Scanning electron microscopy and X-ray diffraction studies in the analysis of medical materials: Gore-Tex versus braided polyester tape for repair of the incompetent cervix

Cathodoluminescence in the scanning electron microscope and roentgenogram diffraction studies were applied to the analysis of two different medical materials used in cervical cerclage, the treatment of cervical incompetence. Braided polyester tape or Gore-Tex was used as suture material and was analyzed both before and after use in cerclage of the cervix. Results of SEM and X-ray diffraction studies showed distinct differences between the two materials, with the Gore-Tex demonstrating a superior morphological integrity and a decreased likelihood of phagocyte adhesion. These results correlated well with the clinical observations, which also showed Gore-Tex to be a superior medical material.     

Bacterial Cellulose as Laryngeal Medialization Material: An Experimental Study

Hypothesis

The use of a material made of bacterial cellulose with the aim of obtaining vocal fold medialization has not hitherto been fully investigated. Although the material has been tested in other animal models, the evaluation did not include the larynx; hence, situations, such as tissue reaction, material absorption, and extrusion, need to be addressed to evaluate its usefulness as a material for laryngeal reconstruction.

Objective

To evaluate the medialization, tissue response, and healing of rabbit vocal folds, after the implantation of a membrane of bacterial cellulose.

Study Design

Experimental study.

Methods

A total of 32 rabbits were used, two of which were used to check out the adequacy of the implant location. The animals were followed for 4 months and grouped according to follow-up times of 2, 4, and 16 weeks. All test animals received an implant of bacterial cellulose in one vocal fold and the injection of distilled water in the other, both performed by videoendoscopic cervicotomy. At the end of the follow-up, the presence of inflammatory and medial displacement was evaluated.

Results

No statistically significant difference in the inflammatory parameters between the study and control vocal folds or among follow-up times was found. All animals receiving cellulose presented medial displacement of vocal folds, and all retained this material at the implant site up to study endpoint.

Conclusion

Bacterial cellulose is a useful material for laryngeal medialization, showing no signs of rejection or absorption.     

Minifenestration Type I Thyroplasty Using an Expanded Polytetrafluoroethylene Implant

Several methods have been used to treat laryngeal incompetence, but no ideal technique has been identified. This paper describes a clinical experience with minifenestration type I thyroplasty using a new device made of expanded polytetrafluoroethylene (ePTFE). The device, a thin ribbon of ePTFE, is inserted through a 4-mm fenestration to produce vocal fold medialization. At our center, 26 of these devices have been implanted in the past 3 years. Good or satisfactory results were achieved in 96% of cases. Advantages of this technique include easy insertion of the implant, nominal cost and biocompatibility of the ePTFE device, ready availability of all instruments required for the procedure, and elimination of the need to perform arytenoid adduction.     

Quantitation of atherosclerosis by magnetic resonance imaging and 3-D morphology operators

The objective was to ascertain whether MRI and image processing can be used to quantify atherosclerosis by measuring wall thickness in rabbit aorta. The abdominal aortas of 2 healthy and 5 atherosclerotic rabbits were examined with a gradient-echo inflow angiography sequence (2DI) and a proton density weighted turbo-spin-echo sequence (PDW). Using thresholding by four observers and 3D morphology operators, segmentation of the artery and vein lumina was performed from the 2DI sequence, and of surrounding fat and muscle from the PDW sequence. Remaining voxels adjacent to the aortic lumen were classified as vessel wall. By measuring the vessel wall volume and the lumen volume, the wall percentage was calculated. The values were significantly higher for the diseased animals than for unaffected individuals (p < 0.01). It is concluded that aortic wall thickening in atherosclerotic rabbits can be measured quantitatively by using MRI combined with 3D morphology image processing operators.     

