Direct Tissue Contact Research Articles

Quantification of hemolysis rates from pulsed field ablation

Abstract Introduction Pulsed electric fields induce hemolysis of red blood cells as a dose-dependent effect of the electric field. Voltage pulsations induce a transmembrane potential across the cell membrane and either open up or create pores in the red cells. In isotonic conditions, the pores allow passage of potassium and sodium ions but not sucrose or hemoglobin, and leakage of ions leads to an osmotic imbalance which in turn causes a colloidal hemolysis of the red cells. Objective To quantify hemolysis rates during pulsed field ablation (PFA). Methods We created a computational model of PFA to determine the total volume of blood hemolyzed from each pulse during catheter ablation using pulsed field energy. The percentage hemolysis was calculated as a function of electric field intensity utilizing existing published experimental data. A single electrode delivering a single pulse of 100 microseconds duration was modeled at voltages of 1 kV, 1.5 kV, and 2 kV. Results The total volume of hemolyzed blood per pulse increased with increasing applied voltage (Figure). For 2 electrodes in direct tissue contact, the electrode surface exposed to the blood pool generated 19 microliters of hemolyzed red blood cells with a single pulse of a 2 kV field strength. In the case of a single pulse train consisting of 50 pulses, using a catheter configuration with 20 electrodes, an estimate of total volume per pulse train is approximately 9.5 mL of hemolyzed blood. In the case of electrodes not in direct contact with endocardial tissue, and exposed to the blood pool, up to double this volume could be anticipated per pulse train. Hemolyzed volume can be reduced with better tissue contact (reducing exposure to blood), or potentially with the use of irrigation to dilute the local red blood cell concentration. Increased tonicity of the irrigant fluid may also reduce the osmotic pressure increases that result in hemolysis. Conclusions Typical voltages utilized in pulsed field ablation can cause significant hemolysis, which is exacerbated by inadequate tissue contact. A greater number of electrodes and number of pulses delivered increases the risk, whereas better tissue contact, and the use of irrigation, may reduce it.

Hvdroquinone: Assessment of genotoxic potential in the in vivo alkaline comet assay.

Hydroquinone (HQ) exposure is common as it is a natural component of plant-based foods and is used in some fingernail polishes, hair dyes, and skin lighteners. Industrially it is used as an antioxidant, polymerization inhibitor, and reducing agent. The current study was undertaken to determine whether HQ may cause DNA damage in an in vivo comet assay in F344 rats. DNA strand breaks were assessed in the duodenum as a direct tissue contact site, the testes, and the liver and kidneys, which were tumor sites in bioassays. Rats were exposed to HQ by gavage at 0, 105, 210, or 420 mg/kg/day. At all dose levels, mean % tail intensity and tail moment values for all tissues in animals given HQ were similar to the control. There were no statistically significant increases in tail intensity in any tissue following HQ treatment of male and female rat and data for all animals fell within the available historical control ranges for each tissue. There was no evidence of induction of DNA damage in cells isolated from duodenum, kidney or liver of male and female rats or in the testes of male rats following exposure to HQ at a dose levels up to 420 mg/kg/day, which caused acute renal necrosis.

EVIDENCE OF HUMAN INTER-TISSUE BIOELECTROMAGNETIC TRANSFER: THE HUMAN BLOOD TISSUE INTRINSIC BIOELECTROMAGNETIC ENERGY TRANSFERRING ONTO A MINIORGAN

