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Biomedical subjects

Takashi Nakatsuka

Publications and source records attributed to Takashi Nakatsuka.

At least 19 recordsLinked to original sources
PubMed2006

Cartilage tissue engineering using human auricular chondrocytes embedded in different hydrogel materials.

To seek a suitable scaffold for cartilage tissue engineering, we compared various hydrogel materials originating from animals, plants, or synthetic peptides. Human auricular chondrocytes were embedded in atelopeptide collagen, alginate, or PuraMatrix, all of which are or will soon be clinically available. The chondrocytes in the atelopeptide collagen proliferated well, while the others showed no proliferation. A high-cell density culture within each hydrogel enhanced the expression of collagen type II mRNA, when compared with that without hydrogel. By stimulation with insulin and BMP-2, collagen type II and glycosaminoglycan were significantly accumulated within all hydrogels. Chondrocytes in the atelopeptide collagen showed high expression of beta1 integrin, seemingly promoting cell-matrix signaling. The N-cadherin expression was inhibited in the alginate, implying that decrease in cell-to-cell contacts may maintain chondrocyte activity. The matrix synthesis in PuraMatrix was less than that in others, while its Young's modulus was the lowest, suggesting a weakness in gelling ability and storage of cells and matrices. Considering biological effects and clinical availability, atelopeptide collagen may be accessible for clinical use. However, because synthetic peptides can control the risk of disease transmission and immunoreactivities, some improvement in gelling ability would provide a more useful hydrogel for ideal cartilage regeneration.

Atrial Appendage↗
PubMed2006

Hepatic artery reconstruction with double-needle microsuture in living-donor liver transplantation.

In living-donor liver transplantation (LDLT), reconstruction of the hepatic artery is challenging because the recipient artery is located deep in the abdominal cavity and the operating field is limited. Also, the hepatic artery of the graft is short and the recipient artery is occasionally damaged. To overcome these difficulties, we developed a double-needle microsuture technique for artery reconstruction. A total of 161 adult patients received 163 LDLTs using this new technique. The first suture was placed at the most difficult point in the artery to be visualized through the microscope. Each stitch was placed from the inner side of the arterial wall to the outer side. The posterior stitch was tied pulling toward the back. The subsequent sutures were advanced anteriorly on either side adjacent to the previous suture. Hepatic artery thrombosis occurred in 4 patients (2.5%), only 2 (1.2%) of which were associated with arterial reconstruction. Intimal dissection developed in the recipient artery in 2 patients (1.2%). Three (50%) of these 6 complications occurred more than 10 days after LDLT. In conclusion, this suturing technique allows for safe intimal adaptation even when the arterial tunica intima is separated from the tunica media, because all stitches are carried from inside of the vessel to the outside, contributing to more satisfactory results.

Adult↗
PubMed2006

Clinical evaluation and morbidity of 201 free jejunal transfers for oesophagopharyngeal reconstruction during the 20 years 1984-2003.

We evaluated 192 patients who had 201 free jejunal transfers for oesophagopharyngeal reconstruction during the 20 years 1984-2003. The main postoperative complications were thrombosis, leaks, and stenosis. In this series, the rate of thrombosis was 7/201 (3.5%), that of leaks was 17/201 (8.5%), and that of stenosis was 25/201 (13.0%). When we assessed the relation between pre-existing conditions, surgical techniques, and these complications, we found only one significant difference: a history of alcohol misuse was associated with a reduction in the incidence of thrombosis. The surgical techniques did not affect the development of leaks or stenosis, which means that a complicated surgical technique is unnecessary.

Adult↗
PubMed2006

Standardization of free jejunum transfer after total pharyngolaryngoesophagectomy.

