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Sakr MA, Yacoub MH. Structural variations of pectinate muscles across sheep and rabbit atria. Glob Cardiol Sci Pract 2024; 2024:e202415. [PMID: 38746069 PMCID: PMC11090173 DOI: 10.21542/gcsp.2024.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/14/2024] [Indexed: 05/16/2024] Open
Abstract
The venous inflow of each atrial cortex is asymmetric and coupled to geometry and outflow to produce optimal vortices and flow patterns in each chamber. In the right atrium, fiber orientation is dependent on the crista terminals and pectinate muscles, which produce a circumferential squeezing effect to propel blood into the desired direction. The left atrial fiber orientation is a more complex fiber that suits its its geometry and function. This study demonstrates the structural differences between the right and left atria. BACKGROUND The right and left atria play important roles in overall cardiac performance, both at rest and during exercise. Atrial dysfunction due to congenital or acquired heart diseases can result in significant disability or death. The prevalence of such conditions has been rising due to the increasing age of the population as well as the progressively larger number of patients with Grown-up congenital heart disease (GUCH). METHODS Left and right atria were collected from rabbits and juvenile sheep, and pattern recognition and image analysis were used to illustrate the microstructure and orientation of the pectinate muscles. RESULTS The aim of this study is to observe the differences in the structure of the pectinate muscles in both rabbits and sheep. Through image analysis and pattern recognition, we were able to identify the orientation of the patterns that can help produce off-the-shelf patches that are capable of mimicking and/or reproducing most of the functions of normal atrial tissue. CONCLUSION The microstructure of the pectinate muscles is unique and provides remarkable functionality to the atria.
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Affiliation(s)
- Mahmoud A. Sakr
- Biomedical Engineering and Innovation Laboratory, Department of Research, Aswan Heart Centre, Magdi Yacoub Heart Foundation, Aswan, Egypt
| | - Magdi H. Yacoub
- Biomedical Engineering and Innovation Laboratory, Department of Research, Aswan Heart Centre, Magdi Yacoub Heart Foundation, Aswan, Egypt
- Harefield Heart Science Centre, Magdi Yacoub Institute, Harefield, United Kingdom
- Department of Surgery, Aswan Heart Centre, Magdi Yacoub Heart Foundation, Aswan, Egypt
- National Heart and Lung Institute, Imperial College, London, United Kingdom
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Sakr MA, Sakthivel K, Hossain T, Shin SR, Siddiqua S, Kim J, Kim K. Recent trends in gelatin methacryloyl nanocomposite hydrogels for tissue engineering. J Biomed Mater Res A 2021; 110:708-724. [PMID: 34558808 DOI: 10.1002/jbm.a.37310] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 07/21/2021] [Accepted: 09/01/2021] [Indexed: 12/17/2022]
Abstract
Gelatin methacryloyl (GelMA), a photocrosslinkable gelatin-based hydrogel, has been immensely used for diverse applications in tissue engineering and drug delivery. Apart from its excellent functionality and versatile mechanical properties, it is also suitable for a wide range of fabrication methodologies to generate tissue constructs of desired shapes and sizes. Despite its exceptional characteristics, it is predominantly limited by its weak mechanical strength, as some tissue types naturally possess high mechanical stiffness. The use of high GelMA concentrations yields high mechanical strength, but not without the compromise in its porosity, degradability, and three-dimensional (3D) cell attachment. Recently, GelMA has been blended with various natural and synthetic biomaterials to reinforce its physical properties to match with the tissue to be engineered. Among these, nanomaterials have been extensively used to form a composite with GelMA, as they increase its biological and physicochemical properties without affecting the unique characteristics of GelMA and also introduce electrical and magnetic properties. This review article presents the recent advances in the formation of hybrid GelMA nanocomposites using a variety of nanomaterials (carbon, metal, polymer, and mineral-based). We give an overview of each nanomaterial's characteristics followed by a discussion of the enhancement in GelMA's physical properties after its incorporation. Finally, we also highlight the use of each GelMA nanocomposite for different applications, such as cardiac, bone, and neural regeneration.
