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R Hakimi

Publications and source records attributed to R Hakimi.

27 records · Page 2Linked to original sources
PubMed2003

Competitive binding of Pu and Am with bone mineral and novel chelating agents.

Effective direct removal of actinides such as Pu and Am from bone in vivo has not been accomplished to date, even with the strong chelating agents CaNa3DTPA or ZnNa3DTPA. This study, using an established in vitro system, compared removal of Pu and Am bound to bone mineral by ZnNa3DTPA and 10 chelating agents designed specifically to sequester actinides, including Pu and Am. Ligands tested were tetra, hexa, and octadentate, with linear or branched backbones containing sulfocatechol [CAM(S)], hydroxycatechol [CAM(C)], hydroxipyridinone (1,2-HOPO, Me-3,2-HOPO), or hydroxamate functional groups. The wide range of Pu and Am removal exhibited by the test ligands generally agreed with their metal coordination and chemical properties. The most effective agents for Pu (100 microM concentration, 24-48 h contact) are all octadentate as follows: 3,4,3-LICAM(S) (54% unbound); 3,4,3-LICAM(C) (6.2%); 3,4,3-LI(1,2-HOPO) (3.8%); H(2,2)-(Me-3,2-HOPO) (2.2%) and DFO-(1,2-HOPO) (1.8%). The other ligands removed less than 1% of the bound Pu; and ZnNa3DTPA removed only 0.086%. The most effective ligands for Am removal (100 microM, 24-48 h contact) are as follows: octadentate H(2,2)-(Me-3,2-HOPO) (21% unbound); 3,4,3-LI(1,2-HOPO) (14.5%) and 3,4,3-LICAM(C) (5.9%); hexadentate TREN-(Me-3,2-HOPO) and TREN-(1,2-HOPO) (9.6%); and tetradentate 5-LIO(Me-3,2-HOPO) (5.2%). Am removal by ZnNa3DTPA was about 1.4%. Among the ligands presently considered for possible human use, only 3,4,3-LI(1,2-HOPO) removed potentially useful amounts of both Pu and Am from bone mineral.

Americium↗
PubMed1999

Structure-activity relationships for a class of inhibitors of purine nucleoside phosphorylase.

Values of inhibition constants, Ki, for a family of structurally related, competitive inhibitors of calf spleen purine nucleoside phosphorylase (PNP) have been determined employing both inosine as substrate and a manual assay and 2-amino-6-mercapto-7-methylpurine ribonucleoside (MESG) as substrate and a robot-based enzyme kinetics facility. Several of the values determined robotically were confirmed employing the same substrate and a manual assay. Surprisingly, for many of the inhibitors examined, values of Ki determined with MESG as substrate are smaller than those obtained employing inosine as substrate by a factor that varies from less than 2 to 10. Values of concentrations required for 50% inhibition of PNP, IC50, have also been determined for the same family of inhibitors employing inosine as substrate. Values of IC50ino and those for Kiino and Kimesg for subsets of the inhibitors have been employed as training sets to create quantitative structure-activity relationships (QSAR) which have substantial power to predict values of IC50 and Ki for inhibitors outside the training set. These QSAR models should be useful in guiding future medicinal chemistry efforts designed to discover inhibitors of PNP having increased potency.

Animals↗
PubMed1997

[Natural healing methods versus alternative medicine--attempt at a distinction].

In this decade we can realize--especially in Europe--that many patients turn their back on established medicine and want to undergo alternative medicine. Alternative medicine is often mixed up with natural medicine, although classical natural medicine is very different from alternative medicine and is a part of established medicine. This paper gives a survey of the important methods of natural medicine on one side and of alternative medicine on the other side including their difference.

Complementary Therapies↗
PubMed1996

[Chronic fatigue syndrome--also an insurance medicine problem].

Not everybody who is chronically tired has a chronic fatigue syndrome. The diagnosis of the chronic fatigue syndrome is still a problem, and is becoming a problem in health insurance medicine too. There is a lack of knowledge concerning the causes, the diagnosis and the therapy of the chronic fatigue syndrome. And there is still the question if the chronic fatigue syndrome is an entity of its own. For these reasons we should apply the few facts we really know about the chronic fatigue syndrome. This is the working case definition of Kaplan et al. from 1988. Otherwise there will be done hundreds of expensive laboratory tests, which are useless for the patient and very costly for the health insurance companies.

Cost-Benefit Analysis↗