Basically the human hair consists of a follicle a.k.a root penetrating the skin and an outer skin structure commonly called the shaft. The hair follicle has been classified as a miniorgan having its own cells divisions; aging stages and also demonstrated to emit electromagnetic radiation. The intent of this manuscript is to demonstrate via in vitro experiments evidence of human inter-tissue electromagnetic energy transfer through a glass slide, namely from human blood tissue to the previously described miniorgan or follicle. 
 The mechanism behind this new finding was possible due to the introduction in 2015 of a tabletop optical microscopy method designed to display plants and animal tissue electromagnetic energy emissions. Essential to present finding is the described property of anisotropic crystals of full absorption of incoming electromagnetic radiation waves. K3Fe is an anisotropic crystal. For example, a single layer human blood smear was sandwiched (SDW) by a second glass slide. On the top slide of the SDW, a freshly plucked in toto human hair was then covered by drops diluted K3Fe. Control experiments had repeatedly shown orderly semicircular periodic crystals of K3Fe triggered by the electromagnetic waves emitted by the hair follicle. Prior experiments by this author, have hinted at a “bioelectromagnetic cross-talk” between the follicle and blood. This was seen when there was physical contact between the follicle and blood drops on a glass slide. In the present experiments there is no direct tissue contact, the energy is transmitted through a 1 mm glass barrier. The data herein presented introduces Bioelectromagnetic Fields (BEMFs) energy from human blood onto a miniorgan. This energy is shown penetrating a 1 mm glass slide barrier. Further research is warranted to assess the physiological implications of the human blood tissue as a molecular and BEMFs energy source.

Biological Activation of Bioinert Medical High-Performance Oxide Ceramics by Hydrolytically Stable Immobilization of c(RGDyK) and BMP-2.

High-performance oxide ceramics (HPOC), such as alumina, zirconia, and dispersion ceramics thereof are successfully used as articulating components in joint arthroplasty. HPOC exhibit excellent wear resistance, high strength, and cytocompatible behavior; however, they lack sufficient tissue bonding capability. Thus, they are primarily deployed as low-wear-bearing articulating components in arthroplasty without direct tissue contact, although proper cellular stimulation would hold significant advantages. Here, we describe a surface modification approach for HPOC, enabling hydrolytically stable interfacial binding of c(RGDyK) peptides and BMP-2 proteins to significantly improve the adhesion and osteogenic differentiation of human mesenchymal stem cells (hMSCs) without altering the mechanical properties of the underlying ceramic substrates. Analyses of cellular attachment of murine fibroblasts (L929), human alveolar basal epithelial cells (A549), hMSCs on c(RGDyK), and osteogenic differentiation of hMSCs on BMP-2-coated interfaces demonstrate significant improvements of cell adhesion and an enhanced osteogenic differentiation potential in vitro. The presented approach provides a strategy for the development of a novel class of bioactive HPOC with osseointegration potential that could lead to novel therapeutic solutions for biomedical applications. Furthermore, the developed surface modification is designed in a way to be readily translated to other medically employed bioinert materials in the future.

Effect of Bipolar Radiofrequency Energy on Canine Stifle Joint Fluid Temperature.

The aim of this study was to evaluate the effect of bipolar radiofrequency (RF) energy on canine stifle joint fluid temperature. A standard stifle arthroscopy was performed on 15 canine large breed cadaveric stifle joints. A bipolar RF (VAPR III, 2.3-mm side effect electrode; Depuy Mitek, Raynham, Massachusetts, United States) unit was activated in the joint (1) with or without direct tissue contact, (2) with or without additional 18-gauge needle outflow and (3) for 15 and 30 seconds. The joint fluid temperature was monitored with two fibre optic intra-articular sensors. The stifle joint fluid temperature was significantly higher when there was no contact between the tissue and RF probe (mean: 58.6°C with 95% confidence interval [CI]: 53.3-64.0°C) compared with when tissue was contacted (mean: 29.0°C with 95% CI: 26.3-31.6°C). An 18-gauge egress needle had minimal effect on reducing joint fluid temperature. The temperature was higher during the 30-second application of RF energy than the 15-second group. Bipolar RF energy without firm tissue contact rapidly and significantly increased joint fluid temperature beyond the level reported to damage chondrocytes (above 45°C). Caution is required in the use of bipolar RF energy in the canine stifle joint.

Ex vivo laser lipolysis assisted with radially diffusing optical applicator.

