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Biomedical subjects

Y Hamada

Publications and source records attributed to Y Hamada.

At least 109 records · Page 6Linked to original sources
PubMed2000

Results from coronary artery bypass surgery combined abdominal aortic aneurysm repair.

OBJECTIVE: Complication from coronary artery disease is a major cause of mortality and morbidity in patients undergoing abdominal aortic aneurysm repair. We report our results from coronary artery bypass surgery performed in combination with abdominal aortic aneurysm repair in patients with coronary artery disease and abdominal aortic aneurysm, each being an indication for an emergency operation. METHODS: Seventeen patients underwent combined coronary artery bypass surgery and abdominal aortic aneurysm repair. The mean age of the patients was 67.6 +/- 5.2 years. Four had left main disease, 8 patients had triple-vessel disease, and 12 had a prior myocardial infarction. The average left ventricular ejection fraction was 0.49 +/- 0.13. The average abdominal aortic aneurysm diameter was 6.2 +/- 1.0 cm (range 4.5-8.0 cm). Thirteen patients underwent coronary artery bypass surgery followed by abdominal aortic aneurysm repair after discontinuation of cardiopulmonary bypass. In the remaining four patients, including one patient with severe left ventricular dysfunction, cardiopulmonary bypass was continued as a circulatory assist until the abdominal aortic aneurysm repair was completed. The left internal thoracic artery was used in 14 patients, and the right internal thoracic artery in one patient. RESULTS: Postoperative surgical complications occurred in three patients (bleeding in one patient requiring reoperation, abdominal subcutaneous wound infection in another and transient neural disorder in the others). There were no surgical or in-hospital death. There was no late cardiac complication and no late cardiac death after a mean of 29 months follow-up. CONCLUSIONS: We concluded that combined surgery was reasonable for selected patients with combined coronary artery disease and abdominal aortic aneurysm, each of which is an indication for an urgent operation. The aortic aneurysm repair during cardiopulmonary bypass for patients with severe left ventricular dysfunction was safe and effective.

Aged↗
PubMed2000

Cisplatin (CDDP) specifically induces apoptosis via sequential activation of caspase-8, -3 and -6 in osteosarcoma.

PURPOSE: Osteosarcoma is a common malignant tumor. The first choice of treatment plan for osteosarcoma is chemotherapy. In particular, preoperative chemotherapy is most important in clinical treatment in orthopedics. In these chemotherapies, multiple anticancer drugs such as Adriamycin (ADM), CDDP, cyclophosphamide (CPM), methotrexate (MTX) and vincristine (VCR) are commonly used in combination. Recently, anticancer drugs have been shown to trigger apoptosis in various cancer cells. However, many studies on this topic have been examined using leukemia cell lines, and many kinds of cancer cells established from solid tumor are resistant to the induction of apoptosis by anticancer drugs. So in this study, we examined the effects of the anticancer drugs ADM, CDDP, CPM, MTX and VCR on osteosarcoma cells in vitro. We also examined the signaling pathways of each anticancer drug by studying the induction of apoptosis and activation of caspases in the osteosarcoma cells. METHODS: We examined the effects of the anticancer drugs ADM, CDDP, CPM, MTX and VCR, which are used clinically for the treatment of osteosarcoma, on cells of the human osteosarcoma (HOS) cell line. The cytotoxic effects of the anticancer drugs were evaluated using the MTT assay. We used both flow cytometry and activation of caspases to confirm the induction of apoptosis in the HOS cells. To dissect the pathway of the caspase cascade in apoptosis in HOS cells, we used the tetrapeptides YVAD-CHO, DMQD-CHO, VEID-CHO and IETD-CHO, which selectively inhibit caspase-1, -3, -6 and -8, respectively. RESULTS: ADM, CDDP, CPM and VCR, but not MTX, induced death of HOS cells in a dose-dependent manner. CDDP at 10 microM, CPM at 7.5 microM, ADM at 20 microM and VCR at 150 microM caused 80% cell death of HOS cells after 12 h. However, the percentages of apoptotic cells were 5.6% (medium alone), 75.9% (CDDP), 20.0% (CPM), 22.2% (ADM), 20.5% (VCR) and 13.1% (MTX). In addition, direct measurement of caspase-3 activity revealed that CDDP but not the other drugs activated caspase-3 in HOS cells. These analyses revealed that only CDDP induced apoptosis of HOS cells via activation of caspases. Furthermore, DMQD-CHO, VEID-CHO and IETD-CHO inhibited CDDP-induced apoptosis of HOS cells, suggesting that caspase-3, -6 and -8 are involved in the signaling pathway of CDDP-induced apoptosis. In contrast, none of the caspase inhibitors inhibited cell death induced by the other anticancer drugs. CONCLUSIONS: This study demonstrates that CDDP specifically induces apoptosis via activation of caspases and the other anticancer drugs induce death of HOS cells via different signaling pathways. It also demonstrates that caspase-8 is a key molecule in the earliest stage of the signaling pathway of CDDP-induced apoptosis of HOS cells, and caspase-3 works downstream of caspase-8.

