Background This investigation examined the mechanisms by which coronary perivascular adipose tissue (PVAT)-derived factors influence vasomotor tone and the PVAT proteome in lean vs. obese swine. Methods and Results Coronary arteries from Ossabaw swine were isolated for isometric tension studies. We found that coronary (P=0.03) and mesenteric (P=0.04), but not subcutaneous adipose tissue, augmented coronary contractions to KCl (20 mM). Inhibition of CaV1.2 channels with nifedipine (0.1 μM) or diltiazem (10 μM) abolished this effect. Coronary PVAT increased baseline tension and potentiated constriction of isolated arteries to PGF2α in proportion to the amount of PVAT present (0.1–1.0 g). These effects were elevated in tissues obtained from obese swine and were observed in intact and endothelium denuded arteries. Coronary PVAT also diminished H2O2-mediated vasodilation in lean, and to a lesser extent in obese arteries. These effects were associated with alterations in the obese coronary PVAT proteome (detected 186 alterations) and elevated voltage-dependent increases in intracellular [Ca2+] in obese smooth muscle cells. Further studies revealed that a Rho-kinase inhibitor fasudil (1 μM) significantly blunted artery contractions to KCl and PVAT in lean, but not obese swine. Calpastatin (10 μM) also augmented contractions to levels similar to that observed in the presence of PVAT. Conclusions Vascular effects of PVAT vary according to anatomic location and are influenced by an obese phenotype. Augmented contractile effects of obese coronary PVAT are related to alterations in the PVAT proteome (e.g. calpastatin), Rho-dependent signaling, and the functional contribution of K+ and CaV1.2 channels to smooth muscle tone.

Glucagon-Like Peptide 1 (GLP-1) has insulin-like effects on myocardial glucose uptake which may contribute to its beneficial effects in the setting of myocardial ischemia. Whether these effects are different in the setting of obesity or type 2 diabetes (T2DM) requires investigation. We examined the cardiometabolic actions of GLP-1 (7–36) in lean and obese/T2DM humans, and in lean and obese Ossabaw swine. GLP-1 significantly augmented myocardial glucose uptake under resting conditions in lean humans, but this effect was impaired in T2DM. This observation was confirmed and extended in swine, where GLP-1 effects to augment myocardial glucose uptake during exercise were seen in lean but not in obese swine. GLP-1 did not increase myocardial oxygen consumption or blood flow in humans or in swine. Impaired myocardial responsiveness to GLP-1 in obesity was not associated with any apparent alterations in myocardial or coronary GLP1-R expression. No evidence for GLP-1 mediated activation of cAMP/PKA or AMPK signaling in lean or obese hearts was observed. GLP-1 treatment augmented p38-MAPK activity in lean, but not obese cardiac tissue. Taken together, these data provide novel evidence indicating that the cardiometabolic effects of GLP-1 are attenuated in obesity and T2DM, via mechanisms that may involve impaired p38-MAPK signaling.

Introduction Unlike endoskeletal connectors and prosthetic feet, prosthetic sockets are not subjected to structural strength testing using internationally recognized test standards, such as International Organization for Standardization (ISO) 10328. Definitive prosthetic sockets fabricated in the traditional manner have been shown to be inconsistent in the ability to withstand the loads applied by these standards. Persistent concerns regarding the strength and durability of 3D-printed prosthetic sockets are a barrier to clinical adoption of 3D-printing technologies in prosthetic socket fabrication. To develop a robust prosthetic socket design based on 3D-printing technology, an iterative development process was used with integral validation testing using the ISO 10328 loading conditions performed independently by two testing centers. Materials and Methods Twenty-four 3D-printed transtibial prosthetic sockets were tested using ISO 10328 loading conditions designed to represent the greatest atypical elevated loads a 125-kg user would be expected to place on their prosthesis without failure (ultimate strength test at the P6 load level). Several design iterations and variations were tested. One socket of a design that withstood the ultimate strength loading was reprinted and subjected to cyclic testing, up to 3 million cycles. All tests were conducted under the forefoot loading condition (Condition II of the ISO 10328 standard), which generates greater moments at the distal end of the socket than the heel loading condition. Results Early socket designs were unable to withstand the ISO 10328 ultimate strength test to the P6 load level. Successive design improvements increased the strength until a robust final design was achieved. Variations of that final design for different suspension types and a different limb model demonstrated consistent performance. The final design was significantly stronger than the initial design (P = 1.35 × 10−7). The socket that was tested for durability completed the 3 million loading cycles at the P6 load level without damage and withstood the subsequent static proof loads. Conclusions An iterative design process with integral structural testing can result in strong, durable prosthetic sockets made using 3D-printing technology that may be robust to variations in limb size/shape and suspension type.

Introduction Prosthetic sockets must withstand instances of maximum loading without failure. The goal of the present study is to evaluate the strength at failure and the failure mechanism for 3D-printed transtibial sockets, thermoplastic transtibial check sockets, and carbon-fiber definitive laminated transtibial sockets. Materials and Methods Three clinically available materials (carbon fiber, PETG thermoplastic, and 3D print polylactic acid [PLA]) were used to produce identically shaped sockets. In final assembly, the carbon-fiber sockets were designed for use both with and without a pin-lock system. Thermoplastic sockets and 3D-printed sockets were designed for use without a pin-lock system. These socket systems were then tested following International Standards Organization (ISO) 10328. Ultimate strength (US) at failure, maximum deflection at failure, and failure mechanism were determined. Results Both designs of carbon-fiber sockets had higher US values at failure than thermoplastic sockets and 3D-printed PLA sockets. Thermoplastic sockets had a slightly higher average US than 3D-printed sockets, but 3D-printed sockets exhibited a greater strength-to-weight ratio. Four distinct socket failure mechanisms were determined. Conclusions Failure mechanisms and US values differed for all socket types. Carbon-fiber sockets exhibited the highest US, but 3D-printed PLA sockets showed comparable strength to current thermoplastic sockets. Although the ISO 10328 testing standard was sufficient to complete these evaluations, the method lacked some socket-specific measures and loading conditions that could have improved comparisons between socket types.