Laser-assisted lipolysis has been implemented to reduce body fat in light of thermal interactions with adipose tissue. However, using a flat fiber with high irradiance often needs rapid cannula movements and even undesirable thermal injury due to direct tissue contact. The aim of the current study was to explore the feasibility of a radially diffusing optical applicator to liquefy the adipose tissue for effective laser lipolysis. The proposed diffuser was evaluated with a flat fiber in terms of temperature elevation and tissue liquefaction after laser lipolysis with a 980-nm wavelength. Given the same power (20 W), the diffusing applicator generated a 30% slower temperature increase with a 25% lower maximum temperature (84±3.2°C in 1 min; p<0.001) in the tissue, compared with the flat fiber. Under the equivalent temperature development, the diffuser induced up to fivefold larger area of the adipose liquefaction due to radial light emission than the flat fiber. Ex vivo tissue tests for 5-min irradiation demonstrated that the diffuser (1.24±0.15 g) liquefied 66% more adipose tissue than the flat fiber (0.75±0.05 g). The proposed diffusing applicator can be a feasible therapeutic device for laser lipolysis due to low temperature development and wide coverage of thermal treatment.

New noncontact sensor for detecting pulmonary tumors during video-assisted thoracic surgery

BackgroundSmall pulmonary tumors are difficult to localize during video-assisted thoracic surgery (VATS) because of lack of direct tissue contact. However, in partial lung resection, tumor localization is quite important. The aim of this study was to evaluate the safety and feasibility of a new noncontact sensor for detecting pulmonary nodules during VATS using human and porcine models. MethodsThe sensor, based on the principle of phase differences, comprises an air nozzle for producing air pulse jets and an optical fiber sensor to measure phase differences and visualize object stiffness. For in vivo assessment, we developed a porcine model by inserting plastic balls mimicking tumors into the pig lungs after thoracotomy and then scanned the lungs. The sensor sensitivity was evaluated by measuring the ratio of the depth of the ball from the lung surface to the ball diameter (D/S). For the ex vivo human model, partially resected lung tissue with tumors was obtained from six patients and then scanned. ResultsIn the porcine model, 32 of 37 (86.5%), 70 of 94 (74.5%), and 60 of 100 (60.0%) tumors were detected in the categories D/S ≤ 1, 1 < D/S ≤ 2, and D/S > 2, respectively. Sensor safety was confirmed with an air jet at pressures between 0.05 and 0.15 MPa directed onto the lung surface; all the examined lungs including the pleura remained intact microscopically. In six patients, all nodules were successfully detected. ConclusionsOur noncontact sensor is a safe and feasible tool for detecting small pulmonary tumors during VATS.

Colonic Microbiota and Colorectal Cancer

It has recently been recognized that invasive biofilms composed of complex polymicrobial communities residing within polymeric matrices are present along mucosal surfaces in a number of inflammatory disease states. Normally, a protective mucus layer covers the colonic epithelium, preventing direct tissue contact with microbial cells. Given that mucosal inflammation may contribute to the development of colorectal cancer, might invasive biofilms be …

Determination of relative in vivo osteoconductivity of modified potassium fluorrichterite glass–ceramics compared with 45S5 bioglass

Potassium fluorrichterite (KNaCaMg(5)Si(8)O(22)F(2)) glass-ceramics were modified by either increasing the concentration of calcium (GC5) or by the addition of P(2)O(5) (GP2). Rods (2 × 4 mm) of stoichiometric fluorrichterite (GST), modified compositions (GC5 and GP2) and 45S5 bioglass, which was used as the reference material, were prepared using a conventional lost-wax technique. Osteoconductivity was investigated by implantation into healing defects in the midshaft of rabbit femora. Specimens were harvested at 4 and 12 weeks following implantation and tissue response was investigated using computed microtomography (μCT) and histological analyses. The results showed greatest bone to implant contact in the 45S5 bioglass reference material at 4 and 12 weeks following implantation, however, GST, GC5 and GP2 all showed direct bone tissue contact with evidence of new bone formation and cell proliferation along the implant surface into the medullary space. There was no evidence of bone necrosis or fibrous tissue encapsulation around the test specimens. Of the modified potassium fluorrichterite compositions, GP2 showed the greatest promise as a bone substitute material due to its osteoconductive potential and superior mechanical properties.