OBJECTIVE: Our latest free jejunum transfer procedure was reviewed and compared with previous procedures to standardize the operation. METHODS: This was a retrospective study of 269 patients who had undergone total pharyngolaryngoesophagectomy and free jejunum transfer from 1992 through 2004. The patients were divided into two groups: a late group, in which surgery was performed with our latest standard procedure from 2000 through 2004, and an early group, in which various procedures had been used from 1992 through 1999. Surgical times, postoperative progress, and complications were evaluated. RESULTS: The mean surgical time was shortened from 3 hours 25 minutes in the early group to 3 hours 9 minutes in the late group, and ischemic time was shortened from 2 hours 44 minutes to 2 hours 20 minutes. For recipient vessels, branches of the external carotid artery and the internal jugular vein were more often used in the late group. Length of hospitalization decreased from 31.7 days in the early group to 24.4 days in the late group, although the start of drinking was similar (15.4 days versus 12.1 days). The rates of complications were significantly reduced in the late group, particularly those associated with the enteric anastomosis such as minor leakage (18.2-5.2%) and stenosis (17.6-3.0%). CONCLUSION: Our latest method of free jejunum transfer reconstruction has become reliable and expeditious through simple and stable minor revisions of procedures.

Esophagectomy↗
PubMed2006

Availability of end-to-side arterial anastomosis to the external carotid artery using short-thread double-needle microsuture in free-flap transfer for head and neck reconstruction.

We seldom have difficulties in the selection of appropriate recipient arteries for microvascular free flap transfer in the head and neck region because many sizable branches (branch artery) of the external carotid artery (ECA) or subclavian artery are available. However, we occasionally encountered the lack of an appropriate recipient artery, especially in secondary reconstruction or reconstruction following the extensive ablation of recurrent cancer. For these challenging cases, we have used end-to-side arterial anastomosis directly to the ECA. Between July 1997 and December 2004, end-to-side anastomosis of the flap artery to the ECA was employed in 16 cases. The reason for its use included the marked size discrepancy between the jejunal artery and branch artery in 4 jejunal transfer cases, the lack of 2 appropriate recipient arteries for double free flap transfers in 1 case, and the lack of an available branch artery as a recipient due to poor regional conditions in 11 cases. Fifteen of 16 flaps underwent an uneventful postoperative course, except 1 whose flap artery was pressed by the submandibular gland and sustained thrombosis 3 days postoperatively. In this case, however, the flap survived perfectly after prompt thrombectomy and reanastomosis. Eventually, all 16 flaps survived completely. We reconfirmed the availability of end-to-side anastomosis to the ECA when a suitable branch artery is not available. Although end-to-side anastomosis to the ECA is laborious compared with end-to-end anastomosis, our newly developed short-thread double-needle microsuture combined with the back-wall-first technique helps to ensure easier anastomosis. Using this device, because all stitches are carried from inside the vessel to outside, the surgeon can place the first stitch at any point on the posterior wall and advance the next suture to the preferred site of the previous suture, and suturing can be performed more safely even in cases where the tunica intima is separated from the tunica media due to arteriosclerosis, previous irradiation, or surgery.

Adolescent↗
PubMed2005

Two different transposable elements inserted in flavonoid 3',5'-hydroxylase gene contribute to pink flower coloration in Gentiana scabra.

Pink-flowered gentian plants (Gentiana scabra) have been bred from spontaneous mutations of blue-flowered gentian plants, but the formation mechanism(s) is unknown so far. To investigate the process, two independent pink-flowered gentian plant lines were analyzed by a molecular biological approach. HPLC analysis showed that petals of the blue-flowered cultivar contained a small amount of cyanidin derivatives and major delphinidin derivatives, whereas pink petals had only a small amount of cyanidin derivatives. To find the causal factor(s) of this change, we focused on flavonoid 3',5'-hydroxylase (F3',5'H), which is a key enzyme for delphinidin biosynthesis in the flavonoid biosynthetic pathway. Molecular analyses confirmed that the loss of delphinidin synthesis could be attributed to the insertions of different transposable elements in the F3',5'H gene in each independent pink-flowered gentian plant. Sequence analysis showed that these transposable elements were classified into an hAT superfamily and terminal-repeat retrotransposon in miniature (TRIM), by which normal F3',5'H transcripts were interrupted. Southern blot analysis indicated that they belong to high copy number elements and are also found in a related gentian species (G. triflora). These results suggest that the transposable elements inserted in F3',5'H are the source of the mutations and may also play a substantial role in the genomic evolution of the genus Gentiana.

Amino Acid Sequence↗
PubMed2005

Flavonoid components and flower color change in transgenic tobacco plants by suppression of chalcone isomerase gene.

