ALBERT

Description: The Spruce Budworm Decision Support System (SBW DSS) quantifies the marginal timber supply (m3/ha) benefits of protecting stands against spruce budworm (Choristoneura fumiferana (Clem.)) defoliation. It allows the user to quantify the volume benefit of protecting alternative areas and determine effects on forest development and annual allowable cut. Implementing the SBW DSS on a land base involves seven steps: (i) defining the base defoliation, or an explicit forecast of the defoliation level included in yield forecasts; (ii) compiling historical defoliation; (iii) defining base volume yields; (iv) obtaining the harvest schedule from the land base management plan; (v) building the stand impact matrix, which quantifies direct impacts of defoliation; (vi) building the forest impact matrix, which quantifies indirect impacts of defoliation on harvest schedules; and (vii) building the stand-history file, which contains all stand-level and defoliation data. These tasks are usually completed every 5 years. The remaining aspects of the planning methodology are implemented annually, including (i) recording the previous year's defoliation, (ii) estimating potential defoliation in the current year from budworm survey data, (iii) calculating volume loss or protection priority, (iv) generating budworm-caused volume loss maps, (v) digitizing potential spray blocks, and (vi) evaluating the protection program. Using ARC/INFO® and ArcView® geographic information system programs, the Protection Planning System component (PROPS) generates volume loss maps that can be used to help design and analyze costs and benefits of insecticide spray programs. Implementation of PROPS for the 450 000 ha Upper Miramichi Crown License in New Brunswick is described. Under "normal" and "severe" budworm outbreak scenarios, defined based on predictions of 19992008 defoliation, losses of 6.6 × 106 and 16.7 × 106 m3 of spruce (Picea sp.) balsam fir (Abies balsamea (L.) Mill.) volume were projected to occur on this land base.

Description: Inhibition of cutaneous nitric oxide (NO) synthase reduces the magnitude of cutaneous vasodilation during whole body heating in humans. However, this observation is insufficient to conclude that NO concentration increases in the skin during a heat stress. This study was designed to test the hypothesis that whole body heating increases cutaneous interstitial NO concentration. This was accomplished by placing 2 microdialysis membranes in the forearm dermal space of 12 subjects. Both membranes were perfused with lactated Ringer solutions at a rate of 2 microl/min. In both normothermia and during whole body heating via a water perfused suit, dialysate from these membranes were obtained and analyzed for NO using the chemiluminescence technique. In six of these subjects, after the heat stress, the membranes were perfused with a 1 M solution of acetylcholine to stimulate NO release. Dialysate from these trials was also assayed to quantify cutaneous interstitial NO concentration. Whole body heating increased skin temperature from 34.6 +/- 0.2 to 38.8 +/- 0.2 degrees C (P 〈 0.05), which increased sublingual temperature (36.4 +/- 0.1 to 37.6 +/- 0.1 degrees C; P 〈 0.05), heart rate (63 +/- 5 to 93 +/- 5 beats/min; P 〈 0.05), and skin blood flow over the membranes (21 +/- 4 to 88 +/- 10 perfusion units; P 〈 0.05). NO concentration in the dialysate did not increase significantly during of the heat stress (7.6 +/- 0.7 to 8.6 +/- 0.8 microM; P 〉 0.05). After the heat stress, administration of acetylcholine in the perfusate significantly increased skin blood flow (128 +/- 6 perfusion units) relative to both normothermic and heat stress values and significantly increased NO concentration in the dialysate (15.8 +/- 2.4 microM). These data suggest that whole body heating does not increase cutaneous interstitial NO concentration in forearm skin. Rather, NO may serve in a permissive role in facilitating the effects of an unknown neurotransmitter, leading to cutaneous vasodilation during a heat stress.

Description: The purpose of the present study was to evaluate a novel approach for determining skeletal muscle-specific glucose flux using radioactive stereoisomers and the microdialysis technique. Microdialysis probes were inserted into the vastus lateralis muscle of human subjects and perfused (4 microl/min) with a Ringer solution containing small amounts of radioactive D- and L-glucose as the internal reference markers for determining probe recovery as well as varying concentrations of insulin (0-10 microM). The rationale behind this approach was that both stereoisomers would be equally affected by the factors that determine probe recovery, with the exception of L-glucose, which is nonmetabolizable and would not be influenced by tissue uptake. Therefore, any differences in the probe recovery ratios between the D- and L-stereoisomers represent changes in skeletal muscle glucose uptake directly at the tissue level. There were no differences in probe recovery between the D- (42.3 +/- 3.5%) and L- (41.2 +/- 3.5) stereoisomers during the control period (no insulin), which resulted in a D/L ratio of 1.04 +/- 0.03. However, during insulin perfusion (1 microM), The D/L ratio increased to 1.62 +/- 0.08 and 1.58 +/- 0.07 (P 〈 0.05) during the two collection (0-15 and 15-30 min) periods, respectively. This was accomplished solely by an increase (P 〈 0.05) in D-glucose probe recovery, as L-glucose probe recovery remained unchanged. In a second set of experiments, the perfusion of 10 microM insulin did not increase the D/L ratio (1.40 +/- 0.11) above that observed during 1.0 microM (1.41 +/- 0.07) insulin perfusion. These data suggest that this method is sufficiently sensitive to detect differences in insulin-stimulated glucose uptake; thus the use of radioactive stereoisomers in conjunction with the microdialysis technique provides a novel and useful technique for determining tissue-specific glucose flux and insulin sensitivity.

Description: The purpose of the present study was to use the microdialysis technique to simultaneously measure the interstitial concentrations of several putative stimulators of the exercise pressor reflex during 5 min of intermittent static quadriceps exercise in humans (n = 7). Exercise resulted in approximately a threefold (P 〈 0.05) increase in muscle sympathetic nerve activity (MSNA) and 13 +/- 3 beats/min (P 〈 0.05) and 20 +/- 2 mmHg (P 〈 0.05) increases in heart rate and blood pressure, respectively. During recovery, all reflex responses quickly returned to baseline. Interstitial lactate levels were increased (P 〈 0.05) from rest (1.1 +/- 0.1 mM) to exercise (1. 6 +/- 0.2 mM) and were further increased (P 〈 0.05) during recovery (2.0 +/- 0.2 mM). Dialysate phosphate concentrations were 0.55 +/- 0. 04, 0.71 +/- 0.05, and 0.48 +/- 0.03 mM during rest, exercise, and recovery, respectively, and were significantly elevated during exercise. At the onset of exercise, dialysate K(+) levels rose rapidly above resting values (4.2 +/- 0.1 meq/l) and continued to increase during the exercise bout. After 5 min of contractions, dialysate K(+) levels had peaked with an increase (P 〈 0.05) of 0.6 +/- 0.1 meq/l and subsequently decreased during recovery, not being different from rest after 3 min. In contrast, H(+) concentrations rapidly decreased (P 〈 0.05) from resting levels (69.4 +/- 3.7 nM) during quadriceps exercise and continued to decrease with a mean decline (P 〈 0.05) of 16.7 +/- 3.8 nM being achieved after 5 min. During recovery, H(+) concentrations rapidly increased and were not significantly different from baseline after 1 min. This study represents the first time that skeletal muscle interstitial pH, K(+), lactate, and phosphate have been measured in conjunction with MSNA, heart rate, and blood pressure during intermittent static quadriceps exercise in humans. These data suggest that interstitial K(+) and phosphate, but not lactate and H(+), may contribute to the stimulation of the exercise pressor reflex.