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PubMed1990

Boron requirement in cyanobacteria : its possible role in the early evolution of photosynthetic organisms.

The effect of boron on heterocystous and nonheterocystous dinitrogen fixing Cyanobacteria was examined. The absence of boron in culture media inhibited growth and nitrogenase activity in Nodularia sp., Chlorogloeopsis sp., and Nostoc sp. cultures. Examinations of boron-deficient cultures showed changes in heterocyst morphology. However, cultures of nonheterocystous Cyanobacteria, Gloeothece sp. and Plectonema sp., grown in the absence of boron did not show any alteration in growth or nitrogenase activity. These results suggest a requirement of boron only by heterocystous Cyanobacteria. A possible role for this element in the early evolution of photosynthetic organisms is proposed.

Journal Article↗

PubMed2003

2-(6-bromopyridin-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane and (6-bromopyridin-3-yl)boronic acid, new bifunctional building blocks for combinatorial chemistry.

The first comparative study between two new heterocyclic boron derivatives, viz. a (6-bromopyridin-3-yl)boronic ester, C(11)H(15)BBrNO(2), and (6-bromopyridin-3-yl)boronic acid, C(5)H(5)BBrNO(2), shows a small but not significant difference in their C-B bond lengths, which cannot explain the experimentally observed difference in their stabilities. The crystal packing of the boronic ester consists principally of van der Waals interactions, while the boronic acid molecules interact in their crystal through hydrogen bonds.

Journal Article↗

PubMed2001

Determination of trace amounts of boron in steel by reversed-phase high-performance liquid chromatography with azomethine-H as a precolumn derivatizaion agent.

The determination of trace amounts of boron in steel by reversed-phase high-performance liquid chromatography (HPLC) is described. As a derivatizing reagent for the HPLC determination of boron, 8-hydroxy-1-(salicylideneamino)-3,6-naphtalenedisulfonic acid (azomethine-H) was used with a spectrophotometric detection. A peak of boron-azomethine-H chelate was resolved from other peaks using an acetonitrile-water (29 + 71 m/m) eluent containing 8 x 10(-3) mol kg(-1) tetrabutylammonium bromide and 5 x 10(-3) mol kg(-1) acetate buffer (pH 5.0). The lower determination limit (10sigma) of boron was 3.3 x 10(-8) mol dm(-3) for a solution injected into HPLC, which is translated to 0.09 microgB/g when 0.1 g of a steel sample was subjected to the analysis. The analytical results of certified steel samples were in good agreement with the guaranteed values. The addition of ethylenediamine-N,N,N',N'-tetraacetate as a masking agent for the iron(III) matrix with the optimized eluent enables one to achieve the direct determination of trace amounts of boron in such steel sample solutions without any tedious matrix removal or preconcentration.

Journal Article↗

PubMed1994

Radiation dose heterogeneity in receptor and antigen mediated boron neutron capture therapy.

Boron neutron capture therapy, BNCT, might be a valuable tumour therapeutical modality for the treatment of cells that are difficult to handle with conventional methods such as surgery or external radiotherapy. The principle is that tumour associated 10B atoms capture thermal neutrons and thereby forms high-LET helium and lithium ions as reaction products. An interesting development is to conjugate 10B atoms to macromolecules that bind to tumour cells with over-expressed receptors or specific antigens. The targeting macromolecules might be receptor-ligands, antibodies or antibody-fragments containing 10B. The present study deals with the limitations of such an approach. One problem is the background dose from capture of neutrons in physiologically occurring elements, especially nitrogen. We showed, with computer simulations, that the background specific energy (the stochastic analogy of dose) in the cell nuclei, due to captures in nitrogen, had a wide spread and could be rather high, up to 3 Gy in some cells, when relevant neutron fluencies were applied. The maximal amount of 10B that can be delivered to single tumour cells due to receptor-ligand, receptor-antibody or antigen-antibody mediated binding is probably in the range 10(8)-10(10) atoms/cell. Our calculations showed that the tumour cells had to contain about 10(9) 10B/cell to give a therapeutically interesting dose to the nuclei of the targeted cells. The doses were highest when the boron was in the cell nucleus. There was also a wide spread of specific energy absorbed by the nuclei after neutron capture in 10B. When, for example, 10(8) 10(10)B/nucleus were applied the specific energy to the analysed nuclei varied from 0 Gy up to about 7 Gy. These variations were due to the stochastic nature of the capture processes. Some helium or lithium ion tracks passed through the centre of the cell nuclei delivering a lot of energy, some passed through only a smaller part delivering small amounts of energy and sometimes the nuclei escaped without any hits at all. The results were obtained when relevant neutron fluencies (2-5 x 10(12) n/cm2) were applied. Increased neutron fluencies gave higher doses both due to capture in boron and in nitrogen but in order to improve the ratio between the dose to targeted tumour cells and the dose to normal cells, the number of 10B atoms in the targeted cells had to be increased and/or the boron placed in the cell nuclei.

