The use of Geiger-Müller Counters for Locating Radium and for Measuring Gamma-Ray Intensities

Locher, Gordon L.; Weatherwax, J. L.

doi:10.1148/27.2.149

Cited by 25 publications

(41 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…B1oH14 + 2Et3N [Et3NH]2B1oH1o + H2 [1] B1oH2-+ C6H5N+ 1-BjoH9NH=NCjH [2] B10H2-+ 3H20 a BloH93H2-+ H3HO [3] Although the liposomes that contained B10H2 did not provide therapeutically useful concentrations of boron in tumor, this initial biodistribution experiment did provide an excellent point of reference. A therapeutically useful technique requires significant amounts of boron to remain within the tumor in order to provide sufficient time for the clearance of boron from other tissues.…”

Section: Resultsmentioning

confidence: 99%

Model studies directed toward the boron neutron-capture therapy of cancer: boron delivery to murine tumors with liposomes.

Shelly

Feakes

Hawthorne

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

153

View full text Add to dashboard Cite

The successful treatment of cancer by boron neutron-capture therapy (BNCT) requires the selective concentration of boron-10 within malignant tumors. The potential of liposomes to deliver boron-rich compounds to tumors has been assessed by the examination of the biodistribution of boron delivered by liposomes in tumor-bearing mice. Small unilamellar vesicles with mean diameters of 70 nm or less, composed of a pure synthetic phospholipid (distearoyl phosphatidylcholine) and cholesterol, have been found to stably encapsulate high concentrations of water-soluble ionic boron compounds. The hydrolytically stable borane anions B,.H01, B,2H11SH2-, B20H170H4-B2]HT3, and the normal form and photoisomer of B2oH 2-were encapsulated in liposomes as their soluble sodium salts. The tissue concentration of boron in tumor-bearing mice was measured at several time points over 48 h after i.v. injection of emulsions of liposomes containing the borane anions. Although the boron compounds used do not exhibit an affinity for tumors and are normally rapidly cleared from the body, liposomes were observed to selectively deliver the borane anions to tumors. The highest tumor concentrations achieved reached the therapeutic range (>15 jtg of boron per g of tumor) while maintaining high tumor-boron/blood-boron ratios (>3). The most favorable results were obtained with the two isomers of B2OH _. These boron compounds have the capability to react with intracellular components after they have been deposited within tumor cells by the liposome, thereby preventing the borane ion from being released into blood.Boron neutron-capture therapy (BNCT), first proposed by Locher in 1936 (1), is based upon the propensity of the 10B nucleus to undergo the 10B + 1n -* 'Li + 'He reaction with thermal neutrons. This process releases 2.28 MeV of kinetic energy, which is distributed between the a-particle and the 7Li+ ion. The effective distance of travel of these two ions in tissue is limited to approximately one cell diameter. During their passage through the interior of a cell, the energetic fission products cause ionization-tracking and cellular damage with associated cytotoxicity. Since the neutron capture cross-section of the 10B nucleus is 103 to 104 greater than that of all elements of physiological importance, the selective concentration of 10B atoms within cancer cells, followed by irradiation with thermal neutrons, should result in the destruction of the tumor cells even in the presence of neighboring normal cells.The development of effective targeting strategies for the selective transport ofboron to cancer cells has been the single most urgent problem in the area of BNCT. Successful therapy requires the site-specific delivery of relatively large amounts (15-20 jig of B per g of tissue) of boron to tumors (2). Strategies employed have included the use of boron compounds with some natural affinity for tumors, such as 4-(dihydroxyboryl)phenylalanine (BPA) (3) or the mercaptoundecahydro-closo-dodecaborate dianion (B12H,,SH2-; BSH) (4); the attac...

show abstract

Section: Resultsmentioning

confidence: 99%

Model studies directed toward the boron neutron-capture therapy of cancer: boron delivery to murine tumors with liposomes.

Shelly

Feakes

Hawthorne

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

153

View full text Add to dashboard Cite

show abstract

“…It is postulated that successful boron neutron capture therapy (BNCT) of human gliomas would require the preferential accumulation of 10B in the tumor (1), low levels of 10B in the blood and in the surrounding normal tissues, and the delivery of sufficiently high thermal neutron fluences at tumor sites (2). The initial clinical trials of BNCT of malignant brain tumors, conducted in the U.S.A. from 1951 through 1961, were disappointing, apparently because some of these conditions were not fulfilled (3).…”

mentioning

confidence: 99%

Boron neutron capture therapy of intracerebral rat gliosarcomas.

