leprosy and the potential for artificially manipulating these responses, as proposed with vaccines or immunotherapy.
A comparison of activities and affinities of several known and novel compounds in the isolated rat thoracic aorta (RA) and the rabbit femoral artery (RFA) was undertaken to evaluate these two tissues for use in screening for functional 5-hydroxytryptamine2 (5-HT2) receptor activity. Affinities for 5-HT and for ketanserin against 5-HT-elicited contractions in both vascular tissues suggested the presence of homogeneous 5-HT2 receptors with values consistent with other reported 5-HT2 receptor preparations. However, further studies showed compounds which exhibited either partial agonism in the RFA and competitive antagonism of 5-HT in the RA, or antagonism of 5-HT in both arteries with different affinities. Affinity constants calculated from the isolated vascular tissue studies were compared with affinity constants calculated for inhibition of [3H]ketanserin binding in the frontal cortices of both the rat and the rabbit. There were no significant differences between the pKi values in the rat and the rabbit cortical membranes or between these pKi's in either species and the pA2 values in the RA. Several of the affinities for both the partial agonists and the antagonists in the RFA were significantly different from the binding pKi and the pA2 values in the RA. These findings suggest identity between the [3H]ketanserin binding site in the cortices of both species and the 5-HT2 receptor in the RA; however, the contractile 5-HT receptor in the RFA, although showing some characteristics of a 5-HT2 receptor, is significantly different. We suggest that there may be functional subtypes of the vascular 5-HT receptor.
We serially assayed soluble interleukin 2 receptor (sIL-2R) levels in the peripheral blood (PB) of 22 patients with rheumatoid arthritis (RA) followed for a period of 12 months, and correlated these levels with disease activity. We examined the relationship between the direction in which each of the disease measures changed between assessments and the direction of change in sequential sIL-2R levels. In 22 of the 25 (88%) instances where there was a 30% change in the active joint count between sequential assessments, the direction of change of the PB sIL-2R level was found to be in parallel (chi 2 = 11.7, p less than 0.008). Our results suggest that serial sIL-2R levels are a useful means of confirming clinically significant changes in disease activity in patients with RA, irrespective of therapy.
MDL 73005EF has been recently described as a potent, highly selective 5-HT1A ligand. Although proposed to act predominantly as an antagonist (M. Hibert, A.K. Mir, G. Maghioros, P. Moser, D.N. Middlemiss, M.D. Trickleband and J.R. Fozard, 1988, The Pharmacological properties of MDL 73005EF: a potent and selective ligant at 5-HT1A receptors, Br. J. Pharmacol. 93, 2P), we have demonstrated that MDL 73005EF also acts as a highly efficacious partial agonist at the 5HT1A receptor, based on its ability to inhibit forskolin-stimulated adenylate cyclase in rat hippocampal membranes. Compared with two structurally related 5-HT1A partial agonists, the rank order of potency of MDL 73005EF in the FSC assay was comparable to affinity calculated by radioligand binding.
Two soluble cAMP-dependent protein kinases were purified from the cytoplasm of Paramecium tetraurelia. Both kinases consisted of a 40-kDa catalytic subunit and a 44-kDa regulatory subunit. The two forms of the enzyme were separated by anion-exchange chromatography. Affinity chromatography on cAMP-Sepharose separated the regulatory subunit (retained by the column) from the cAMP-independent catalytic subunit (not retained). Four classes of monoclonal antibodies were generated. One class was specific for the catalytic subunit of both cAMP-dependent protein kinases, and three classes recognized the regulatory subunit of both forms of the enzyme. Subunits of 40 and 44 kDa were detected on immunoblots of purified cilia and of crude cell extracts. In addition, one class of antibodies specific for the regulatory subunit detected a ciliary protein with a molecular mass of 48 kDa. The monoclonal antibodies did not recognize type I or type II cAMP-dependent protein kinase from rabbit muscle nor did they cross-react with proteins from several unicellular eucaryotes, with one exception: antibodies specific for the catalytic subunit recognized a 40-kDa protein of Tetrahymena pyriformis.
