Combined Extract of Heated 4T1 and a Heat-Killed Preparation of Lactobacillus Casei in a Mouse Model of Breast Cancer.

BACKGROUND: The adjuvanticity potential of Lactobacillus casei was first suggested in an old survey. The present study was designed to investigate the efficacy of a new immunotherapy against breast cancer made by mixing an extract of heated 4T1 mammary carcinoma cell line and a heat-killed preparation of Lactobacillus casei. METHODS: Female BALB/c mice (6-8 weeks old, n=40) were challenged subcutaneously in the right flanks with 4T1 cells. When all the animals developed a palpable tumor, they were allocated to 4 equal groups and immunotherapy was initiated. The tumor-bearing mice in the experimental groups received the extract of heated 4T1 or heated Lactobacillus casei and/or a combination of both, twice at a 1-week interval. The mice in the control group received phosphate-buffered saline. One week after the last immunotherapy, one half of the mice were euthanized to determine the immune response profile. The remaining animals were kept until death occurred spontaneously. RESULTS: The animals receiving the combined treatment significantly showed more favorable survival curves and slower rates of tumor development than the tumor-bearing mice receiving only the heated 4T1 and/or the negative control mice. The combined immunization significantly amplified the production of nitric oxide and the cytotoxicity of natural killer cells in the spleen cell culture of the tumor-bearing mice. Moreover, the combined immunotherapy significantly increased the secretion of IFN-γ and conversely diminished the secretion of IL-4 and TGF-ß in the splenocyte population compared to the splenocytes from the other groups. CONCLUSION: The combined immunotherapy with heated 4T1 cells and heated Lactobacillus casei conferred beneficial outcomes in our mouse model of breast cancer.

In-vitro biodegradation and corrosion-assisted cracking of a coated magnesium alloy in modified-simulated body fluid.

A calcium phosphate coating was directly synthesized on AZ91D magnesium (Mg) alloy. Resistance of this coating to corrosion in a modified-simulated body fluid (m-SBF) was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Mechanical properties of the bare and coated alloy were investigated using slow strain rate tensile (SSRT) and fatigue testing in air and m-SBF. Very little is reported in the literature on human-body-fluid-assisted cracking of Mg alloys, viz., resistance to corrosion fatigue (CF) and stress corrosion cracking (SCC). This study has a particular emphasis on the effect of bio-compatible coatings on mechanical and electrochemical degradations of Mg alloys for their applications as implants. The results suggest the coating to improve the general as well as pitting corrosion resistance of the alloy. The coating also provides visible improvement in resistance to SCC, but little improvement in CF resistance. This is explained on the basis of pitting behaviour in the presence and absence of the coating.

Stress corrosion cracking and corrosion fatigue characterisation of MgZn1Ca0.3 (ZX10) in a simulated physiological environment.

Magnesium (Mg) alloys have attracted great attention as potential materials for biodegradable implants. It is essential that an implant material possesses adequate resistance to cracking/fracture under the simultaneous actions of corrosion and mechanical stresses, i.e., stress corrosion cracking (SCC) and/or corrosion fatigue (CF). This study investigates the deformation behaviour of a newly developed high-strength low-alloy Mg alloy, MgZn1Ca0.3 (ZX10), processed at two different extrusion temperatures of 325 and 400°C (named E325 and E400, respectively), under slow strain tensile and cyclic tension-compression loadings in air and modified simulated body fluid (m-SBF). Extrusion resulted in a bimodal grain size distribution with recrystallised grain sizes of 1.2 µm ± 0.8 µm and 7 ± 5 µm for E325 and E400, respectively. E325 possessed superior tensile and fatigue properties to E400 when tested in air. This is mainly attributed to a grain-boundary strengthening mechanism. However, both E325 and E400 were found to be susceptible to SCC at a strain rate of 3.1×10-7s-1 in m-SBF. Moreover, both E325 and E400 showed similar fatigue strength when tested in m-SBF. This is explained on the basis of crack initiation from localised corrosion following tests in m-SBF.