Boron↗

PubMed1996

Progress in the field of compounds for boron neutron capture therapy.

For successful application of boron neutron capture therapy to the treatment of cancer, selective accumulation of boron is required. This can be achieved by the preparation of suitable substances, which must contain boron and at the same time accumulate or be retained in tumor tissue. The radiobiological rationale for selection of suitable compounds is discussed. Examples of useful new compounds are given for which boronated analogues exist.

Boron Compounds↗

PubMed2004

Boronated epidermal growth factor as a delivery agent for neutron capture therapy of EGF receptor positive gliomas.

The purpose of the present study was to further evaluate a boronated dendrimer (BD)-epidermal growth factor bioconjugate (BD-EGF), administered by means of convection enhanced delivery (CED), as a molecular targeting agent for boron neutron capture therapy (BNCT) of the F98(EGFR) glioma. Twenty-four hours following CED of (125)I-labeled BD-EGF 47.4% of the injected dose (ID) was retained in F98(EGFR) gliomas compared to 12.3% in F98(WT) (wildtype) receptor negative tumors. Normal brain values were in the range of 5.9-10.1% ID in the tumor bearing cerebral hemisphere. Boron concentrations in F98(EGFR) gliomas were 22.3 and 11.7 microg/g following CED and i.t. injection, respectively. Based on these results, BNCT studies were initiated at the Massachusetts Institute of Technology nuclear reactor (MITRII). The mean survival time (MST) of rats that received BD-EGF either alone or in combination with boronophenylalanine (BPA), injected i.v., were 53+/-13 d and >61+/-14 d, respectively, compared to 40+/-5 d for BPA alone and 31+/-4 d for irradiated controls. These data show that CED improved the radiobiological effectiveness of BD-EGF and lay the groundwork for future studies using combinations of boron delivery agents for NCT of EGFR(+) gliomas.

Animals↗

PubMed2004

Combination of boron neutron capture therapy and external beam radiotherapy for brain tumors.

PURPOSE: Boron neutron capture therapy (BNCT) has been used clinically as a single modality treatment for high-grade gliomas and melanomas metastatic to the brain. The purpose of the present study was to determine whether its efficacy could be enhanced by an X-ray boost administered after BNCT. Two brain tumor models were used, the F98 glioma as a model for primary brain tumors and the MRA 27 human melanoma as a model for metastatic brain tumors. METHODS AND MATERIALS: For biodistribution studies, either 10(5) F98 glioma cells were implanted stereotactically into the brains of syngeneic Fischer rats or 10(6) MRA 27 melanoma cells were implanted intracerebrally into National Institutes of Health (NIH)-rnu nude rats. Biodistribution studies were performed 11-13 days after implantation of the F98 glioma and 20-24 days after implantation of the MRA 27 melanoma. Animals bearing the F98 glioma received a combination of two boron-containing drugs, sodium borocaptate at a dose of 30 mg/kg and boron phenylalanine (BPA) at a dose of 250 mg/kg. MRA 27 melanoma-bearing rats received BPA (500 mg/kg) containing an equivalent amount of 10B (27 mg B/kg). The drugs were administered by either intracarotid or i.v. injection. RESULTS: The tumor boron concentration after intracarotid injection was approximately 50% greater in the F98 glioma and MRA 27 melanoma after intracarotid injection (20.8 and 36.8 microg/g, respectively) compared with i.v. injection (11.2 and 19.5 microg/g, respectively). BNCT was carried out at the Brookhaven National Laboratory Medical Research Reactor approximately 14 days after tumor implantation of either the F98 glioma or the MRA 27 melanoma. Approximately 7-10 days after BNCT, subsets of animals were irradiated with 6-MV photons, produced by a linear accelerator at a total dose of 15 Gy, delivered in 5-Gy daily fractions. F98 glioma-bearing rats that received intracarotid or i.v. sodium borocaptate plus BPA, followed 2.5 h later by BNCT and 7-10 days later by X-rays, had similar mean survival times (61 days and 53 days, respectively, p = 0.25), and the non X-irradiated, BNCT-treated animals had a mean survival time of 52 and 40 days, respectively, for intracarotid vs. i.v. injection; the latter was equivalent to that of the irradiated animals. The corresponding survival time for MRA 27 melanoma-bearing rats that received intracarotid or i.v. BPA, followed by BNCT and then X-irradiation, was 75 and 82 days, respectively (p = 0.5), 54 days without X-irradiation (p = 0.0002), 37 days for X-irradiation alone, and 24 days for untreated controls. In contrast to the data obtained with the F98 glioma, MRA 27 melanoma-bearing rats that received i.v. BPA, followed by BNCT, had a highly significant difference in mean survival time compared with the irradiated controls (54 vs. 37 days, p = 0.008). CONCLUSION: Our data are the first to suggest that a significant therapeutic gain may be obtained when BNCT is combined with an X-ray boost. Additional experimental studies are required to determine the optimal combination of X-radiation and neutron doses and whether it is more advantageous to administer the photon boost before or after BNCT.

