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Takumi Takeuchi

Publications and source records attributed to Takumi Takeuchi.

8 recordsLinked to original sources
PubMed2004

Does ICSI require acrosomal disruption? An ultrastructural study.

BACKGROUND: Aggressive immobilization of sperm prior to ICSI significantly improves fertilization rates, but the mechanism of this effect is not yet clear. This study was performed in order to assess the characteristics of mechanically immobilized human sperm by transmission electron microscope (TEM). METHODS: Sperm obtained from ejaculated semen samples from three different donors were immobilized in a standard manner for ICSI. They were then injected into the perivitelline space of mouse oocytes in order to be able to locate them by TEM. Intact motile sperm injected subzonally served as controls (n=160). Finally, the 'carrier' oocytes were fixed and processed for TEM. RESULTS: A total of 300 sperm were mechanically immobilized and inserted into the perivitelline space of mouse oocytes. Ultrathin sections revealed consistent alterations in the acrosomal region including disruption of the plasma membrane, and disruption, vesiculation or even loss of the acrosome. Thus, all of the sperm assessed had undergone some disorganization of the head, in contrast to a majority of control sperm. CONCLUSIONS: Immobilization of sperm for ICSI by compressing and rolling the sperm tails induces a variable disruption and sometimes loss of the acrosome. This could well be a reason for the higher success rates when ICSI is performed using immobilized sperm.

Acrosome↗
PubMed2004

Tiny nodule in the testicle: case report of a sertoli cell tumor.

Sex cord-stromal tumors of the testis are rare. We report on a small Sertoli cell tumor in the testicle. According to published reports, a nodular lesion on the testicle has a variety of differential diagnoses. Preoperatively, it is very difficult to differentiate between a tumorous lesion and an inflammatory change. When a tiny nodule in the testicle is encountered, we propose limited, testicular-sparing surgery according to the frozen section diagnosis.

Adult↗
PubMed2002

Dendritic cell immunotherapy for patients with metastatic renal cell carcinoma: University of Tokyo experience.

BACKGROUND: Dendritic cells (DC) are the most potent antigen-presenting cells and induce host antitumor immunity through the T-cell response. A clinical study of immunotherapy using cultured DC loaded with tumor antigen, for patients with metastatic renal cell carcinoma (RCC) was performed. METHODS: Dendritic cells were generated by culturing monocytes from peripheral blood for 7 days in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4. On day 6 the DC were pulsed with lysate from autologous tumor as the antigen and with keyhole limpet hemocyanin (KLH) as immunomodulator. The patients were given four doses of lysate-pulsed DC by intradermal injection with a 2-week interval between doses. Clinical effect and immune response were, respectively, evaluated by radiological examination and delayed-type hypersensitivity (DTH) test. RESULTS: Three patients were enrolled and the immunotherapy was well tolerated without significant toxicity. The vaccination induced a positive DTH reaction to tumor lysate in two patients and to KLH in all patients. Clinical responses consisted of one case of no change and two cases of progression of disease. However, we did not see a significant reduction of tumor volume in any case. CONCLUSION: Dendritic cell vaccination can safely induce an immunological response against RCC. Further trials are needed to fully evaluate its efficacy.

Adult↗
PubMed2002

Technical approaches to correction of oocyte aneuploidy.

