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Koichi Gonda

Publications and source records attributed to Koichi Gonda.

10 recordsLinked to original sources
PubMed2006

Requirement of the protein B23 for nucleolar disassembly induced by the FRGY2a family proteins.

In Xenopus somatic cell nuclear cloning, the nucleoli of donor nuclei rapidly and almost completely disappear in egg cytoplasm. We previously showed that the germ cell-specific proteins FRGY2a and FRGY2b were responsible for this unusually drastic nucleolar disassembly. The nucleolar disassembly occurs without inhibition of pre-rRNA transcription, a well known trigger for nucleolar segregation, and the mechanism for the nucleolar disassembly by FRGY2a and FRGY2b remains largely unknown. In this study, we searched for FRGY2a-interacting proteins and investigated the functional consequences of their interactions through a series of experiments. We showed that during the nucleolar disassembly, FRGY2a localized to the nucleoli of isolated nuclei and was capable of disassembling purified nucleoli, suggesting a direct interaction between FRGY2a and nucleolar components. Using a His tag pulldown approach, we identified the abundant and multifunctional nucleolar protein B23 as a potential target of FRGY2a and its related human protein YB1. A specific interaction between FRGY2a/YB1 and B23 was confirmed by co-immunoprecipitation. Finally, B23 knockdown using short interfering RNA and a subsequent add-back experiment confirmed that B23 was necessary for nucleolar disassembly by YB1. We propose that FRGY2a and YB1 disassemble nucleoli by sequestering B23, which is associated with pre-ribosomes and other structurally important nucleolar components.

Animals↗
PubMed2006

Characterization of freshly isolated and cultured cells derived from the fatty and fluid portions of liposuction aspirates.

Liposuction aspirates (primarily saline solution, blood, and adipose tissue fragments) separate into fatty and fluid portions. Cells isolated from the fatty portion are termed processed lipoaspirate (PLA) cells and contain adipose-derived adherent stromal cells (ASCs). Here we define cells isolated from the fluid portion of liposuction aspirates as liposuction aspirate fluid (LAF) cells. Stromal vascular fractions (SVF) were isolated separately from both portions and characterized under cultured and non-cultured conditions. A comparable number of LAF and PLA cells were freshly isolated, but fewer LAF cells were adherent. CD34+ CD45- cells from fresh LAF isolates were expanded by adherent culture, suggesting that LAF cells contain ASCs. Although freshly isolated PLA and LAF cells have distinct cell surface marker profiles, adherent PLA and LAF cells have quite similar characteristics with regard to growth kinetics, morphology, capacity for differentiation, and surface marker profiles. After plating, both PLA and LAF cells showed significant increased expression of CD29, CD44, CD49d, CD73, CD90, CD105, and CD151 and decreased expression of CD31 and CD45. Multicolor FACS analysis revealed that SVF are composed of heterogeneous cell populations including blood-derived cells (CD45+), ASCs (CD31- CD34+ CD45- CD90+ CD105- CD146-), endothelial (progenitor) cells (CD31+ CD34+ CD45- CD90+ CD105low CD146+), pericytes (CD31- CD34- CD45- CD90+ CD105- CD146+), and other cells. After plating, ASCs showed a dramatic increase in CD105 expression. Although some adherent ASCs lost CD34 expression with increasing culture time, our culture method maintained CD34 expression in ASCs for at least 10-20 weeks. These results suggest that liposuction-derived cells may be useful and valuable for cell-based therapies.

Adipocytes↗
PubMed2006

Nuclear remodeling assay in Xenopus egg extract.

Xenopus egg extract is an ideal material to identify nuclear remodeling activities important for nuclear cloning. Since the protocol for egg extract preparation was established more than 20 yr ago, egg extract has been widely used as a source for the purification of factors associated with a number of physiological activities. The eggs are large, easily obtained in large quantities, and are abundant in a variety of bioactive proteins. Many aspects of somatic nuclear remodeling observed in nuclear cloning are recapitulated in somatic nuclei incubated in egg extract. Our in vitro nuclear remodeling assay has proven effective for the purification of two novel nuclear remodeling activities, ISWI, a key player in the dissociation of TATA binding protein from chromatin, and FRGY2a and FRGY2b, two proteins capable of nucleolar disassembly. Here we outline our protocol of egg extract preparation and in vitro nuclear remodeling assay, as well as the purification method for FRGY2a and FRGY2b. Our in vitro nuclear remodeling assay in combination with egg extract will serve as a powerful tool with which to biochemically uncover molecular events involved in nuclear cloning.

Animals↗
PubMed2006

A supermicrosurgical flap model in the rat: a free true abdominal perforator flap with a short pedicle.

BACKGROUND: Perforator flaps have recently gained considerable popularity in reconstructive surgery, and their importance and advantages over conventional flaps have been widely accepted. Given the improvements in microsurgical techniques, researchers have encouraged the search for further perforator flap sources, such as a perforator flap with a short pedicle only. The purpose of this study was to describe a true perforator flap model with a short vascular pedicle in the abdominal region in the rat. METHODS: Twenty-six adult Sprague-Dawley rats weighing 400 to 500 g were used. In 10 rats, the perforator vascular anatomy of the abdominal region was determined by anatomic dissection. In the remaining 16 rats, a true abdominal perforator-based flap was created based on a short segment of deep epigastric vessels. In eight rats, the flap was transferred to the groin region as a free flap, and anastomosis was performed between the artery and vein of the flap and the superficial inferior epigastric artery and vein of the recipient site. In addition, in two of these flaps, the long thoracic vein of the flap was anastomosed to the femoral vein. In the remaining eight rats, the flap was transferred to the groin region, but in this group anastomosis was not performed. The latter group was designated as the control group. RESULTS: The skin islands of seven free perforator flaps survived completely, and the one remaining flap was determined to be necrotic. All the flaps in the control group underwent complete necrosis. CONCLUSIONS: Not only is the free abdominal perforator flap a reliable and true perforator flap model for future physiological, biological, and pharmacological studies, it is also an excellent self-controlled supermicrosurgical training model for learning proper techniques, meticulous intramuscular dissection of true perforator flaps, and anastomosis of small-caliber vessels.

