10 research outputs found
A combined synchrotron powder diffraction and vibrational study of the thermal treatment of palygorskiteâindigo to produce Maya blue
The heating process (30â200 ÂșC) of a palygorskite-
indigo mixture has been monitored in situ and
simultaneously by synchrotron powder diffraction and
Raman spectroscopy. During this process, the dye and the
clay interact to form Maya blue (MB), a pigment highly
resistant to degradation. It is shown that the formation of a
very stable pigment occurs in the 70â130 ÂșC interval; i.e.,
when palygorskite starts to loose zeolitic water, and is
accompanied by a reduction of the crystallographic a
parameter, as well as by alterations in the C=C and C=O
bonds of indigo. Mid- and near-infrared spectroscopic
work and microporosity measurements, employed to study
the rehydration process after the complex formation, provide
evidence for the inhibition of the rehydration of MB as
compared with palygorskite. These results are consistent
with the blocking of the palygorskite tunnel entrance by
indigo molecules with a possible partial penetration inside
the tunnels. The surface silanols of palygorskite are not
perturbed by indigo, suggesting that MB is not a surface
complex
Abstract 3261: Impact of CTLA-4 blockade in conjunction with metronomic chemotherapy on preclinical breast cancer growth
Background:Although there are reports that metronomic cyclophosphamide (CTX) can be immune stimulating, the impact of its combination with anti-CTLA-4 immunotherapy for the treatment of cancer remains to be evaluated.Methods:Murine EMT-6/P breast cancer, or its cisplatin or CTX-resistant variants, or CT-26 colon, were implanted into Balb/c mice. Established tumours were monitored for relative growth following treatment with anti-CTLA-4 antibody alone or in combination with; (a) metronomic CTX (ldCTX; 20âmgâkg-1âday-1), b) bolus (150âmgâkg-1) plus ldCTX, or (c) sequential treatment with gemcitabine (160âmgâkg-1 every 3 days).Results:EMT-6/P tumours responded to anti-CTLA-4 therapy, but this response was less effective when combined with bolus plus ldCTX. Anti-CTLA-4 could be effectively combined with either ldCTX (without a bolus), or with regimens of either sequential or concomitant gemcitabine, including in orthotopic EMT-6 tumours, and independently of the schedule of drug administration. Tumour responses were confirmed with CT-26 tumours but were less pronounced in drug-resistant EMT-6/CTX or EMT-6/DDP tumour models than in the parent tumour. A number of tumour bearing mice developed spontaneous metastases under continuous therapy. The majority of cured mice rejected tumour re-challenges.Conclusions:Metronomic CTX can be combined with anti-CTLA-4 therapy, but this therapy is impaired by concomitant bolus CTX. Sequential therapy of anti-CTLA-4 followed by gemcitabine is effective in chemotherapy-naive tumours, although tumour relapses can occur, in some cases accompanied by the development of spontaneous metastases.British Journal of Cancer advance online publication, 5 January 2017; doi:10.1038/bjc.2016.429 www.bjcancer.com