In Vitro Atrial Septal Ablation Using High-Intensity Focused Ultrasound

High-intensity focused ultrasound (HIFU) has been applied clinically as a noninvasive therapeutic tool. Atrial septostomy is a palliative treatment for pulmonary artery hypertension. The purpose of this study was to assess the feasibility of atrial septal ablation invitro using HIFU. Fourteen sections of atrial septum from pig hearts were treated. Focused ultrasound energy was applied with an operating frequency of 5.25 MHz at the nominal focal point intensity of 4.0 kW/cm(2) for 0.4sec in 1-sec intervals. Lesions were created with ultrasonic exposures ranging from 40 to 120 pulses. There were significant relationships between HIFU exposure time and lesion area on the exposed site (R(2)= 0.3389, P < .0001) and lesion volume (R(2)= 0.6161, P < .0001). HIFU has the potential to create focal perforations without direct tissue contact. This method may prove useful for noninvasive atrial septostomy.

Extracardiac Ablation of the Left Ventricular Septum in Beating Canine Hearts Using High-Intensity Focused Ultrasound

High-intensity focused ultrasound (HIFU) produces immediate focal lesions without direct tissue contact. Previously, we reported the HIFU potential for cardiac ablation. The purpose of this study was to evaluate the possibility of myocardial ablation in the left ventricle of beating dog hearts with monitoring by 2-dimensional echocardiography. The operating frequency and the acoustic intensity were 5.25 MHz and 23 kW/cm(2), and the focal length and diameter were 3.3 mm axial and 0.37 mm wide at a distance of 35 mm from the transducer. Three dogs underwent a left-sided thoracotomy. The right ventricular surface was coupled with the transducer. The timing of the HIFU exposure was set during the early systolic phase using an electrocardiographic triggering system. The focal point was set in the left ventricular septum using 2-dimensional echocardiography mounted in the HIFU transducer. Ultrasound energy was delivered for 0.2 seconds. For each dog, we created 18 lesions. Exposures were performed 20, 30, or 40 times. Lesion size was assessed by manually measuring its length and width. All lesions except one were clearly visible. The histologic lesion area was 18.7 +/- 8.3, 26.3 +/- 8.7, and 35.5 +/- 15.7 mm(2) (20, 30, and 40 times, respectively). The intraclass correlation coefficients were found to be 0.72, 0.63, 0.75, and 0.73 for lesion length, width, area, and depth, respectively. HIFU can be used to create targeted, well-demarcated thermal lesions in the ventricular septum myocardium during cardiac contraction.

Myocardial Lesion Formation Using High-intensity Focused Ultrasound

The potential therapeutic uses of ultrasound energy in cardiac disease have not been extensively studied. We have developed a means to deliver high-intensity focused ultrasound (HIFU) to myocardial tissue. Unlike other therapy modalities such as radiofrequency catheter ablation, this system has the advantages of not requiring direct tissue contact and the ability to focus intense energy within a small volume. Sections of left and right ventricles from freshly excised canine hearts were treated in vitro with HIFU pulses. Lesions were created using 1-second HIFU pulses with ultrasonic powers ranging from 19.8 to 45.8 W. There was a dose-response relationship between the applied HIFU energy and lesion size (r = 0.70, P < .001). Myocardial lesion formation with HIFU was also performed in vivo in a canine open-chest beating heart model. With 200-millisecond HIFU pulses gated to the electrocardiogram, focal myocardial lesions were created ranging in length from 2 to 6 mm depending on the dose used. Furthermore, both in vitro and in vivo, focal lesions were successfully formed in the midmyocardial wall that spared both the endocardial and epicardial surfaces. HIFU is a novel means to create focal myocardial lesions without direct tissue contact. HIFU energy delivery can be gated to the electrocardiogram in an in vivo model, and lesions can be formed intramyocardially. Further application of this technology may prove to be useful for the ablation of myocardial lesions such as arrhythmogenic foci and the hypertrophic ventricular septum in hypertrophic cardiomyopathy. The potential therapeutic uses of ultrasound energy in cardiac diseases have not been well studied. We tested a novel system to deliver high-intensity focused ultrasound energy in vitro and in vivo to canine myocardial samples without direct contact with the target tissue. Focal myocardial lesions were formed in a dose-dependent manner, and myocardial lesions were created. This technology may prove useful for ablation of focal intramyocardial lesions such as arrhythmogenic foci and the hypertrophic left ventricular septum in hypertrophic cardiomyopathy.