Soft tissue response in the rabbit larynx following implantation of Lactosorb (PLA/PGA copolymer) prosthesis for medialization laryngoplasty

This project is designed to provide initial data regarding the use of polylactic acid/polyglycolic acid (PLA/PGA) copolymer ("LactoSorb" [Walter Lorenz Corp]), an alloplastic, resorbable material, as a prosthesis in an animal model of vocal fold medialization. Fifteen New Zealand white rabbits were utilized for left medialization laryngoplasty with LactoSorb implants after undergoing left recurrent laryngeal nerve section. At 1, 3, 6, and 9 months, the rabbits were sacrificed and their larynges were evaluated both grossly and histologically for tissue response to, and resorption characteristics of the implant, tissue cellularity, maintenance of vocal fold medialization, and airway patency. Additionally, 4 rabbits were used as controls, implanted with silicone rubber medialization implants, and sacrificed at 9 months for comparison. One rabbit underwent no surgery and was likewise used as a control. Grossly, no airway obstruction was noted, and no extrusions of the implants occurred. The LactoSorb implant maintained medialization in each group of sacrificed rabbits. Histologic findings revealed a very discrete, fibrous capsule around the implant in the 1- and 3-month rabbits, and the LactoSorb was still grossly visible. At 6 months, the thin fibrous capsule partially remained; at 9 months, the capsule was no longer evident, and the implant was no longer grossly visible. Endoscopic findings at the time of sacrifice in those rabbits implanted with silicone rubber included grossly patent airways with maintenance of medialization. In the rabbits implanted with silicone rubber, the histologic findings are similar to those described elsewhere. LactoSorb, because of its intermittent resorption rate, could offer an ideal alternative to currently utilized temporary, or resorbable, materials, and as such will hopefully prove an invaluable tool in the laryngologist's treatment planning and surgical repair of the patient with a paralyzed vocal fold.     

Bone‐nanohydroxyapatite spheres interface evaluation by synchrotron radiation X‐ray microfluorescence

Hydroxyapatite (HA) is largely used as bone graft; it seems to be the most promising synthetic implant material, mainly because of its excellent biocompatibility. The crystallinity, particle and pore size of HA are important characteristics and can be modified by decreasing basic structural form below 100 nm and have evoked a great amount of attention for improving prevention, diagnosis, and disease treatment, besides improving bone repair through the biodegradation of the material. The aim of this study was to investigate bone mineral content in bone samples with nanohydroxyapatite and HA spheres, specially its spatial distribution on bone microarchitecture. Circular bone defects were made in both tibiae of 12 White New Zeland adult rabbits (Oryctolagus cuniculus) and were divided randomly into five groups – blood clot (control group), sintered HA, non‐sintered HA, sintered nanoHA and non‐sintered nanoHA – all materials in spherical shape, to smooth handling and accommodation of the surgical bed, and to minimize inflammatory response. The rabbits were euthanatized according to the experimental period of 1 and 4 weeks after surgery. The samples were evaluated by polarized microscopy as well as X‐ray microfluorescence in order to account the bone mineral content bone‐implant interfaces, through synchrotron radiation. Our results revealed greater newly formed bone area in the non‐sintered materials and control groups, and the used technique showed that the amount of calcium of new bone was consistent with both mature bone and HA spheres. In conclusion, the present findings suggest that HA‐based biomaterials are biocompatible, promote osteoconduction and favored bone repair. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of lung volume on vertical larynx position during phonation

The vertical position of the larynx seems to be relevant to voicefunction. As a high vertical larynx position is often seen in hyperfunctional and strained voices, a lowering of a habitually elevated larynx is sometimes a specific goal in clinical voice therapy and different larynx-lowering exercises are used to achieve this goal. Earlier investigations have shown that pitch and to some extent also vocal loudness are relevant to vertical larynx position. In the present investigation, we examine if lung volume affects vertical larynx position. Using a multi-channel electroglottograph, the larynx position was measured in 29 healthy, vocally untrained subjects, who phonated at different lung volumes, pitches, and degrees of vocal loudness. The main results were that high lung volume was clearly associated with a lower larynx position as compared to low lung volume. In addition, vertical larynx position was strongly correlated with pitch. Both of these dependencies were shown to be stronger in males than in females. Our results suggest that lung volume is a factor that is highly relevant to larynx height in untrained subjects.     

Electromagnetic stimulation on the bone growth using backscattered electron imaging

The events at the hydroxyapatite implant material/tissue interface following electromagnetic stimulation were studied in the rabbit. Two kinds of hydroxyapatite were used: natural (NA) and synthetic (HA) both with a grain size of <50 microm. Bone defects, artificially created in rabbit tibiae, were filled with the material examined. One group of animals was exposed immediately after surgery and every 12h thereafter to 30-min treatments with electromagnetic fields (PEMFs). A second group was used as a control (untreated). Two and 4 weeks after implantation, animals were sacrificed and bone samples processed for LM, TEM and SEM using a backscatter electron detector for the evaluation of bone growth. This study indicates that HA has more osteoconductivity than NA, and shows that PEMF-treatment results in a benefit in accelerating bone formation at early time periods.     