Anastomosis, Surgical↗
PubMed2006

Repeated treatment protocols for melasma and acquired dermal melanocytosis.

BACKGROUND AND OBJECTIVE: Melasma and acquired dermal melanocytosis (ADM; acquired bilateral nevus of Ota-like macules) are both seen most commonly symmetrically on the face of women with darker skin and are also known as difficult conditions to treat. METHODS: Our topical bleaching protocol with 0.1 to 0.4% tretinoin gel and 5% hydroquinone was performed repeatedly (1-3 times) for melasma (n=163), and a combination treatment with topical bleaching and Q-switched ruby (QSR) laser was performed repeatedly (1-3 times) for ADM (n=62). RESULTS: There is a significant correlation between clinical results (clearance of pigmentation) and the number of sessions in both melasma (p=.019) and ADM (p<.0001). CONCLUSION: The repeated treatment protocol for melasma and ADM showed successful clinical results compared with conventional ones, and they may be applied to other pigment conditions. It may be better that epidermal and dermal pigmentations are treated separately, especially in dark-skinned people who are more likely to suffer postinflammatory hyperpigmentation after inflammation-inducing therapies.

Adult↗
PubMed2005

Treatment of lymphedema with lymphaticovenular anastomoses.

Although lymphedema in the extremities is a troublesome adverse effect following radical resection of various cancers, conventional therapies for lymphedema are not always satisfactory, and new breakthroughs are anticipated. With the introduction of supermicrosurgical techniques for the anastomosis of blood or lymphatic vessels less than 0.8 mm in diameter, we have developed a novel method of lymphaticovenular anastomosis for the treatment of primary as well as secondary lymphedema in the extremities. Here, we review the pathophysiological aspects of lymphedema, emphasizing the importance of smooth-muscle cell function in the affected lymphatic walls. We then describe the theoretical basis and detailed operative techniques of our lymphaticovenular anastomoses. Although technically demanding, especially for beginners, we believe that this method will become a new clinical standard for the treatment of lymphedema in the near future.

Anastomosis, Surgical↗
PubMed2005

Posterior tibial adiposal flap for repair of wide, full-thickness defect of the Achilles tendon.

Wide, full-thickness defects on the posterior aspect of the distal lower leg involving the Achilles tendon are usually repaired with free fasciocutaneous flaps or local skin flaps. The former require microvascular techniques; there is a donor-site scar due to skin grafting; and a longer operating time. The latter results in a wide scar near the donor defect. The authors developed a new reconstructive procedure using local fascia turned over to create a new Achilles tendon, and wrapping it with a posterior tibial adiposal island flap based on the dominant perforator of the posterior tibial artery, which was elevated from the medial aspect of the lower leg. The advantages of this method are that no donor scar appeared on the posterior aspect of the lower leg, and there was no need for microvascular techniques. This method is especially suitable for young women.

Achilles Tendon↗
PubMed2003

Reversible disassembly of somatic nucleoli by the germ cell proteins FRGY2a and FRGY2b.

Egg cytoplasm has the capability to reprogramme differentiated somatic nuclei, as shown by nuclear transplantation in animal cloning. The nucleoli of donor nuclei are rapidly disassembled on injection into interphase eggs and are correctly reassembled when donor transcription initiates in the early embryos of frogs and mammals, recapitulating the physiological nucleolar dynamics of early embryogenesis. This is one of the most remarkable structural reorganizations of somatic nuclei in nuclear cloning. Despite the long history of nuclear cloning, almost nothing is known about the molecular mechanism of nucleolar disassembly in egg cytoplasm. Here we show that the Xenopus germ cell proteins FRGY2a and FRGY2b reversibly disassemble somatic nucleoli in egg cytoplasm, independently of continuing ribosomal RNA transcription. The carboxy-terminal domain of FRGY2a, which localizes to the nucleoli, is sufficient for nucleolar disassembly in transfected cells. Our results show that a single protein fragment can trigger reversible disassembly of the complex nucleolar structure.

Animals↗
PubMedDate not supplied

Anti-androgenic therapy using oral spironolactone for acne vulgaris in Asians.

BACKGROUND: Few studies have addressed anti-androgenic therapy using oral spironolactone for acne in Asians. Obtaining this race-specific information is important because Westerners and Asians respond differently to hormone therapy. This study aimed to examine the efficacy and safety of oral spironolactone used to treat acne in Asians. METHODS: Spironolactone (initial dose, 200 mg/day) was administered orally to 139 Japanese patients (116 females and 23 males) with acne. Serum laboratory data, including various hormones and electrolytes, were examined for 25 of the subjects. RESULTS: Most of the female patients who completed the 20-week regimen exhibited excellent improvement (evaluated by a photographic grading scale), although some discontinued treatment because of menstrual disturbances or other reasons. The treatment was less efficacious for the males than for the females, and because gynecomastia developed in three male patients, spironolactone treatment for males was stopped. Examination of the serum of 25 patients did not identify any toxicity associated with the treatment. Drug eruptions and edema in the lower extremities were each seen in three patients. CONCLUSION: Oral spironolactone is effective and safe for the treatment of acne in Asian females, and can be a good option for severe, recurring, and widespread types of the condition.

Acne Vulgaris↗