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Dive into the research topics where Naoki Yoshizawa is active.

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Featured researches published by Naoki Yoshizawa.


Journal of Burn Care & Rehabilitation | 1997

A burn wound healing model in the hairless descendant of the Mexican hairless dog

Hajime Matsumura; Naoki Yoshizawa; Tohru Kimura; Katsueki Watanabe; Nicole S. Gibran; Loren H. Engrav

Wound contraction and epithelialization occur much faster in animals than in humans. Therefore it is sometimes not valid to apply the results of animal wound healing studies to humans. Hairless descendants of Mexican hairless dogs (HD-MHD) have attracted attention because their skin characteristics approximate those of humans. We used this animal and compared the rate of healing of superficial dermal burns (SDB) and deep dermal burns (DDB) in the HD-MHD and normal beagles. We also compared the rate of healing with use of Vaseline (Chesebrough-Ponds) gauze (VG) and hydrocolloid dressings in the HD-MHD. The HD-MHD demonstrated less contraction (p < 0.05). Small pigmented spots could be seen in the HD-MHD wounds, suggesting that epithelialization started from epidermal appendages. SDBs treated with VG and hydrocolloid dressings were both epithelialized on day 18. DDBs treated with hydrocolloid dressings were epithelialized on day 24, whereas DDBs treated with VG were epithelialized on day 30. Like human wounds, burns in the HD-MHD epithelialize from appendages with less wound contraction. These similarities support the use of this burn wound healing model.


Journal of Plastic Surgery and Hand Surgery | 2010

Infraeyebrow excision blepharoplasty for Japanese blepharochalasis: Review of 35 patients over 60 years old

Akira Sugamata; Naoki Yoshizawa

Abstract Since 2005 we have treated many older patients with upper blepharochalasis but no obvious aponeurotic ptosis by infraeyebrow excision of skin and orbicular muscle with tucking of the orbital septum. Thirty-five patients (70 lids) were studied, age range 61-80 years (mean 68). There were 6 men and 29 women, who were followed up for 3 months to 2 years (mean 7 months). All patients reported improvement in the upper visual fields and lessening of headaches and neck stiffness. The lateral drooping of the lid also improved, and the crease was more clearly defined than before the operation. There were no serious complications. We conclude that infraeyebrow blepharoplasty with tucking of the orbital septum is a simple and effective treatment for blepharochalasis in older East Asian patients.


Journal of Plastic Surgery and Hand Surgery | 2013

Timing of operation for blowout fractures with extraocular muscle entrapment

Akira Sugamata; Naoki Yoshizawa; Kosuke Shimanaka

Abstract Many authors have advocated early surgical intervention to avoid muscle degeneration in patients with blowout fractures with evidence of extraocular muscle entrapment imaged under computed tomography. However, there is still no golden standard with regard to the target timing of operations for releasing extraocular muscle. Between January 2002 and December 2011, the authors treated eight cases of blowout fracture with extraocular muscle entrapment. Notes from presumed cases of blowout fracture were retrospectively reviewed for information relating to surgical treatment and prognosis. In this series, a patient who was operated on 7 hours after injury showed the quickest recovery from diplopia. In contrast, a patient who was operated on 18 days after injury showed persistent diplopia for 2 years. Nevertheless, in patients who were operated on 3–11 days after injury, there was no obvious correlation between the outcome and the number of days between injury and the operation. It is concluded that, when emergency surgical intervention within several hours is not possible, it should be performed as soon after the injury as possible in order to prevent the increase of predictive fibrosis around the extraocular muscle.


Journal of Plastic Surgery and Hand Surgery | 2010

Clinical analysis of orbital blowout fractures caused by a globe-to-wall contact mechanism.

Akira Sugamata; Naoki Yoshizawa

Abstract Computed tomograms of blowout fractures of the pure medial and inferomedial wall that showed that the size of the orbital displacement exactly fitted the shape of the globe in many cases were investigated. To examine the veracity of a “globe-to-wall contact mechanism”, we have analysed our own cases of medial or inferomedial blowout fractures (and also the charts of presumptive cases in which this mechanism was suspected), for the clinical information. The size of the displacement of the orbital wall exactly fitted the globe in 20/45 patients (44%). All fractures occurred in the inferomedial area of the orbital wall. In our study, serious complications such as corneal laceration, global rupture, paralysis of the cranial nerve, and ophthalmic nerve neuropathy were seen more often than in other studies.


Journal of Burn Care & Rehabilitation | 1997

Residual myocardial damage following electrical injuries

Hajime Matsumura; Y. Kobayashi; Robert E. Mann; A. Sugamata; Katsueki Watanabe; Nobuyuki Harunari; Naoki Yoshizawa; T. Kamada; Loren H. Engrav; David M. Heimbach

It is unknown to what degree electrical injury causes cardiac muscle damage. We used standard clinical methods and varying combinations of 201Tl scintigraphy (TI), 123I-metaiodobenzylguanidine scintigraphy, echocardiography, 99mTc-RBC angiography, and coronary catheterization to evaluate five patients with high-tension electrical injuries for cardiac damage. The first follow-up examination was performed within 2 months of injury, and the second follow-up was performed more than 6 months after the first follow-up. Electrocardiographic abnormalities were observed in two patients in the acute stage, but no abnormality was detected in the follow-up period. Myocardial perfusion abnormalities were found in all cases with Tl. The degree of injury indicated by Tl was more severe than that indicated by 123I-metaiodobenzylguanidine scintigraphy. Moreover, Tl showed progression of injury in all cases. These preliminary findings must now be confirmed and verified in a larger group of patients.