A cDNA encoding chalcone isomerase (CHI) was isolated from the petals of Nicotiana tabacum and the effect of its suppression on flavonoid biosynthesis was analyzed in transgenic tobacco plants. CHI-suppression by RNA interference (RNAi) showed reduced pigmentation and change of flavonoid components in flower petals. The plants also accumulated high levels of chalcone in pollen, showing a yellow coloration. Our results first demonstrated that suppression of CHI by genetic transformation is possible in higher plants. This suggests that CHI plays a major part in the cyclization reaction from chalcone to flavanone, and that spontaneous reactions are few, if any, in tobacco plants.

Chalcone↗
PubMed2005

Bone marrow-impregnated collagen matrix for wound healing: experimental evaluation in a microcirculatory model of angiogenesis, and clinical experience.

OBJECTIVES: This study aims to investigate the effect of collagen matrix impregnated with bone marrow on wound healing angiogenesis in an effective microcirculatory model and to describe our clinical experience. METHODS: We used a skinfold chamber of original design which visualises microcirculation following wound creation on the dorsal skin of the mouse to establish an in vivo experimental model to estimate angiogenesis. Animals were divided into two groups: a bone marrow group (n = 6) in which bone marrow-impregnated collagen matrix was applied to the wound; and a control group (n = 7), in which collagen immersed in saline was applied, and functional capillary density was quantified during the repair process. RESULTS: The increase rate in functional capillary density during wound healing significantly increased in the bone marrow group on days 3, 5 and 7 after creation of the wound but no significant difference was detected on day 10. A patient with a chronic leg ulcer that had not responded to conventional therapy for 1 year was treated with autogenous bone marrow-impregnated collagen matrix and successful wound closure was obtained. CONCLUSION: The present study suggested that collagen matrix impregnated with bone marrow significantly promoted the repair process, especially in the early stage. The features of the treatment, including the possible use of a patient's own cells, simple method, immediate application without any processing procedure and preservation of the inclusive potentiality of bone marrow suspension, offer significant advantages in terms of the anticipated routine clinical use.

Animals↗
PubMed2005

A peroxiredoxin Q homolog from gentians is involved in both resistance against fungal disease and oxidative stress.

An antifungal protein (GtAFP1) showing antimicrobial activity against phytopathogenic fungi was purified from leaves of Gentiana triflora. The deduced amino acid sequence of the cDNA of the corresponding gene, GtAFP1, showed 94, 75, 72 and 63% amino acid identities with peroxiredoxin Q from Populus balsamifera x P. deltoides subsp. trichocarpa, Sedum lineare, Suaeda maritima and Arabidopsis thaliana, respectively. The GtAFP1 gene is suggested to be present in the genome in one to two copies and was expressed in the leaves, roots and stems. Expression of GtAFP1 was induced by treatment with salicylic acid, but not methyl jasmonate. Recombinant GtAFP1 protein showed not only antifungal activity but also thioredoxin-dependent peroxidase activity. Overexpression of GtAFP1 in tobacco plants improved tolerance not only against fungal diseases but also against oxidative stress. These results indicate that GtAFP1 might act as a disease and oxidative stress defensive gene in plants and could be useful for engineering stress-resistant plants.

Amino Acid Sequence↗
PubMed2005

Choice of osseous and osteocutaneous flaps for mandibular reconstruction.

Microvascular free flap transfer currently represents one of the most popular methods for mandibular reconstruction. With the various free flap options now available, there is a general consensus that no single kind of osseous or osteocutaneous flap can resolve the entire spectrum of mandibular defects. A suitable flap, therefore, should be selected according to the specific type of bone and soft tissue defect. We have developed an algorithm for mandibular reconstruction, in which the bony defect is termed as either "lateral" or "anterior" and the soft-tissue defect is classified as "none," "skin or mucosal," or "through-and-through." For proper flap selection, the bony defect condition should be considered first, followed by the soft-tissue defect condition. When the bony defect is "lateral" and the soft tissue is not defective, the ilium is the best choice. When the bony defect is "lateral" and a small "skin or mucosal" soft-tissue defect is present, the fibula represents the optimal choice. When the bony defect is "lateral" and an extensive "skin or mucosal" or "through-and-through" soft-tissue defect exists, the scapula should be selected. When the bony defect is "anterior," the fibula should always be selected. However, when an "anterior" bone defect also displays an "extensive" or "through-and-through" soft-tissue defect, the fibula should be used with other soft-tissue flaps. Flaps such as a forearm flap, anterior thigh flap, or rectus abdominis musculocutaneous flap are suitable, depending on the size of the soft-tissue defect.

