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Biomedical subjects

N Isshiki

Publications and source records attributed to N Isshiki.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of a bilayer artificial skin capable of sustained release of an antibiotic.

A bilayer artificial skin, composed of an upper silicone sheet and a lower collagen sponge, has been developed by modifying a technique proposed by Yannas and Burke. We have applied it clinically with success, but infection sometimes occurred in the area where the artificial skin was placed. To use it safely in an infected wound, we developed a new type of artificial skin capable of sustained release of antibiotic. Microspheres of poly-L-lactic acid containing an antibiotic, were installed in the upper silicone sheet. The usefulness of the new type of artificial skin was suggested by in vitro studies.

Biocompatible Materials↗
PubMed1992

Time series analysis of glottal airflow in normal and pathological phonation.

Time series analysis of glottal airflow was carried out on 26 normal controls and 40 patients with voice disorders, using a modification of Isshiki's original technique which uses a hot-wire flowmeter, taking cycle-by-cycle fluctuations into consideration. The mean flow rate and mean AC/DC were shown to have significant differences among normal and patient groups. The standard deviations of AC/DC and AC/DC perturbation were calculated from the AC/DC value of 50 cycles and shown not to vary significantly among the normal and patient groups. The relationship between AC/DC and perceptual impression of voice was also studied among 20 selected patients with breathy voices. Using Spearman's rank correlation coefficient, this relationship was found to have statistical significance (P < .05).

Glottis↗
PubMed1992

Experimental studies on the viscoelasticity of the vocal fold.

Viscoelasticity of the vocal fold was assessed by analyzing the stress-strain relationship under several experimental conditions. The stiffness increased with greater tension of the vocal fold. Marked differences in the mechanical properties were noted between the "body" and the "cover" of the vocal fold, especially when tension was applied. Contraction of the thyroarytenoid muscle tended to make the vocal fold less stiff and more viscous. Dry vocal-fold mucosa was associated with greater stiffness. Submucosal injection of saline solution to simulate edema increased the stiffness and viscosity of the vocal fold.

Animals↗
PubMed1992

Mechanical properties of the vocal fold. Stress-strain studies.

The viscoelasticity of the vocal and ventricular folds was experimentally assessed by analyzing the stress-strain relationships obtained using a newly developed measuring system. The degree of stiffness of the mid-membranous portion of the vocal fold was less than that near the anterior commissure or the vocal process. The ventricular fold was much less stiff and significantly more viscous than the vocal fold. At the membranous portion of the vocal fold, the degree of stiffness was less and that of viscosity greater at 2 mm above and below the free margin than at the free margin itself.

Adult↗
PubMed1991

Salvage of distal flap necrosis by topical superoxide dismutase.

Significance of the reactive oxygen species in distal flap necrosis and the efficacy of superoxide dismutase (SOD) in salvaging necrosis have become indicated in recent studies. To enhance the therapeutic effect of SOD, topical application was designed. Water-soluble ointment containing 1% SOD was prepared, and three experiments were made to study the effect of topical SOD in improving flap survival. Simple application of SOD ointment to the upper surface of the flap had no effect, whereas its application to the under surface or occlusive dressing was effective. These effects were corroborated by assay of tissue SOD activity.

Administration, Topical↗
PubMed1991

Reconstruction of both eyelids following electrical burn.

A case of severe electrical burn of the unilateral upper and lower eyelids is reported, together with the surgical technique of reconstruction. A 25-year-old man suffered an electrical burn on his left eyelids. On admission, his left upper and lower eyelids were subtotally necrotic. Total eyelid reconstruction was performed 2 1/2 months later. A chondromucosal graft taken from the nasal septum was utilized as the deep layer of the upper eyelid, which was covered by sliding down the remaining levator muscle and connective tissues to maintain the blood supply to the composite graft. The outer layer of the upper lid was reconstructed with a free split-thickness skin graft. The lower lid was reconstructed with a local flap lined with a free mucosal graft. This sandwich method using the levator muscle as a core was found useful for reconstructing both the upper and lower eyelids.

Adult↗
PubMed1991

Electrical pacing for dynamic treatment of unilateral vocal cord paralysis. Experiment in long-denervated muscle.

