Changes in aortic lysyl oxidase activity in diet-induced atherosclerosis in the rabbit

This study assessed the responses of lysyl oxidase, the enzyme that initiates covalent crosslinking in elastic and collagen, by studying the aortic tissue of rabbits after arteriosclerosis had been induced by diet. Rabbits in the experimental group were fed an atherogenic diet of rabbit chow supplemented with 8% peanut oil and 2% cholesterol for varying periods of time, while the control group was fed only rabbit chow. Lysyl oxidase activity was found to be distributed throughout the length of the thoracic and abdominal aortas of the normal rabbits, However, rabbits fed the atherogenic diet showed marked increases in enzyme in the aortic arch, a change that was initially evident after 30 days and became greatest (2.5 times that of the controls) after 90 days. Enzyme activity in the study rabbits increased only minimally in the abdominal aortic wall. Aortic prolyl hydroxylase activity measured after 60 days of feeding changed in degree and manner similar to lysyl oxidase activity. These region-specific changes in enzyme activities correlated with the distribution and severity of aortic lesions in this model of the disease. Lysyl oxidase activity increased dramatically in this model of atherosclerosis, suggesting that this extracellular enzyme activity may prove to be a vulnerable and accessible point of control of the fibrotic response in atherosclerosis.

Long-term effect of an ethanol/sodium citrate locking solution on the mechanical properties of hemodialysis catheters

PURPOSE

To investigate the effect of a 30% ethanol/4% sodium citrate catheter locking solution on the mechanical properties of hemodialysis (HD) catheters over 36 weeks.

METHODS

Twenty-one HD catheters were used in this study. Three catheters, not exposed to locking solutions, underwent mechanical testing to determine baseline properties. Nine of the remaining 18 catheters were filled with normal saline and underwent mechanical testing in groups of three at 12, 24 and 36 weeks. Similarly, nine catheters were filled with the 30% ethanol/4% sodium citrate locking solution and tested in a similar manner.

RESULTS

The average force required to break the catheter lumens tended to be smaller in the catheters exposed to 30% ethanol/4% sodium citrate compared to saline controls at 12 and 24 weeks; however, there were no statistically significant differences between the groups after 36 weeks of exposure. The forces required to break these HD catheters are magnitudes greater than forces generated during a typical HD session.

CONCLUSIONS

We conclude that the 30% ethanol/4% sodium citrate locking solution had an effect on the mechanical properties of the catheters investigated, but not to the degree that would preclude further in vivo investigation. Further studies are necessary to determine the safety and efficacy of this catheter locking solution.

Immuno-phenotyping of IDH-mutant grade 3 astrocytoma and IDH-wildtype glioblastoma reveals specific differences in cells of myeloid origin

Gliomas are heavily infiltrated with immune cells of myeloid origin. Past studies have shown that high-grade gliomas have a higher proportion of alternatively activated and suppressive myeloid cells when compared to low-grade gliomas, which correlate with poor prognosis. However, the differences in immune cell phenotypes within high-grade gliomas (between grade 3 and grade 4 or GBM) are relatively less explored, and a correlation of phenotypic characteristics between immune cells in the blood and high-grade tumors has not been performed. Additionally, myeloid cells of granulocytic origin present in gliomas remain poorly characterized. Herein, we address these questions through phenotypic characterizations of monocytes and neutrophils present in blood and tumors of individuals with glioblastoma (GBM, IDH-wild type) or grade 3 IDH-mutant gliomas. We observe that neutrophils are highly heterogeneous among individuals with glioma, and are different from healthy controls. We also show that CD163 expressing M2 monocytes are present in greater proportions in GBM tissue when compared to grade 3 IDH-mutant glioma tissue, and a larger proportion of granulocytic myeloid-derived suppressor cells are present in grade 3 IDH-mutant gliomas when compared to GBM. Finally, we demonstrate that the expression levels of CD86 and CD63 showed a high correlation between blood and tumor and suggest that these may be used as possible markers for prognosis.

Sterile inflammation alters neutrophil kinetics in mice

Neutrophils play a crucial role in establishing inflammation in response to an infection or injury, but their production rates, as well as blood and tissue residence times, remain poorly characterized under these conditions. Herein, using a biomaterial implant model to establish inflammation followed by in vivo tracking of newly formed neutrophils, we determine neutrophil kinetics under inflammatory conditions. To obtain quantifiable information from our experimental observations, we develop an ordinary differential equation-based mathematical model to extract kinetic parameters. Our data show that in the presence of inflammation resulting in emergency granulopoiesis-like conditions, neutrophil maturation time in the bone marrow reduces by around 60% and reduced half-life in the blood, compared with noninflammatory conditions. Additionally, neutrophil residence time at the inflammatory site increases by 2-fold. Together, these data improve our understanding of neutrophil kinetics under inflammatory conditions, which could pave the way for therapies that focus on modulating in vivo neutrophil dynamics.