Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The electrophoretic distribution of lactate dehydrogenase (LDH) isoenzymes, Michaelis constant, reaction with substrate, and dissociation into subunits with guanidine hydrochloride was examined in undifferentiated and differentiated human myeloid leukemia cells. Differentiation was induced with 1/microgram/ml tunicamycin. Undifferentiated cells did not display phagocytic ability, and less than 5% of these cells had Fc receptors. After exposure to tunicamycin for 40 hr, 40% of these differentiated cells had Fc receptors, and 35% showed phagocytic activity after 160 hr. The majority of the LDH activity in the undifferentiated cells was found in fraction 3, and following differentiation almost a 50% reduction in LDH activity was observed in this fraction. In addition, LDH 3 isoenzyme levels were found to be greater in patients containing a high percentage of undifferentiated cells than in patients containing a high percentage of differentiated cells. Differentiated cells displayed LDH isoenzyme fraction pattern, Michaelis constant, and reaction with substrate similar to those found in the normal granulocytes. Differences in the dissociation of LDH into subunits with guanidine hydrochloride were found between undifferentiated and differentiated acute myeloid leukemia (AML) cells. Treatment with 0.75 M guanidine hydrochloride caused complete inactivation of LDH derived from normal differentiated cells, whereas similar treatment caused complete inactivation of LDH derived from AML or normal granulocytes. LDH isoenzymes derived from normal granulocytes and differentiated AML cells were also more sensitive to guanidine hydrochloride depression of fluorescence intensity. The sedimentation constant for single peak LDH at 5.5 M guanidine hydrochloride was calculated as 1.65 sec for differentiated and 1.70 sec for undifferentiated cells. The molecular weight of the polypeptide subunits for undifferentiated cells was 30,000 and for differentiated cells was 39,000. The apparent parallel between leukemic cells after induction of differentiation and normal granulocytes indicates that the leukemic cells retain their maturation potential when exposed to an inducer of differentiation.
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PMID:Electrophoretic distribution and dissociation into subunits of lactate dehydrogenase derived from human myeloid leukemia cells before and after induction of differentiation. 345 28

The involvement of the cytoplasmic membrane in electron transport to nitrogenase has been studied. Evidence shows that nitrogenase activity in Azotobacter vinelandii is coupled to the flux of electrons through the respiratory chain. To obtain information about proteins involved, the changes occurring in A. vinelandii cells transferred to nitrogen-free medium after growth on NH4Cl (depression of nitrogenase activity) were studied. Synthesis of the nitrogenase polypeptides was detectable 5 min after transfer to nitrogen-free medium. No nitrogenase activity could be detected until t = 20 min, whereupon a linear increase of nitrogenase activity with time was observed. Synthesis of nitrogenase was accompanied by synthesis of flavodoxin II and two membrane-bound polypeptides of Mr 29,000 and 30,000. Analysis with respect to changes in membrane-bound NAD(P)H dehydrogenase activities revealed the induction of an NADPH dehydrogenase activity, which was not detectable in membranes isolated from cells grown in the presence of NH4OAc. This induced activity was associated with the appearance of a polypeptide of Mr 29,000 in the NADPH dehydrogenase complex.
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PMID:Studies on the mechanism of electron transport to nitrogenase in Azotobacter vinelandii. 345 4

A difference Fourier map of the projected structure of bacteriorhodopsin has been synthesized from electron diffraction amplitudes collected from membranes prepared in the glucose-embedded state and the frozen-hydrated state. Phases of a recently published data set for glucose-embedded specimens were used for the difference Fourier map. Moderate resolution (9 A) and high resolution (4.25 A) maps both indicate that glucose is exchangeable for water in the region of the map corresponding to the lipid regions. We interpret this as indicating that there is a small surface depression in this region of the structure. The depth of this feature is estimated to be 1/6 the thickness of the protein region in the membrane. The data obtained in this study rules out the existence of an aqueous transmembrane channel, the dimensions of which are large enough to allow free exchange of glucose for water. Several new features are also observed in the protein region of the membrane. These features are probably due to segments of the polypeptide at the aqueous interface that are well ordered in frozen-hydrated specimens but not in glucose-embedded specimens. Candidate structures for the origin of these features are extensions of the helices, or linker regions connecting the helices.
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PMID:Difference Fourier analysis of "surface features" of bacteriorhodopsin using glucose-embedded and frozen-hydrated purple membrane. 366 Apr 90