Stable aqueous ZnO nanoparticles with green photoluminescence and biocompatibility

Semiconductor quantum dots (QDs) as a kind of biological labeling material have many unique fluorescence properties relative to conventional organic dyes, which can be used for long-term fluorescence tracking. In this work, a facile method was developed for synthesizing water-stable ZnO nanoparticles with green emission. The as-synthesized ZnO nanoparticles were shown to be highly stable and soluble in water. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) as well as UV–vis and fluorescence spectrophotometry (PL) were employed to investigate the structures and properties of ZnO nanoparticles. Furthermore, hemolysis assay was performed to evaluate the biocompatibility of these ZnO nanoparticles in vitro. The results indicate that the as-prepared ZnO nanoparticles have biocompatibility, which make them a promising cell label.     

Quantitative assessment of voice quality following laser surgery for reinke''s edema

Although laser surgery has been widely advocated for use in the treatment of vocal fold papilloma because it does not incur bleeding, it has been questioned for use in treating Reinke's edema due to the possibility of heat dispersion to normal surrounding tissue and of scarring. We present a series of 8 cases in which laser surgery was the method of treatment for bilateral Reinke's edema. In each case, voice therapy was selected as the initial treatment; laser surgery was performed following voice therapy. Prior to and following surgery, videostroboscopic examinations were performed on the subjects. Only 4 subjects were available for assessment at the 1-month postoperative period. From the audio track of the videotape, the speaking fundamental frequency, perturbation measures for the vowel /i/, and noise-to-harmonic ratio of a completely voiced sentence were obtained. From the videostroboscopic recordings, the symmetry of the vocal folds, the presence or absence of the mucosal wave and the glottic closure pattern, prior to and after surgery, were judged independently by 3 examiners. The fundamental frequencies approximated the normal male and female ranges for those subjects seen 1 month after surgery. In addition, the noise-to-harmonic ratio and the relative average perturbation improved. Stroboscopy revealed irregularities in the symmetry of vocal folds, mucosal wave, and glottic closure 1 month after surgery.     

Surgical anatomy of the larynx

Modern functionally oriented surgery of the larynx increasingly requires exact knowledge of the anatomy and landmarks of the endolaryngeal structures in relation to the laryngeal skeleton. Review of the literature reveals several opposing statements and controversial anatomical definitions regarding several clinically critical points. In order to obtain basic anatomical data morphological measurements were performed on a total of 50 laryngeal specimens. Measurements were taken on whole organs and on cuts in the horizontal and in the frontal plane, as well. The data were evaluated statistically, which resulted in the determination of average configurations and dimensions of cartilages and soft tissues of the larynx. In particular, the projection of the deeper structures on the surface and the distances and angles between the different structures were taken into consideration. In order to make these data clinically applicable a scale model has been developed that will allow a direct correlation and application for individual surgery.     

Magnetic resonance imaging of malignant fibrous histiocytoma

The magnetic resonance imaging (MRI) changes in 39 patients with malignant fibrous histiocytoma (MFH) were reviewed retrospectively. Twenty-one sarcomas were in the lower extremity, five each in the upper extremity and trunk, two each in the neck and heart, and one each in the maxillary sinus, sella turcica, tongue, and spermatic cord. The examinations were performed with spin-echo sequences on a 1.5 Tesla Signa Scanner (GE, Milwaukee WI). Twenty-two tumors exhibited intermediate signal intensity on T1-weighted images and 23 were of high signal intensity on T2-weighted images. There was no significant differences in signal intensity of 12 preoperative and 13 recurrent neoplasms. Twelve of 13 patients were correctly diagnosed as having postoperative changes. The MR sensitivity and specificity for detecting a neoplasm were 96% and 83% respectively, but the signal changes were nonspecific for MFH. When compared to CT in 14 patients, MR better defined the extent of the MFH, its relationship to surrounding tissues and vessels, and best differentiated residual or recurrent disease from postoperative changes when examined at least 3 months after surgery.     

