Biomedical subjects

J R Van Wazer

Publications and source records attributed to J R Van Wazer.

4 recordsLinked to original sources

PubMed1977

Clinical evaluation of some phosphorus bone-imaging agents: concise communication.

Four different Tc-99m labeled phosphorus-based bone-imaging agents were compared by a scan-evaluation technique in which the skeletal uptake was visually assessed at selected sites. A detailed statisticalanalysis of scans, by each of three independent evaluators, on a total of 140 different patients showed that two of the agents (based on pyro- and on trimetaphosphate) were superior. The statistical analysis showed good agreement between the investigators and consistency in thier repeat evaluations.

Analysis of Variance↗

PubMed1976

Cyclization of the phosphorus chain of the methylene-bridged analogs of adenosine triphosphate.

The phosphorus-containing side chains of two methylene-bridged analogs of adenosine triphosphate have been cyclized to produce the corresponding analogs of monoadenosine-5'-trimetaphosphate. (The structures are given in the journal.) The molecules, which were generated in anhydrous media through a carbodimide-mediated condensation, were characterized by 31P nuclear-magnetic resonance, and the white-noise 1H decoupled spectra were simulated. These molecules are quite reactive and readily converted to their corresponding linear forms upon hydrolysis. The second structure contains an asymmetric phosphorus atom, and both of the possible cyclic molecules have been observed and the diasteroisomeric mixture has been isolated.

Adenosine Triphosphate↗

PubMed1976

Carbodiimide-intermediated esterification of the inorganic phosphates and the effect of tertiary amine base.

Detailed analysis of appropriate 31P nuclear-magnetic-resonance spectra shows that under the usual laboratory conditions, carbodiimide-induced condensation of orthophosphoric acid in a number of solvents leads to condensation only slightly beyond the metaphosphate composition in the presence of strong tertiary amines; whereas in the absence of amine, the condensation proceeds into the ultraphosphate region about halfway between the metaphosphate and phosphoric anhydride compositions. With amine, the principal product consists of the cyclic trimetaphosphate anion, with one of the nonbridging oxygen atoms substituted by the urea resulting from hydration of the carboiimide, i.e., (O2-) P-O-P(O2-) -O-P(O) [N[CH(CH3)2] see article [C(O)NHCH(CH3)2]] for the condensation with diisopropylcarbodiimide. Without amine, the major product is the 1,5-mu-oxotetrametaphosphate anion see article. The well-known carbodiimide-mediated phosphorylation of alcohols with orthophosphoric acid is shown to be directly attributable to the high reactivity of the phosphate branch groups of the carbodiimide-generated ultraphosphates.

Amines↗

PubMedDate not supplied

Phosphorus and mankind's problems today.

The unprecedented increase in the worldwide population of humans--a growth which has been underway for two centuries and has been continuously accelerating--seems to be a root cause of many of the problems of today, including including those treated in this symposium. Current events once more arouse fears that the probable conclusion of our present growth era will unfortunately consist of widespread death from famine, pestilence, and social disruption of various kinds (perhaps involving nuclear devices). Non-local efforts to avoid famine induced by rapid population growth seem only to delay an eventuality that will thereby finally lead to many more people starving. In this paper, phosphate pollution and soil erosion are treated as indirect results of the population boom; and some radical changes in soil and water management are suggested for lessening these problems for large populations.

Conservation of Natural Resources↗