Animals↗

PubMedDate not supplied

Transferrin-loaded nido-carborane liposomes: tumor-targeting boron delivery system for neutron capture therapy.

The nido-carborane lipid 2 as a double-tailed boron lipid was synthesized from heptadecanol in five steps. The lipid 2 formed stable liposomes at 25% molar ratio toward DSPC with cholesterol. Transferrin was able to be introduced on the surface of boron liposomes (Tf(+)-PEG-CL liposomes) by the coupling of transferrin to the PEG-CO(2)H moieties of Tf(-)-PEG-CL liposomes. The biodistribution of Tf(+)-PEG-CL liposomes, in which (125)I-tyraminyl inulins were encapsulated, showed that Tf(+)-PEG-CL liposomes accumulated in tumor tissues and stayed there for a sufficiently long time to increase tumor/blood concentration ratio, although Tf(-)-PEG-CL liposomes were gradually released from tumor tissues with time. A boron concentration of 22 ppm in tumor tissues was achieved by the injection of Tf(+)-PEG-CL liposomes at 7.2 mg/kg body weight boron in tumor-bearing mice. After neutron irradiation, the average survival rate of mice not treated with Tf(+)-PEG-CL liposomes was 21 days, whereas that of the treated mice was 31 days. Longer survival rates were observed in the mice treated with Tf(+)-PEG-CL liposomes; one of them even survived for 52 days after BNCT.

Animals↗

PubMed2005

A family of main-chain polymeric Lewis acids: synthesis and fluorescent sensing properties of boron-modified polythiophenes.

A new family of main-chain organoborane polymeric Lewis acids (PTh-BAr) that contain Lewis acidic boron groups embedded into a polythiophene backbone has been prepared under mild conditions through tin-boron exchange reaction. When phenyl and pentafluorophenyl groups are attached to boron, blue and green luminescence is observed, respectively, while the attachment of ferrocenyl substituents leads to a characteristic red color. The incorporation of readily accessible highly Lewis acidic groups into the conjugated polymer backbone provides an opportunity for sensing of Lewis basic substrates. For instance, treatment of the polymer containing phenyl substituents on boron with pyridine leads to efficient quenching of the fluorescence, while the polymer containing ferrocenyl groups changes color from dark red to light orange.

Boron↗

PubMed1997

Boron-containing polyamines as DNA targeting agents for neutron capture therapy of brain tumors: synthesis and biological evaluation.

