Evaluation of commercial glucometer test strips for potential measurement of glucose in tears.

Tear glucose measurements have been suggested as a potential alternative to blood glucose monitoring for diabetic patients. While previous work has reported that there is a correlation between blood and tear glucose levels in humans, this link has not been thoroughly established and additional clinical studies are needed. Herein, we evaluate the potential of using commercial blood glucose test strips to measure glucose in tears. Of several blood glucose strips evaluated, only one brand exhibits the low detection limit required for quantitating glucose in tears. Calibration of these strips in the range of 0-100 µM glucose with an applied potential of 150 mV to the working electrode yields a sensitivity of 0.127 nA/µM and a limit of quantitation (LOQ) of 9 µM. The strips also exhibit ≤13% error (n = 3) for 25, 50, and 75 µM glucose in the presence of 10 µM acetaminophen, 100 µM ascorbic acid, and 100 µM uric acid. Measurements of glucose in tears from nine normal (nondiabetic) fasting human subjects using strips yielded glucose values within the range of 5-148 µM (mean = 47 µM, median = 43 µM), similar to those for human tears reported by others with more complex LC-MS methods. The glucometer strip method could facilitate more clinical studies to determine whether tear glucose and blood glucose levels sufficiently correlate for application to routine measurements in tears to supplement blood glucose testing. This would be especially helpful for children, adolescents, other Type 1 diabetics, and also for Type 2 diabetics who require treatment with insulin and cannot tolerate multiple finger sticks per day.

Dietary source of stearidonic acid promotes higher muscle DHA concentrations than linolenic acid in hybrid striped bass.

Rapid expansion of aquacultural production is placing increasing demand on fish oil supplies and intensified the search for alternative lipid sources. Many of the potential alternative sources contain low concentrations of long chain n-3 fatty acids and the conversion of dietary linolenic acid to longer chain highly unsaturated fatty acids is a relatively inefficient process in some species. A 6-week study was conducted to compare tissue fatty acid (FA) concentrations in hybrid striped bass fed either 18:3n-3 (alpha-linolenic acid; ALA) or 18:4n-3 (stearidonic acid; SDA). Hybrid striped bass were fed either a control diet containing fish oil, or diets containing ALA or SDA at three different levels (0.5, 1 and 2% of the diet). There were no significant differences in whole animal responses between fish fed ALA or SDA. Liver and muscle concentrations of ALA and SDA were responsive to dosages fed. However, only 22:6n-3 concentrations in muscle were significantly affected by dietary source of 18 carbon precursors. Muscle 22:6n-3 concentrations were significantly higher in fish fed SDA compared to fish fed ALA. Based on these data, it appears that feeding SDA can increase long chain n-3 fatty acid concentrations in fish muscle.

Specific expression of activation-induced cytidine deaminase (AID), a novel member of the RNA-editing deaminase family in germinal center B cells.

We have identified a novel gene referred to as activation-induced deaminase (AID) by subtraction of cDNAs derived from switch-induced and uninduced murine B lymphoma CH12F3-2 cells, more than 80% of which switch exclusively to IgA upon stimulation. The amino acid sequence encoded by AID cDNA is homologous to that of apolipoprotein B (apoB) mRNA-editing enzyme, catalytic polypeptide 1 (APOBEC-1), a type of cytidine deaminase that constitutes a catalytic subunit for the apoB mRNA-editing complex. In vitro experiments using a glutathione S-transferase AID fusion protein revealed significant cytidine deaminase activity that is blocked by tetrahydrouridine and by zinc chelation. However, AID alone did neither demonstrate activity in C to U editing of apoB mRNA nor bind to AU-rich RNA targets. AID mRNA expression is induced in splenic B cells that were activated in vitro or by immunizations with sheep red blood cells. In situ hybridization of immunized spleen sections revealed the restricted expression of AID mRNA in developing germinal centers in which modulation of immunoglobulin gene information through somatic hypermutation and class switch recombination takes place. Taken together, these findings suggest that AID is a new member of the RNA-editing deaminase family and may play a role in genetic events in the germinal center B cell.