Plaques, cancer, and confusion.
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Asbestosis↗
Biomedical subjects
D D Smith
Publications and source records attributed to D D Smith.
Transfer nuclear Overhauser effect study of the conformation of oxytocin bound to bovine neurophysin I.
This study reports the structure of the peptide hormone oxytocin bound to its carrier protein, neurophysin I, obtained by nuclear magnetic resonance techniques. At the pH value of 2.1 in our experiments, the ligand is in fast exchange with its carrier protein, allowing the use of transfer-NOE methods. The number of distance constraints for the peptide being limited, considerable attention has been paid to an accurate distance determination. The resulting accurate distance limits were used as input for a distance geometry calculation followed by a restrained molecular dynamics run. Convergence to a well-defined family of structures for oxytocin in its bound state was reached. Both the backbone and the side-chain conformations differ between the bound form and the crystal structure of free oxytocin [Wood, S. P., et al. (1986) Science 232, 633]. These differences, as well as other structural features of the bound form, are discussed in terms of interactions made with the carrier protein. Transfer-NOE experiments at low peptide protein ratios provide direct experimental evidence for contacts between the oxytocin Tyr2 residue and an aromatic residue of neurophysin. The resonance assignments of the aromatic groups [Whittaker, B. A., et al. (1985) Biochemistry 24, 2782] together with the recently published X-ray structure of the neurophysin II protein complexed with a dipeptide [Chen et al. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 4240] allow us to assign the aromatic signal on the protein to the neurophysin Phe22 residue.
Amino Acid Sequence↗
Synthesis and biological activity of C-terminally truncated fragments of human alpha-calcitonin gene-related peptide.
C-terminally truncated fragments of human alpha-calcitonin gene-related peptide (h-alpha-CGRP) were tested for their ability to stimulate amylase secretion from pancreatic acinar cells and relax precontracted mesenteric arteries. h-alpha-CGRP, h-alpha-CGRP (1-36), h-alpha-CGRP (1-35), and h-alpha-CGRP (1-34) were made by Merrifield's solid-phase peptide synthesis methodology. Peptides were purified by gel filtration, cation-exchange chromatography, and semipreparative reversed-phase high-performance liquid chromatography. The products were characterized by amino acid analysis, mass spectrometry, and tryptic digestion. h-alpha-CGRP stimulated amylase secretion from dispersed guinea pig pancreatic acini in a biphasic concentration-dependent manner. The initial increase in amylase secretion reached 8% of total cellular amylase content with an ED50 value of 7.7 nM, and the second increase reached 11% of total cellular amylase content at a concentration of h-alpha-CGRP of 10(-4)M. h-alpha-CGRP (1-36) caused a small, significant increase in amylase release. C-terminally truncated fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) did not increase amylase release at concentrations < 10(-5) M. At concentrations > 10(-5) M the fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) caused a smaller increase in amylase release than that caused by h-alpha-CGRP whereas h-alpha-CGRP (1-36) caused the same increase. h-alpha-CGRP caused a concentration-dependent relaxation of rat mesenteric artery, precontracted with prostaglandin F2 alpha, with an EC50 of 2.9 nM and a maximal relaxation that was 60% of the prostaglandin F2 alpha-induced tone. h-alpha-CGRP (1-35) also relaxed the mesenteric artery in a concentration-dependent manner with a maximum response that was 40% of the prostaglandin F2 alpha-induced tone. The remaining fragments did not relax rat mesenteric arteries. Additionally, h-alpha-CGRP (1-36) and h-alpha-CGRP (1-34) did not block h-alpha-CGRP-induced relaxation of the mesenteric artery. An intact C-terminus is required for h-alpha-CGRP to cause potent biological effects in pancreatic acini and mesenteric artery. The different effects of h-alpha-CGRP (1-35) in mesenteric artery compared with those in pancreatic acini suggest that the CGRP receptors in these two tissues may be different.
Amino Acid Sequence↗
Proinflammatory cytokines enhance human synoviocyte expression of functional intercellular adhesion molecule-1 (ICAM-1).