Plastic Surgery International | 2011

Open Reduction of Subcondylar Fractures Using a New Retractor

Akira Sugamata; Naoki Yoshizawa; Yoshio Jimbo

Many operative approaches have been described for the open reduction of subcondylar fractures and rigid fixation. However, fracture portions are deep and embedded among facial nerves so that visual surgery in this region is extremely limited. Once the operative field is exposed, the displacement of the condylar head is often dislocated by the anteromedial pull of the lateral pterygoid muscle and the fracture end of the condylar process is pulled up to the mandibular fossa by contraction of the masseter muscle. We made a new retractor to achieve a better field of view. It is possible to pull down the condylar process by opening the tips of the retractor using the specially made wrench system without special effort and keep the condylar process in the same position during reduction. In using this retractor, the fracture stumps were clearly exposed and more easily reposited.


Acta Oto-laryngologica | 2018

Prevention of anastomotic leak using an advanced pectoral flap in total pharyngolaryngectomy and free jejunal reconstruction for hypopharyngeal or laryngeal carcinoma

Takahito Kondo; Kiyoaki Tsukahara; Naoki Yoshizawa; Isaku Okamoto; Ray Motohashi; Masaki Nomoto; Yasuaki Katsube; Masanori Yatomi; Takashi Iwasawa; Kenji Hanyu; Yasuo Ogawa

Abstract Background: We devised an advanced pectoral flap (APF) to prevent anastomotic leak after total pharyngolaryngectomy (TPL) and free jejunal reconstruction (FJR) in patients with hypopharyngeal or laryngeal carcinoma. The APF alleviates tension on the skin in the neck, reduces the subcutaneous dead space, and promotes adhesion between the neck skin and the anastomosis. Objective: To investigate whether an APF is effective for prevention of anastomotic leak associated with TPL/FJR. Patients and methods: Anastomotic leak was compared between APF (n = 65) and non-APF groups (n = 25). Patients who had received preoperative radiotherapy or undergone tracheostomy or skin infiltration requiring neck reconstruction using a pedicle flap were excluded. Results: There were significantly fewer cases of anastomotic leak in the APF group than in the non-APF group (1.5% [1/65] vs. 16.0% [4/25]; p = .02). An APF could be created bilaterally within approximately 15 minutes. Unlike a deltopectoral flap, an APF does not require a skin graft. Conclusions: The postoperative anastomotic leak rate was 1.5% in patients who underwent TPL and FJR for hypopharyngeal or laryngeal carcinoma with an APF. Significance: An APF is easily created and can reduce the incidence of anastomotic leak after TPL and FJR.


International Medical Case Reports Journal | 2015

A case of blowout fracture of the orbital floor in early childhood

Akira Sugamata; Naoki Yoshizawa

There are few reports of blowout fractures of the orbital floor in children younger than 5 years of age; in a search of the literature, we found only six reported cases which revealed the exact age, correct diagnosis, and treatment. We herein report the case of a 3-year-old boy with a blowout fracture of the orbital floor. Computed tomography showed a pure blowout fracture of the left orbital floor with a slight dislocation of the orbital contents. The patient was treated conservatively due to the absence of abnormal limitation of eye movement or enophthalmos. The patient did not develop any complications that necessitated later surgical intervention. Computed tomography at 6 months after the injury showed the regeneration of the orbital floor in the area of the fracture and no abnormalities in the left maxillary sinus. We herein present our case and the details of six other cases reported in the literature, and discuss their etiology, diagnosis, and treatment methods.


International Medical Case Reports Journal | 2011

Relaxation incisions of venomous snake “Japanese mamushi” bites to the hand

Akira Sugamata; Naoki Yoshizawa; Takahiro Okada

Gloydius blomhoffii, commonly known as Japanese mamushi, is a venomous viper species found widely in Japan. The most frequently bitten regions are the fingers and toes, and severe swelling causes compression of peripheral arteries and/or compartment syndrome of the extremities. We experienced four cases of mamushi bites to the hand, and undertook relaxation incision in the hands of three of these patients. As a result, the patients who underwent relaxation incision did not show any skin necrosis or permanent sensory disturbance in the affected fingers. Relaxation incision can be useful to not only decompress subcutaneous and compartment pressure of the hand, but also to wash out the venom from the bitten region by improving venous and lymphatic drainage.


British Journal of Plastic Surgery | 2001

PRECONDITIONING OF THE DISTAL PORTION OF A RAT RANDOM-PATTERN SKIN FLAP

Hajime Matsumura; Naoki Yoshizawa; Katsueki Watanabe; Nicholas B. Vedder

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Akira Sugamata

Tokyo Medical University

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Isaku Okamoto

Tokyo Medical University

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Kaori Tsuji

Tokyo Medical University

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Kenji Hanyu

Tokyo Medical University

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