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Affiliation(s)
- Mahmoud A Sakr
- School of Engineering, The University of British Columbia, Kelowna, British Columbia, Canada
| | - Kabilan Sakthivel
- School of Engineering, The University of British Columbia, Kelowna, British Columbia, Canada
| | - Towsif Hossain
- School of Engineering, The University of British Columbia, Kelowna, British Columbia, Canada
| | - Su Ryon Shin
- Division of Engineering in Medicine, Department of Medicine, Harvard Medical School, Brigham Women's Hospital, Cambridge, Massachusetts, USA
| | - Sumi Siddiqua
- School of Engineering, The University of British Columbia, Kelowna, British Columbia, Canada
| | - Jaehwan Kim
- Advanced Geo-materials Research Department, Korea Institute of Geosciece and Mineral Resources, Pohang-si, South Korea
| | - Keekyoung Kim
- Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada.,Biomedical Engineering Graduate Program, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
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Sakr MA, Elgammal K, Delin A, Serry M. Performance-Enhanced Non-Enzymatic Glucose Sensor Based on Graphene-Heterostructure. Sensors (Basel) 2019; 20:E145. [PMID: 31878328 PMCID: PMC6982948 DOI: 10.3390/s20010145] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 12/14/2022]
Abstract
Non-enzymatic glucose sensing is a crucial field of study because of the current market demand. This study proposes a novel design of glucose sensor with enhanced selectivity and sensitivity by using graphene Schottky diodes, which is composed of graphene (G)/platinum oxide (PtO)/n-silicon (Si) heterostructure. The sensor was tested with different glucose concentrations and interfering solutions to investigate its sensitivity and selectivity. Different structures of the device were studied by adjusting the platinum oxide film thickness to investigate its catalytic activity. It was found that the film thickness plays a significant role in the efficiency of glucose oxidation and hence in overall device sensitivity. 0.8-2 μA output current was obtained in the case of 4-10 mM with a sensitivity of 0.2 A/mM.cm2. Besides, results have shown that 0.8 A and 15 A were obtained by testing 4 mM glucose on two different PtO thicknesses, 30 nm and 50 nm, respectively. The sensitivity of the device was enhanced by 150% (i.e., up to 30 A/mM.cm2) by increasing the PtO layer thickness. This was attributed to both the increase of the number of active sites for glucose oxidation as well as the increase in the graphene layer thickness, which leads to enhanced charge carriers concentration and mobility. Moreover, theoretical investigations were conducted using the density function theory (DFT) to understand the detection method and the origins of selectivity better. The working principle of the sensors puts it in a competitive position with other non-enzymatic glucose sensors. DFT calculations provided a qualitative explanation of the charge distribution across the graphene sheet within a system of a platinum substrate with D-glucose molecules above. The proposed G/PtO/n-Si heterostructure has proven to satisfy these factors, which opens the door for further developments of more reliable non-enzymatic glucometers for continuous glucose monitoring systems.
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Affiliation(s)
- Mahmoud A. Sakr
- Graduate Program in Nanotechnology, The American University in Cairo (AUC), New Cairo 11835, Egypt;
- Department of Mechanical Engineering, The American University in Cairo (AUC), New Cairo 11835, Egypt
| | - Karim Elgammal
- Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Electrum 229, SE-16440 Kista, Sweden; (K.E.); (A.D.)
- Swedish e-Science Research Center (SeRC), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Anna Delin
- Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Electrum 229, SE-16440 Kista, Sweden; (K.E.); (A.D.)