Bone Transplantation↗
PubMed2005

Total reconstruction of the upper lip after resection of a malignant melanoma.

The upper lip was totally reconstructed with a radial forearm sensory flap and vermilionplasty using medical tattooing after resection of a malignant melanoma. Three courses of chemotherapy (dacarbazine, nimustine, and vincristine) were given postoperatively. The reconstructed lip had good contour, colour, and sensory recovery.

Aged↗
PubMed2005

Secondary reconstruction of failed esophageal reconstruction.

Between June 1992 and November 2002, 17 patients underwent secondary reconstruction of circumferential esophageal defects due to the failure of immediate reconstruction following ablation of thoracic esophageal cancer. Salvage reconstruction was achieved using free jejunal transfer in 13 patients (including long segment with double vascular pedicle in 2 cases), skin and/or musculocutaneous flap in 2 cases, and jejunal pull-up in 2 cases. In 5 patients, the second salvage surgery was required because of the failed first salvage. However, successful restoration of the esophagus and peroral alimentation was finally achieved in 16 of 17 patients, except 1 patient with several salvage operations using skin and musculocutaneous flap because the gut was unusable. We concluded that the preferred first choice for salvage restoration is free jejunal transfer. If the length of the esophageal defect is extensive, colonic interposition or jejunal pedicle with microvascular anastomosis for supercharging is the next option. If these procedures cannot be used, the transfer of a long jejunal segment with double vascular pedicles is recommended. Reconstruction using skin and/or musculocutaneous flap is the final option. As primary wound closure is often difficult in secondary reconstruction of the esophagus, a pectoralis major musculocutaneous flap is reliable to cover the reconstructed esophagus because skin flaps located in the neck region may be damaged by neck dissection or irradiation, and coverage of the anastomosis with muscle between the digestive tracts is effective to prevent leakage.

Aged↗
PubMed2005

Consistent transcriptional silencing of 35S-driven transgenes in gentian.

In this study, no transgenic gentian (Gentiana triflora x Gentiana scabra) plants produced via Agrobacterium-mediated transformation exhibited transgene (GtMADS, gentian-derived MADS-box genes or sGFP, green fluorescent protein) expression in their leaf tissues, despite the use of constitutive Cauliflower mosaic virus (CaMV) 35S promoter. Strikingly, no expression of the selectable marker gene (bar) used for bialaphos selection was observed. To investigate the possible cause of this drastic transgene silencing, methylation-specific sequences were analysed by bisulfite genomic sequencing using tobacco transformants as a control. Highly methylated cytosine residues of CpG and CpWpG (W contains A or T) sites were distinctively detected in the promoter and 5' coding regions of the transgenes 35S-bar and 35S-GtMADS in all gentian lines analysed. These lines also exhibited various degrees of cytosine methylation in asymmetrical sequences. The methylation frequencies in the other transgene, nopaline synthase (NOS) promoter-driven nptII, and the endogenous GtMADS gene coding region, were much lower and were variable compared with those in the 35S promoter regions. Transgene methylation was observed in the bialaphos-selected transgenic calluses expressing the transgenes, and methylation sequences were distributed preferentially around the as-1 element in the 35S promoter. Calluses derived from leaf tissues of silenced transgenic gentian also exhibited transgene suppression, but expression was recovered by treatment with the methylation inhibitor 5-aza-2'-deoxycytidine (aza-dC). These results indicated that cytosine methylation occurs exclusively in the 35S promoter regions of the expressed transgenes during selection of gentian transformants, causing transcriptional gene silencing.

Base Sequence↗
PubMed2005

Two cases of Tessier no. 4 cleft with anophthalmia.