Antineoplastic Agents↗
PubMed2000

Effects of a phosphodiesterase III inhibitor on circulating blood volume after cardiopulmonary bypass.

Using a new method based on pulse dye densitometry, circulating blood volume (BV) was measured without direct sampling in patients undergoing open-heart surgery, and the effects of phosphodiesterase (PDE) III inhibitor administration during cardiopulmonary bypass (CPB) were evaluated. Sixteen patients scheduled for elective coronary artery bypass grafting were randomly assigned to the PDE III inhibitor group or control group. BV was determined before CPB, and immediately, and 4 and 12h after operation. After declamping of the aorta, the PDE III inhibitor amrinone (1 mg/kg) was infused as a single bolus into the venous reservoir in the PDE III inhibitor group. BV decreased significantly soon after the operation in the control group. It did not decrease in the PDE III inhibitor group (48.6 +/- 44 and 60.6 +/- 8.0 ml/kg for the control and PDE III inhibitor groups. respectively). Four hours after surgery and beyond no significant changes in BV were observed in either group. The body fluid balance was negative in both groups. In conclusion, a single administration of PDE III inhibitor during CPB was found to sustain BV soon after operation and, therefore, is useful for postoperative management of open-heart surgery.

Aged↗
PubMed2000

Influence of CO2 pneumoperitoneum during laparoscopic surgery on cancer cell growth.

BACKGROUND: CO2 pneumoperitoneum provides a new surgical environment to treat malignant disease. The purpose of this study was to investigate the influence of CO2 pneumoperitoneum during laparoscopic surgery on cancer cell growth. METHODS: WiDr human colon cancer cells were incubated for 3 h under the following two conditions: 100% CO2 at 10 mmHg, and 95% air/5% CO2 (control). Cell proliferation was assessed by the WST-1 assay and BrdU assay. Tumor growth was assessed by subcutaneous injection into 20 nude mice. Cellular damage was measured by lactate dehydrogenase (LDH) assay. RESULTS: The number of WiDr cells under pneumoperitoneal conditions decreased in the first 24 h. However, no significant difference was observed in the proliferation rate and tumor growth of the viable cells. LDH release of the CO2 pneumoperitoneal group was higher than that of the controls. CONCLUSIONS: Our data indicate that CO2 pneumoperitoneum does not promote cancer cell proliferation but instead has a toxic effect on cancer cells.

Carbon Dioxide↗
PubMed2000

Congenital hemangiopericytoma: report of a case.

We report a case of congenital hemangiopericytoma arising in the lower right leg of a 4-day-old male neonate. Despite the generally good prognosis associated with this neoplasm, a complete surgical excision has so far been recommended to avoid recurrences, because no definite criteria for determining whether or not the tumor will regress spontaneously have been established to date.

Hemangiopericytoma↗
PubMed2000

Ultrastructural study of upper surface layer in rat articular cartilage by "in vivo cryotechnique" combined with various treatments.

The ultrastructures of the upper surface layer of rat articular cartilage were studied with our "in vivo cryotechnique" followed by freeze-substitution method for scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Rat hip or knee articular cartilage was quickly frozen by the in vivo cryotechnique with liquid isopentane-propane cryogen (-193 degrees C), and surface areas of some frozen specimens were freeze-fractured with a scalpel in liquid nitrogen. They were freeze-substituted and freeze-dried, ion-sputtered, and then observed in SEM. Other frozen specimens were routinely freeze-substituted and embedded in epoxy resin for TEM. Many globular structures were detected in the thick upper surface layer that had not been revealed by the conventional fixation methods. Their sizes were reduced by Triton X-100 treatment, and their localization was also detected in synovial fluid, as revealed by SEM. Such globular lipid-like structures in the upper surface layer of hip or knee articular cartilage might contribute to joint lubrication.

Animals↗
PubMed2000

Histological study of articular cartilage in experimental rat knee arthritis induced by intracapsular injection of cationic polyethyleneimine.

