118 EXOSOME-MEDIATED OXIDATIVE STRESS RESPONSE IN BOVINE GRANULOSA CELLS

Exosomes are nano-sized (30–100 nm) extracellular membrane vesicles released through exocytosis process in most cells and biological fluids. They contain a cargo of nucleic acids, proteins, lipids and play a vital role in cell-cell communications. Various cell types have been shown to release exosomes into extracellular space as a response to various environmental stress conditions. However, little is known about the response of granulosa cells to oxidative stress, with regard to release of exosomes that may carry mRNA and protein molecules related to cellular oxidative stress response. Here we aimed to investigate the potential release of stress elements by granulosa cells to culture media through exosomes under oxidative stress conditions. For that, bovine granulosa cells from small follicles were aspirated and cultured in DMEM/F-12 media supplemented with exosome free fetal bovine serum (Exo-FBS) and treated with 5 µM H2O2 for 40 min. Granulosa cells were collected 24 h post-treatment to quantify the expression of antioxidants (Nrf2, Keap1, SOD1, CAT1, PRDX1, HOMOX1, TXN1, and NQO1), cell proliferation (PCNA and CNND2), cell differentiation (CYP11A1 and STAR), apoptosis (Casp3), and antiapoptosis (BCL2L1) genes. Reactive oxygen species accumulation, mitochondrial distribution, cell viability, and cell cycle assays were performed in cultured granulosa cells, and the culture medium was used to isolate exosomes using ultracentrifugation procedure. The identity of exosomes was confirmed by immunoblotting of Alix and CD63 proteins, and the expression level of antioxidant was analysed in mRNA isolated from exosomes. Data from 3 independent biological replicates were statistically analysed using the 2-tailed t-test. Results showed that H2O2 treatment increased mRNA and protein level of antioxidants (Nrf2, PRDX1, and TXN1), as well as cell differentiation and apoptosis-related genes compared to untreated controls. However, granulosa cells treated with H2O2 showed lower expression of cell proliferation marker genes (PCNA and CNND2). Cells treated with H2O2 showed increases in reactive oxygen species level, inadequate mitochondrial distribution, and lower cell viability. Cell cycle assay revealed a reduction in G0/G1 proportion and increase in G2 phase in cells treated with H2O2. Higher levels of antioxidant (Nrf2, CAT1, and TXN1) transcripts were detected in exosomes isolated from media with cells under oxidative stress conditions compared to the controls. Labelling and co-transfection of exosomes from stressed cell culture medium with untreated treated recipient granulosa cells resulted in increased abundance of cellular mRNA and protein of Nrf2 and CAT1 in those cells. In conclusion, granulosa cells exposed to oxidative stress could release exosomes that carry molecules related to oxidative stress response, which can be up taken by recipient cells.

Uptake of metabolites by gonococci grown with lactate in a medium containing glucose: evidence for a surface location of the sialyltransferase

Promotion of uptake of essential metabolites is a possible reason for the general stimulation of gonococcal metabolism which is caused by lactate (1 mM) in a defined medium containing glucose (5 mM). However, although uptake of(14)C adenine by gonococci [strain BS4(agar)] held for 4 or 7 min at 37 degrees C in Hanks balanced salt solution was increased for lactate treated gonococci compared with control organisms, uptake of(14)C glucose and(14)C proline under these conditions was unaffected. Hence, there is no evidence that lactate produces general stimulation of metabolite uptake. Unlike the other metabolites, cytidine 5'-monophospho-(14)CN-acetyl neuraminic acid (CMP-(14)CNANA), the substrate for sialylation of gonococcal lipopolysaccharide (LPS), was adsorbed in substantial quantities by gonococci held on ice for 6 min. Also, the increase in uptake of CMP-(14)CNANA at 37 degrees C over that adsorbed at 0 degrees C was much smaller (less than two-fold) than for the other compounds (4-30-fold). The substantial adsorption at 0 degrees C suggested a surface receptor for CMP-(14)CNANA. It is probably the sialyltransferase because a sialyltransferase deficient mutant, JB1, did not absorb CMP-(14)CNANA at 0 degrees C or take it up at 37 degrees C, in contrast to its parent strain, F62, which behaved similarly to strain BS4 (agar). This supports previous evidence for a surface location of the sialyltransferase. There was a small increase in adsorption of CMP-(14)CNANA in lactate treated gonococci indicating a slight increase in the surface enzyme. This could enhance LPS sialylation and hence affect pathogenicity.

Adjusting the cost-quality equation: utilizing work sampling and time study data to redesign clinical practice

Quality patient care through effective resource utilization is a health care imperative. While developing a patient classification system based on work sampling and time study data, quality and cost issues were analyzed. The purpose of this study was to compare cost and quality outcomes from practice redesign that resulted from work sampling and time study data. Practice redesign included standards of care documentation, research-based procedures, system reorganization, and role clarification. Results included increased nurse satisfaction, decreased time and money for indirect care, and positive patient outcomes. Work sampling and time study data provide opportunities to impact clinical practice, resulting in improved outcomes for patients and staff.