Safety of gold in stapes surgery

Gold prostheses in middle ear surgery were found to have a higher extrusion rate than prostheses made from titanium. Incidences of deafness after insertion of a gold piston into the vestibule during stapes surgery have been observed. The aim of this study was to find out to what degree gold cations can diffuse from the prosthesis piston into the perilymph. For this, gold prostheses were incubated in artificial perilymph for four months, after which the gold content of the perilymph was analysed. As gold exhibits a special behaviour in complex fluids like the perilymph, a new analysing method was developed. The results show that gold does leak out of the pistons, that it can be reliably measured and that the amount of gold reaching the perilymph depends on the contact area. As the amount of gold measured in the perilymph stays far below the toxic level, it is very unlikely that the gold cations diffusing from a stapes prosthesis into the perilymph have a toxic effect on the inner ear hair cells. Inflammatory or allergic reactions to gold induced by direct tissue contact, however, cannot be excluded.

'Cup cell disease' in the colonial tunicate Botryllus schlosseri.

A new progressive, fatal disease called 'cup cell disease' was characterized in ex situ cultures of Botryllus schlosseri, a colonial tunicate. The disease originated as a few dark spots growing within zooids. The infected colonies then started to deteriorate, morphologically diagnosed by ampullar retraction, lethargic blood circulation and by a swollen and soft tunic matrix. In later stages of the disease, developed buds were also affected. Many large black dots were scattered within the tunic matrix, and zooids were transformed to opaque, dilated, sac-like structures, signaling impending death. Colonies were infected periodically, even without direct tissue contact. The time course from first appearance to colony death ranged between 30 and 45 d. Histological studies, in vitro culturing of blood cells and blood smears revealed the existence of numerous cup-like cells (up to 4.8 microm diameter on average) with a yellowish cell wall and transparent cytoplasm that was not stained by various dyes (except azocarmine-G). Cells were refractive under bright-field illumination and revealed a flattened wall with flanges, characteristic of species of the phylum Haplosporidia. Cup cells aggregated in blood vessels and in internal parts of zooids and buds and were phagocytosed by blood cells. In a single case, plasmodia-like structures were found only in the tunic matrix of an infected colony. This is the first record in botryllid ascidians of an infectious lethal disease associated with haplosporidian protists.

Focal myocardial lesion formation using high intensity focused ultrasound without direct tissue contact

Focal myocardial lesion formation using high intensity focused ultrasound without direct tissue contact

Comparative chronic toxicity and carcinogenicity of acrylonitrile by drinking water and oral intubation to Spartan® Sprague–Dawley rats

Comparative chronic toxicity and carcinogenicity of acrylonitrile by drinking water and oral intubation to Spartan® Sprague–Dawley rats

CO 2 Laser in Rhinology

Summary During the last decade, laser therapy developed to be one of the most important new therapeutical approaches in the field of otorhinolaryngolgy. Specifically in nasal applications, laser-assisted surgery offers many advantages including precision vaporization or incision associated with decreased edema, decreased postoperative pain, improved hemostasis, decreased direct tissue contact and instrumentation as well as avoid the need for nasal packing. Different laser systems have been implemented for nasal application. The greatest experience by far could be gathered with the argon laser. In addition, there have been reports of the successful application of CO2 laser, KTP laser, Ho:YAG laser, magnet laser, diode laser and Nd:YAG laser. Based on the limited depth of each laser system, each system is potentially useful for treating a special type of nasal disease including nasal airway obstruction, polyposis or benign lesions of the nasal cavity. This article focusses on main indications for the CO2 laser in rhinologic surgery.

