The sensitivity and specificity of red-starch paper for the detection of saliva.
Martin, N. C., Clayson, N. J. & Scrimger, D. G. (2006). Science & Justice, 46(2), 97-105.
The detection of saliva in forensic casework is extremely important in many types of case. This study describes a relatively sensitive method, based on a red dye bound to starch, for the detection of amylase. The sensitivity and specificity of the method has been examined by testing over 50 household products, various body fluids and five laboratory chemicals. This study demonstrated for the first time that positive results can be obtained from certain washing powders as well as other household products. As well as detecting amylase in saliva, positive Red-Starch results were obtained from faeces and urine. The method was found to be suitable for the detection of mixtures of saliva and semen in conjunction with the Brentamine test for the detection of acid phosphatase.
Inhibition of starch digestion by the green tea polyphenol, (−)‐epigallocatechin‐3‐gallate.
Forester, S. C., Gu, Y. & Lambert, J. D. (2012). Molecular Nutrition & Food Research, 56(11), 1647-1654.
Scope: Green tea has been shown to ameliorate symptoms of metabolic syndrome in vivo. The effects could be due, in part, to modulation of postprandial blood glucose levels. Methods and results: We examined the effect of coadministration of (−)-epigallocatechin-3-gallate (EGCG, 100 mg/kg, i.g.) on blood glucose levels following oral administration of common corn starch (CCS), maltose, sucrose, or glucose to fasted CF-1 mice. We found that cotreatment with EGCG significantly reduced postprandial blood glucose levels after administration of CCS compared to control mice (50 and 20% reduction in peak blood glucose levels and blood glucose area under the curve, respectively). EGCG had no effect on postprandial blood glucose following administration of maltose or glucose, suggesting that EGCG may modulate amylase-mediated starch digestion. In vitro, EGCG noncompetitively inhibited pancreatic amylase activity by 34% at 20 μM. No significant change was induced in the expression of two small intestinal glucose transporters (GLUT2 and SGLT1). Conclusions: Our results suggest that EGCG acutely reduces postprandial blood glucose levels in mice when coadministered with CCS and this may be due in part to inhibition of α-amylase. The relatively low effective dose of EGCG makes a compelling case for studies in human subjects.
Application of binary packing for chromatographic separation.
Mota, M., Teixeira, J. A., Yelshin, A., Dias, R. & Cortez, S. (2005). 10th World Filtration Congress, 392-396.
Columns packed with commercial glass beads of 5 and 19 microns average diameter and binary mixtures with finest fraction of 5 micron (30 % volume fraction of the mixture) were used to analyse starch by hydrodynamic chromatography (HDC). Experiments were carried out at 3 and 15°C. The observed resolution increased with the application of binary packing as compared with single-size packing. The best results were obtained at starch’s amylopectin and amylose separation with a glass beads mixture (5 + 19 micron) at 3°C. In what concerns amylopectin and amylose separation, a lower pressure drop were obtained for the mixed binary packing when compared with the packing containing uniform 5 micron glass beads. For the Hylon VII starch RRT were 0.777 and 0.964 for amylopectin (AP) and amylose (AM), respectively, while for the Tapioca starch the obtained RRTs were 0.799 and 0.923. Application of unbound glass beads as column packing might reduce equipment and running costs in preparative scale separations.
Sensitivity and specificity of presumptive tests for blood, saliva and semen.
Vennemann, M., Scott, G., Curran, L., Bittner, F. & Tobe, S. S. (2014). Forensic Science, Medicine, and Pathology, 10(1), 69-75.
Purpose: Despite their wide use, the limits of presumptive tests can be poorly understood. The aim of this study was to investigate the specificity and sensitivity of conventional, as well as innovative, presumptive tests for blood, semen and saliva. Methods: We investigated Kastle–Meyer (KM) and leucomalachite green (LMG) tests for blood with regard to their sensitivity and specificity in the presence of oxidizing (hypochlorite) and anti-oxidizing (ascorbic acid) agents. The suitability and specificity of the red starch paper (RSP) test for saliva was assessed. Finally, the inhibitory effect of detergent on the acid phosphatase (AP) test for semen was investigated along with possible cross reactions to tea stains. Results: Our results confirm previous findings of higher sensitivity and specificity of the KM test compared to LMG test for blood. Contrary to previous studies, no statistically significant difference was observed in the sensitivity of the tests between dry and wet stains. The novel RSP test was found to successfully detect saliva. We demonstrated that acid phosphatase (AP) testing for semen is possible on used RSP. A common multipurpose detergent had an inhibitory effect on AP tests. False positive results were obtained from tea stains. Testing different sorts of tea (black, green and herbal teas) revealed that only Camellia varieties produce positive result with the AP test, due to AP being present in the plants. Conclusions: From our results we conclude that specific knowledge of each test, including substances that may affect the test outcome, is imperative to ensure correct interpretation of presumptive test results.
ApuA, a multifunctional α-glucan-degrading enzyme of Streptococcus suis, mediates adhesion to porcine epithelium and mucus.
Ferrando, M. L., Fuentes, S., de Greeff, A., Smith, H. & Wells, J. M. (2010). Microbiology, 156(9), 2818-2828.
We have identified apuA in Streptococcus suis, which encodes a bifunctional amylopullulanase with conserved α-(amylase and pullulanase substrate-binding domains and catalytic motifs. ApuA exhibited properties typical of a Gram-positive surface protein, with a putative signal sequence and LPKTGE cell-wall-anchoring motif. A recombinant protein containing the predicted N-terminal α-(amylase domain of ApuA was shown to have α-(1,4) glycosidic activity. Additionally, an apuA mutant of S. suis lacked the pullulanase α-(1,6) glycosidic activity detected in a cell-surface protein extract of wild-type S. suis. ApuA was required for normal growth in complex medium containing pullulan as the major carbon source, suggesting that this enzyme plays a role in nutrient acquisition in vivo via the degradation of glycogen and food-derived starch in the nasopharyngeal and oral cavities. ApuA was shown to promote adhesion to porcine epithelium and mucus in vitro, highlighting a link between carbohydrate utilization and the ability of S. suis to colonize and infect the host.
Inhibition of key digestive enzymes by cocoa extracts 1 and procyanidins.
Gu, Y., Hurst, W. J., Stuart, D. A. & Lambert, J. D. (2011). Journal of Agricultural and Food Chemistry, 59(10), 5305-5311.
We determined the in vitro inhibitory effects of cocoa extracts and procyanidins against pancreatic α-amylase (PA), pancreatic lipase (PL), and secreted phospholipase A2 (PLA2) and characterized the kinetics of such inhibition. Lavado, regular, and Dutch-processed cocoa extracts as well as cocoa procyanidins (degree of polymerization (DP) = 2–10) were examined. Cocoa extracts and procyanidins dose-dependently inhibited PA, PL, and PLA2. Lavado cocoa extract was the most potent inhibitor (IC50 = 8.5–47 μg/mL). An inverse correlation between log IC50 and DP (R2 > 0.93) was observed. Kinetic analysis suggested that regular cocoa extract, the pentamer, and decamer inhibited PL activity in a mixed mode. The pentamer and decamer noncompetitively inhibited PLA2 activity, whereas regular cocoa extract inhibited PLA2 competitively. This study demonstrates that cocoa polyphenols can inhibit digestive enzymes in vitro and may, in conjunction with a low-calorie diet, play a role in body weight management.