金属板疲劳损伤非线性兰姆波混频检测

针对金属板结构安全运行需要,开展了金属板结构疲劳损伤非线性兰姆波混频检测方法研究.通过数值仿真,研究了两列A0兰姆波与材料损伤间的非线性相互作用.结果 表明,两列共线A0兰姆波在结构材料损伤处产生单向传播的和频S0波,且和频波幅值随传播距离具有积累增长效应.对不同疲劳程度金属板试件进行了共线混频兰姆波检测实验,结果表明...     

Different magnetic resonance imaging features in two types of nontraumatic rabbit osteonecrosis models

A single injection of high-dose steroid (20 mg/kg) has been reported to induce necrotic lesions in the proximal metaphysis and diaphysis of the rabbit femur. In the rabbit osteonecrosis (ON) model induced by two-dose horse serum injections, contrast-enhanced magnetic resonance imaging (MRI) and T2*-weighted dynamic MRI have been reported to detect necrotic lesions at 3 days after the second serum injection sensitively. The purpose of the present study was to determine whether contrast-enhanced MRI and T2*-weighted dynamic MRI could detect early development of necrotic lesions in the rabbit proximal femora after a single high-dose steroid injection and compare MRI features of the two types of nontraumatic rabbit ON models. We performed nonenhanced MRI, contrast-enhanced MRI and T2*-weighted dynamic MRI of bilateral proximal femora 3 days (10 femora), 1 week (10 femora), 3 weeks (10 femora), 6 weeks (18 femora) and 9 weeks (18 femora) after a single 20 mg/kg steroid injection. Femoral signal intensity of each T2*-weighted dynamic MRI was measured from a 1-cm(2) region of interest in the proximal metaphysis and diaphysis. As a control, MRI was performed in untreated animals (six femora). Histologically, no necrotic lesions were observed in the proximal femora at 3 days and 1 week. Bone marrow necrosis was observed in four (40%) femora at 3 weeks, two (11.1%) femora at 6 weeks and six (33.3%) femora at 9 weeks. Bone marrow lesion completely replaced by granulation tissue was observed in one femur at 6 weeks and one femur at 9 weeks. Histologic evidence of repair tissue surrounding bone marrow necrosis was seen after 6 weeks. Average lesion area including repair tissue was 4.40 mm(2) (range, 0.32 to 20.2 mm(2)). At 9 weeks, contrast-enhanced MRI could detect four (66.7%) femora with bone marrow necrosis of more than 4 mm(2) in the lesion area, while T2*-weighted dynamic images showed a finding of complete ischemia in only one of these four femora. In conclusion, neither contrast-enhanced MRI nor T2*-weighted dynamic MRI could detect early development of necrotic lesions in the single-dose steroid ON model. These results indicated that development of necrotic lesions in the single-dose steroid ON model was not accompanied by as diffuse a femoral hemodynamic change as the two-dose horse serum ON model.     

一个新的提煉超纯金属镓的区域熔化法

本文描述了一个提炼超高纯镓的新的区域熔化方法。把镓装在一个塑料管中,做成螺旋蜷线形式,一边提高温度到镓的熔点之上,于是在这螺旋蜷线上就有许多个熔区。当螺旋蜷线转动的时候,熔区则往复前进。估计如此装置的区域熔化方法比通常的效率要高。     

Animal model for training and improvement of the surgical skills in endolaryngeal microsurgery

Animal models for training of surgical skills were widely used for a long time in the education of medical practitioners. It is recognized, however, that endolaryngeal microsurgery requires highly refined skills to handle the delicate structures of the vocal folds under the microscope. The availability of fresh human laryngeal specimens is markedly restricted by legal and hygienic issues. The aim of this work was to report on the design of a feasible and effective model to provide the much needed skills in an animal laryngeal model that is as close as possible to the human vocal fold structure. In the initial phase of the research, three animal larynges were studied: porcine/pig, bovine/calf, and ovine/sheep larynges. The pig/porcine larynx was chosen for this experimental training model because it closely resembled the human laryngeal/glottal configurations. A study was carried out on 10 porcine/pig larynges to assess the dimensions of the glottis and study the histology of the layered structure of the vocal fold. The study was pursued to confirm the resemblance of this animal specimen to the human vocal fold. A wooden box with a black finished interior was prepared with an acrylic bed at its floor. This bed allows placement of the porcine/pig larynx. The design of the box allows the endoscopic exposure of the porcine/pig larynx through a rubber diaphragm. The darkness and confinement of the box, apart from the light of the endoscope, approximates the situation in live endoscopy. The operating microscope is then used to expose the glottis. Routine fine microlaryngeal instruments were used for training in the prescribed skills.     

