A comparison of four endosseous dental implants: single-crystal sapphire; pyrolytic carbon; an alloy of titanium, aluminum, and vanadium; and a biologically active ceramic composite composed of calcium phosphate and magnesium aluminate spinel

The objective of this research was to compare the response of bony and soft tissues to three dental implants that are currently used experimentally in human clinical dentistry with that of a biologically active ceramic composite developed at Iowa State University. The three commercial dental implant materials were single-crystal sapphire (Bioceram°ler), pyrolytic carbon (Pyrolite°ler), and a titanium alloy (Core-Vent[superscript] TM). The fourth implant material, that was developed at Iowa State University, was a biologically active ceramic composite consisting of tricalcium phosphate and magnesium aluminate spinel;Ten of each of these implants were inserted into the mandibles of dogs and evaluated clinically and histologically for 18 months. The clinical performance was evaluated using rating scales to assess the gingival health, plaque accumulation, gingival sulcus depth, implant mobility, and radiolucency. The histological response of the bony and soft tissue was evaluated using optical microscopic techniques;A gradual increase in tissue reaction with time was observed adjacent to the sapphire implant. Direct bony contact to this implant increased to a moderate amount by 12 months (59%) after which it fell to a low amount (24%). The pyrolytic carbon implant proved to be unsuitable because it was not retained. The combined influences of initial mobility and inflammation caused 90% of these implants to be lost in six months. The titanium alloy implant was associated with a moderate amount of inflammation early in the study. Bony contact increased to a relatively high amount at 12 months (83%). The osteoceramic implant was generally not associated with inflammation. A high amount of bony contact, approximately 80%, developed by three months; nine months earlier than the maximum bony contact observed for the other three implants. This high amount of bony contact was maintained throughout the remainder of the study. Based on this study, the tissue response of the osteoceramic implant was found to be superior to that of the three commercial implants studied

Three-Dimensional Morphology and Platelet Adhesion on Pyrolytic Carbon Heart Valve Materials

Low-temperature isotropic pyrolytic carbon (LTIC) is the preferred material for mechanical heart valve prosthetics due to its durability and good thromboresistance, although thromboembolic complications remain a significant clinical problem. LTlC morphology has been previously studied using scanning (SEM) and transmission electron microscopy (TEM), and scanning tunneling microscopy (STM). However, these microscopies have limitations with imaging rough surfaces. In this study, LTIC valve leaflets from CarboMedics, Inc. and St. Jude Medical, Inc. were prepared and polished exactly as used in clinical prosthetics, and examined at magnifications up to macromolecular resolution using stereo-pair low-voltage SEM (LV -SEM). LV -SEM reveals that LTIC leaflets have a complex topography of 10 nm to 1 ~m features, with height differences of 100- 500 nm occurring over lateral distances of 10-50 nm. Compared to previous reports using conventional SEM and STM, LV -SEM shows a much rougher surface. In contrast to studies that have reported minimal platelet interaction with LTIC, very ex tensive adhesion and spreading were observed. That our observations are different from previous reports may be ex plained by the physics of SEM image formation at low and conventional (higher) accelerating voltages. Due to the low atomic density of LTIC and platelets, obscuration of small features due to specimen coatings, and since platelets closely follow LTIC\u27s three-dimensional contours, the surface sensitivity of conventional SEM is unable to provide sufficient contrast to image either the material topography or thin adherent platelets. These results suggest that the ex tent of platelet interaction on L TIC vascular prosthetics may have been previously underestimated

Description and evaluation of a ventriculo-coronary artery bypass device that provides bi-directional coronary flow

Objective: The objective of this study was to assess acute patency of a new myocardial revascularization device that connects the left ventricular cavity to a coronary artery (termed ventriculo-coronary artery bypass, VCAB) thereby providing proximal and distal blood flow from the site of the anastomosis. Methods: A device made of expanded polytetrafluoroethylene and low density polyethylene was implanted from the base of the left ventricle to the mid left anterior descending coronary artery (LAD) in 11 juvenile domestic pigs using a beating heart approach. Flow rates were measured in the distal LAD before and after implant using ultrasonic flow techniques, and patency was assessed at explant at either 2 or 4 weeks post-implantation. Myocardial perfusion using positron emission tomography (PET) was assessed in a separate set of pigs (n=2) revascularized by VCAB 2 weeks post-implant. Results: Net forward flow distal to the implanted device was 73±15% of native LAD flow. PET demonstrated that the target myocardium was perfused at 85% of that seen in the remote, control myocardium. Device patency rate was 80% (4/5) at 2 weeks in one set of pigs and 83% (5/6) at 4 weeks in a second set of pigs. Histologic analysis showed formation of neointima along the extraventricular segment of the device. Conclusions: This study demonstrates the promise of perfusing ischemic myocardium using a VCAB approach with a device that provides blood flow both proximal and distal to the anastomosis. Patency of the transmyocardial device was encouraging at 2 and 4 weeks and warrants further investigatio

Clinical use of a 180-day implantable glucose sensor improves glycated haemoglobin and time in range in patients with type 1 diabetes

