Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aiming to decrease the acute side effects and genotoxic hazards of PUVA, pyrido (3,4-C) psoralen (PP) and 7-methyl pyrido (3,4-C) psoralen (MPP) were synthesized and studied. Their UVA maximum absorption lies at 325 and 330 nm, respectively. Their photostability is comparable to that of 8-MOP. They complex to DNA in the dark, and, in the presence of UVA, produce only monoadditions to DNA, as shown by fluorescence and DNA denaturation-renaturation studies. In diploid eukaryotic yeast they are more effective than 8-MOP for the induction of lethal effects and mitochondrial damage. Their mutagenic activity per unit dose of UVA is in the same range as that of 8-MOP. However, per viable cell they are clearly less mutagenic than 8-MOP. This difference is also observed for recombinogenic activity. No oxygen effect is observed. In mammalian cells the following ranges of effectiveness are found: inhibition of DNA synthesis in human fibroblasts: MPP greater than PP greater than 8-MOP; mutagenic activity in V79 Chinese hamster cells: MPP greater than PP greater than 8-MOP; cell transforming ability in C3H embryonic mouse cells: MPP greater than 8-MOP greater than PP as a function of UVA dose, and: 8-MOP greater than MPP greater than PP as a function of survival; induction of sister chromatic exchanges (SCE) per unit dose: MPP greater than PP greater than 8-MOP in the linear part of the induction curve, and : 8-MOP greater than PP greater than MPP at the maximum level of SCE obtained.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Photochemotherapy using pyridopsoralens. 389 94

Isolated Golgi apparatus membranes from the germinal elements (spermatocytes and early spermatids) of rat testis were examined for their ability to incorporate [14C]mannose and [14C]galactose into glycolipid and glycoprotein fractions. Transfer of mannose from GDP-[14C]mannose into a Lipid I fractions (GPD:MPP mannosyl transferase activity), identified as mannosyl phosphoryl dolichol, showed optimal activity at 1.5 mM manganese and at pH 7.5. Low concentrations of Triton X-100 (0.1%) stimulated transferase activity in the presence of exogenous dolichol phosphate (Dol-P); however, inhibition occurred at Triton X-100 concentrations greater than 0.1%. Maximal activity of this GDP:MPP mannosyl transferase occurred at 25 microM Dol-P. Activity using endogenous acceptor was 2.34 pmole/min/mg, whereas in the presence of 25 microM Dol-P the specific activity was 284 pmole/min/mg, a stimulation of 125-fold. Incorporation of mannose into a Lipid II (oligosaccharide pyrophosphoryl dolichol) and a glycoprotein fraction was also examined. In the absence of exogenous Dol-P, rapid incorporation into Lipid I occurred with a subsequent rise in Lipid II and glycoprotein fractions suggesting precursor-product relationships. Addition of exogenous Dol-P to galactosyl transferase assays showed only a minor stimulation, less than twofold, in all fractions. Over the concentration range of 9.4 to 62.5 micrograms/ml Dol-P, only 1% of radioactive product accumulated in the combined lipid fractions. These observations suggest that the mannose transfer involves Dol-P intermediates and also that spermatocyte Golgi membranes may be involved in formation of the oligosaccharide core as well as in terminal glycosylations.
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PMID:Involvement of dolichol phosphates as intermediates in the mannosyl and galactosyl transferases of rat testicular germ cell Golgi apparatus membranes. 617 52

A very rare case of intraosseous meningioma accompanied with osteoma is reported. A 57-year-old male was admitted with left chronic subdural hematoma and an operation was immediately performed. At the time of admission skull X-ray film showed a high density area in the right frontoparietal region. Postoperative CT scanning showed no abnormality at standard window, widths and levels or at higher window, widths and levels. 99m Tc MPP scinti gram showed increased activity in the right frontoparietal region. Tomography of the skull indicated hyperostosis involving all layers. This skull tumor was diagnosed as osteoma. At the second operation the osteoma was removed. There seemed to be no changes in the bone and underlying dura. Histological examination indicated multiple microscopic meningotheliomatous meningioma with psammoma bodies in Haversian canals, leading to the conclusion that this was osteoid osteoma. It is suggested that this case be designated as type Lopez II and that it raises some interesting points regarding histogenesis and development of meningioma.
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PMID:[Osteoid oteoma associated with intraosseous meningioma. A case report]. 652 30