In order to explore the possibility of clinical application of laryngeal pacing as a treatment for unilateral vocal cord paralysis, we examined the reactivity of atrophic muscle to electrical stimulation in dogs whose recurrent laryngeal nerves were damaged by crushing, dissection followed by resuturing, or a 3-cm neurectomy. The threshold level to induce enough vocal cord adduction reached the maximum at 2 weeks after nerve injury, decreased with time, and never surpassed 7 V in each case. On the basis of results of these preliminary probings, laryngeal pacing was conducted on a dog 15 months after resection of the laryngeal nerve. Adduction of the paralyzed vocal cord for synchrony with the intact cord was achieved by 7 V of electrical stimulation of the thyroarytenoid muscle that was triggered by signals from the cricothyroid muscle.

Animals↗
PubMed1991

Surgical treatment of laryngeal web with mucosa graft.

Surgical treatment of laryngeal webbing varies with the extent and site of the web. An extensive one seems to be best treated by laryngofissure and skin or mucosa transplantation. Recent experiences with four cases of thick glottal webbing indicated that a mucosa graft was better for the voice result than a skin graft. For success in the airway and voice results, the salient points in surgery include 1) precise midline thyrotomy, 2) shaping of the vocal cord under fiberoptic control, and 3) mucosa grafting with the combined use of a pliable stent or fibrin glue for fixation.

Adult↗
PubMed1991

Special instruments for laryngeal framework surgery.

Thyroplasties involve a variety of delicate surgical techniques that affect the outcome decisively. In particular, opening a window in the thyroid cartilage, undermining around the window frame and fixation of a window plug in thyroplasty, and passing a suture through the muscular process and thyroid ala are some examples of difficult procedures. Several instruments were devised to facilitate such procedures. They include a special raspatory, an ultrasonic osteotome for cartilage cutting, a narrow polyvinyl tube for suture passing, a suture holder for passing through the muscular process, and a wound retractor for arytenoid adduction. These were found useful in minimizing soft tissue damage and in precise performance of the procedures.

Humans↗
PubMed1990

Laryngeal pacing in unilateral vocal cord paralysis. An experimental study.

In an attempt to remobilize a unilaterally paralyzed vocal cord, experiments were made in five adult dogs. Adduction of the paralyzed vocal cord for phonation in synchrony with the intact cord was achieved by electrical stimulation of the adductor muscles that was triggered by the signals from the cricothyroid muscle. The difference in the level of action potentials of the cricothyroid muscle between during phonation and during respiration was used for setting the threshold so as to differentiate phonation from respiration. Nearly synchronous movement of the two vocal cords thereby attained during phonation greatly improved the voice quality that was hoarse without the paced stimulation.

Action Potentials↗
PubMed1990

Clinical evaluation of a new bilayer "artificial skin" composed of collagen sponge and silicone layer.

A bilayer "artificial skin" composed of an outer layer of silicone and an inner sponge layer of collagen and chondroitin sulphate has been developed by modifying the technique proposed by Yannas et al. (1980). Following experimental successes, the "artificial skin" was applied clinically. It was placed on the skin defects of 10 patients. Three weeks after application the outer layer of silicone sheet was peeled off and thin split thickness skin was grafted onto the newly synthesised dermis-like tissue. Secondary skin grafts took perfectly in all cases and postoperative appearance was satisfactory.

Adolescent↗
PubMed1990

Influence of glycosaminoglycans on the collagen sponge component of a bilayer artificial skin.

A bilayer artificial skin composed of a silicone membrane and a collagen sponge layer containing glycosaminoglycans (GAGs) was first developed by Yannas and Burke. They reported that GAGs contained in the collagen sponge layer contributed to the function of the artificial skin. In an attempt to assess the effect of GAGs in the collagen sponge layer, the electron microscopic structure, mechanical strength of collagen sponges, and cell proliferation were examined in vitro, using four kinds of collagen sponges containing: no GAG, chondroitin 6-sulphate (C6S), dermatan sulphate (DER), and hyaluronic acid (HYA). The results indicated that: (1) addition of GAGs scarcely affected the mechanical structure of collagen sponges; (2) addition of C6S and DER reinforced mechanical strength, while addition of HYA did not; (3) addition of C6S and DER significantly decreased cell proliferation.

