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Biomedical subjects

Yoshio Nakayama

Publications and source records attributed to Yoshio Nakayama.

12 recordsLinked to original sources
PubMed2006

Crystal structure of the high-pressure phase of hexahydro-1,3,5-trinitro-1,3,5-triazine (gamma-RDX).

The crystal structure of the high-pressure phase of hexahydro-1,3,5-trinitro-1,3,5-triazine (gamma-RDX), which is stable above 4 GPa at room temperature, was investigated by using infrared spectroscopy and powder X-ray diffraction measurements followed by Rietveld refinements using a diamond anvil cell (DAC). Although gamma and alpha phases were found to belong to the same space group Pbca, they exhibited a different crystal packing. The molecular structure of the gamma phase exhibited the same conformation as that of the alpha phase; however, the torsion angles of N-NO2 changed marginally.

Journal Article↗
PubMed2006

A new surgical method for treating lateral ray polydactyly with brachydactyly of the foot: lengthening the reconstructed fifth toe.

Lateral ray polydactyly is the most common anomaly of the foot. However, when both the fifth and sixth toes are markedly shorter than a normal toe, reconstruction of a normal-length fifth toe has not been performed, because the toe rarely serves a functional purpose. The authors devised a new method whereby the fifth toe could be lengthened using the excess toe as a composite flap. Fifteen patients (15 toes) underwent our procedures and were evaluated in this study. The stepladder island flap is used. The decision as to which toe to use as the flap was made preoperatively based on nail size, and its morphologic and radiographic conditions. Stepladder incision lines were designed on the dorsal and plantar sides of the duplication. Care was taken to preserve the neurovascular bundle with the subcutaneous pedicle and osteotomies were made at the middle phalanx of the flap and the distal or middle phalanx of the recipient in almost all cases. The elevated composite toe flap was advanced and the bone was fixed rigidly for 1-2 months after the operation. During our follow-up periods, the reconstructed toes grew normally, and good aesthetic results had been achieved apart from the bulkiness of the reconstructed toes. There was no deficiency in circulation or function for walking, running, or shoe-fitting in this series.

Child↗
PubMed2006

[Stepwise technique of the proximal anastomosis with the new proximal anastomotic system for the prevention of kinking of the graft].

In using the proximal anastomotic system, the anastomotic site should be carefully selected to prevent the kinking of the graft, because the angle of the graft and the aortic wall is perpendicular. There recommended anastomotic sites are the left lateral aortic wall adjacent to the pulmonary artery for the left coronary system grafting and the lower aortic wall adjacent to the right atrium for the right coronary system grafting respectively. When the selection of these sites are difficult because of the atherosclerotic lesion of the aorta, the short vein graft (2-3 cm) was first anastomosed with PAS-Port device to the site free from atherosclerosis. Then, the long vein graft was anastomosed to the short graft with monofilament suture under end-to-side fashion. The angle of the anastomosis was decided according to the relationship of the aorta and the target coronary artery to establish a smooth graft line. By this stepwise technique, the optimal graft design could be obtained without a risk of the kinking of the graft.

Anastomosis, Surgical↗
PubMed2004

Dermal neoformation during skin wound healing as demonstrated using scanning electron microscopy.

Little is known about how the structures of connective tissue newly form during the wound-healing process. The authors investigated the repair process of excised skin wounds using alkali water cell maceration scanning electron microscopy. The development of the papillary dermis on the granulation surface proceeded toward the center of the wound, coupled with epidermis migration. No papillary dermis was evident on the granulation surface that had yet to be epithelialized. Finally, a layered structure as observed in normal dermis was reconstructed in the scar tissue. In other words, epidermis, basement membrane, and papillary dermis developed on the granulation surface accompanying epidermal migration, and reticular dermis as the result of maturation of granulation tissue. These findings demonstrate that both the papillary dermis and the reticular dermis develop differently after wounding, and that new papillary dermis and new epidermis develops as if completing "a unit" during the epithelialization process. The authors denote this unit the epithelialization unit.

Animals↗
PubMed2003

Nevoid basal cell carcinoma syndrome: report of an aggressive case with ethmoid sinus invasion.

Nevoid basal cell carcinoma syndrome, also referred to as Gorlin-Goltz syndrome, is a rare autosomal dominant disorder characterized by multiple basal cell carcinomas, jaw cysts, palmar or plantar pits, ectopic calcification of the falx cerebri, and various skeletal developmental abnormalities. A minority of basal cell carcinomas demonstrate aggressive behavior and involve the craniofacial bones in nevoid basal cell carcinoma syndrome. A non-familial case of nevoid basal cell carcinoma syndrome with a basal cell carcinoma of the eyelid invading to the ethmoid sinus is reported.

Aged↗
PubMed2003

Treatment of nevus using medical tattooing.