Three series of new boron-containing spermidine/spermine (SPD/SPM) analogues have been synthesized: N1- and N5-(4-carboranylbutyl) SPD/SPM derivatives (SPD-1, SPD-5, SPM-1, SPM-5); N1,N10-diethyl-N5-(4-carboranylbutyl)spermidine (DESPD-5), N1,N14-diethyl-N5-(4-carboranylbutyl)spermine (DESPM-5); and N5,N10-bis(4-carboranylbutyl)spermine (SPM-5,10). In vitro studies using rat F98 glioma cells have shown that these polyamines retain the ability to displace ethidium bromide from calf thymus DNA and are rapidly taken up by F98 glioma cells. However, their cytotoxicities, especially those with terminal N-substituted (SPD-1, SPM-1) boron compounds, are greater than those of SPD/SPM. Nevertheless, the groundwork has been created for a new class of boron-containing compounds that maybe useful for boron neutron capture therapy of tumors.

Animals↗

PubMed1997

Central nervous system tolerance to boron neutron capture therapy with p-boronophenylalanine.

A rat spinal cord model was used to evaluate the effects of boron neutron capture irradiation on the central nervous system (CNS), using a range of doses of the boron delivery agent p-boronophenylalanine (BPA). Three doses of BPA 700, 1000 and 1600 mg kg(-1) were used to establish the biodistribution of boron-10 (10B) in blood, spinal cord and brain over a 3-h period after intraperitoneal (i.p.) administration. At the lowest dose of BPA used, blood 10B levels remained relatively stable over the 3-h sampling period. With the two higher doses of BPA, blood 10B concentrations were greatest at 1 h after BPA administration, and thereafter exhibited a biphasic clearance profile. The largest decline in blood 10B levels occurred between 1 and 2 h after i.p. injection and was most pronounced (approximately 45%) in the highest BPA dose group. Considered overall, 10B concentrations were marginally lower in the spinal cord than in the brain. Levels of 10B in both of these organs showed a slow but progressive increase with time after administration of BPA. The 10B concentration ratio for blood relative to CNS tissue increased with BPA dosage and reached a peak value of approximately 10:1 in the highest BPA dose group, at 1 h after i.p. injection. However, at 3 h after injection the 10B concentration ratios had decreased to approximately 3:1 in all of the BPA dose groups. After irradiation with thermal neutrons in combination with BPA at blood 10B concentrations of approximately 42 and approximately 93 microg g(-1), myelopathy developed after latent intervals of 20.0 +/- 0.6 and 20.0 +/- 1.2 weeks respectively. ED50 values (+/- s.e.) for the incidence of myelopathy were calculated from probit-fitted curves, and were 17.5 +/- 0.7 and 25.0 +/- 0.6 Gy after irradiation with thermal neutrons at blood 10B levels of approximately 42 and approximately 93 microg g(-1) respectively. The compound biological effectiveness (CBE) factor values, estimated from these data, were 0.67 +/- 0.23 and 0.48 +/- 0.18 respectively. This compared with a previous estimate of 0.88 +/- 0.14 at a blood 10B concentration of approximately 19 microg g(-1). It was concluded that the value of the CBE factor was not influenced by the level of 10B in the blood, but by the blood:CNS 10B concentration ratio. In effect, the CBE factor decreases as the concentration ratio increases. Simulations using boron neutron capture therapy (BNCT) treatment planning software indicate a significant therapeutic advantage could be obtained in moving to higher BPA doses than those in current clinical use.

Animals↗

PubMedDate not supplied

Preparation and characterization of liposomal systems entrapping the boronated compound o-carboranylpropylamine.

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when the stable isotope, Boron-10, is irradiated with low-energy thermal neutrons to yield ionizing Helium and Lithium ions that are highly damaging and usually lethal to cells. The successful treatment of cancer by BNCT requires the selective concentration of Boron-10 within malignant tumours. Liposomes have been used as therapeutic compound delivery vehicles for in vivo application, including several anticancer agents. The ability of the boron-containing compound, o-carboranylpropylamine chloride, to accumulate within unilamellar liposomes in response to a transmembrane pH gradient is evaluated. Characterization of the systems obtained is performed for conventional and polyethylene glycol (PEG)-modified (stealth) liposomes, in terms of lipid and CPA contents, vesicle size and stability in detergent solutions. Results demonstrate that CPA loading and vesicle stability can be controlled by the experimental procedure. The loading of CPA into liposomes with average diameters of 100 nm is estimated at 13000 molecules per vesicle for the most stable systems. CPA toxicity to normal human peripheral blood lymphocytes and to adherent glioblastoma multiforme SK-MG-1 cells in vitro is observed to decrease as a result of the entrapment of CPA in liposomes.