Artificial Organs↗
PubMed1990

Experimental study of a newly developed bilayer artificial skin.

A bilayer artificial skin composed of an outer layer of silicone polymer and an inner sponge layer of collagen containing chondroitin 6-sulphate was developed by modifying the technique proposed by Yannas et al. The artificial skin was placed on the skin defects on the backs of rats. Histological observation indicated that fibroblasts and capillaries infiltrated into the pores and filled in lattice spaces, resulting in synthesis of the connective tissue matrix and absorption of the original network of collagen and chondroitin 6-sulphate. Epidermal cells migrated from the edge of the wound between the two layers. Post-operative contracture in the wound with the artificial skin was significantly less than in the control.

Animals↗
PubMed1990

Distally based lateral calcaneal flap.

In our cadaver dissection, the connection between the lateral calcaneal artery, the lateral tarsal artery, and the branch of the lateral plantar artery was corroborated, indicating possible reverse blood flow in the lateral calcaneal artery. The distally based lateral calcaneal flap has been successfully used in 2 patients. Vascular anatomy, indication, and technical points of the surgery as well as advantages and disadvantages of the flap are discussed.

Adult↗
PubMed1990

Effects of lateral manual compression upon glottic incompetence: objective evaluations.

Forceful manual compression of the thyroid and cricoid cartilages modifies the position, shape, and tension of the vocal folds. This is the basis of the four laryngeal manual compression tests, adjunctive examinations used as a means of preoperative assessment of patients for medialization laryngoplasty, ie, Isshiki thyroplasty types I and IV and arytenoid adduction. The laryngeal manual compression tests are simple to perform and noninvasive. Each of the four examinations yields valuable information on the effects on the voice of changes in vocal cord characteristics produced by manual compression. In this report, one of the four tests, lateral manual compression, is evaluated objectively with well-attested methods of videostroboscopic, aerodynamic, and acoustic analysis. The technique of performing lateral manual compression is described, and advantages and disadvantages are noted and compared in 10 patients. Preliminary findings in 4 patients in this group indicate that medialization laryngoplasty should be considered when test results are conclusive of effective glottic closure. Data derived in this preliminary study will be augmented as patients are added to the series.

Adult↗
PubMed1990

Technique of total ear reconstruction with open framework, composite pseudomeatus graft, and postauricular transposition flap.

Modifications of Tanzer's technique of total reconstruction of the auricle are described, emphasizing the construction of a deep conchal cavity and pseudomeatus, with ample projection of the auricle. To obtain a more prominent projection of the auricle, a transposition flap from retroinfra-auricular skin is used, with placement of small cartilage props beneath the framework. The depth of the conchal cavity is enhanced by excavation of soft tissues and placement of an additional cartilage graft at the posterior wall of the choncha. The external meatus is imitated by a cone-shaped composite graft taken from the cymba of the opposite ear.

Child↗
PubMed1989

Significance of reactive oxygen species in distal flap necrosis and its salvage with liposomal SOD.

In an attempt to elucidate whether reactive oxygen species (ROS) have a role in causing distal necrosis of random pattern flaps, and to develop measures to prevent necrosis, three experiments were made using a rat flap model. The flap-salvaging effect of liposomal superoxide dismutase (L-SOD) was assessed. The results were as follows: (1) Measurements of changes in cutaneous blood flow in a flap, with time, revealed an initial remarkable decrease followed by gradual but significant increase in the distal portion 24 hours after operation. (2) The SOD activity in the flap continued to decrease gradually with time until 24 hours after operation both in L-SOD treated and control groups. However, SOD activity in L-SOD treated flaps was always significantly higher than in the control. (3) S-D value (survival length minus dye distance) was significantly greater in the L-SOD treated flap than in the control flap, indicating a significant effect of L-SOD in preventing the expected flap necrosis. These results suggest a possible role, in causing flap necrosis, of ROS which are generated by reperfusion following ischaemia, and the effectiveness of L-SOD in salvaging distal flap necrosis.

Animals↗