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Hiroyasu Yamashiro

Publications and source records attributed to Hiroyasu Yamashiro.

8 recordsLinked to original sources
PubMed2006

In situ regeneration of adipose tissue in rat fat pad by combining a collagen scaffold with gelatin microspheres containing basic fibroblast growth factor.

This study is an investigation to evaluate in situ adipose tissue regeneration in fat pads. Gelatin microspheres with different water contents were prepared for the controlled release of basic fibroblast growth factor (bFGF). After a collagen sponge scaffold was incorporated by the microspheres containing 0, 0.01, 0.1, 1, and 10 microg of bFGF with or without syngeneic rat preadipocytes (1 x 10(5) cells/site) into a defect of rat fat pad, adipogenesis at the implanted site of scaffold was evaluated histologically. in situ formation of adipose tissue accompanied with angiogenesis was observed in the scaffold implanted with the microspheres containing 1.0 microg of bFGF, although the extent was less at the lower and higher bFGF doses. The in situ formation induced by the microspheres containing bFGF was significantly higher than that induced by free bFGF of the same dose. Adipogenesis was enhanced with time after implantation up to 4 weeks and thereafter leveled off. Such in situ adipogenesis was reproducibly induced by implantation of collagen scaffold incorporating gelatin microspheres containing 1 microg of bFGF, whereas addition of rat syngeneic preadipocytes did not promote the adipogenesis. The degradation of microspheres and the consequent FGF release became faster with an increase in the water content of gelatin microspheres. Less in situ formation of adipose tissue was observed at the lower water content of microspheres, which showed longer-term bFGF release. We conclude that combination of scaffold collagen with an appropriate controlled release of bFGF was essential to achieve the in situ formation of adipose tissue even without preadipocytes.

Adipose Tissue↗
PubMed2006

Evidence-based risk factors for seroma formation in breast surgery.

BACKGROUND: Seroma is a common problem in breast surgery. The aim of this systematic review was to identify risk factors for seroma formation. METHODS: Articles published in English were obtained from searches of Medline and additional references were found in the bibliographies of these articles. Risk factors were graded according to the quality and strength of evidence and to the direction of association. RESULTS: One meta-analysis, 51 randomized controlled trials, 7 prospective studies and 7 retrospective studies were identified. There was no risk factor supported by strong evidence, but there was moderate evidence to support a risk for seroma formation in individuals with heavier body weight, extended radical mastectomy as compared with simple mastectomy, and greater drainage volume in the initial 3 days. On the other hand, the following factors did not have a significant influence on seroma formation: duration of drainage; hormone receptor status; immobilization of the shoulder; intensity of negative suction pressure; lymph node status or lymph node positivity; number of drains; number of removed lymph nodes; previous biopsy; removal of drains on the fifth postoperative day versus when daily drainage volume fell to minimal; stage; type of drainage (closed suction versus static drainage); and use of fibrinolysis inhibitor. In contrast, sentinel lymph node biopsy reduced seroma formation. Evidence was weak, or unproven, for other factors that were commonly cited in the literature. CONCLUSIONS: Although a number of factors have been correlated with seroma formation, strong evidence is still scarce. However, there is evidence showing that sentinel lymph node biopsy reduces seroma formation.

Breast Neoplasms↗
PubMed2006

Effect of mechanical closure of dead space on seroma formation after breast surgery.

Seroma, a collection of serous fluid, is the most common problem after breast surgery. The aim of this study was to review the effect of mechanical closure of dead space on seroma formation after breast surgery. There are two mechanical methods for closure of the dead space beneath skin flaps: compression by external pressure, and fixation of the flaps with sutures. There is no evidence to suggest that the routine use of a pressure garment or compression dressing is beneficial. However, it appears that suture flap fixation does reduce seroma formation, simplify postoperative care and dressing, and thus allow early removal of drains and discharge. Drains are helpful for mechanical closure of dead space, but in breast-conserving surgery this technique may preclude the use of a drain. However, previous studies have often been small in scale and poor in quality. Further studies should examine the effect of this technique on quality of life, cosmesis, and medical economics.