BACKGROUND: This study describes the technical approaches used in treatment of age-related oocyte aneuploidy, the efficiency of each step of nuclear transplantation into mouse and human oocytes, and the ability of germinal vesicle (GV) transplantation to restore artificially induced ooplasmic damage. Finally, it examines the possibility of constructing viable female gametes by transferring diploid somatic cell nuclei into enucleated oocytes. METHODS: GV stage mouse oocytes were collected from unstimulated ovaries, and human GV oocytes were donated from consenting patients undergoing ICSI. Stromal (somatic) cells were isolated from uterine biopsies of consenting patients. Mouse cumulus cells were obtained after ovarian stimulation. GV ooplasts prepared by removing nuclei were transplanted either with GV nuclei or with somatic cells by micromanipulation. Grafted oocytes were electrofused and cultured to allow maturation, following which they were inseminated or analysed cytogenetically. Ooplasmic dysfunction was induced by photosensitization with a mitochondria-specific fluorescent dye. RESULTS: GV transplantation had an overall efficiency of 87 and 73% in the mouse and humans respectively. Maturation rates of 95 (mouse) and 64% (human) following reconstitution were comparable with those in control oocytes, as was the incidence of aneuploidy for five chromosome-specific probes after aneuploidy among the reconstituted oocytes. Photosensitization of oocytes significantly reduced the maturation rate to 4.2%, whereas 61.9% of oocytes matured after transfer of photosensitized GV karyoplasts into healthy ooplasts, with 52% of these mature oocytes being successfully fertilized by ICSI. Enucleated immature oocytes receiving mouse cumulus or human endometrial cell nuclei extruded a polar body in >40% of cases. Five out of seven successfully transferred aged human nuclei exhibited the expected number of signals with five chromosome-specific probes suggesting an appropriate chromosome separation in young ooplasm. CONCLUSIONS: Nuclear transplantation itself does not appear to interfere with chromosome segregation and can possibly rescue oocytes with damaged mitochondria. Finally, immature mouse ooplasm supported separation of somatic chromosomes to expected numbers, implying that haploidization may be occurring. The roles of genetic imprinting and fidelity of chromosome segregation are unknown.

Aneuploidy↗
PubMed2002

EMP combination chemotherapy and low-dose monotherapy in advanced prostate cancer.

Many chemotherapeutic regimens combined with estramustine phosphate (EMP) have been elaborated for the treatment of hormone-refractory prostate cancer over 30 years. However, older EMP-based combination chemotherapies with vinblastine, vinorelbine, doxorubicin or cyclophosphamide showed relatively low PSA response rate (25-58%) accompanied with high toxicities. On the other hand, newly developed EMP-based combination regimens with etoposide, pacitaxel, carboplatin or docetaxel demonstrated promising PSA response rate (43-77%) with moderate to severe toxicity in the rate of thromboembolic event (5-18%) and of neutropenia (9-41%). Treatment-related death was less in the latter combination group (5/615, 0.8%) than that in the former group (3/234, 1.3%). Of note, in the docetaxel combination with EMP, PSA response rate is as high as 77% with high rate (41%) of neutropenia but no treatment-related death was observed. Docetaxel combination with EMP seems to be the best regimen, though not completely justified by randomized trials, to be selected in the modern era, which will be followed by paclitaxel, carboplatin and EMP combination with PSA response rate of 71%. In addition, an interim report in 83 patients was presented. They were not consecutively enrolled but were treated on low-dose EMP monotherapy for previously untreated advanced prostate cancer in Department of Urology of Tokyo University and our 21 affiliated hospitals. Overall PSA response rate was as high as 93.4% out of 76 assessable patients. However, overall toxicity rate was abnormally high (39.5%) with drug discontinuation rate of 32.1%. The reason of low drug compliance may be attributed to gastrointestinal symptoms. To overcome the low drug compliance, appropriate patients for EMP administration should be selected by using gene analysis on the basis of sophisticated tailor-made medicine.

Aged↗
PubMed2002

[Surgical outcomes of nephron-sparing surgery for renal tumors].

