Development and Evaluation of a Novel pH Indicator Biodegradable Film Based on Cassava Starch

A pH indicator film based on cassava starch plasticized with sucrose and inverted sugar and incorporated with grape and spinach extracts as pH indicator sources (anthocyanin and chlorophyll) has been developed, and its packaging properties have been assessed. A second-order central composite design (2(2)) with three central points and four star points was used to evaluate the mechanical properties (tensile strength, tensile strength at break, and elongation at break percentage), moisture barrier, and microstructure of the films, and its potential as a pH indicator packaging. The films were prepared by the casting technique and conditioned under controlled conditions (75% relative humidity and 23 degrees C), at least 4 days before the analyses. The materials were exposed to different pH solutions (0, 2, 7, 10, and 14) and their color parameters (L*, a*, b*, and haze) were measured by transmittance. Grape and spinach extracts have affected the material characterization. Film properties (mechanical properties and moisture barrier) were strongly influenced by extract concentration presenting lower results than for the control. Films containing a higher concentration of grape extract presented a greater color change at different pH`s suggesting that anthocyanins are more effective as pH indicators than chlorophyll or the mixture of both extracts. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1069-1079,2011

Tibouchina pulchra (Cham.) Cogn., a native Atlantic Forest species, as a bio-indicator of ozone: Visible injury

Tibouchina pulchra saplings were exposed to carbon filtered air (CF), ambient non-filtered air (NF) and ambient non-filtered air + 40 ppb ozone (NF + O-3) 8 h per day during two months. The AOT40 values at the end of the experiment were 48, 910 and 12,895 ppb h(-1), respectively, for the three treatments. After 25 days of exposure (AOT40=3871 ppb h(-1)), interveinal red stippling appeared in plants in the NF + O-3 chamber. In the NF chamber, symptoms were observed only after 60 days of exposure (AOT40 = 910 ppb h(-1)). After 60 days, injured leaves per plant corresponded to 19% in NF + O-3 and 1% in the NF treatment; and the average leaf area injured was 7% within the NF + O-3 and 0.2% within the NF treatment. The extent of leaf area injured (leaf injury index) was mostly explained by the accumulated exposure of ozone (r(2) = 0.89; p < 0.05). (C) 2007 Elsevier Ltd. All rights reserved.

Tyrosine hydroxylase immunoreactivity as indicator of sympathetic activity: simultaneous evaluation in different tissues of hypertensive rats

Burgi K, Cavalleri MT, Alves AS, Britto LRG, Antunes VR, Michelini LC. Tyrosine hydroxylase immunoreactivity as indicator of sympathetic activity: simultaneous evaluation in different tissues of hypertensive rats. Am J Physiol Regul Integr Comp Physiol 300: R264-R271, 2011. First published December 9, 2010; doi: 10.1152/ajpregu.00687.2009.-Vasomotor control by the sympathetic nervous system presents substantial heterogeneity within different tissues, providing appropriate homeostatic responses to maintain basal/stimulated cardiovascular function both at normal and pathological conditions. The availability of a reproducible technique for simultaneous measurement of sympathetic drive to different tissues is of great interest to uncover regional patterns of sympathetic nerve activity (SNA). We propose the association of tyrosine hydroxylase immunoreactivity (THir) with image analysis to quantify norepinephrine (NE) content within nerve terminals in arteries/arterioles as a good index for regional sympathetic outflow. THir was measured in fixed arterioles of kidney, heart, and skeletal muscle of WistarKyoto rats (WKY) and spontaneously hypertensive rats (SHR) (123 +/- 2 and 181 +/- 4 mmHg, 300 +/- 8 and 352 +/- 8 beats/min, respectively). There was a differential THir distribution in both groups: higher THir was observed in the kidney and skeletal muscle (similar to 3-4-fold vs. heart arterioles) of WKY; in SHR, THir was increased in the kidney and heart (2.4- and 5.3-fold vs. WKY, respectively) with no change in the skeletal muscle arterioles. Observed THir changes were confirmed by either: 1) determination of NE content (high-performance liquid chromatography) in fresh tissues (SHR vs. WKY): +34% and +17% in kidney and heart, respectively, with no change in the skeletal muscle; 2) direct recording of renal (RSNA) and lumbar SNA (LSNA) in anesthetized rats, showing increased RSNA but unchanged LSNA in SHR vs. WKY. THir in skeletal muscle arterioles, NE content in femoral artery, and LSNA were simultaneously reduced by exercise training in the WKY group. Results indicate that THir is a valuable technique to simultaneously evaluate regional patterns of sympathetic activity.

Analytical quantification of low-density lipoprotein using europium tetracycline indicator

Low-density lipoprotein (LDL) is known as `bad` cholesterol. If too much LDL circulates in the blood it can be retained in the walls of the arteries, causing atherosclerosis. In this paper we showed an alternative method to quantify LDL using the europium tetracycline (EuTc) indicator. The optical properties of the EuTc complex were investigated in aqueous solutions containing LDL. An enhancement was observed of the europium luminescence in the solutions with LDL compared those without the lipoprotein. A method to quantify the amount of LDL in a sample, based on EuTc enhanced luminescence, is proposed. The enhancement mechanism is also discussed. Copyright (C) 2009 John Wiley & Sons, Ltd.