Efficacy of zinc citrate ascorbate was evaluated in 146 dogs (265 eyes) that had various lens opacities. Zinc citrate ascorbate or saline placebo drops were applied topically once or twice daily for 4 to 31 weeks. Of 138 eyes treated with zinc citrate ascorbate, 86 eyes (62.3%) had no change, 48 eyes (34.8%) had increased lens opacity, and 4 eyes (2.9%) had decreased lens opacity. Of 127 eyes treated with a saline placebo, 99 eyes (77.9%) had no change, 25 eyes (19.7%) had increased lens opacity, and 3 eyes (2.4%) had decreased lens opacity. Zinc citrate ascorbate drops were not significantly (P = less than 0.05) more effective in clearing cataracts than were saline drops. Seemingly, zinc citrate ascorbate drops may have caused lens opacities to increase in area and density.
To identify protein targets for calmodulin (CaM) in the cilia of Paramecium tetraurelia, we employed a 125I-CaM blot assay after resolution of ciliary proteins on SDS/polyacrylamide gels. Two distinct types of CaM-binding proteins were detected. One group bound 125I-CaM at free Ca2+ concentrations above 0.5-1 microM and included a major binding activity of 63 kDa (C63) and activities of 126 kDa (C126), 96 kDa (C96), and 36 kDa (C36). CaM bound these proteins with high (nanomolar) affinity and specificity relative to related Ca2+ receptors. The second type of protein bound 125I-CaM only when the free Ca2+ concentration was below 1-2 microM and included polypeptides of 95 kDa (E95) and 105 kDa (E105). E105 may also contain Ca2+-dependent binding sites for CaM. Both E95 and E105 exhibited strong specificity for Paramecium CaM over bovine CaM. Ciliary subfractionation experiments suggested that C63, C126, C96, E95, and E105 are bound to the axoneme, whereas C36 is a soluble and/or membrane-associated protein. Additional Ca2+-dependent CaM-binding proteins of 63, 70, and 120 kDa were found associated with ciliary membrane vesicles. In support of these results, filtration binding assays also indicated high-affinity binding sites for CaM on isolated intact axonemes and suggested the presence of both Ca2+-dependent and Ca2+-inhibitable targets. Like E95 and E105, the Ca2+-inhibitable CaM-binding sites showed strong preference for Paramecium CaM over vertebrate CaM and troponin C. Together, these results suggest that CaM has multiple targets in the cilium and hence may regulate ciliary motility in a complex and pleiotropic fashion.
We report the purification of a CaATPase of high specific activity from Paramecium tetraurelia. The enzyme is preferentially released into solution upon deciliation of cells by a Ca2+ shock procedure. Purification by ion exchange and gel filtration chromatography yields major peptides of 68 and 53 kDa and a minor peptide of 58 kDa, as determined by electrophoresis on sodium dodecyl sulfate polyacrylamide gels. These three peptides yield similar proteolytic peptide maps. Rabbit antisera to the purified enzyme inhibit enzyme activity and specifically label 68- and 53-kDa bands on nitrocellulose blots of the deciliation supernatant from which the enzyme is isolated. Concanavalin A-Sepharose precipitates about 60% of ATPase activity; only the 53-kDa band binds concanavalin A on nitrocellulose blots. The purified enzyme has a specific activity of 620 +/- 70 mumol/min/mg with ATP as substrate in the presence of Ca2+, which is required for enzyme activity. As substrates, ATP and GTP are strongly preferred to UTP and CTP. The Km for ATP in the presence of 3 mM Ca2+ is approximately 20 microM. Enzyme activity is strongly inhibited by the calmodulin antagonists trifluoperazine, fluphenazine, W7, and calmidazolium. However, calmodulin is not associated with the purified enzyme, based on the enzyme's inability to bind anti-calmodulin antibodies or to stimulate brain phosphodiesterase. The intracellular origin of this ATPase, its possible function, and its relationship to several other ATPases of Paramecium are discussed.
The cAMP-dependent protein kinases of the cilia of the protozoan Paramecium tetraurelia were resolved and characterized. Two cAMP-dependent activities were present in cilia; the two ciliary kinases resemble types I and II from vertebrate tissues. Part of the ciliary kinase activity (primarily type II) was released by freeze-thawing, but a significant amount remained particulate. Both kinases were found as aggregates of about 220 kDa and of about 70 kDa. A portion of the cAMP-binding activity in ciliary extracts separated from kinase activity, and eluted at 36 kDa during gel filtration. Photoaffinity labeling with 8-azido-cAMP identified cAMP-binding proteins of 45-52 kDa in type II kinase from cilia, and of 43-46 kDa in type I kinase. The type II kinase was apparently autophosphorylated, causing a decrease in mobility during sodium dodecyl sulfate-polyacrylamide gel electrophoresis.