- Swedish e-Science Research Center (SeRC), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
- Department of Physics and Astronomy, Materials Theory Division, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
| | - Mohamed Serry
- Department of Mechanical Engineering, The American University in Cairo (AUC), New Cairo 11835, Egypt
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Magdy N, Sakr MA, El-Bahnasy K. A generic trajectory similarity operator in moving object databases. Egyptian Informatics Journal 2017. [DOI: 10.1016/j.eij.2016.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ghoniem GM, Aertker MW, Sakr MA, Shaaban AM, Shoukry MS. A telemetric multichannel computer-based system for monitoring urodynamic parameters in awake rhesus monkeys. J Urol 1997; 157:704-9. [PMID: 8996402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
For comprehensive telemetric monitoring of bladder function in monkeys, transducers were implanted in the bladder wall and abdominal cavity. The EMG lead was buried in the external sphincter. All wires terminated in a subcutaneous transmitter. Conventional urodynamics were performed for comparison. Excellent reproducibility with conventional urodynamics was found. Implantation caused detrusor instability, which subsided in 6 to 8 weeks. Real-time computer-based multichannel telemetric studies of voiding are feasible and reliable. Telemetric studies monitor for long periods without stress or anesthesia and provide an excellent model for lower urinary tract studies.
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Affiliation(s)
- G M Ghoniem
- Department of Urology, Tulane Regional Primate Research Center, New Orleans, Louisiana, USA
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Ghoniem GM, Shoukry MS, Fayed AA, Hellstrom WJ, Sakr MA. Human vasal changes after vasectomy: in vitro studies. Eur Urol 1997; 31:231-6. [PMID: 9076472 DOI: 10.1159/000474456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
UNLABELLED Failure to impregnate, after successful vasovasostomy, has been attributed to immunologic, testicular, and epididymal factors. OBJECTIVES To study the effect of vasectomy on human vas innervation and vesicoelastic properties. METHODS Vas rings were obtained from 8 healthy males during vasectomy as controls and compared to those of 3 vasovasostomy patients. The active and passive properties were determined and the cumulative blocking effects of phenoxybenzamine, propranolol, atropine and tetrodotoxin were studied. RESULTS There was significantly higher rigidity in the vasovasostomy group as compared to the control group but there were similar active forces between the two groups up to 100-120% of stretch. In the control group, phenoxybenzamine blocked 33.3%, propranolol blocked 15.8%, and atropine blocked 36.5% but tetrodotoxin had no further effect. In the vasovasostomy group, phenoxybenzamine blocked 33.3% (similar to control), propranolol blocked 2%, atropine blocked 11.7% and tetrodotoxin blocked 37.1%. CONCLUSIONS In vasovasostomy group there was increased rigidity without reduction of the active force. There were also decreased cholinergic and possible existence of nonadrenergic noncholinergic neurotransmitters.
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Affiliation(s)
- G M Ghoniem
- Department of Urology, Alexandria University Medical School, Alexandria, Egypt
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Abstract
A comparison between three different techniques for monitoring urodynamic parameters in non-human primates was conducted in six adult female rhesus monkeys. This study was divided into two phases. In phase I, the animals were studied by conventional and continuous methods. During the study, uroflow and micturition pattern were obtained while the animals housed in a specially designed metabolic cage. Pressure transducers and EMG electrodes were surgically implanted. Then the animals were trained for 6 weeks to sit in a specially designed chair. Upon completion of the training period, continuous monitoring of the urodynamic parameters could be carried out for periods up to 14 hours. In phase II, the animals were studied with the conventional and telemetric methods. The same type of pressure transducers and EMG electrodes were implanted but they terminated in a radio transmitter powered by a long-life battery and controlled by a radio-operated switch. Conventional studies under ketamine sedation significantly increased bladder capacity, as well as the pressure at capacity (P < 0.05). Continuous monitoring was feasible, physiological, and more sensitive than the conventional techniques. Telemetric studies are superior to continuous monitoring, since the animal is not tethered to wires and provide data over a longer period of time. It is concluded that telemetric monitoring provides significantly different parameters, which could help in diagnosis and management of different voiding dysfunctions. In normal non-human primates, lower bladder capacity, higher maximum voiding pressure, higher bladder compliance, and higher incidence of detrusor instability without urethral relaxation were found. Telemetric urodynamic data on different pathological processes are currently unavailable and further work is needed in this area.
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Affiliation(s)
- G M Ghoniem
- Department of Urology, Tulane Primate Research Center, New Orleans, Louisiana, USA
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