Medical tattooing is used to color skin with a pigment loss. Currently, however, a trial-and-error scheme is employed to obtain the desired color appearance of tattooed skin because prediction of the color appearance is dependent on the experiences of medical doctors. We propose a method for predicting the color appearance of tattooed skin. Two trial dyes are first injected in the area of pigment loss, and the color appearance of a third dye to be injected can be predicted using measured spectrocolorimeter data and mathematical formula. The spectrocolorimeter measures the color appearances of the skin before and after tattooing using the first two dyes, and the mathematical formula calculates the color appearance of the tattooed skin using any third dye. In the derivation of the mathematical formula, light propagation in the skin has been modeled using the modified Lambert-Beer law considering the strong scattering of light by biological tissues. The proposed method was successfully validated by a preliminary tattooing of the skin to an area with pigment loss. Predicting the color appearance of tattooed skin significantly reduces the number of trial-and-error attempts required in the current methods. Medical tattooing using this method can also be applied to treat various skin color abnormalities such as leukoderma, intradermal nevi, and reconstructed nipples.

Colorimetry↗
PubMed2003

Inverse estimation of the acoustic impedance of a porous woven hose from measured transmission coefficients.

A porous tube, comprised of a resin-coated woven fabric has recently been used as an effective component for use in intake systems of internal combustion engines to reduce the intake noise. For the prediction of the acoustic performance of an engine intake system with a porous woven hose, the acoustic wall impedance of the hose must be known. However, the accurate measurement of the wall impedance of a porous woven hose is not easy because of its peculiar acoustical and structural characteristics. A new measurement technique is proposed herein, that is valid over the low to mid frequency ranges. The acoustics impedance is inversely estimated from an overdetermined set of measured pressure transmission coefficients for specimens of different lengths and the reflection coefficient of end termination. The method involves only one measurement setup, and, as a result, it is very simple. A variation of the proposed method, an inverse estimation method using one of the four-pole parameters is also proposed. An error sensitivity analysis was performed to investigate the effect of measurement error on the accuracy of the final result. The measured TL for samples with arbitrary lengths and arbitrary porous frequency are in reasonably good agreement with values predicted from curve-fitted impedance data.

Journal Article↗
PubMed2002

Microtransfers for nail and fingertip replacement.

We have reported the cases of vascularized nail flap transfer with a short pedicle fashion. We consider that reconstruction of fingers should be conducted positively, even in the case of the nail defect, except the thumb. Because these operations are aimed at aesthetic improvement, reconstruction with a short pedicle fashion seems to be the method worth employing because it leaves short skin incisions. The final goal of nail surgery is for the patients to use the reconstructed finger in public. To achieve this goal, we must keep in our mind the aesthetic considerations in nail surgery.

Adolescent↗
PubMedDate not supplied

In vivo study of the effects of cryopreservation on heart valve xenotransplantation.

BACKGROUND: Recent reports have suggested that cryopreservation reduces the immunogenicity of donor tissue. The immunomodulation by cryopreservation might influence on the tissue durability after xenotransplantation. We investigated the in vivo morphologic changes in cryopreserved xenograft (CXG) heart valves. MATERIAL AND METHOD: We transplanted a fresh (fresh xenograft; FXG) and a cryopreserved (CXG) porcine aortic root and a cryopreserved canine (cryopreserved allograft; CAG) aortic root into the abdominal aorta of a dog without any immunosuppressive agents. Explanted grafts on the 21st to 49th days after implantation were analyzed morphologically with light microscopy using some special stains, immunohistochemical analysis, and scanning electron microscopy (SEM). RESULT: Light microscopy showed the absence of smooth muscle cells in the media of the aorta in any group after transplantation. FXG valves did not maintain any cellularity after transplantation. CXG valves contained cellular infiltration in themselves. CAG valves contained numerous fibroblasts, which showed the maintenance of tissue integrity without allowing cellular infiltration. The structure of elastic fibers was well maintained, even in the part of CXG valve with cellular infiltration. Immunohistochemical studies documented the infiltration of T lymphocytes in CXG valves that were labeled by anti-CD3 antibodies. SEM demonstrated that no endothelia were seen on the surface of the valves in any group after transplantation. CONCLUSION: We concluded that the cryopreservation method might provide an immunomodulation of xenogeneic heart valves for transplantation.

Animals↗
PubMedDate not supplied

Conjunctival squamous cell carcinoma of the orbit 40 years after enucleation.

Conjunctival squamous cell carcinoma developed in a 51-year-old man 40 years after he had enucleation of his left eye because of an explosion injury. He had worn several ocular prostheses for more than 40 years. Recently he had noticed an increasing sanguineous conjunctival discharge, a foreign body sensation, and swelling of his left lower eyelid. Incisional biopsies of an underlying conjunctival mass revealed squamous cell carcinoma. His work history did not involve exposure to radiation, chemicals, or the sun. The authors concluded that squamous cell carcinoma in this case was caused by chronic irritation as the result of long-standing use of a poorly fitting ocular prosthesis.

Blast Injuries↗