Aims: This real-world study evaluated the changes in glycated haemoglobin (HbA1c) and continuous glucose monitoring (CGM) metrics associated with use of the implantable 180-day Eversense CGM System (Eversense) in patients with type 1 diabetes. Materials and methods: This was a prospective, multicentre, observational study among adult participants aged ≥18 years with type 1 diabetes across seven diabetes-care centres in Italy who had Eversense inserted for the first time. HbA1c was measured at baseline and at 180 days. Changes in time in range [TIR (glucose 70–180 mg/dL)], time above range [TAR (glucose >180 mg/dL)], time below range [TBR (glucose <70 mg/dL)] and glycaemic variability were also assessed. Data were also analysed by previous CGM use and by mode of insulin delivery. Results: One-hundred patients were enrolled (mean age 36 ± 12 years, mean baseline HbA1c 7.4 ± 0.92% [57 ± 10 mmol/mol]). Fifty-six per cent of patients were users of the continuous subcutaneous insulin infusion pump and 45% were previous users of CGM. HbA1c significantly decreased in patients after 180 days of sensor wear (−0.43% ± 0.69%, 5 ± 8 mmol/mol, P < 0.0001). As expected, CGM-naïve patients achieved the greatest reduction in HbA1c (−0.74% ± 0.48%, 8 ± 5 mmol/mol). TIR significantly increased and TAR and mean daily sensor glucose significantly decreased while TBR did not change after 180 days of sensor wear. Conclusions: Real-world clinical use of the Eversense CGM System for 180 days was associated with significant improvements in HbA1c and CGM metrics among adults with type 1 diabetes. The study is registered on clinicaltrials.gov (NCT04160156)

A comparison of four endosseous dental implants: single-crystal sapphire; pyrolytic carbon; an alloy of titanium, aluminum, and vanadium; and a biologically active ceramic composite composed of calcium phosphate and magnesium aluminate spinel

The objective of this research was to compare the response of bony and soft tissues to three dental implants that are currently used experimentally in human clinical dentistry with that of a biologically active ceramic composite developed at Iowa State University. The three commercial dental implant materials were single-crystal sapphire (Bioceram°ler), pyrolytic carbon (Pyrolite°ler), and a titanium alloy (Core-Vent[superscript] TM). The fourth implant material, that was developed at Iowa State University, was a biologically active ceramic composite consisting of tricalcium phosphate and magnesium aluminate spinel;Ten of each of these implants were inserted into the mandibles of dogs and evaluated clinically and histologically for 18 months. The clinical performance was evaluated using rating scales to assess the gingival health, plaque accumulation, gingival sulcus depth, implant mobility, and radiolucency. The histological response of the bony and soft tissue was evaluated using optical microscopic techniques;A gradual increase in tissue reaction with time was observed adjacent to the sapphire implant. Direct bony contact to this implant increased to a moderate amount by 12 months (59%) after which it fell to a low amount (24%). The pyrolytic carbon implant proved to be unsuitable because it was not retained. The combined influences of initial mobility and inflammation caused 90% of these implants to be lost in six months. The titanium alloy implant was associated with a moderate amount of inflammation early in the study. Bony contact increased to a relatively high amount at 12 months (83%). The osteoceramic implant was generally not associated with inflammation. A high amount of bony contact, approximately 80%, developed by three months; nine months earlier than the maximum bony contact observed for the other three implants. This high amount of bony contact was maintained throughout the remainder of the study. Based on this study, the tissue response of the osteoceramic implant was found to be superior to that of the three commercial implants studied.</p

Description and evaluation of a ventriculo-coronary artery bypass device that provides bi-directional coronary flow

Objective: The objective of this study was to assess acute patency of a new myocardial revascularization device that connects the left ventricular cavity to a coronary artery (termed ventriculo-coronary artery bypass, VCAB) thereby providing proximal and distal blood flow from the site of the anastomosis. Methods: A device made of expanded polytetrafluoroethylene and low density polyethylene was implanted from the base of the left ventricle to the mid left anterior descending coronary artery (LAD) in 11 juvenile domestic pigs using a beating heart approach. Flow rates were measured in the distal LAD before and after implant using ultrasonic flow techniques, and patency was assessed at explant at either 2 or 4 weeks post-implantation. Myocardial perfusion using positron emission tomography (PET) was assessed in a separate set of pigs (n=2) revascularized by VCAB 2 weeks post-implant. Results: Net forward flow distal to the implanted device was 73±15% of native LAD flow. PET demonstrated that the target myocardium was perfused at 85% of that seen in the remote, control myocardium. Device patency rate was 80% (4/5) at 2 weeks in one set of pigs and 83% (5/6) at 4 weeks in a second set of pigs. Histologic analysis showed formation of neointima along the extraventricular segment of the device. Conclusions: This study demonstrates the promise of perfusing ischemic myocardium using a VCAB approach with a device that provides blood flow both proximal and distal to the anastomosis. Patency of the transmyocardial device was encouraging at 2 and 4 weeks and warrants further investigation