Degeneration of proteoglycans and abnormalities in their metabolism have been assumed to be critical at an early stage of osteoarthritis. To clarify a trigger mechanism of osteoarthritis, anionic sites of knee articular cartilage were blocked by intracapsular injection of cationic polyethyleneimine of 2000 or 70,000 molecular weight (MW) into rat knee joints. Experimental or normal rats were examined by gross observation, roentgenography, cytokine interleukin-1beta (IL-1beta) assay, and light or electron microscopy. In both groups with the polyethyleneimine injection, the rats showed temporarily limping and swelling of their knee joints. By light or electron microscopic studies, knee articular cartilage was found to be degenerated at an early stage, but IL-1beta was within normal levels. At 2, 4, or 6 months, the deformity of the knee joints was obvious by roentgenography. Degeneration and hypofunction of proteoglycans might be related to the ultrastructural changes of articular cartilage at an early stage, though the inflammatory cytokine was not involved. At later stages the pathophysiology of the knee joints advanced chronically to typical osteoarthritis, which was more radically induced by the large molecular polyethyleneimine (70,000 MW). The functional impairment of anionic sites is a key point for elucidating the mechanism of osteoarthritic development in this animal model.

Animals↗
PubMed2000

Analysis of B cell epitopes of a glycoprotein porcine zona pellucida (pZP1).

The zona pellucida (ZP) of mammalian oocytes forms an extracellular matrix composed of three major glycoproteins and plays an important role in sperm-zona interactions. As ZP had a strong organ-specific but species-cross-reactive antigenicity and passive or active immunization with ZP antigens could impair fertilization, the possibility of developing a immunocontraceptive vaccine has been extensively studied. Studies on active immunization with porcine ZP (pZP) that contain B cell epitopes and T cell epitopes demonstrated that a temporary infertility could be induced along with the elevation of antibody titers, but it was always associated with ovarian failure. This could be due to the oophoritis by activation of pathogenic T cell immunity. It is the general consideration that any adverse effects by vaccination should be avoided for an immunocontraception. From this point of view, the analysis of B cell epitopes of pZP protein would be helpful for construction of a safe immunocontraceptive vaccine with zona antigens. We determined the amino acid sequence of the B epitope in the pZP1 protein by using a monoclonal antibody (MAb-5H4) that possesses a fertilization blocking ability. In addition, antiserum raised to the epitope sequence was revealed to block in vitro fertilization of homologous animal species.

Amino Acid Sequence↗
PubMed2000

Magnetic resonance imaging findings and clinical symptoms in the temporomandibular joint in patients with mandibular continuity defects.

PURPOSE: This study explored the morphologic changes and clinical symptoms related to the temporomandibular joint (TMJ) associated with long-term lack of mandibular continuity. PATIENTS AND METHODS: The subjects were 20 patients (40 TMJs) who underwent mandibulectomy including the condyle or segmental mandibulectomy without mandibular reconstruction more than 6 months previous to the study. The 40 TMJs were classified into the following 3 groups: group I: TMJs with a major mandibular fragment including the mandibular body (n = 21), group II: TMJs with a minor mandibular fragment including only the condylar process or the mandibular ramus (n = 10), and group III: TMJs without a condyle (n = 9). All TMJs were examined with respect to disc position, condylar position, bony changes, and appearance of joint effusion on magnetic resonance imaging, as well as for the presence of joint or muscle pain and joint noise. RESULTS: The rate of anterior disc displacement was 28.6% in group I, 10.0% in group II, and 100% in group III. All condyles in group I were located in the glenoid fossa. Seven of 10 condyles in group II were dislocated anteriorly out of the glenoid fossa. However, these condyles were situated in the intermediate zone of the disc. Osteoarthritic changes was found in 1 joint in group II. Joint effusion was not observed in group I. However, joint effusion was detected in the posterior region of the upper joint compartment in 7 of 10 TMJs in group H and in 8 of 9 TMJs in group III. In group II, the 7 TMJs with joint effusion were the same joints with anteriorly dislocated condyles. Clinical symptoms of TMJ pain, TMJ noise, or muscular pain were not found in any patients. CONCLUSIONS: Partial mandibulectomy does not affect the relationship between the disc and the condyle or the bony condition of the TMJ. The disc without a condyle will become anteriorly displaced with time. The condyle not connected to the mandibular body often dislocates anteriorly out of the glenoid fossa, while retaining a normal relationship with the disc. Joint effusion, which is detected in nonfunctional TMJs, is not associated with an inflammatory reaction in the joint compartment.

Humans↗
PubMed2000

Co-segregation of benign infantile convulsions and paroxysmal kinesigenic choreoathetosis.