We determined the ability of proinflammatory cytokines to enhance ICAM-1 (CD54) expression on, and PBMC adhesion to, human synoviocytes. Surface molecules were characterized by cell ELISA and by flow cytometry. Adhesion of PBMC to synoviocyte monolayers was measured by direct counting or by colorimetric staining. Most cytokines upregulated ICAM-1 expression (IL-1 beta > TNF alpha > IFN-gamma >> PDGF-bb, IL-6), but not GM-CSF or TGF beta. A similar concentration-dependent increase was observed for synoviocytes derived from patients with rheumatoid or osteoarthritis. Kinetic studies of ICAM-1 expression differed among several cytokines: an early rise with IL-1 beta or TNF alpha stimulation, a gradual increase with IFN-gamma, a transient increase with PDGF-bb, and a plateau with IL-6. Adhesion of PBMC to synoviocytes was increased by IL-1 beta or TNF alpha and reduced by MAb to CD54 or CD18. Increased synoviocyte adhesiveness may promote interactions with infiltrating inflammatory cells.
Arthritis, Rheumatoid↗
Laboratory assessment of the Baxter disposable patient-controlled analgesia system.
The performance of the Baxter patient-controlled analgesia infusor system was assessed in the laboratory. The flow of the 5 ml.h-1 infusor was measured gravimetrically with the flow restrictor maintained at 31 degrees C and the reservoir at either 20 degrees C or 25 degrees C. At 25 degrees C the mean flow was 4.98 (SEM 0.06) ml.h-1 and at 20 degrees C the mean flow was 4.32 (0.05) ml.h-1. The patient-control module performed reliably, delivering a mean of 0.42 (0.001) ml following depression of the button, slightly less than the manufacturer's quoted value of 0.5 ml.
Analgesia, Patient-Controlled↗
Contraction history modulates isotonic shortening velocity in smooth muscle.
The effect of contraction history on the isotonic shortening velocity of canine tracheal smooth muscle was investigated. Muscles were contracted isometrically for 20 s at initial lengths of L(o) (length of maximal active force), 85% L(o), or 70% L(o) using electrical field stimulation. Muscles were then allowed to shorten isotonically under different afterloads either with or without first being subjected to a step decrease in length to 70% L(o). Instantaneous velocities were plotted against instantaneous muscle length during isotonic shortening. Regardless of protocol, the velocity at any muscle length during shortening was lower when the muscle was initially activated at a longer length. The isotonic shortening velocity decreased progressively during shortening at a nearly linear rate with respect to instantaneous muscle length under all conditions. Results suggest that a longer muscle length at the time of activation leads to the development of higher loads on the contractile element during subsequent shortening, resulting in a slower shortening velocity. This plasticity of the force-velocity relationship may result from cytostructural reorganization of the smooth muscle cells in response to contractile activation at different muscle lengths.
Animals↗
Brain, environment, heredity, and personality.
Behavior genetics research, committed to a model of the origins of personality and intellectual development restricted to heredity and environment, consistently generates evidence for two types of environmental influences. One of these, termed the between-family or shared environment, creates no conceptual problems. The other, termed the nonshared or within-family or unique environment, does. The other, termed the nonshared or within-family or unique environment, does. The latter accounts for a substantial portion of the variance in personality and intellect, it must be unique to each individual, and its origin has not been determined. It is contended here that the brain itself, as an inherently indeterminate dynamic system, is the source of this unresolved developmental variability.
Animals↗
Personality is indeterminate.
The so-called unique environmental factor in behaviour genetics research, the longitudinal instability of personality, and the unpredictability of human creativity are all manifestations of the same process. Thus a scientific explanation of any one of them should account for them all. That process, it is proposed, is the inherently indeterminate global dynamics of the human brain. The clear implication is that all social sciences have inherently indeterminate phenomena as their subject matter. Predictions of the results of an appropriately designed psychometric study based on this hypothesis are offered.
Adult↗
More on DPT controversy.
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Education, Graduate↗
A strategy for maximizing time efficiency in protocols requiring multiple centrifugation steps.
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Biotechnology↗
Evidence for two histidine ligands at the diiron site of methane monooxygenase.
Circular dichroism spectroscopy has shown the hydroxylase component of methane monooxygenase to have a high helical content. The apoprotein has the same secondary structure as the holoenzyme. Chemical modification shows 12 histidines to be reactive with diethylpyrocarbonate in the holoenzyme, whereas 14 are reactive in the apoenzyme. Two histidine residues are implicated as iron ligands. Further chemical modification results suggest a cysteine residue is in close proximity to the diiron centre.
Apoenzymes↗
Isolation and primary structure of urotensin II from the brain of a tetrapod, the frog Rana ridibunda.