OBJECTIVE: Tessier no. 4 cleft is a very rare craniofacial anomaly, and the primary surgical procedure has not been definitely standardized. The cheek advancement flap, technique, which was first reported by Van der Meulen (1985), has produced cosmetically favorable results. In this report, two cases with Tessier no. 4 cleft, which were treated with the cheek advancement flap technique, are presented. DESIGN AND PATIENTS: The first case was unilateral and the second was bilateral, and both were accompanied with anophthalmia on the cleft side. At the primary operation, dissection of the nasal soft tissue, medial canthopexy, and reconstruction of the lower eyelid and conjunctival fornix were performed. Cleft lip was repaired according to the rotation-advancement procedure. RESULTS AND CONCLUSIONS: Postoperative appearances were acceptable in both cases, because the resulting scars were made along the esthetic facial units. However, the soft tissue deficiency of the lower eyelid was prominent. Furthermore, in the unilateral case, caudal displacement of the palpebral fissure and cephalic deviation of the nasal ala was recognized.

Anophthalmos↗
PubMed2005

Synergistic effects of FGF-2 with insulin or IGF-I on the proliferation of human auricular chondrocytes.

Chondrocyte preparation with the safety and efficiency is the first step in cartilage regenerative medicine. To prepare a chondrocyte proliferation medium that does not contain fetal bovine serum (FBS) and that provides more than a 1000-fold increase in cell numbers within approximately 1 month, we attempted to use the medium containing 5% human serum (HS), but it exerted no more than twofold increase in 2 weeks. To compensate for the limited proliferation ability in HS, we investigated the combinational effects of 12 factors [i.e., fibroblast growth factor (FGF)-2, insulin-like growth factor (IGF)-I, insulin, bone morphogenetic protein-2, parathyroid hormone, growth hormone, dexamethasone, 1alpha25-dihydroxy vitamin D3, L-3,3',5'-triodothyronine, interleukine-1 receptor antagonist, 17beta-estradiol, and testosterone] on the proliferation of human auricular chondrocytes by analysis of variance in fractional factorial design. As a result, FGF-2, dexamethasone, insulin, and IGF-I possessed promotional effects on proliferation, while the combination of FGF-2 with insulin or IGF-I synergistically enhanced the proliferation. Actually, the chondrocytes increased 7.5-fold in number in 2 weeks in a medium containing 5% HS with 10 ng/ml FGF-2, while the cell number synergistically gained a 10-12-fold increase with 5 microg/ml insulin or 100 ng/ml IGF-I in the same period. The proliferation effects were more enhanced at a concentration of 100 ng/ml for FGF-2, and especially for the combination of 100 ng/ml FGF-2 and 5 microg/ml insulin (approximately 16-fold within 2 weeks). In the long-term culture with repeated passaging, this combination provided more than 10,000-fold within 8 weeks (i.e., passage 4). Thus, we concluded that such a combination of FGF-2 with insulin or IGF-I may be useful for promotion of auricular chondrocyte proliferation in a clinical application for cartilage regeneration.

Adolescent↗
PubMed2004

Distal perforator-based fasciocutaneous V-Y flap for treatment of sacral pressure ulcers.

Although the gluteal V-Y advancement flap has been recognized as the most reliable method for management of sacral pressure ulcers, its limited mobility has been a challenging problem. The authors present a new modification of the V-Y advancement flap to overcome the problem. After débridement, a large triangle is designed to create a V-Yadvancement flap on the unilateral buttock and the medial half is elevated as a fasciocutaneous flap, preserving the distal perforators in the muscular attachment. Then an arc-shaped incision is made in the gluteus maximus muscle along with the lateral edge of the triangular flap. The split muscle is elevated at a depth above the deeper fascia until sufficient advancement of the flap is obtained. This full-thickness elevation of the gluteus maximus muscle from the distal (lateral) side avoids the impairment of perforators or their mother vessels and achieves great advancement. Thirty-one patients with sacral pressure defects larger than 8 cm in diameter were treated using this surgical procedure. Overall, 93.5 percent of the flaps (29 of 31) healed primarily. The largest defect that was closed with a unilateral flap was 16 cm in diameter. The present technique accomplishes remarkable excursion of the unilateral V-Y fasciocutaneous flap, with high flap reliability and preservation of the contralateral buttock as well as gluteus maximus muscle function.

Adult↗