Joel

Fairchild

Laissue

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The efficacy ofboron neutron capture therapy (BNCT) for the treatment of intracerebrally implanted rat gliosarcomas was tested. Preferential accumulation of 10B in tumors was achieved by continuous infusion of the sulfhydryl borane dimer, Na41°B24H22S2, at a rate of 45-50 pg of 10B per g of body weight per day from day 11 to day 14 after tumor initiation (day 0). This infusion schedule resulted in average blood 10B concentrations of 35 pig/ml in a group of 12 gliosarcoma-bearing rats and 45 /Ag/ml in a group of 10 similar gliosarcoma-bearing rats treated by BNCT. Estimated tumor 10B levels in these two groups were 26 and 34 pg/g, respectively.On day 14, boron-treated and non-boron-treated rats were exposed to 5.0 or 7.5 MW-min ofradiation from the Brookhaven Medical Research Reactor that yielded thermal neutron fluences of -2.0 x 1012 or "'3.0 x 1012 n/cm2, respectively, in the tumors. Untreated rats had a median postinitiation survival time of 21 days. Reactor radiation alone increased median postinitiation survival time to 26 (5.0 MWimin) or 28 (7.5 MW-min) days. The 12 rats that received 5 MW-min of BNCT had a median postinitiation survival time of 60 days. Two of these animals survived >15 months. In the 7.5 MWmin group, the median survival time is not calculable since 6 of the 10 animals remain alive >10 months after BNCT. The estimated radiation doses to tumors in the two BNCT groups were 14.2 and 25.6 Gy equivalents, respectively. Similar gliosarcoma-bearing rats treated with 15.0 or 22.5 Gy of 250-kilovolt peak x-rays had median survival times of only 26 or 31 days, respectively, after tumor initiation.It is postulated that successful boron neutron capture therapy (BNCT) of human gliomas would require the preferential accumulation of 10B in the tumor (1), low levels of 10B in the blood and in the surrounding normal tissues, and the delivery of sufficiently high thermal neutron fluences at tumor sites (2). The initial clinical trials of BNCT of malignant brain tumors, conducted in the U.S.A. from 1951 through 1961, were disappointing, apparently because some of these conditions were not fulfilled (3).The polyhedral sulfhydryl borane (monomer), Na2B12-H11SH, was first investigated in the 1960s for possible use in BNCT (4). Evidence in animal tumor models indicates that tumor uptake after administration of the sulfhydryl borane dimer (Na4B24H22S2) is about double the tumor uptake after administration of equal amounts of boron as monomer (5, 6).Furthermore, it was observed that the decrease in tumor boron concentration is much slower after infusion of dimer than of monomer (6). Studies in rats bearing transplanted cerebral gliosarcomas indicate that slow infusion of dimer at the rate of =50 ug of 10B per g of body weight per day for 3 days consistently yields tumor boron concentrations >25 jig of 10B per g with average concentrations in normal brain tissue <2 ,ug of '0B per g. This degree of selective tumor boron uptake should provide an adequate therapeutic gain for BNCT. We used this infusion sched...

show abstract

“…BNCT is based on the 10 B(n, ) 7 Li reaction, which occurs when boron-10, which has a large capture cross section relative to the more abundant endogenous nuclei ( 1 H, 12 C, 31 P, 14 N), is exposed to thermal neutrons. The reaction releases high linear-energy-transfer radiation particles consisting of α-particles ( 4 He) and lithium atoms ( 7 Li) [Locher, 1936]. These particles cause direct DNA damage and tumor cell death.…”

Section: Introductionmentioning

confidence: 99%

Platinum Metal Complexes of Carbaboranylphophines: Potential Anti Cancer Agents

Maulana

Loennecke

Hawkins

2010

Indones J Cancer Chemoprevent

View full text Add to dashboard Cite

Polyhedral heteroboranes in particular dicarba-closo-dodecaboranes(12) and their organic derivatives have been the subject of intense research for over 40 years due to their unique chemical and physical properties. The initial attraction to dicarba-closododecaboranes(12) In the medicinal chemistry research, was a result of their high boron content and stability to catabolism, which are important criteria for cancer therapy, such as BNCT (boron neutron capture therapy) agents. The coordination compounds of the platinum group metals have also received large interest for their potential application as chemotherapeutic agents, since cis-diamminedichloroplatinum(II), cisplatin, has been reported to have capability as tumor inhibitor. Hence, applications can be envisioned for related cis platinum complexes. Complex of cis-rac-[PtCl2{1,2-(PRCl)2C2B10H10}] (R=Ph, t Bu, NEt2, NPh2) have been synthesized by employing known carbaborane based phosphine ligands of clorophoshino-closo-dodecaborane , with complex of cis-[PtCl2(COD)] (COD = 1,5-cyclooctadiene) in an N2-atmosphere. The obtained complexes possess expected structure configuration, namely cis-rac. The characterization of the complex has been carried out using 1 H, 31 P, 13 C and 11 B-NMR (Nuclear Magnetic Resonance), X-ray of single crystals, elemental analysis, IR (infra red) and mass spectroscopy (MS). The 31 P{ 1 H} NMR spectra of all the platinum complexes distinctly show the typical platinum satellites which are attributed to 31 P-195 Pt-coupling, in which the 31 P{ 1 H} NMR spectrum exhibits three lines with an intensity ratio of ca. 1:4:1. The structure of the platinum complexes consists of a slightly distorted square-planar coordination sphere, in which the platinum atom is bonded to two chlorides and two phosphorus atoms of the chelating carbaboranylphosphine. Thus the platinum atoms exhibit the coordination number four, which is preferred in platinum(II) complexes.

show abstract

The use of Geiger-Müller Counters for Locating Radium and for Measuring Gamma-Ray Intensities

Cited by 25 publications

References 0 publications

Model studies directed toward the boron neutron-capture therapy of cancer: boron delivery to murine tumors with liposomes.

Model studies directed toward the boron neutron-capture therapy of cancer: boron delivery to murine tumors with liposomes.

Boron neutron capture therapy of intracerebral rat gliosarcomas.

Platinum Metal Complexes of Carbaboranylphophines: Potential Anti Cancer Agents

Contact Info

Product

Resources

About