We report seven families and two sporadic cases in which benign infantile convulsions and paroxysmal kinesigenic choreoathetosis were co-segregated. Clinical investigations included physical and neurological examinations, blood electrolyte values, interictal and ictal electroencephalograms, and computed tomography or magnetic resonance imaging of the brain. The family pedigree was confirmed and the clinical history of the relatives was obtained. Seventeen individuals developed infantile convulsions followed by paroxysmal dyskinesias during childhood or adolescence. Six had only infantile convulsions, and two had only paroxysmal dyskinesias. The seizures never persisted into childhood or recurred in adulthood. The seizure type was a complex partial seizure, with or without secondary generalization, in nine of 14 patients. Paroxysmal dyskinesias, a subgroup of paroxysmal kinesigenic choreoathetosis, occurred for less than 5 min. The attacks of dyskinesias began at age 5-12 years in most patients, and tended to remit in adulthood. The mode of inheritance was apparently autosomal dominant in four of the families (17 affected individuals), who were diagnosed with ICCA syndrome (infantile convulsions and paroxysmal choreoathetosis). However, the condition occurred only among siblings in three families (six patients), and sporadically in two patients, suggesting genetic heterogeneity in this distinct co-segregation.

Adolescent↗
PubMed2000

Treatment of murine angiosarcoma with etoposide, TNP-470 and prednisolone.

To develop effective therapies for angiosarcoma, we investigated the anti-tumor effects of etoposide (ETO), TNP-470 and prednisolone (PSL) using an established murine angiosarcoma cell line (ISOS-1). We examined the direct anti-tumor and anti-angiogenic effects of these drugs on ISOS-1 cells and normal murine microvascular endothelial cells (mECs) in vitro. Cell growth of ISOS-1 was inhibited significantly by ETO, moderately by TNP-470, and not at all by PSL (IC(50): 0.25 microg/ml, 10 microg/ml, >8000 microg/ml, respectively). One the other hand, cell growth of mECs was inhibited significantly by TNP-470, slightly by PSL, and negligibly by ETO (IC(50): 0.85 ng/ml, 0.7 microg/ml, 10 microg/ml, respectively). In an in vivo assay, tumor growth of ISOS-1 was significantly inhibited by more than 2.5 mg/kg of ETO dose-dependently, and by more than 30 mg/kg of TNP-470, and 100 mg/kg of PSL individually. Combination treatments of ETO+TNP-470 and TNP-470+PSL showed synergistic enhancement of inhibition (% control inhibition: ETO vs. TNP-470 vs. ETO+TNP-470: 55 versus 55 vs. 16%) (% control inhibition: TNP-470 vs. PSL vs. TNP-470+PSL: 41 vs. 86 vs. 21%). ETO+PSL combination treatment, however, failed to show significant enhancement of anti-tumor effects. In conclusion, our results indicated that TNP-470 may be a very effective drug for angiosarcoma treatment, especially in combination with ETO or PSL. We eagerly anticipate the use of TNP-470 in clinical treatment of angiosarcoma.

Angiogenesis Inhibitors↗
PubMed2000

Studies on cytotoxicity of nickel ions using C3H10T1/2 fibroblast cells.

Cytotoxicity of Ni ions were examined using C3H mouse derived 10T1/2 fibroblast cells. It became evident that Ni ions had dose-dependent cytotoxicity. The cell number incubated in DME medium containing 0.04 mM/L Ni ion for 6 days was reduced to half that in control DME medium without Ni. The cell totally disappeared in DME medium containing 2 mM/L Ni ion. The dissolution of Ni ions from Ni-containing metallic restorations must be lower than these concentration levels so that oral tissues might not be damaged. No neoplastic transformation was found on all cells examined.

Animals↗
PubMed2000

Isolated heterotopic pancreas causing intussusception.

Pediatric intussusception is usually idiopathic in origin, and a pathological lesion at the leadpoint is identified in only a small proportion of cases. Meckel's diverticulum is the most common location when such a lesion is found. Heterotopic pancreas has been seen most frequently in the stomach or duodenum; however, ileal lesions are rare. In the ileum, heterotopic pancreas is usually associated with Meckel's diverticulum and may cause intestinal obstruction by intussusception. However, isolated heterotopic pancreas in the ileum is distinctly rare and usually discovered incidentally during surgery for other conditions. In a review of English language literature, there were only a few pediatric cases of isolated ileal heterotopic pancreas causing intussusception. We report three additional pediatric cases and discuss the clinical significance of this unexpected rare entity.

Choristoma↗