Analysis of particle size generated during plaque ablation with a flashlamp pumped pulsed dye laser.

To examine debris size generated during in vitro plaque ablation by laser energy and estimate the risk of peripheral embolization following laser angioplasty. A flashlamp pumped pulsed dye laser of 480-nm wavelength was used to ablate calcified arteriosclerotic plaque, fibrous fatty plaque, and normal aortic wall on samples of human cadaver aortas. Each tissue sample was immersed in saline solution and treated with the same amounts of laser energy transmitted by a 320 microns-diameter glass fiber in direct tissue contact. The debris generated during plaque ablation was then separated from the supernatant and the particles were counted and analyzed for size. Depending on the underlying type of tissue and the setting of laser energy, a wide range of particles with sizes between 5.3 mm2 and 64 microns 2 was found in samples. The largest particles were found after ablation of calcified atherosclerotic plaque, whereas fibrous, fatty plaque and normal aortic wall showed smaller particles and a lesser amount of debris. Our study demonstrates that a considerable amount of debris is generated during laser angioplasty at 480 nm and that particle size is sufficient to cause potentially symptomatic embolic occlusions of mid- and small-sized peripheral arteries.

Soft tissue reactions to non-submerged unloaded titanium implants in beagle dogs.

The soft tissue reactions to non-submerged unloaded titanium implants were examined. A total of 24 implants were placed in 6 beagle dogs. The implants differed in their crestal area by having either a rough sandblasted, a fine sandblasted, or a polished surface. After 3 months, all implants were firmly anchored in the bone and had no clinical signs of peri-implant inflammation. Undecalcified histologic sections demonstrated that all implants achieved osseointegration with direct bone contact. The epithelial structures showed a peri-implant sulcus with a non-keratinized sulcular epithelium and a junctional epithelium. None of the sections exhibited epithelial downgrowth to the alveolar crest. In the supracrestal area, a direct connective tissue contact to the implant post was observed. An approximately 50 to 100 microns wide zone of dense circular fibers was found close to the implant surface. It was free of blood vessels and resembled closely an inflammation-free scar tissue formation. This zone was surrounded by a looser connective tissue with a 3-dimensional network of collagen fibers running in different directions. No significant differences concerning soft tissue reactions were found between the 3 implant surfaces. In particular, the length of direct connective tissue contact was similar. Concerning bone reactions, a significantly shorter distance from the top of the implant to the most coronal bone-implant contact was observed for rough surfaces. It is concluded that non-submerged unloaded titanium implants achieved a complication-free tissue integration with a dense connective tissue in direct contact to the implant surface in the supracrestal area, and epithelial structures similar to those around natural teeth. The different surface textures did not influence the healing pattern of the soft tissues, but had an influence on the location of the most coronal bone-implant contact.

手の血管性腫よう手術におけるＮｄ‐ＹＡＧレーザーの応用

Three patients with three different types of vascular tumors of the hand were treated using an Nd-YAG laser. The patients, one male and two females were aged 32, 15, and 51 years old, respectively. The resection of the venous hemangioma in the right palm and little finger of the 32 year old male resulted in a good range of motion, good function, and a pain free state. Equally good results were achieved in both a 15-year-old female, who had cavernous hemangiomas in her left thumb, index, and middle fingers; and a 51-year-old female, who had spindle cell hemangioendotherioma in her right elbow and right hand. Partial excisions were performed in all three cases because the tumors involved digital or ulnar nerves. Blood loss was minimal (averaged 230 grams) compared with usual surgical excisions. The Nd-YAG laser is the only current laser capable of direct tissue contact and the best possible available thermal coagulator giving good penetration with distinct advantage in this type of surgery.