PURPOSE: We retrospectively assessed the surgical outcomes of nephron-sparing surgery (NSS) for patients with renal tumors. PATIENTS AND METHODS: From 1985 to March 2001, a total of 99 NSSs were performed on 94 patients with renal tumors. The patients were divided into three groups. Group I comprised of 22 patients who underwent imperative surgeries for renal cell carcinoma (RCC). The tumors were found in 18 patients bilaterally (including 8 patients with von Hippel-Lindau disease), in 3 with solitary kidney, and in 1 with chronic renal failure. The mean +/- standard deviation of patient age and tumor diameter was 46 +/- 23 years and 36 +/- 23 mm, respectively. Twenty-three in situ NSSs were performed on 18 patients in Group I, and the remaining 4 patients were treated with 3 simultaneous operations for bilateral renal tumors with or without 2 ex vivo surgeries. Group II consisted of 49 patients who had small RCCs with the normal contralateral kidney and underwent NSSs (elective indication). The mean age and tumor diameter was 54 +/- 10 years and 28 +/- 11 mm, respectively. Group III consisted of 23 patients with non-RCC tumor (10 angiomyolipomas, 8 cystic tumors, 2 adenomas, 2 metastatic tumors, and 1 degenerative lesion), all of whom were treated with NSS. The mean age and tumor diameter was 47 +/- 14 years and 41 +/- 29 mm, respectively. RESULTS: In Group I, 3 patients died of cancer including 2 patients who had had multiple lung metastases preoperatively. The five-year tumor specific survival rate was 87.3% with a postoperative follow-up of 49 +/- 36 months. In Group II, there were few peri-operative complications or no local recurrence at follow-up of 52 +/- 38 months. A patient developed lung metastasis, which was removed surgically with no evidence of recurrence at 159 months after NSS. Postoperative renal scintigraphy on 35 patients showed well-preserved renal function of the operated kidney. Improvement in surgical techniques resulted in less-invasive surgery in 22 operations during the last 4 years. The patients of Group III were also operated uneventfully, although 1 experienced postoperative bleeding. In 12 patients with solitary kidney (11 in Group I and 1 in Group III) serum creatinine level increased transiently, decreased to 1.3 times of preoperative values within 3 months, and almost recovered at 1-year follow-up. CONCLUSION: Excellent outcomes in cancer control and preservation of renal function support the validity of nephron-sparing surgery to treat renal tumors. The candidate patients may include those with bilateral kidney tumors, tumor occuring in the solitary kidney or small renal cell carcinomas with the normal contralateral kidney. Earlier detection of small lesions and less invasive surgical techniques will facilitate a wider indication of NSS.

Adult↗
PubMedDate not supplied

Oocyte-induced haploidization.

This paper describes the technical approach to treatment of age-related oocyte aneuploidy. Although one solution can be oocyte/embryo selection, another is represented by the nuclear transplantation procedure. The efficiency of nuclear transplantation into immature oocytes is described as a way of generating embryos, and the possibility that viable female gametes can be constructed by transfer of diploid somatic cell nuclei into enucleated oocytes. Germinal vesicle (GV)-stage mouse oocytes were collected from unstimulated ovaries and somatic nuclei were obtained from mouse cumulus cells obtained after ovarian stimulation. Spare human GV-stage oocytes were donated from consenting patients undergoing intracytoplasmic sperm injection (ICSI) treatment, and human somatic cells were stromal cells coming from uterine biopsies performed on consenting patients undergoing endometrial cell co-culture. GV ooplasts, prepared by enucleation, were transplanted with either GV or somatic nuclei by micromanipulation. Grafted oocytes were electrofused and cultured to allow maturation, following which they were selected at random for insemination or cytogenetic analysis. GV transplantation was accomplished with an overall efficiency of approximately 80 and 70% in the mouse and the human respectively. The maturation rate of 96% (mouse) and 62% (human) following reconstitution was comparable to that of control oocytes, as was the incidence of aneuploidy among the reconstituted oocytes. The reconstituted human oocytes were successfully fertilized by ICSI at a rate of 52%. After the transfer of mouse cumulus or human endometrial cell nuclei into enucleated immature oocytes, a polar body was extruded in >40%. In a limited number of observations where the nucleus of an aged oocyte was transferred into a younger ooplasm, the chromosomes segregated normally at the time of polar body extrusion. The technique of nuclear transplantation itself did not increase the incidence of chromosomal anomalies in the mouse or human, since their oocytes reconstituted with homologous donor GV resumed meiosis to metaphase II and maintained a normal ploidy. In addition, immature mouse ooplasts induced haploidization of transplanted somatic cell nuclei. Although further evaluation of their genetic status is needed, the procedure may offer a realistic way of producing normal oocytes in cases of aged-related infertility. While the procedure is technically similar to cloning, it would generate a unique individual as a result of the contribution of both parental genomes.

Aneuploidy↗