Physiological aspects of a vocal exercise

The physiological aim of vocal exercises is mostly understood in intuitive terms only. This article presents an attempt to document the phonatory behavior induced by a vocal exercise. An elevated vertical position of the larynx is frequently associated with hyperfunctional phonatory habits, presumably because it induces an exaggerated vocal fold adduction. Using the multichannel electroglottograph (MEGG), the laryngeal position was determined in a group of subjects who performed a voice exercise that contained extremely prolonged versions of the consonant /b:/. This exercise is used by the coauthor (N.E.) as part of a standard vocal exercise program. Two of the seven subjects were dysphonic phonastenic patients, and the rest were normal trained or untrained persons. Different attempts to calibrate the MEGG confirmed a linear relationship with larynx height, provided electrode positioning was correct. The results showed that the exercise induced substantial vertical displacements of the larynx. Comparison with larynx height during voicing of other consonants showed that the /b/, in particular, tended to lower the larynx.     

Laryngeal and Vocal Changes During Vagus Nerve Stimulation in Epileptic Patients

Left vagus nerve stimulation (VNS) by means of an implanted electrode has proven to reduce seizure frequency in epileptic patients with medically refractory seizures. This technique is now widely applied over the world. Voice changes appear to be one of the major side effects. The morphodynamic changes in the larynx and the acoustic impacts have been analyzed in detail in 7 implanted patients. Basic vagus stimulation is well tolerated. Extra stimulation induces an adductory spasm of either the ipsilateral vocal fold or the vestibular fold. The result, when the patient phonates, consists of a slight increase of F0 as well as a moderate increase of random period perturbation, but there is no evidence for the occurrence of "bifurcations." Further, as the glottic closure remains sufficient, there is no increase in turbulent noise. The lack of increase in turbulent noise and the lack of "bifurcations" appears to clearly differentiate a spasmodic contraction of the vocal cord from a unilateral vocal fold paralysis.     

Mechanical properties of flat braided composite with flexible interphase

Textile composites have been used extensively as industrial materials because of the excellent mechanical properties resulting from the continuously oriented fiber bundle. In a study of the mechanical properties, it is important to consider the fiber/matrix interface property as for other composite materials. In a recent study, the fiber/matrix interface is regarded as an interphase that has its own material constants and thickness; consequently, the mechanical properties of a composite can be controlled by specifically designing the interphase. In this study, we applied this concept to braided composites with flexible resin as interphase for the purpose of designing the interphase. In a static tensile test, though there were no improvements in Noncut specimens (normal braided composites), but a Cut specimen (each side of the Noncut specimen was cut) with flexible interphase was improved in fracture load and displacement. The observation of the specimen edge was carried out and it was confirmed that the progress of debonding at the fiber bundle intersection was interrupted by a flexible interphase, and a matrix crack did not occur in the Cut specimen with flexible interphase. In a fiber bundle pull-out test, it was confirmed that debonding progressed not into the fiber/resin interface but into the flexible interphase in the specimen with flexible interphase, and the interfacial property at the fiber bundle intersection was improved.     

基于光弹性贴片法的材料表面应变场测量研究

针对常用电阻应变片法的点测结果不易反映构件表面应变场分布的问题,将光弹性贴片方法应用于材料表面应变场测量。制作了光弹性贴片,并标定光弹性贴片的材料条纹值,通过几种典型形状光弹性贴片试件的加载实验掌握应力场分布的条纹图像判读方法。开展光弹性贴片在简支钢梁的应变场测量应用,在薄弱点位置光弹性贴片法相比电阻应变片法应变值偏差在5%以内。对C30混凝土试块进行4.4 MPa～39.6 MPa的应力加载过程中,有效监测到混凝土表面裂缝产生、稳定扩展及失稳破坏过程中的条纹图像变化过程。实验表明,光弹性贴片方法可以直观可靠地测量金属及混凝土的表面应力场变化。