Cultured mouse lymphoma cells incorporated [3H]leucine and [32P]phosphate into nuclear stress proteins within 3 h after exposure to either elevated temperature (45 degrees C) or sodium arsenite. Radiolabeled proteins were detected by autoradiography after two-dimensional polyacrylamide gel electrophoresis. To determine the cell cycle stage specificity of labeling, nuclei were isolated and sorted into two cell cycle phases using a fluorescent activated cell sorter. After either heat shock or sodium arsenite treatment, the majority of [3H]leucine incorporation into stress proteins occurred during the G0 + G1 phase with minimal labeling in the G2 phase. On the other hand, 32P labeling of stress proteins occurred in both the G0 + G1 and G2 phases after exposure to sodium arsenite, while incorporation of 32P was limited after heat stress. Following sodium arsenite treatment, a distinct set of four stress proteins (80-84 kDa) was detected with [3H]leucine only in G0 + G1 phase, but with [32P]phosphate these stress proteins were labeled in both G0 + G1 and G2. There was differential [32P]phosphate labeling between proteins of the 80-84 kDa set during cell cycling. Individual proteins of this set were isolated from gel plugs after sodium arsenite or heat-shock treatment. Coelectrophoresis of proteins from the two treatment groups showed that they had similar electrophoretic mobilities. All four proteins of the 80-84 kDa set (sodium arsenite induced) possessed similar polypeptide maps after digestion with V8 protease. Cytofluorometric analysis demonstrated a reduction in the number of nuclei in both S and G2 phases of the cell cycle two h after heat shock, but not following sodium arsenite treatment. However, there was a significant depression in the number of nuclei in S and G2 4 h after exposure to sodium arsenite and very modest labeling with 32P of stress proteins was observed at this time.
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PMID:Cell cycle-specific effects of sodium arsenite and hyperthermic exposure on incorporation of radioactive leucine and phosphate by stress proteins from mouse lymphoma cell nuclei. 381 26

Cortical neurons are densely innervated by noradrenergic fibers and by intrinsic cortical interneurons containing vasoactive intestinal polypeptide (VIP). Biochemically, VIP and norepinephrine (NE) synergistically interact to stimulate the synthesis of cyclic AMP in cortical slices. Therefore, we sought physiological indices of this peptide-monoamine interaction by applying VIP and NE to single cortical neurons of the rat while recording their spontaneous discharge. VIP applied alone inhibited discharge of 24% and accelerated discharge in 20% of cortical neurons. NE alone had a predominantly depressant effect on the same neurons. However, when VIP was retested during the continuous application of subthreshold currents of NE, VIP exerted predominantly depressant effects. These synergistic inhibitions resulted even in cells previously showing excitations to VIP alone. If VIP alone was depressant, subthreshold NE further enhanced the VIP depression. Subthreshold amounts of phenylephrine, an alpha-adrenoceptor agonist, also produced comparable interactions, suggesting involvement of an alpha receptor, as in the biochemical studies. These results support a peptide-monoamine interaction in cortex that could have important ramifications for neuronal integration.
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PMID:Vasoactive intestinal polypeptide acts synergistically with norepinephrine to depress spontaneous discharge rate in cerebral cortical neurons. 386 54

Concanavalin A, a phytohemagglutinin isolated from the jack bean, crystallizes at pH 6.8 in the orthorhombic space group 1222 with a = 89.9, b = 87.2, and c = 63.1 A. We have analyzed x-ray diffraction intensity data to 4 A resolution on native concanavalin A and five heavy-metal derivatives: lead, mersalyl, chloroplatinate, uranyl, and o-mercuri-p-nitrophenol. Heavy-atom positions, occupancies, and isotropic thermal parameters have been refined by least-squares methods. The electron density maps clearly show the molecular shape and the packing of the concanavalin A molecules. The asymmetric unit (mol wt 27,000) forms an elliptical dome or "gumdrop" with a base of approximately 46 x 26 A and a height of 42 A. The subunits are paired across 2-fold axes parallel to the c-axis to form dimers. The dimers are in turn paired across points of D(2) symmetry to form tetramers of roughly tetrahedral shape. Each unit has a depression located on the surface which could be the site of saccharide binding. In many regions we have been able to trace the course of the polypeptide chain.
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PMID:Structure of soncanavalin A at 4 A resolution. 528 72

Transmural electrical stimulation depressed the spontaneous activity of the longitudinal muscle of the rat portal vein in modified Krebs solution containing guanethidine (5 X 10(-6)M). This non-adrenergic inhibitory response was frequency-dependent and recovered slowly after cessation of stimulation. Tetrodotoxin (5 X 10(-7)M) but not atropine (2 X 10(-7)M) completely prevented this electrically-induced inhibitory response, indicating that it is due to a stimulation of non-adrenergic, non-cholinergic inhibitory nerves. Of the putative transmitters tested, only vasoactive intestinal polypeptide (VIP) mimicked the depression of the spontaneous activity elicited by transmural electrical stimulation. Using an indirect immunofluorescence technique, VIP-immunoreactive nerve fibres were observed in the wall of the rat portal vein. Such fibres were located both in the adventitia close to the longitudinal muscle layer and between the longitudinal and circular muscle layers. These observations suggest a possibility that VIP acts as a transmitter substance of vasodilator nerves in the rat portal vein.
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PMID:Non-adrenergic inhibitory response in the rat portal vein. 613 91