A peptide related to urotensin II has been isolated in pure form from an extract of the brain of the European green frog, Rana ridibunda. The primary structure of the peptide was established as Ala-Gly-Asn-Leu-Ser-Glu-Cys-Phe-Trp-Lys-Tyr-Cys-Val and this sequence was confirmed by chemical synthesis. Frog urotensin II contains an additional amino acid residue compared with fish urotensin II peptides but the structure of the cyclic region of the molecule has been fully conserved. The data show that urotensin II is not confined to the caudal neurosecretory system of fish but is present in the central nervous system of a tetrapod.
Amino Acid Sequence↗
Measurement of T-kinin in rat plasma using a specific radioimmunoassay.
T-kinin (Ile-Ser-Bradykinin) has been isolated only from the plasma of the rat and it is unclear whether the peptide, or its biosynthetic precursor, T-kininogen, circulates in the human. An NH2-terminally directed antiserum to T-kinin was raised in rabbits using an immunogen prepared by coupling the free -SH group of T-kinin extended from its COOH-terminus by a cysteinyl residue to an -NH2 group on human serum albumin. A radioimmunoassay was developed using this antiserum and 125I-labelled [Tyr10]T-kinin as tracer that was sensitive (least-detectable concentration 3 fmol/tube) and relatively specific for T-kinin (cross-reactivity with bradykinin and kallidin less than 1%). Treatment of rat plasma with an excess of trypsin in the presence of a kininase inhibitor generated T-kinin immunoreactivity equivalent to 455 +/- 71 pmol/ml (mean +/- S.E.M.; n = 9) and this immunoreactivity was eluted from a reversed-phase HPLC column as a single peak with the same retention time as synthetic T-kinin. In contrast, treatment of plasma from healthy human subjects (n = 8) and from patients (n = 8) with inflammation due to acute or chronic gastrointestinal disease under the same conditions did not generate any detectable T-kinin immunoreactivity. It is concluded, therefore, that T-kininogen, the biosynthetic precursor of T-kinin in the rat, is either absent from the plasma of human subjects or is present in a concentration less than 30 fmol/ml. Similarly, T-kininogen is probably not an acute phase reactant in humans.
Adult↗
Structure-activity studies of a novel bicyclic oxytocin antagonist.
In this report, we describe structure-activity studies of the bicyclic oxytocin antagonist [Mpa1,cyclo(Glu4,Lys8)]oxytocin. The monocylic analogue [dPen1, (Glu4,Lys8)]oxytocin was a weak oxytocin antagonist with a pA2 value of 5.8 in the uterotonic assay. Bicyclization of this analogue yielded [dPen1,cyclo(Glu4,Lys8)]oxytocin, a potent antagonist of oxytocin in the uterotonic assay (pA2 8.74) with a potency 3 times greater than that of [Mpa1,cyclo(Glu4,Lys8)]oxytocin. [dPen1,cyclo(Glu4,Lys8)]oxytocin also was a weak antagonist in the pressor assay with a pA2 of 6.3. To establish if the potent antagonistic effects of these bicyclic compounds was because of the lactam ring or merely the result of obtaining an optimal degree of lipophilicity of the side chains in positions 4 and 8, we synthesized a series of analogues containing neutral and/or charged groups on these side chains. Monocyclic derivatives of [Mpa1,Gln4,Lys(CHO)8]oxytocin were moderate to weak agonists of oxytocin all following classical structure-activity profiles of oxytocin. The monocyclic derivatives of [dPen1,Gln4,Lys(CHO)8]oxytocin were antagonists of oxytocin which was attributed to the dPen1 substitution. However, the potency of all of these latter derivatives was at least 1 order of magnitude less than [dPen1,cyclo(Glu4,Lys8)]oxytocin. These results suggest that the potent antagonistic properties of the bicyclic analogues [Mpa1,cyclo(Glu4,Lys8)]oxytocin and [dPen1,cyclo(Glu4,Lys8)]oxytocin can be attributed to the effect of the lactam bridge on the conformational flexibility and topographical properties of the analogues, rendering them more favorable for binding to the receptor in such a manner as to prevent transduction of a biological response.
Amino Acid Sequence↗
Regulation of the expression of adhesion molecules by human synoviocytes.
The capacity of synoviocytes to participate in inflammatory responses may be altered by the cytokine-enhanced expression of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1). To examine this possibility, the ability of selected cytokines to enhance ICAM-1 expression was examined. The data indicated that each of these cytokines (interleukin-1 beta greater than tumor necrosis factor-alpha, interferon-gamma much greater than interleukin-6) can up-regulate synoviocyte ICAM-1 expression. This can potentially increase the ability of these cells to interact with infiltrating inflammatory cells, thereby propagating immunologically mediated inflammation such as occurs in rheumatoid synovitis.