Breast Neoplasms↗
PubMed2005

Pathophysiology of seroma in breast cancer.

PURPOSE: Seroma is the most common complication of mastectomy. The aim of this systematic review is to clarify the pathophysiology of seroma. MATERIALS AND METHODS: A computer-assisted MEDLINE search was conducted, and additional references were found in the bibliographies of these articles. The reference terms ''breast cancer'', ''mastectomy'', ''seroma'', ''lymphocele'' and ''lymphocyst'' were used as both keyword and subject terms. The search was limited to studies published in English. RESULTS: The definition of seroma was highly variable across studies, but was most commonly a seroma large enough to be noticed by the patient or medical staff and affecting the patient's satisfaction in the immediate or acute postoperative period. So far, only limited data are available on the severity of seroma. With respect to the pathophysiology of seroma, the data indicated that several anatomical factors, especially dead space, likely contribute to seroma formation. However, it was obscure whether seroma was due to lymph-like fluid or exudate. CONCLUSION: There is considerable variability in the way seroma is defined across studies, and its pathophysiology remains uncertain.

Breast Neoplasms↗
PubMed2004

Current status of antibody therapy for breast cancer.

Antibody therapy with trastuzumab has greatly impacted breast cancer treatment. Combination treatment with trastuzumab is regarded currently as a first-line therapy for metastatic breast cancers that overexpress Her-2. It has become routine practice to examine the status of Her-2 expression in primary tumors. The impact of this therapy might be as great as that of endocrine therapy from a historical point of view. A number of new approaches using trastuzumab for seeking individualized treatment are being tested in current clinical trials. We reviewed recent advances in trastuzumab treatment and discuss the future of antibody therapy for breast cancer.

Antibodies, Monoclonal↗
PubMed2004

[Trastuzumab treatment for breast cancer].

Trastuzumab is a recombinant humanized monoclonal antibody directed against the HER-2. HER-2 is overexpressed in 20-25% of invasive breast cancer and known as poor prognostic factor and its status of a tumor is related to response to trastuzumab. Combination therapy with trastuzumab and chemotherapy increases response rate, time to progression, and survival thus trastuzumab is perceived to be the first line treatment for HER-2 overexpressed metastatic breast cancer. The optimal duration and period of trastuzumab treatment are still unknown and result of large scale randomized trial will be expected.

Antibodies, Monoclonal↗
PubMed2003

Efficient proliferation and adipose differentiation of human adipose tissue-derived vascular stromal cells transfected with basic fibroblast growth factor gene.

Human vascular stromal (VS) cells obtained from mature adipose tissue were transfected with an adenovirus vector carrying the basic fibroblast growth factor (bFGF) gene. bFGF protein was observed in VS cell nuclei 24 h after transfection and in the cytoplasm and extracellular space 72 h after transfection. Naive VS cells were almost static in vitro and proliferated in a dose-dependent manner on stimulation with recombinant bFGF (rbFGF). However, bFGF-transfected VS cells proliferated spontaneously to the same extent as naive VS cells when stimulated with rbFGF at 100 ng/ml. The former cells started to proliferate on day 3 after transfection and the proliferation pattern was similar to that of the latter cells, although only a slight amount of bFGF protein was detected in the culture medium when the bFGF-transfected cells started to proliferate. The proliferation of bFGF-transfected VS cells was completely inhibited by bFGF neutralizing antibody, which also completely inhibited the proliferation of naive VS cells stimulated with rbFGF. Under conditions favoring differentiation to adipocytes, bFGF-transfected VS cells stopped proliferating and started to accumulate lipid in the cytoplasm. bFGF-transfected VS cells, which spontaneously and efficiently proliferate while preserving their ability to differentiate into adipocytes, may be an adequate cell source for human adipose tissue regeneration.

Adipose Tissue↗