Long-term treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) of dorsal skin of 7,12-dimethylbenz(a)anthracene-initiated Syrian golden hamsters does not lead to the formation of epithelial tumors and leaves the epidermis essentially unchanged. However, previous histological studies by others have shown that hamster epidermis can be hyperplastically transformed by a single application of TPA but that the tissue is capable of gradually adapting to the drug after extended TPA exposure. We have investigated the response of hamster back epidermis to single and multiple treatments with increasing doses of TPA with regard to histological, proliferative, and biochemical alterations, and we show that in our animal strain the dorsal epidermis is resistant to even a single exposure to TPA, although the clearance rate of TPA is comparable to that in mouse epidermis and the metabolism of the substance is negligible. In contrast, the epidermis could be moderately stimulated by a single application of the nonpromoting calcium ionophore A 23187 and exhibited a strong proliferate and hyperplastic response following the simultaneous exposure to the calcium ionophore and TPA. Both types of hyperproliferation did not reveal an initial depression of the proliferative activity and were accompanied by typical alterations of the keratin polypeptide pattern, which was not detectable after treatment with TPA alone.
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PMID:Histological, proliferative, and biochemical alterations in dorsal epidermis of the Syrian golden hamster induced by 12-O-tetradecanoylphorbol-13-acetate and the calcium ionophore A 23187. 617 4

Strips of muscularis mucosae from the oesophagi of cat, dog and opossum have been studied to determine their responses to drugs to electrical field stimulation. All tissues were contracted by acetylcholine, histamine and, with the exception of strips of muscularis mucosae from the opossum proximal oesophagus, noradrenaline. The effects of acetylcholine and histamine were competitively antagonized by atropine (50 nM) and mepyramine (50 nM) and were abolished by atropine (1 microM) and mepyramine (1 microM) respectively. Contractile responses to noradrenaline were competitively antagonized by phentolamine (50 nM) but were converted to propranolol (50 nM)-sensitive relaxations by phentolamine (1 microM). Relaxations were abolished by propranolol (1 microM). Cholecystokinin octapeptide, gastrin 1 and vasoactive intestinal polypeptide were ineffective on any of the tissues examined. Substance P caused contractions in tissue from all three species. These effects were atropine and tetrodotoxin insensitive. All tissues gave atropine (50 nM)- and tetrodotoxin (100 nM)-sensitive contractions in response to electrical field stimulation. Contractions were not followed by relaxations and spontaneous mechanical activity was not suppressed between periods of stimulation. No evidence was obtained for the presence of non-adrenergic, non-cholinergic inhibitory innervation of the oesophageal muscularis mucosae in any species. During electrical field stimulation noradrenaline always reduced the amplitude of evoked contractions and, with the exception of tissue from proximal opossum oesophagus, increased resting tension. In opossum distal oesophageal muscularis mucosae, the effects of noradrenaline during electrical field stimulation were abolished by a 30 min pretreatment of the tissue with phentolamine (1 microM) and propranolol (1 microM). To Achieve this in all other tissues, it was also necessary to use yohimbine (1 microM). 7 In all tissues where noradrenaline caused a phentolamine (1 microM)-and propranolol (1 microM)- resistant depression of electrically evoked responses, clonidine produced a yohimbine (1 microM)- sensitive depression. 8 Evidence was obtained for the presence of excitatory alpha 1-and inhibitory alpha 2- and beta-adrenoceptors. Inter-species differences in their distribution are discussed.
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PMID:A pharmacological study of oesophageal muscularis mucosae from the cat, dog and American opossum (Didelphis virginiana). 620 83

Possible involvement of polypeptides of b-c1 complex of beef-heart mitochondria in its redox and protonmotive activity has been investigated, by means of chemical modification of amino acid residues in the soluble as well as in the phospholipid-reconstituted b-c1 complex. Treatment of the enzyme with tetranitromethane (C(NO2)4) or with ethoxyformic anhydride (EFA), that modify reversibly tyrosyl and hystidyl residues respectively, resulted in a marked inhibition of electron transport from reduced quinols to cytochrome c. This was accompanied, in b-c1 reconstituted into phospholipid vesicles, by a parallel inhibition of respiratory-linked proton translocation; the H+/e- stoichiometry remained unchanged. Treatment of b-c1 complex with DCCD, that specifically modifies carboxylic groups of glutammic or aspartic residues caused a marked depression of proton translocation in b-c1 vesicles, under conditions where the rate of electron flow in the coupled state, was enhanced. As a consequence the H+/e- stoichiometry was lowered. SDS gel electrophoresis and [14C]DCCD-labelling of the polypeptides of the b-c1 complex showed a major binding of 14C-DCCD to the 8-kDa subunit of the complex and possible cross-linking, induced by DCCD treatment, of polypeptide(s) in the 8-kDa band and the 12-kDa band, with the Fe-s protein of the complex, with the appearance of a new polypeptide band with an apparent molecular mass of about 40 kDa. Involvement of polypeptides of low molecular mass, for which no functional role was so far described, and possibly of the Fe-S protein in the redox-linked proton translocation in b-c1 complex is suggested.
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PMID:Redox-linked proton translocation in the b-c1 complex from beef-heart mitochondria reconstituted into phospholipid vesicles. Studies with chemical modifiers of amino acid residues. 631 24


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