Nesting box imager: Contact-free, real-time measurement of activity, surface body temperature, and respiratory rate applied to hibernating mouse models.

Noncontact methods to measure animal activity and physiology are necessary to monitor undisturbed states such as hibernation. Although some noncontact measurement systems are commercially available, they are often incompatible with realistic habitats, which feature freely moving animals in small, cluttered environments. A growing market of single-board computers, microcontrollers, and inexpensive sensors has made it possible to assemble bespoke integrated sensor systems at significantly lower price points. Herein, we describe a custom-built nesting box imager (NBI) that uses a single-board computer (Raspberry Pi) with a passive infrared (IR) motion sensor, silicon charge-coupled device (CCD), and IR camera CCD to monitor the activity, surface body temperature, and respiratory rate of the meadow jumping mouse during hibernation cycles. The data are logged up to 12 samples per minute and postprocessed using custom Matlab scripts. The entire unit can be built at a price point below US$400, which will be drastically reduced as IR (thermal) arrays are integrated into more consumer electronics and become less expensive.

Improved peroral delivery of glucagon-like peptide-1 by site-specific biotin modification: design, preparation, and biological evaluation.

Peptide oral delivery is still a significant challenge because of two major impediments, low absorption efficiency and instability in gastrointestinal tract. The aim of this study was to design, prepare, and evaluate an intestine enzyme-resistant, superior intestine absorptive, and biologically preserved glucagon-like peptide-1 (GLP-1) derivative using the site-specific modification of biotin, which can take advantage of the carrier-mediated active intestine transport. Two series of site-specific Lys34- and Lys26,34-biotin-GLP-1 derivatives were prepared, and their intestine membrane permeabilities, proteolytic stabilities against the intestine enzymes, and bioactivities were then evaluated. Especially, Lys26,34-biotin-GLP-1 was found to have the most promising scores: (i) it displayed a 5.6-fold higher Caco-2 cell monolayer permeability than GLP-1; (ii) it showed an 8.5- and 3.5-fold longer half-life than GLP-1 in rat intestine fluid and homogenate, respectively; and interestingly (iii) it had a well-preserved insulinotropic activity (94.5% vs. GLP-1) in the rat islets. Finally, Lys26,34-biotin-GLP-1 showed a 9-fold higher oral hypoglycemic efficacy (25.3%) than native GLP-1 (2.7%) (P<0.005) after direct peroral administration into type 2 diabetic db/db mice. This study highlights the oral hypoglycemic potential of site-specific Lys26,34-biotinylated GLP-1, and this orally available analogue would find a role in the treatment of type 2 diabetes.

Preparation, characterization, and application of biotinylated and biotin-PEGylated glucagon-like peptide-1 analogues for enhanced oral delivery.

Glucagon-like peptide-1 (GLP-1) (7-36) is a type of incretin hormone with unique antidiabetic potential. The introduction of orally active GLP-1 offers substantial benefits in the treatment of type 2 diabetes over conventional injection-based therapies. Because the intestinal absorption of GLP-1 is restricted by its natural characteristics, we developed a series of GLP-1 analogues via the site-specific conjugation of biotin-NHS and/or of biotin-poly(ethylene glycol)-NHS at Lys 26 and Lys 34 of GLP-1 (7-36), respectively, in order to improve oral delivery. The resultant GLP-1 analogues, Lys 26,34-DiBiotin-GLP-1 (DB-GLP-1) and Lys 26-Biotin-Lys 34-(Biotin-PEG)-GLP-1 (DBP-GLP-1), were prepared and studied in terms of their chemical, structural, and biological properties. DBP-GLP-1 demonstrated superior proteolytic stability against trypsin, intestinal fluid, and the major GLP-1 inactivation enzyme (dipeptidyl peptidase-IV (DPP-IV)) to native GLP-1 or DB-GLP-1 ( p < 0.001). The in vitro insulinotropic effects of DB-GLP-1 and DBP-GLP-1 showed potent biological activity in a dose-dependent manner, which resembled that of native GLP-1 in terms of stimulating insulin secretion in isolated rat islets of Langerhans. Intraperitoneal glucose tolerance tests (IPGTT) after the oral administration of GLP-1 analogues in diabetic db/db mice demonstrated that DB-GLP-1 and DBP-GLP-1 significantly reduced the AUC 0-180 min of glucose for 3 h by 14.9% and 24.5% compared to that of native GLP-1, respectively ( p < 0.01). In particular, DBP-GLP-1 concentration in plasma rapidly increased 30 min after oral administration in rats, presumably due to improved intestinal absorption. These findings revealed that site-specific biotinylated and biotin-PEGylated GLP-1 is absorbed by intestine and that it has biological activity in vivo. Therefore, we propose that this orally active bioconjugated GLP-1 might be considered as a potential oral antidiabetic agent for type 2 diabetes mellitus.