All synaptically-based neuropsychological theories of learning postulate that there are changes resulting from neural activity which are long-lasting and confined to specific sets of synapses. In the past decade a form of synaptic strengthening known as long-term potentiation (LTP) has been found which results from high-frequency neural activity and is of sufficient duration to model as a learning mechanism. Some early tests of the synaptic specificity of LTP in area CA1 of the hippocampus indicated that although LTP was specific to the tetanized pathway, in a converging untetanized pathway it was associated with depression of synaptic transmission lasting for at least 30 min. However, others have found that this heterosynaptic depression more usually decays within 5-15 min post-tetanus despite the maintenance of LTP in the tetanized pathway. Similarly, in the dentate gyrus (DG), LTP of either the lateral (LPP) or medial (MPP) components of the perforant path afferents has been associated with only short-lasting reciprocal heterosynaptic depression. Here, using more detailed measurement of stimulus intensity curves, we report that tetanization of either MPP or LPP reliably depresses synaptic transmission in the other pathway for at least 3 h. This heterosynaptic depression, considerably smaller than the usual magnitude of LTP, was obtained regardless of whether LTP had been produced in the tetanized homosynaptic pathway. Heterosynaptic long-term depression was not observed if the test pathway had been previously tetanized.
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PMID:Asymmetric relationships between homosynaptic long-term potentiation and heterosynaptic long-term depression. 663 40

1-(o-methoxyphenyl)-piperazine (o-MPP) is regarded as an antagonist of the dopamine receptor. Its effects were studied for the hind limb flexor reflex in the spinal rat, the body temperature in rats maintained at ambient temperature of 28 degrees C and stereotypy induced in rats by a low dose of apomorphine (0.5 mg/kg). o-MPP (2-12.5 mg/kg) stimulated the flexor reflex and, in higher doses (10-40 mg/kg), elevated the body temperature of heat-adapted rats. Both effects were inhibited by central serotonin receptor blocking agents--cyproheptadine or metergoline. Low doses of o-MPP (below 5 mg/kg) did not affect stereotypy induced by apomorphine; higher doses (5-25 mg/kg) attenuated the stereotypy in a dose-dependent manner. The results obtained suggest that o-MPP may facilitate the central serotonergic transmission similarly as several other phenylpiperazines. The role of this effect in the "antidopamine" action of o-MPP is discussed.
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PMID:A serotonergic component in the central action of 1-(o-methoxyphenyl)-piperazine. 666 37

This paper reports further psychophysical studies on a multiple-channel cochlear implant patient evaluating the feasibility of a speech processing strategy which converts the acoustic fundamental frequency to electric repetition rate, the second-formant frequency to electrode position, and the acoustic amplitude to current level. The first four studies evaluated the use of a special pulse pattern to minimize the loudness variation with electric repetition rate. The chosen pulse pattern consisted of multiple pulses occurring in the first half of each repetitive period (MPP) in contrast to the more conventional pattern with a single pulse per period (SPP). The results showed that MPP approximately equalized the loudness variation with repetition rate. The dynamic range of current, the pitch variation with repetition rate, and the difference limens for repetition rate were found to be similar to MPP and SPP. Two other studies investigated interaction between electrode position and repetition rate (RR). The first of these showed that the patient could make use of information provided by rising or falling RR trajectories superimposed on individual electrodes or electrode trajectories as an indicator of the direction of intonation variation. The second of these studies showed that the dissimilarities amongst the hearing sensations produced by steady-state stimuli differing in electrode position and repetition rate were characterized by two perceptual components, relating to the two electric parameters, respectively.
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PMID:Psychophysical studies evaluating the feasibility of a speech processing strategy for a multiple-channel cochlear implant. 668 34