Coronary perivascular adipose tissue (PVAT) is a naturally occurring adipose tissue depot that normally surrounds the major coronary arteries on the surface of the heart. While originally thought to promote vascular health and integrity, there is a growing body of evidence to support that coronary PVAT displays a distinct phenotype relative to other adipose depots and is capable of producing local factors with the potential to augment coronary vascular tone, inflammation, and the initiation and progression of coronary artery disease. The purpose of the present review is outline previous findings regarding the cardiovascular effects of coronary PVAT and the potential mechanisms by which adipose-derived factors may influence coronary vascular function and the progression of atherogenesis.

Objective The effects of coronary perivascular adipose tissue (PVAT) on vasomotor tone are influenced by an obese phenotype and are distinct from other adipose tissue depots. The purpose of this investigation was to examine the effects of lean and obese coronary PVAT on end-effector mechanisms of coronary vasodilation and to identify potential factors involved. Approach and Results Hematoxylin and eosin staining revealed similarities in coronary perivascular adipocyte size between lean and obese Ossabaw swine. Isometric tension studies of isolated coronary arteries from Ossabaw swine revealed that factors derived from lean and obese coronary PVAT attenuated vasodilation to adenosine. Lean coronary PVAT inhibited KCa and KV7, but not KATP channel mediated dilation in lean arteries. In the absence of PVAT, vasodilation to KCa and KV7 channel activation was impaired in obese arteries relative to lean arteries. Obese PVAT had no effect on KCa or KV7 channel mediated dilation in obese arteries. In contrast, obese PVAT inhibited KATP channel mediated dilation in both lean and obese arteries. The differential effects of obese versus lean PVAT were not associated with changes in either coronary KV7 or KATP channel expression. Incubation with calpastatin attenuated coronary vasodilation to adenosine in lean but not obese arteries. Conclusions These findings indicate that lean and obese coronary PVAT attenuates vasodilation via inhibitory effects on vascular smooth muscle K+ channels and that alterations in specific factors such as calpastatin are capable of contributing to the initiation and/or progression of smooth muscle dysfunction in obesity.

Background and Aims Coronary artery disease (CAD) is progressive, classified by stages of severity. Alterations in Ca2+ regulation within coronary smooth muscle (CSM) cells in metabolic syndrome (MetS) have been observed, but there is a lack of data in relatively early (mild) and late (severe) stages of CAD. The current study examined alterations in CSM Ca2+ regulation at several time points during CAD progression. Methods MetS was induced by feeding an excess calorie atherogenic diet for 6, 9, or 12 months and compared to age-matched lean controls. CAD was measured with intravascular ultrasound (IVUS). Intracellular Ca2+ was assessed with fura-2. Results IVUS revealed that the extent of atherosclerotic CAD correlated with the duration on atherogenic diet. Fura-2 imaging of intracellular Ca2+ in CSM cells revealed heightened Ca2+ signaling at 9 months on diet, compared to 6 and 12 months, and to age-matched lean controls. Isolated coronary artery rings from swine fed for 9 months followed the same pattern, developing greater tension to depolarization, compared to 6 and 12 months (6 months= 1.8±0.6 g, 9 months= 5.0±1.0 g, 12 months= 0.7±0.1 g). CSM in severe atherosclerotic plaques showed dampened Ca2+ regulation and decreased proliferation compared to CSM from the wall. Conclusions These CSM Ca2+ regulation data from several time points in CAD progression and severity help to resolve the controversy regarding up- vs. down-regulation of CSM Ca2+ regulation in previous reports. These data are consistent with the hypothesis that alterations in sarcoplasmic reticulum Ca2+ contribute to progression of atherosclerotic CAD in MetS.

Previous investigations indicate that diminished functional expression of voltage-dependent K+ (KV) channels impairs control of coronary blood flow in obesity/metabolic syndrome. The goal of this investigation was to test the hypothesis that KV channels are electromechanically coupled to CaV1.2 channels and that coronary microvascular dysfunction in obesity is related to subsequent increases in CaV1.2 channel activity. Initial studies revealed that inhibition of KV channels with 4-aminopyridine (4AP, 0.3 mM) increased intracellular [Ca2+], contracted isolated coronary arterioles and decreased coronary reactive hyperemia. These effects were reversed by blockade of CaV1.2 channels. Further studies in chronically instrumented Ossabaw swine showed that inhibition of CaV1.2 channels with nifedipine (10 μg/kg, iv) had no effect on coronary blood flow at rest or during exercise in lean swine. However, inhibition of CaV1.2 channels significantly increased coronary blood flow, conductance, and the balance between coronary flow and metabolism in obese swine (P < 0.05). These changes were associated with a ~50 % increase in inward CaV1.2 current and elevations in expression of the pore-forming subunit (α1c) of CaV1.2 channels in coronary smooth muscle cells from obese swine. Taken together, these findings indicate that electromechanical coupling between KV and CaV1.2 channels is involved in the regulation of coronary vasomotor tone and that increases in CaV1.2 channel activity contribute to coronary microvascular dysfunction in the setting of obesity.