Mice learn to identify and discriminate sugar solutions based on odor cues.

This study examined how olfaction impacts ingestive responses of mice to sugar solutions. Experiment 1 asked whether naïve C57BL/6 (B6) mice could identify 1 M glucose, fructose, or sucrose solutions based on odor cues, during a 30-min 2-bottle acceptability test. We tested mice both before and after they were rendered anosmic with ZnSO4 treatment. We used 2 indirect measures of odor-mediated response: number of trials initiated and latency to initiate licking. Before ZnSO4 treatment, the mice learned how to identify 1 M glucose and fructose (but not sucrose) solutions based on odor cues. ZnSO4 treatment eliminated their ability to identify the glucose and fructose solutions. Experiment 2 asked whether 2 d of exposure to a 1 M glucose, fructose, or sucrose solution improved the identification of the same sugar solution. Following exposure, the B6 mice identified all 3 sugar solutions based on odor cues. Experiment 3 asked whether T1R3 knockout mice (i.e. mice lacking the T1R3 subunit of the T1R2 + R3 sweet taste receptor) could learn to discriminate 0.44 M glucose and fructose solutions based on odor cues. All mice were subjected to a 1-h preference test, both before and after exposure to the 0.44 M glucose and fructose solutions. During exposure, the experimental mice received ZnSO4 treatment, whereas the control mice received saline treatment. Before exposure, neither type of mouse preferred the glucose solution. After exposure, the control mice preferred the glucose solution, whereas the experimental mice did not. Our results reveal that mice can learn to use odor cues to identify and discriminate between sugar solutions.

Olfaction contributes to the learned avidity for glucose relative to fructose in mice.

When offered glucose and fructose solutions, rodents consume more glucose solution because it produces stronger postoral reinforcement. Intake of these sugars also conditions a higher avidity for glucose relative to fructose. We asked which chemosensory cue mediates the learned avidity for glucose. We subjected mice to 18 days of sugar training, offering them 0.3, 0.6, and 1 M glucose and fructose solutions. Before and after training, we measured avidity for 0.3 and 0.6 M glucose and fructose in brief-access lick tests. First, we replicated prior work in C57BL/6 mice. Before training, the mice licked at a slightly higher rate for 0.6 M fructose; after training, they licked at a higher rate for 0.6 M glucose. Second, we assessed the necessity of the glucose-specific ATP-sensitive K+ (KATP) taste pathway for the learned avidity for glucose, using mice with a nonfunctional KATP channel [regulatory sulfonylurea receptor (SUR1) knockout (KO) mice]. Before training, SUR1 KO and wild-type mice licked at similar rates for 0.6 M glucose and fructose; after training, both strains licked at a higher rate for 0.6 M glucose, indicating that the KATP pathway is not necessary for the learned discrimination. Third, we investigated the necessity of olfaction by comparing sham-treated and anosmic mice. The mice were made anosmic by olfactory bulbectomy or ZnSO4 treatment. Before training, sham-treated and anosmic mice licked at similar rates for 0.6 M glucose and fructose; after training, sham-treated mice licked at a higher rate for 0.6 M glucose, whereas anosmic mice licked at similar rates for both sugars. This demonstrates that olfaction contributes significantly to the learned avidity for glucose.

Low-calorie sweeteners cause only limited metabolic effects in mice.

There are widespread concerns that low-calorie sweeteners (LCSs) cause metabolic derangement. These concerns stem in part from prior studies linking LCS consumption to impaired glucose tolerance in humans and rodents. Here, we examined this linkage in mice. In experiment 1, we provided mice with chow, water, and an LCS-sweetened solution (saccharin, sucralose, or acesulfame K) for 28 days and measured glucose tolerance and body weight across the exposure period. Exposure to the LCS solutions did not impair glucose tolerance or alter weight gain. In experiment 2, we provided mice with chow, water, and a solution containing saccharin, glucose, or a mixture of both for 28 days, and tested for metabolic changes. Exposure to the saccharin solution increased the insulinemic response of mice to the glucose challenge, and exposure to the saccharin + glucose solution increased the rate of glucose uptake during the glucose challenge. However, neither of these test solutions altered glucose tolerance, insulin sensitivity, plasma triglycerides, or percent body fat. In contrast, exposure to the glucose solution increased glucose tolerance, early insulin response, insulin sensitivity, and percent body fat. We conclude that whereas the LCS-containing solutions induced a few metabolic changes, they were modest compared with those induced by the glucose solution.

Evidence of the involvement of dystrophin Dp71 in corneal angiogenesis.

Purpose: The aim of this study was to define the role of dystrophin Dp71 in corneal angiogenesis. Methods: Inflammation-induced corneal neovascularization experiments were performed in Dp71-null mice and C57BL/6J wild-type mice. Results: The corneal neovascular area covered by neovascularization was larger in the injured corneas of the Dp71-null mice compared to the corneas of the wild-type mice: 40.72% versus 26.33%, respectively (p<0.005). Moreover, increased angiogenesis was associated with a high expression of vascular endothelial growth factor (VEGF). Similarly, aortic ring assays showed a significant enhancement of the neovascular area. Conclusions: These results suggest that dystrophin Dp71 could play an important role as a negative regulator of corneal angiogenesis.

Acute Shortening and re-lengthening in the management of open tibia fractures with severe bone of 14 CMS or more and extensive soft tissue loss.

INTRODUCTION: A traumatic event to the tibia with more than 14 cm of bone and soft tissue loss represents a challenge to most orthopedic surgeons and is considered a limb-threatening condition. Few solutions are available in such clinical situations and among them is the acute shortening and re-lengthening of bone and soft tissue. MATERIALS AND METHODS: Our study presents the management of 7 patients with grade III B open fractures (according to the Gustillo-Anderson classification) of the tibia who underwent resection of all the devitalized tissues, acute limb shortening to close the defect, application of an external fixator, and metaphyseal osteotomy for re-lengthening. The patient outcomes were based on different parameters using the evaluation system established by Paley et al. RESULTS: Results acquired during the study show an average bone loss of 19cm (with a minimum of 14 cm and a maximum of 31.50cm). The average time to full recovery of all patients was 19 months with a minimum of 14 months and a max of 34 months. Patient presented with excellent bony union and none existent or small refractory leg length discrepancy and did not require bone grafts or free flaps. Complications that the patients had were contractures, which required secondary procedures such as Achilles tendon re-lengthening and recurrent infections. DISCUSSION: Overall patients had excellent bone union and were able to perform activities of their daily living. The Ilizarov technique of compression-dis- traction osteogenesis is an elegant treatment option that should be considered in patients suffering such traumatic events providing excellent bony union and good functional outcomes for the patient.