boron and Necrosis

Shoot tip necrosis is a physiological condition that negatively impacts the growth and development of in vitro plant shoot cultures across a wide range of species. Shoot tip necrosis is a physiological condition and disorder that can arise in plantlets or shoots in vitro that results in death of the shoot tip. This condition, which can spread basipetally and affect the emergence of axillary shoots from buds lower down the stem, is due to the cessation of apical dominance. STN can occur at both shoot multiplication and rooting stages. One of the most common factors that cause STN is nutrient deficiency or imbalance. Moreover, the presence or absence of plant growth regulators (auxins or cytokinins) at specific developmental stages may impact STN. The cytokinin to auxin ratio within an in vitro plant can be modified by varying the concentration of cytokinins used in the culture medium. The supply of nutrients to in vitro shoots or plantlets might also affect their hormonal balance, thus modifying the occurrence of STN. High relative humidity within culture vessels and hyperhydricity are associated with STN. An adequate supply of calcium as the divalent cation (Ca

Topics: Antioxidants; Boron; Calcium; Cell Death; Culture Media; Genotype; Necrosis; Nitrogen; Plant Growth Regulators; Plant Shoots; Tissue Culture Techniques

In the United States, breast cancer is one of the most common and the second leading cause of cancer-related death in women. Treatment modalities for mammary tumor are surgical removal of the tumor tissue followed by either chemotherapy or radiotherapy or both. Radiation therapy is a whole body irradiation regimen that suppresses the immune system leaving hosts susceptible to infection or secondary tumors. Boron neutron capture therapy (BNCT) in that regard is more selective, the cells that are mostly affected are those that are loaded with 109 or more 10B atoms. Previously, we have described that liposomal encapsulation of boron-rich compounds such as TAC and MAC deliver a high payload to the tumor tissue when injected intravenously. Here we report that liposome-mediated boron delivery to the tumor is inversely proportional to the size of the murine mammary (EMT-6) tumors. The plausible reason for the inverse ratio of boron and EMT-6 tumor size is the necrosis in these tumors, which is more prominent in the large tumors. The large tumors also have receding blood vessels contributing further to poor boron delivery to these tumors. We next report that the presence of boron in blood is essential for the effects of BNCT on EMT-6 tumor inhibition as direct injection of boron-rich liposomes did not provide any added advantage in inhibition of EMT-6 tumor in BALB/c mice following irradiation despite having a significantly higher amount of boron in the tumor tissue. BNCT reaction in PBMCs resulted in the modification of these cells to anti-tumor phenotype. In this study, we report the immunomodulatory effects of BNCT when boron-rich compounds are delivered systemically.

Topics: Animals; Boron; Boron Neutron Capture Therapy; Cell Line, Tumor; Cytokines; Female; Humans; Immunomodulation; Isotopes; Leukocytes, Mononuclear; Liposomes; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Necrosis; Tissue Distribution

High global incidence of prostate cancer has led to a focus on prevention and treatment strategies to reduce the impact of this disease in public health. Boron compounds are increasingly recognized as preventative and chemotherapeutic agents. However, systemic administration of soluble boron compounds is hampered by their short half-life and low effectiveness. Here we report on hollow boron nitride (BN) spheres with controlled crystallinity and boron release that decrease cell viability and increase prostate cancer cell apoptosis. In vivo experiments on subcutaneous tumour mouse models treated with BN spheres demonstrated significant suppression of tumour growth. An orthotopic tumour growth model was also utilized and further confirmed the in vivo anti-cancer efficacy of BN spheres. Moreover, the administration of hollow BN spheres with paclitaxel leads to synergetic effects in the suppression of tumour growth. The work demonstrates that hollow BN spheres may function as a new agent for prostate cancer treatment.

Topics: Alarmins; Animals; Antineoplastic Agents; Apoptosis; Biomarkers; Boron; Boron Compounds; Cell Line, Tumor; Cell Shape; Chemical Phenomena; Humans; Injections, Subcutaneous; Male; Mice, Inbred BALB C; Mice, Nude; Nanospheres; Necrosis; Prostatic Neoplasms; Tissue Distribution; Xenograft Model Antitumor Assays

Signs of abiotic toxicity often appear first at the margins of leaves and gradually spread toward the midrib. It has been suggested that the bundle sheath tissue surrounding the shoot vascular system acts as a solute transport-regulating barrier that prevents excessive quantities of toxic ions from entering the leaf and pushes them toward the hydathodes. We examined this hypothesis by examining the distribution of toxic boron (B) in mutant Arabidopsis leaves with flooded mesophyll and comparing it with that observed in control leaves that exuded guttation drops. As opposed to the control plants, which showed classical symptoms of B toxicity (necrosis starting at the leaf margins), in the mutants, necrosis was first observed inside the leaf. We will discuss this result and how it supports the hypothesis that the bundle sheath serves as a selective barrier filtering the xylem-to-leaf radial transport flow and pushing toxic solutes toward the hydathodes.

Topics: Arabidopsis; Biological Transport; Boron; Mesophyll Cells; Mutation; Necrosis; Plant Leaves; Plant Vascular Bundle; Stress, Physiological; Trace Elements; Xylem