Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Anomalous biochemical responses in tests of the delayed neuropathic potential of methamidophos (O,S-dimethyl phosphorothioamidate), its resolved isomers and of some higher O-alkyl homologues (1991)
    Springer
    Archives of toxicology 65 (1991), S. 618-624 
    Details
    ISSN: 1432-0738
    Keywords: Methamidophos ; Pesticide ; Phosphoramidates ; Organophosphorus ; Neuropathy target esterase (NTE) ; Delayed neuropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The interaction with neural neuropathy target esterase (NTE) and acetylcholinesterase (AChE) in vivo of methamidophos (O,S-dimethyl phosphorothioamidate), its resolved stereoisomers and five higher O-alkyl homologues has been examined along with the ability of these compounds to cause organophosphorus-induced delayed polyneuropathy (OPIDP) in adult hens. For the lower homologues AChE was more sensitive than NTE and it was impossible to achieve high inhibition of NTE in vivo without both prophylaxis and therapy against acute anticholinesterase effects; for then-hexyl homologue high inhibition of NTE could be achieved without obvious anticholinesterase effects and spontaneous reactivation of inhibited AChE was seen as in vitro. The maximum tolerated dose ofl(−) methamidophos or of the ethyl oriso-propyl homologues did not inhibit NTE more than 60%, and surviving birds did not develop OPIDP. Then-propyl,n-butyl andn-hexyl compounds caused typical OPIDP at doses causing a peak of 70–95% inhibition of NTE in brain, spinal cord and sciatic nerve soon after dosing. Racemic methamidophos caused unusually mild OPIDP associated with very high inhibition of NTE at doses estimated to be 〉8 times the unprotected LD50 and thed-(+) isomer caused OPIDP at about 5−7× LD50. Clinical effects correlated with histopathology in 19 out of 20 examined birds. In contrast to results of many previous studies with organophosphates and phosphonates, all these cases of OPIDP were associated with formation of inhibited NTE which could be reactivated ex vivo by treatment of autopsy tissue with KF solution. It is not clear whether “aging” of inhibited NTE had occurred but with less associated stabilisation of the enzyme-phosphorus bond or whether, even without aging, the unusual N-unsubstituted phosphoramidate caused sufficient disturbance in or near the NTE target to initiate the same degenerative process as that caused typically by generation of “aged” organophosphorylated NTE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02098026
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Chiral high-performance liquid chromatography and gas chromatography of the stereoisomers of hexyl 2,5-dichlorophenyl phosphoramidate
    Amsterdam : Elsevier
    Journal of Chromatography B: Biomedical Sciences and Applications 622 (1993), S. 179-186 
    Details
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-4347(93)80264-5
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Interaction of some unsubstituted phosphoramidate analogs of methamidophos (O,S-dimethyl phosphorothioamidate) with acetylcholinesterase and neuropathy target esterase of hen brain
    Amsterdam : Elsevier
    Pesticide Biochemistry and Physiology 28 (1987), S. 224-238 
    Details
    ISSN: 0048-3575
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0048-3575(87)90021-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Soluble and Participate Forms of the Organophosphorus Neuropathy Target Esterase in Hen Sciatic Nerve (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neuropathy target esterase (NTE) is the suggested “target” molecule involved in the initiation of organophosphorus-induced delayed polyneuropathy. Sciatic nerve NTE was separated into particulate (P-NTE) and soluble (S-NTE) fractions by ultracentrifugation at 100,000 g for 1 h in 0.32 M sucrose and compared with the corresponding brain extract. Total sciatic NTE activity was 80–100 nmol/min/g tissue from which 50–60% was recovered in the soluble supernatant fraction and the remaining 40–50% in the pellet fraction. About 90% of brain tissue activity (∼ 1,800 nmol/min/g tissue) was recovered as P-NTE. A similar distribution was obtained when more drastic centrifugation without sucrose was performed. P-NTE and S-NTE were distributed with the membrane and cytosolic markers assayed, respectively, glucose-6-phosphatase, Na+,K+-ATPase, 5′-nucleotidase, phospholipids, and lactate dehydrogenase. When the pH during the centrifugation was increased from 6.4 to 11, recovered P-NTE activity decreased from 1,750 to 118 nmol/min/g tissue for brain and from 31 to 12 nmol/min/g for sciatic nerve. However, S-NTE activity and total nonfractionated control activity were only slightly affected by the same pH treatment. The distribution pattern encountered may be better understood as representing two different proteins than an equilibrium between soluble and membrane-bound portions of a single protein, with P-NTE activity depending on a membrane factor from which it is separated through fractionation at high pH. The titration curve corresponding to inhibition by mipafox was studied over the 0.1–200 μM range, in the presence of 40 μM paraoxon, and data obtained were fitted to models of one or two exponential mipafox-sensitive components plus a resistant component. Mipafox-resistant activity was 38 and 52% of total paraoxon-resistant activity for the particulate and soluble fractions, respectively. Particle data suggest that P-NTE contains mainly one component with I50 of ∼5.4–7.3 μM, this representing 〉85% of total mipafox-sensitive activity. However, the soluble fraction data fit better to two sensitive components: high- and low-mipafox-sensitive components with I50 of 4.9 and 43 μM, representing 35 and 65% of total paraoxon-resistant activity, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb03133.