Boron Compounds↗

PubMed2001

The measurement of thermal neutron flux depression for determining the concentration of boron in blood.

Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy that relies on the uptake of the capture element boron by the volume to be treated. The treatment procedure requires the measurement of boron in the patient's blood. The investigation of a simple and inexpensive method for determining the concentration of the capture element 10B in blood is described here. This method, neutron flux depression measurement, involves the determination of the flux depression of thermal neutrons as they pass through a boron-containing sample. It is shown via Monte Carlo calculations and experimental verification that, for a maximum count rate of 1 x 10(4) counts/s measured by the detector, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 32 +/- 2 min. For a source activity of less than 1.11 x 10(11) Bq and a maximum count rate of less than 1 x 10(4) counts/s, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 58 +/- 3 min. It has also been shown that this technique can be applied to the measurement of the concentration of any element with a high thermal neutron cross section such as 157Gd.

Boron↗

PubMed1995

Bispecific antibodies as targeting agents for boron neutron capture therapy of brain tumors.

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10, a stable isotope, is irradiated with low energy (< or = 0.025 eV) or thermal neutrons to yield alpha particles and recoiling lithium-7 nuclei. A major requirement for the success of BNCT is the selective delivery of a sufficient number of boron atoms (approximately 10(9)) to individual cancer cells to sustain a lethal 10B (n, alpha) 7Li capture reaction. A panel of BsAb reactive with polyhedral borane anions (PBA) and a tumor-associated chondroitin sulfate proteoglycan has been produced. All of these BsAb showed strong reactivity with a panel of human glioblastoma and melanoma cell lines, as demonstrated by indirect membrane immunofluorescence. Two of them (H6 and B8) also reacted with cells that had been exposed to PBA (Na2B10H10 and Na2B12H11SH) and a boronated starburst dendrimer, which contained approximately 250-400 B atoms per molecule. The affinity constant (Ka) of BsAb-B8 was 2.57 x 10(8) M-1 on M21 human melanoma cell and 3.49 x 10(8) M-1 on A172 glioblastoma cells, which were almost identical to those of the parental monoclonal antibody (mAb) 9.2.27 on the same cell lines (2.62 x 10(8) M-1). Since our BsAb recognize both human glioblastoma and melanoma-associated antigens, as well as PBA, they potentially could be used to target 10B to these tumors for BNCT.

Animals↗

PubMed2002

Boron-containing aptamers to ATP.

Boron neutron capture therapy (BNCT), an experimental treatment for certain cancers, destroys only cells near the boron; however, there is a need to develop highly specific delivery agents. As nucleic acid aptamers recognize specific molecular targets, we investigated the influence of boronated nucleotide analogs on RNA function and on the systematic evolution of ligands by exponential enrichment (SELEX) process. Substitution of guanosine 5'-(alpha-P-borano) triphosphate (bG) for GTP or uridine 5'-(alpha-P-borano) triphosphate (bU) for UTP in several known aptamers diminished or eliminated target recognition by those RNAs. Specifically, ATP-binding aptamers containing the zeta-fold, which appears in several selections for adenosine aptamers, became inactive upon bG substitution but were only moderately affected by bU substitution. Selections were carried out using the bG or bU analogs with C8-linked ATP agarose as the binding target. The selections with bU and normal NTP yielded some zeta-fold aptamers, while the bG selection yielded none of this type. Non-zeta aptamers from bU and bG populations tolerated the borano substitution and many required it. The borano nucleotide requirement is specific; bU could not be used in bG-dependent aptamers nor vice versa. The borano group plays an essential role, as yet undefined, in target recognition or RNA structure. We conclude that the bG and bU nucleotides are fully compatible with SELEX, and that these analogs could be used to make boronated aptamers as therapeutics for BNCT.

Adenosine Triphosphate↗

PubMed2004

Analysis of boron-10 in soft tissue by dynamic secondary ion mass spectrometry.

