Biology subjects

Dolan, E.

Publications and source records attributed to Dolan, E..

3 recordsLinked to original sources

bioRxiv2021

Skeletal Muscle Histidine Containing Dipeptide Contents are Increased in Freshwater Turtles (Chrysemys picta bellii) with Cold-Acclimation

Freshwater turtles found in higher latitudes can experience extreme challenges to acid-base homeostasis while overwintering, due to a combination of cold temperatures along with the potential for environmental hypoxia. Histidine containing dipeptides (HCDs; carnosine, anserine and balenine) may facilitate pH regulation in response to these challenges, through their role as pH buffers. We measured the HCDs content of three tissues (liver, cardiac muscle and skeletal muscle) from the anoxia-tolerant painted turtle (Chrysemys picta bellii) acclimated to either 3 or 20{degrees}C. HCDs were detected in all tissues, with the highest content shown in the skeletal muscle. Turtles acclimated to 3{degrees}C had more HCD in their skeletal muscle than those acclimated to 20{degrees}C (carnosine = 20.8{+/-}4.5 vs 12.5{+/-}5.9 mmol{middle dot}kg DM-1; ES = 1.59 (95%CI: 0.16 - 3.00), P = 0.013). The higher HCD content observed in the skeletal muscle of the cold-acclimated turtles suggests a role in acid-base regulation in response to physiological challenges associated with living in the cold, with the increase possibly related to the temperature sensitivity of carnosines dissociation constant and buffering power of the skeletal muscle during anoxic submergence. HighlightsO_LIpH regulation is a major challenge for overwintering freshwater turtles. C_LIO_LIHistidine containing dipeptides are important intracellular buffers. C_LIO_LITurtles acclimated to 3{degrees}C had higher HCD content than those at 20{degrees}C. C_LIO_LIHCDs may be important pH regulators in cold-acclimated turtles. C_LI

physiology↗

bioRxiv2019

Human Skeletal Muscle has Large Capacity to Increase Carnosine Content in Response to Beta-Alanine Supplementation. A Systematic Review with Bayesian Individual and Aggregate Data E-Max Model and Meta-Analysis

Beta-alanine (BA) supplementation increases muscle carnosine content (MCarn), and is ergogenic in many situations. Currently, many questions on the nature of the Mcarn response to supplementation are open, and the response to these has considerable potential to enhance the efficacy and applications of this supplementation strategy. ObjectiveTo conduct a Bayesian analysis of available data on the Mcarn response to BA supplementation. MethodsA systematic review with meta-analysis of individual and published aggregate data using a dose response (Emax) model was conducted. The protocol was designed according to PRISMA guidelines. A three-step screening strategy was undertaken to identify studies that measured the Mcarn response to BA supplementation. In addition, individual data from 5 separate studies conducted in the authors laboratory were analysed. Data were extracted from all controlled and uncontrolled supplementation studies conducted on healthy humans. Meta-regression was used to consider the influence of potential moderators (including dose, sex, age, baseline Mcarn and analysis method used) on the primary outcome. Results and ConclusionThe Emax model indicated that human skeletal muscle has large capacity for non-linear Mcarn accumulation, and that commonly used BA supplementation protocols may not come close to saturating muscle carnosine content. Neither baseline values, nor sex, appear to influence subsequent response to supplementation. Analysis of individual data indicated that Mcarn is relatively stable in the absence of intervention, and effectually all participants respond to BA supplementation (99.3% response [95%CrI: 96.2 - 100]).

physiology↗

bioRxiv2019

Targeting dormant ovarian cancer cells in vitro and in an in vivo model of platinum resistance

ObjectiveOvarian cancer cells often exist in vivo as multicellular spheroids. Spheroid formation in vitro has been used to enrich for cancer stem cell populations from primary tumors. Such spheroids exhibit drug resistance and slow proliferation, suggesting involvement in disease recurrence. Our objectives were to characterize cancer spheroid phenotypes, determine gene expression profiles associated with spheroid forming capacity and to evaluate the responsiveness of spheroids to commonly used and novel therapeutic agents.\n\nMethodsTumorigenic potential was assessed using anchorage independent growth assays in 24 cell lines. Spheroids from cell lines (N=12) and from primary cancers (N=8) were grown on non-adherent tissue culture plates in serum-free media. Cell proliferation was measured using MTT assays and Ki67 immunostaining. Affymetrix HT U133A gene expression data was used to identify differentially expressed genes based on spheroid forming capacity. Matched monolayers and spheroids (N=7 pairs) were tested for response to cisplatin, paclitaxel and 7-hydroxystaurosporine (UCN-01) while mitochondrial inhibition was performed using oligomycin. Xenograft tumors from intraperitoneal injection of CAOV2-GFP/LUC ovarian cancer cells into nude mice were treated with carboplatin to reduce tumor burden followed by secondary treatment with carboplatin, UCN-01, or Oltipraz. Tumor formation and response was monitored using live imaging.\n\nResultsOf 12 cell lines with increased anchorage-independent growth, 8 also formed spheroids under serum-free spheroid culture conditions. Spheroids showed reduced proliferation (p<0.0001) and Ki67 immunostaining (8% versus 87%) relative to monolayer cells. Spheroid forming capacity was associated with increased mitochondrial pathway activity (p [≤] 0.001). The mitochondrial inhibitors, UCN-01 and Oligomycin, demonstrated effectiveness against spheroids, while spheroids were refractory to cisplatin and paclitaxel. By live in vivo imaging, ovarian cancer xenograft tumors were reduced after primary treatment with carboplatin. Continued treatment with carboplatin was accompanied by an increase in tumor signal while there was little or no increase in tumor signal observed with subsequent treatment with UCN-01 or Oltipraz.\n\nConclusionsOur findings suggest that the mitochondrial pathway in spheroids may be an important therapeutic target in preventing disease recurrence.

cancer biology↗