Cell Adhesion Molecules↗
Metabolic compartmentation of vertebrate glutamine synthetase: putative mitochondrial targeting signal in avian liver glutamine synthetase.
The evolution of uricoteley as a mechanism for hepatic ammonia detoxication in vertebrates required targeting of glutamine synthetase (GS) to liver mitochondria in the sauropsid line of descent leading to the squamate reptiles and archosaurs. Previous studies have shown that in birds and crocodilians, sole survivors of the archosaurian line, hepatic GS is translated without a transient, N-terminal targeting signal common to other mitochondrial matrix proteins. To identify a putative internal targeting sequence in the avian enzyme, the amino acid sequence of chicken liver GS was derived by a combination of sequencing of cloned cDNA, direct sequencing of mRNA, and sequencing of polymerase chain reaction (PCR) products amplified from reverse-transcribed mRNA. Analysis of the first 20 or so N-terminal amino acids of the derived sequence for the chicken enzyme shows that they are devoid of acidic amino acids, contain several hydroxy amino acids, and can be predicted to form a positively charged, amphipathic helix, all of which are characteristic properties of mitochondrial targeting signals. A comparison of the N-terminus of chicken GS with the N-termini of cytosolic mammalian GSs indicates that at least three amino acid replacements may have been responsible for converting the N-terminus of the cytosolic mammalian enzyme into a mitochondrial targeting signal. Two of these, His15 and Lys19, result in additional positive charges, as well as in changes in hydrophilicity. Both could have resulted from third-base-codon substitutions. A third replacement, Ala12, may contribute to the helicity of the N-terminus of the chicken enzyme. The N-terminus of the cytosolic chicken brain GS (positions 1-36) was found to be identical to that of the liver enzyme. The complete sequence of chicken retinal GS is also identical to that of the liver enzyme. GS is coded by a single gene in birds, so these sequence data suggest that, unlike the situation in other tissue-specific compartmental isozymes, differential targeting of avian GS to the mitochondrial or cytosolic compartments is not dependent on the sequence of the primary translation product of its mRNA but may involve some other tissue-specific factor(s).
Amino Acid Sequence↗
Purification and characterization of urotensin II and parvalbumin from an elasmobranch fish, Scyliorhinus canicula (common dogfish).
The caudal portion of the spinal cord of elasmobranch fish incorporates a diffuse neuroendocrine system. Using an antiserum raised against urotensin II from a teleost fish (goby) to facilitate purification, a peptide structurally related to urotensin II was isolated in pure form from an extract of neuroendocrine tissue from the spinal cord of the European common dogfish, Scyliorhinus canicula. The primary structure of the peptide was established as: Asn-Asn-Phe-Ser-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val. The amino acid sequence was confirmed by chemical synthesis. A comparison of this sequence with those of the known teleost urotensin II peptides shows that the cyclic region of the molecule has been fully conserved between species and suggests that the presence of an acidic residue at position 5 and a hydrophobic residue at position 12 are important features for the biological activity of the peptide. The dogfish spinal cord extract also contained a high concentration of the calcium-binding protein, parvalbumin and the amino acid sequence at its NH2 terminus [residues (1-50)] was determined.
Amino Acid Sequence↗
Ranakinin: a novel NK1 tachykinin receptor agonist isolated with neurokinin B from the brain of the frog Rana ridibunda.
An extract of the whole brain of the frog Rana ridibunda contained high concentrations of substance P-like immunoreactivity, measured with an antiserum directed against the COOH-terminal region of mammalian substance P and neurokinin B-like immunoreactivity, measured with an antiserum directed against the NH2-terminus of neurokinin B. The primary structure of the substance P-related peptide (ranakinin) was established as: Lys-Pro-Asn-Pro-Glu-Arg-Phe-Tyr-Gly-Leu-Met-NH2. Mammalian substance P was not present in the extract. The primary structure of the neurokinin B-related peptide was established as: Asp-Met-His-Asp-Phe-Phe-Val-Gly-Leu-Met-NH2. This amino acid sequence is the same as that of mammalian neurokinin B. Ranakinin was equipotent with substance P and [Sar9,Met(O2)11]substance P in inhibiting the binding of 125I-Bolton-Hunter-[Sar9,Met(O2)11]substance P, a selective radioligand for the NK1 receptor, to binding sites in rat submandibular gland membranes (IC50 1.6 +/- 0.3 nM; n = 5). It is concluded that ranakinin is a preferred agonist for the mammalian NK1 tachykinin receptor subtype.
Amino Acid Sequence↗