We report here a preliminary study in which dynamic secondary ion mass spectrometry (SIMS) has provided images of boron-10 (10B) in biological tissue as used in research into boron neutron capture therapy. Cultured tumour cells incubated in media containing known concentrations of a 10B-containing compound, p-boronophenylalanine (BPA), and intracranial tumour tissue from animals previously injected with BPA were analysed by an in-house constructed SIMS. Investigations were conducted in positive secondary ion detection mode using a 25-keV, 5-nA gallium primary ion source. For calibration purposes, tissue standards were also analysed and their boron-to-carbon signal ratios correlated to bulk boron concentrations measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Ion maps of 10B, 12C, 23Na and 39K showing gross tissue and cell features were acquired. SIMS and ICP-AES standard measurements were in good agreement. Tissue regions with high or low 10B concentrations were identified along with 10B hotspots in normal brain areas. Cultured cells revealed the intracellular localization of 10B. SIMS is capable of producing images showing the distribution of 10B at p.p.m. levels in cells and in normal and tumour-bearing brain tissue.

Animals↗

PubMed2006

Boron containing macromolecules and nanovehicles as delivery agents for neutron capture therapy.

Boron neutron capture therapy (BNCT) is based on the nuclear capture and fission reactions that occur when non-radioactive boron-10 is irradiated with low energy thermal neutrons to yield high linear energy transfer (LET) alpha particles ((4)He) and recoiling lithium -7((7)Li) nuclei. For BNCT to be successful, a sufficient number of (10)B atoms ( approximately 10(9) atoms/cell) must be selectively delivered to the tumor and enough thermal neutrons must be absorbed by them to sustain a lethal (10)B(n, alpha) (7)Li capture reaction. BNCT primarily has been used to treat patients with brain tumors, and more recently those with head and neck cancer. Two low molecular weight (LMW) boron delivery agents currently are being used clinically, sodium borocaptate and boronophenylalanine. However, a variety of high molecular weight (HMW) agents consisting of macromolecules and nanovehicles have been developed. This review will focus on the latter which include: monoclonal antibodies, dendrimers, liposomes, dextrans, polylysine, avidin, folic acid, and epidermal and vascular endothelial growth factors (EGF and VEGF). Procedures for introducing boron atoms into these HMW agents and their chemical properties will be discussed. In vivo studies on their biodistribution will be described, and the efficacy of a subset of them, which have been used for BNCT of tumors in experimental animals, will be discussed. Since brain tumors currently are the primary candidates for treatment by BNCT, delivery of these HMW agents across the blood-brain barrier presents a special challenge. Various routes of administration will be discussed including receptor-facilitated transcytosis following intravenous administration, direct intratumoral injection and convection enhanced delivery by which a pump is used to apply a pressure gradient to establish bulk flow of the HMW agent during interstitial infusion. Finally, we will conclude with a discussion relating to issues that must be addressed if these HMW agents are to be used clinically.

Animals↗

PubMed1994

Cellular binding of carboranylalanine and some effects of boron neutron capture. Analysis of cultured melanoma B16 cells.

The boron containing substances L- and D-carboranylalanine might be of interest for boron neutron capture therapy, BNCT. Cultured mouse melanoma B16 cells were analyzed regarding binding of these substances and some introductory studies on effects of thermal neutron irradiation were also carried out. Comparisons were made with two boron containing compounds, p-boronophenylalanine (BPA) and boronated thiouracil (BTU-1), previously proposed for BNCT of melanomas. The results showed that both L- and D-carboranylalanine bound well in the B16 cells whereas BTU-1 gave no, and BPA only a low, binding. Thus, both forms of carboranes bound better than the two previously proposed substances. The carboranes also bound rather well in two tested human melanoma cell lines, IGR1 and RPMI-7951. Both L- and D-carboranylalanine showed a certain binding to isolated melanin but were not incorporated during melanin synthesis. Cultured glioma cells, used for comparison, bound BPA and to some extent the carboranes. This indicates that the substances are not melanoma specific. The carboranes caused some acute detachment of monolayer growing cells but were not strongly toxic since they did not reduce the growth rate. The cells treated with L-carboranylalanine or BPA showed, after neutron irradiation, a clear decrease in survival compared to the controls whereas no or only small effects were seen for cells treated with D-carboranylalanine or BTU-1. These results were conflicting since BPA gave therapeutical effects although only small amounts were bound while D-carboranylalanine gave no significant therapeutical effect in spite of better binding. One explanation might be different intracellular localizations. This has to be studied in more detail.

Animals↗