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Chromatographic Discrimination of Soluble Neuropathy Target Esterase Isoenzymes and Related Phenyl Valerate Esterases from Chicken Brain, Spinal Cord, and Sciatic Nerve (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 68 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neuropathy target esterase (NTE) activity is operatively defined in this work as the phenyl valerate esterase (PVase) activity resistant to 40 µM paraoxon but sensitive to 250 µM mipafox. Gel filtration chromatography with Sephacryl S-300 of the soluble fraction from spinal cord showed two PVase peaks containing NTE activity (S-NTE1 and S-NTE2). The titration curve corresponding to inhibition by mipafox was studied over the 1–250 µM range, in the presence of 40 µM paraoxon. The data revealed that S-NTE1 and S-NTE2 have different sensitivities to mipafox with I50 (30 min) values of 1.7 and 19 µM, respectively. This was similar to the pattern observed in the soluble fraction from sciatic nerve with two components (Vo peak, or S-NTE1; and 100-K peak, or S-NTE2) with different sensitivity to mipafox. However, in the brain soluble fraction, only the high-molecular-mass (〉700-kDa) peak or S-NTE1 was obtained. It showed an I50 of 5.2 µM in the mipafox inhibition curve. The chromatographic profile was different on changing the pH in the subcellular fractionation. When the homogenized tissue was centrifuged at pH 6.8, the Vo peak activity decreased in the soluble fraction from these nerve tissues. This suggests that the Vo peak could be related to materials partly solubilized from membranes at higher pH. The chromatographic pattern and mipafox sensitivity suggest that the different tissues have a different NTE isoform composition. S-NTE2 should be a different entity than S-NTE1 and particulate NTE. The potential role of soluble forms in the mechanism of initiation or promotion of neuropathy due to organophosphorus remain unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.68052170.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Purification and Characterization of Naturally Soluble Neuropathy Target Esterase from Chicken Sciatic Nerve by HPLC and Western Blot (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 69 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neuropathy target esterase (NTE) activity is defined operatively as the paraoxon-resistant mipafox-sensitive phenyl valerate esterase activity. A preparation containing a soluble isoform (S-NTE2) has been obtained from sciatic nerve. It was inhibited by the biotinylated organophosphorous ester S9B [1-(saligenin cyclic phospho)-9-biotinyldiaminononane] in a progressive manner showing a second-order rate constant of (3.50 ± 0.26) × 106M−1· min−1 with an I50 for 30 min of 6.6 ± 0.4 nM. S-NTE2 was enriched 218-fold by gel filtration followed by strong and weak anion-exchange chromatographies in HPLC. In western blots, this enriched sample showed two bands of endogenous biotinylated polypeptides after treating the blots with streptavidin-alkaline phosphatase complex. When the sample was treated with S9B, another biotinylated band was observed with a molecular mass of ∼56 kDa, which was not seen when the sample had been pretreated with mipafox before the S9B labeling. It was deduced that this band represents a polypeptide (identified as the S-NTE2 protein) that is bound by both mipafox and S9B and that should be responsible for the progressive S9B inhibition. It is possible that S-NTE2 is the target for attack by compounds that promote delayed neuropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.69051975.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    A tyrosinase electrode: A laboratory experiment
    Amsterdam : Elsevier
    Biochemical Education 9 (1981), S. 51-54 
    Details
    ISSN: 0307-4412
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0307-4412(81)90164-3
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effect of some metallic cations and organic compounds on theO-hexylO-2,5-dichlorophenyl phosphoramidate hydrolysing activity in hen plasma (1993)
    Springer
    Archives of toxicology 67 (1993), S. 416-421 
    Details
    ISSN: 1432-0738
    Keywords: Organophosphorus compounds ; Phosphoric triester hydrolases ; Detoxification ; Dichlorophenyl phosphoramidate ; Hen plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One of the main detoxification mechanisms of organophosphorus (OP) compounds is hydrolysis by OP hydrolysing enzymes (OP-hydrolases) or phosphoric triester hydrolases. We previously reported an OP-hydrolase from hen plasma which hydrolysesO-hexylO-2,5-dichlorophenyl phosphoramidate (HDCP). In this study, a total of 18 cations, as well as several thiol blocking reagents, ethylenediaminetetraacetic acid (EDTA) and mipafox (N,N′-diisopropyl phosphorodiamidofluoridate) were assayed as activators or inhibitors of the HDCP hydrolysing activity of hen plasma in vitro. Of the 18 inorganic cations only 1 M Na+ caused any inhibition. Most of the cations, including Ca2+, exerted no detectable effect; however, 1 mM Cu2+ was found to produce an activation of up to 263%, with a lesser activation of up to 168% for 1 mM Zn2+. The thiol blocking reagents methyl vinyl ketone (MVK) andN-ethylmaleimide (NEM) inhibited the enzyme in a time-dependent manner, the maximum effect depending upon concentration in the case of NEM, but not in the case of MVK; however, 5,5′-dithiobis (2-nitrobenzoic acid) caused inhibition that was concentration dependent but which was independent of time. Other thiol blocking reagents such as p-hydroxymercuribenzoic acid (sodium salt), phenylmercuric acetate, iodoacetic acid (sodium salt) and iodoacetamide produced only slight inhibition, as did EDTA. Finally, the OP compound mipafox exerted no detectable effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01977403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Immobilized frog tyrosinase. Stabilization on nylon supports (1982)
    Springer
    Biotechnology letters 4 (1982), S. 341-346 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Frog tyrosinase has been immobilized on nylon supports with high immobilization yield and long storage and reaction stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00135419
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Tuberculous panophthalmitis associated with drug abuse (1987)
    Springer
    International ophthalmology 10 (1987), S. 235-240 
    Details
    ISSN: 1573-2630
    Keywords: ocular tuberculosis ; drug abuse ; tuberculosis panophthalmitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Tuberculous endophthalmitis is a rare condition not described to date in association with intravenous drug abuse. Characteristics such as the lack of proven tuberculous disease in other organs and intense progression towards panophthalmitis make this case all the more interesting. The histopathological diagnosis is based on the identification of acid-alcohol resistant bacilli, and typical granuloma lesions with focal caseosis in stained sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00155630
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...