Chemoproteomics-Enabled Identification of 4-Oxo-β-Lactams as Inhibitors of Dipeptidyl Peptidases 8 and 9

Dipeptidyl peptidases 8 and 9 (DPP8/9) have gathered interest as drug targets due to their important roles in biological processes like immunity and tumorigenesis. Elucidation of their distinct individual functions remains an ongoing task and could benefit from the availability of novel, chemically diverse and selective chemical tools. Here, we report the activity-based protein profiling (ABPP)-mediated discovery of 4-oxo-β-lactams as potent, non-substrate-like nanomolar DPP8/9 inhibitors. X-ray crystallographic structures revealed different ligand binding modes for DPP8 and DPP9, including an unprecedented targeting of an extended S2' (eS2') subsite in DPP8. Biological assays confirmed inhibition at both target and cellular levels. Altogether, our integrated chemical proteomics and structure-guided small molecule design approach led to novel DPP8/9 inhibitors with alternative molecular inhibition mechanisms, delivering the highest selectivity index reported to date.

Palladium-catalyzed incorporation of atmospheric CO2: efficient synthesis of functionalized oxazolidinones

Methods to incorporate atmospheric CO₂ into organic molecules are on demand. Here we present two Pd-catalyzed multicomponent reactions that provide functionalized oxazolidinones from propargylamines, aryl halides and CO₂ as starting materials. These transformations, devoid of high CO₂ pressures, represent a streamlined stereocontrolled synthesis of previously inaccessible versions of these useful heterocycles in an atom-economic manner, as up to four new single bonds are formed in a single synthetic operation.

The effect of exercise on carbohydrate preference in female rats

Exercise has a myriad of health benefits, including positive effects against heart disease, diabetes, and dementia. Cognitive performance improves following chronic exercise, both in animal models and humans. Studies have examined the effect of exercise on feeding, demonstrating a preference towards increased food consumption. Further, sex differences exist such that females tend to prefer carbohydrates over other macronutrients following exercise. However, no clear effect of exercise on macronutrient or carbohydrate selection has been described in animal or human studies. This research project sought to determine the effect of voluntary exercise on carbohydrate selection in female rats. Preference for a complex (starch) versus a simple (dextrose) carbohydrate was assessed using a discriminative preference to context paradigm in non-exercising and voluntarily exercising female rats. In addition, fasting blood glucose and performance in the Morris water task was examined in order to verify the effects of exercise on performance in this task. Female rats given access to running wheels preferred a context previously associated with starch, whereas females with no running wheel access preferred a context previously associated with dextrose. No changes in blood glucose were observed. However, cognitive differences in the Morris water task were observed such that voluntary exercise allowed rats to find a new location of a hidden platform following 4 days of training to an old platform location. These results suggest that voluntary exercise may decrease preservative behaviors in a spatial navigation task through the facilitation of plasticity mechanisms. This study is the first of its kind to demonstrate the influence of exercise on taste preference for complex and simple carbohydrates with this context conditioning paradigm.

Breathing pattern retraining and exercise in persons with chronic obstructive pulmonary disease

Breathing pattern retaining, in the form of pursed-lip breathing, has been used as one method in pulmonary rehabilitation to help alleviate the symptoms of dyspnea endured by people who suffer from airflow obstruction secondary to chronic obstructive pulmonary disease (COPD). Other techniques such as biofeedback also have been successfully used. This article describes the altered breathing patterns used by patients with COPD at rest and during physical activity. The literature is reviewed regarding techniques of breathing pattern retraining that have been developed to improve the capacity of persons with COPD to perform activities of daily living, a primarily rehabilitative outcome.