Today eyes with massive periretinal proliferation which are often seen after uncured retinal detachments or after perforating injuries can be cured at least in 25 to 35% of the cases, even with modern surgical techniques. This is due to proliferation of cells, which enter through different pathways--retinal tears, perforating wounds of sclera and chorioidea, damaged retina or retinal vessels--into the vitreous and form membranes, which prevent the retina to attach. In the vitreous gel these cells of different origin can transform into fibroblast-like or myofibroblast-like cells. They also behave in the same way like fibroblasts or myofibroblasts and cause a kind of excessive wound healing and scar formation in the vitreous cavity. With the use of modern vitreous techniques we could cure nearly 43% of 14 patients with MPP after uncured retinal detachments or after perforating injuries. Because mechanical removal of intravitreal and periretinal membranes alone turned out to be unsuccessful in nearly 60%, methods of medical therapy to suppress this cell-activity seemed to be rather needed. By animal experiment we tried to produce retinal detachments by transplantation of homologue fibroblasts into the vitreous cavity of rabbit eyes, and observed traction detachments in 55% of the eyes. Histologic examination showed a rapid change of loose, round fibroblasts into elongated cells with long nuclei, which formed strands and caused vasoproliferation, especially where the strand reached the rabbit retina. By means of autoradiography the peak of cell activity turned out to be in the 3rd week after cell-transplantation and further examinations of the optic disc showed, that the vascular endothelium cell might be one source of the proliferation. There was no difference between the number of eyes which developed retinal detachment in the aphakic eyes and in the lentectomized and vitrectomized eyes, but we observed the clinical appearance of MPP earlier and more pronounced in the lentectomized and vitrectomized eyes. In the last experiment we tried to inhibit intraocular proliferation with intravitreal dexamethasone alcohol. This leaded to a significant reduce of the number of experimental detachments and vasoproliferations.
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PMID:[Clinical and experimental results in the treatment of massive periretinal proliferation (MPP), a retinal detachment with a most unfavorable prognosis]. 676 5

Two classes of immunomodulators of bacterial origin, peptidoglycan derivatives and lipopolysaccharides, are able to block in vitro the production of plasminogen activator by elicited macrophages: the release of the enzyme into the medium is inhibited and the intracellular activity reduced. In the case of peptidoglycan derivatives, high molecular weight compounds like WSA (water-soluble adjuvant) are stronger inhibitors than small molecules like MPP (muramyl pentapeptide). MDP (muramyl dipeptide) gives partial inhibition only. WSA (at 100 micrograms/ml) completely inhibits plasminogen activator production; the inhibition is reversible and specific. LPS is active at low concentrations (25-100 ng/ml). At concentrations higher than 50-100 ng/ml the action of LPS becomes irreversible and less specific. Peptidoglycan-derived immunomodulators can inhibit plasminogen activator production in the presence of polymixin B or in the case of macrophages obtained from C3H/HeJ mice; LPS is inactive under such conditions.
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PMID:Regulation of plasminogen activator secretion in mouse peritoneal macrophages. II. Inhibition by immunomodulators of bacterial origin. 680 2

The metabolic fate in mice of two 14C labelled meso-A2pm containing muramyl-peptides, the muramyl-tripeptide (Ac-Mur-L-Ala-gamma-D-Glu-14C-meso-A2pm) (MTP) and the muramyl-pentapeptide (Ac-Mur-L-Ala-gamma-D-Glu-meso-A2pm-14C-D-Ala-14C-D-Ala) (MPP) has been studied. As with 14C-MDP, the radioactive muramyl-tripeptide and muramyl-pentapeptide disappear rapidly from the organs and the radioactivity is found mainly in the urine. In contrast to MDP, the two meso-A2pm containing muramyl-peptides are not excreted intact in the urine. In both cases labelled fragments have been identifed: meso-A2pm from MTP and the tetrapeptide gamma-D-Glu-meso-A2pm-D-Ala-D-Ala from MPP. The ability of the two muramyl-peptides to increase nonspecific resistance of mice to Klebsiella infection was also investigated. The muramyl-pentapeptide injected i.v. one day before a lethal dose of K. pneumoniae protects both adult and neonate mice, as does MDP itself; the muramyl-tripeptide is inactive.
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PMID:Fate of two 14C labelled muramyl peptides: Ac-Mur-L-Ala-gamma-D-Glu-meso-A2pm and Ac-Mur-L-Ala-gamma-D-Glu-meso-A2pm-D-Ala-D-Ala in mice. Evaluation of their ability to increase non specific resistance to Klebsiella infection. 704 71

The authors used the unsecured balloon buckle of Lincoff and Kreissig in 15 cases during a six-month period (September 1981 to March 1982) at the Ist Eye Clinic in Vienna and the Eye Department in Salzburg. Cases were selected in which one large tear and a circumscribed detachment existed, as well as detachments with only one tear or a group of holes which did not exceed one hour in extent. After an observation period of between three and nine months the detachment was cured with the balloon buckle in 12 eyes, while in three eyes it failed; in two of them a cure was achieved by permanent buckle operation. In one eye the find result was MPP. This method seems particularly suited to cases where cryocoagulation or photocoagulation alone is too dangerous, but on the other hand a permanent buckle operation might cause muscle disturbances and irritating diplopia in eyes with usually good visual acuity before and after surgery. Further experience with the unsecured balloon buckle will show how far the indications for this method can be extended.
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PMID:[Preliminary results with the Lincoff-Kreissig balloon buckle]. 716 71


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