Adequacy of power wheelchair control interfaces for persons with severe disabilities: a clinical survey

The extreme difficulty with which persons with severe disabilities have been taught to maneuver a power wheelchair has been described in case studies, and anecdotal evidence suggests the existence of a patient population for whom mobility is severely limited if not impossible given currently available power wheelchair control interfaces. Since our review of the literature provided little evidence either in support or refutation of the adequacy of existing power wheelchair control interfaces, we surveyed 200 practicing clinicians, asking them to provide information about their patients and to give their impressions of the potential usefulness of a new power wheelchair navigation technology. Significant survey results were: Clinicians indicated that 9 to 10 percent of patients who receive power wheelchair training find it extremely difficult or impossible to use the wheelchair for activities of daily living. When asked specifically about steering and maneuvering tasks, the percentage of patients reported to find these difficult or impossible jumped to 40. Eighty-five percent of responding clinicians reported seeing some number of patients each year who cannot use a power wheelchair because they lack the requisite motor skills, strength, or visual acuity. Of these clinicians, 32 percent (27 percent of all respondents) reported seeing at least as many patients who cannot use a power wheelchair as who can. Nearly half of patients unable to control a power wheelchair by conventional methods would benefit from an automated navigation system, according to the clinicians who treat them. We believe these results indicate a need, not for more innovation in steering interfaces, but for entirely new technologies for supervised autonomous navigation.

Follow-up assessment of standing mobility device users

The use of standing devices by spinal cord-injured subjects was investigated through a national survey of a sample of individuals who returned their manufacturer's warranty card to two companies. We obtained a 32% response rate (99/310). The majority of respondents were male (87%) with a median age between 41 and 50 years. Seventy-seven percent were paraplegic and 21% were quadriplegic. Forty percent had between 1 and 5 years experience with their device, and 84% of those responding were currently using their standing device. Forty-one percent used their standing device one to six times a week; two-thirds stood between 30 minutes and 1 hour for each use. Less than 10% of subjects experienced any side effects, such as nausea or headaches, from standing. Twenty-one percent of subjects reported being able to empty their bladder more completely. There was also a favorable response by some individuals on the effects of the standing devices on bowel regularity, reduction of urinary tract infections, leg spasticity, and number of bed sores. Finally, 79% of subjects highly recommended use of standing devices to other people with spinal cord injury. The positive responses of individuals using standing devices is a strong recommendation for the assistive technology community to make these devices more available to individuals with spinal cord injury.

Initial clinical evaluation of a wheelchair ergometer for diagnostic exercise testing: a technical note

The purpose of this initial study was to evaluate a new wheelchair ergometer (WCE) and exercise test protocol for the detection of coronary artery disease in men with lower limb disabilities. Forty-nine patients (63 +/- 9 yr) completed WCE tests without complications. Peak heart rate was 84 +/- 15% (mean +/- SD) of age-predicted maximum and peak double product was 223 +/- 62 x 10(2). The specified target heart rate (> or = 80% age-predicted maximal) or a positive result was achieved in 76% of tests. Fourteen tests were rated positive, 21 as negative and 14 as nondiagnostic for exercise-induced ischemia. In 18 patients who underwent coronary angiography, the predictive value was 100% (10/10) for a positive, and 50% (2/4) for a negative WCE test result. These results suggest that WCE is a viable initial diagnostic option for some persons who cannot adequately perform treadmill or cycle ergometry exercise.

Biomechanical and reflex responses to joint perturbations during electrical stimulation of muscle: instrumentation and measurement techniques

A test device is developed to measure ankle joint compliance and muscle activity when the ankle is subjected to perturbations in angular position (or torque) from bias positions achieved volitionally or via electrical stimulation. The ankle measurement system uses a pivoting footplate and is operable with the subject sitting or supine. A companion platform for the knee is developed that uses a rotary arm and attached leg brace and is operable with the subject's leg in the horizontal or vertical plane. The knee fixture's pivoting arm can slide to account for the cam-like movement of the knee during rotation. The devices use similar hardware and share common instrumentation and control. Precise torque or position perturbations are delivered by a computer-controlled torque motor to the ankle or knee. Angular displacement, torque, acceleration, knee fixture moment arm and electromyographic data are collected on analogue tape and simultaneously digitised and stored. A special stimulator/recording amplifier permits the recording of electromyographic signals from the stimulated muscle. Experimental data indicate that the ankle and knee devices, operated horizontally, are purely inertial systems. Sample ankle and knee joint responses to perturbations are presented.