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Biomedical subjects

A Hamasaki

Publications and source records attributed to A Hamasaki.

At least 19 recordsLinked to original sources
PubMed2006

[Advantage of supra-annular patch enlargement in aortic stenosis with a small aortic annulus].

BACKGROUND: We routinely perform supra-annular patch enlargement as a strategy to avoid patient-prosthesis mismatch (PPM) in patients with a small aortic annulus who are undergoing aortic valve replacement (AVR). METHOD: We performed a retrospective review of 128 consecutive single AVR patients from 1999 to 2005. Of these, 34 patients underwent supra-annular patch enlargement. The enlargement was selectively performed in patients at risk of PPM. This involved patch extension of the aortotomy just above the annulus of noncoronary sinus, and valve implantation with stitches placed directly on the patch. Along with this procedure, AVR with a valve size appropriate to body surface area (BSA) was performed. RESULT: Of these patients, 74% were female and the mean BSA was less than 1.50 m2. The enlargement required an average of 33 minutes of additional aortic clamp time. The 30-day mortality was 0%. A favorable hemodynamic outcome was achieved. CONCLUSION: Our results show that supra-annular patch enlargement can be performed with minimal added risk, relative to standard root enlargement and a satisfactory hemodynamic status can be achieved by employing this procedure.

Aged↗
PubMed2006

[Segmental mitral suture annuloplasty combined with resection--suture technique for posterior leaflet prolapse].

A segmental mitral suture annuloplasty technique is consisted of double-layer sutures anchored in the fibrous trigone on the valve repair side and along the annulus to the midpoint of the posterior leaflet. This suture technique is an alternative of Paneth Burr method using only one-side of the procedure. We recommend this technique especially in cases of mitral regurgitation which can be repaired by a simple resection-suture technique for posterior leaflet, and not in cases of severe annular dilatation, rheumatic, or ischemic diseases. We have examined this technique in 40 cases over the last 8 years and the results showed no recurrence of the mitral regurgitation.

Cardiac Surgical Procedures↗
PubMed2001

Reciprocal regulation of tissue-type and urokinase-type plasminogen activators in the differentiation of murine preadipocyte line 3T3-L1 and the hormonal regulation of fibrinolytic factors in the mature adipocytes.

Adipose tissue expresses a variety of genes including tumor necrosis factor alpha and type-1 plasminogen activator inhibitor (PAI-1); and these factors, produced by adipocytes, may be associated with the risk of coronary events in obesity. In this study, we characterized the production of fibrinolytic factors including tissue-type plasminogen activator (tPA), urokinase-type PA (uPA), and PAI-1 in the differentiation of preadipocytes, and examined the hormonal regulation of these fibrinolytic factors in mature adipocytes. Mouse 3T3-L1 preadipocytes were employed as a model of adipocytes. Adipocyte differentiation was induced by insulin, dexamethasone, and 3-isobutyl-1-methyl xanthine (IBMX). alpha-Glycerophosphate dehydrogenase (GPDH) activity and glucose transporter 4 (GLUT4) mRNA, indices for adipocyte maturation, were induced on Day 4, and gradually increased. GPDH activity reached its maximum level on Day 14. The level of tPA, a major PA in preadipocytes, dramatically decreased with differentiation. On the other hand, that of uPA reciprocally increased. PAI-1 production was also dramatically induced concomitant with differentiation. In mature adipocytes, uPA production was dominant (25 microg/ml/24 h vs. 0.8 microg/ml/24 h for tPA). Total PA activity in the mature adipocytes was reduced by insulin or dexamethasone, but not by glucagon. Insulin, IBMX, and dexamethasone significantly decreased both uPA and tPA production, and increased PAI-1 production. Glucagon had no effect on the production of these fibrinolytic factors. Our results reveal that uPA is one of the markers for the differentiation of 3T3-L1 cells and that insulin, IBMX, and dexamethasone are potent regulators of the fibrinolytic activity in differentiated 3T3-L1 cells, reciprocally affecting PA and PAI-1 levels in them.

1-Methyl-3-isobutylxanthine↗
PubMed2001

Temporomandibular disorders: relationship between joint pain and effusion and nitric oxide concentration in the joint fluid.

OBJECTIVES: To evaluate the relationship between joint effusion, contrast enhancement of effusion, nitric oxide concentration in TMJ fluid and TM joint pain. METHODS: Nonenhanced T1- and T2-weighted and gadolinium-enhanced T1-weighted spin-echo sequences were performed in 77 patients with TMD. The nitric oxide concentration in TMJ fluid was analysed spectrophotometrically by the Griess reaction. RESULTS: Some or marked effusion was seen in five (9%) of the 56 asymptomatic joints and in 55 (56%) of the 98 symptomatic joints. The prevalence of contrast enhancement of joint effusion was significantly higher in the joint pain group than in the joint sound or asymptomatic joint groups (chi2 test, P<0.001). On postcontrast T1-weighted images, there was no evidence of synovial proliferation in patients with TMD. Anterior disk displacement without reduction was detected in 93% of the TMJs with marked effusion. The degree of joint pain correlated with raised nitric oxide concentration (Spearman's rank correlation, P<0.05). CONCLUSIONS: Painful joints are more likely to demonstrate contrast enhancement of joint effusion. Nitric oxide concentration in TMJ fluid is closely associated with inflammatory changes and painful TM joints.

Adolescent↗
PubMed2001

[Traumatic diaphragmatic herniation after continuous thoracic drainage: a case report].

We report a case of traumatic diaphragmatic hernia (TDH) resulting from continuous thoracic drainage and was successfully treated by surgical procedures. A 45-year-old man was admitted to our department due to shock after a blunt trauma by a traffic accident. As he revealed left hemothorax on admission, continuous thoracic drainage was performed. Soon after the drainage, diaphragmatic hernia occurred as an incarceration of the spleen into the thoracic cavity. In the literature, 80 cases with TDH have been reported in Japan since 1986. The purpose of this study is to discuss the mechanism of TDH in the acute phase and to consider its appropriate diagnostic tools. The following two results were obtained. (1) TDH may be appeared during the clinical course, especially after a continuous thoracic drainage, in patients with damaged diaphragm by blunt traumas. (2) CT is the most effective tool for the diagnosis of TDH.

Drainage↗
PubMed2000

Automated in vitro selection to obtain functional oligonucleotides.

In vitro selection or systematic evolution of ligand by exponential enrichment (SELEX) has been devised for the identification of high-affinity oligonucleotide aptamers to target molecules. However, the selection process is repetitive and time-consuming. We have developed an automatic for in vitro selection by assembling an affinity chromato-column, a PCR thermal cycler, a HPLC and a sample operation system. Several molecular biology methods were optimized for the machine. Automated selection was used to generate nucleic acid aptamers interacting specifically with an environmental contaminant.

Automation↗
PubMed1998

Accelerated neutrophil apoptosis in mice lacking A1-a, a subtype of the bcl-2-related A1 gene.

To elucidate the role of A1, a new member of the Bcl-2 family of apoptosis regulators active in hematopoietic cell apoptosis, we established mice lacking A1-a, a subtype of the A1 gene in mice (A1-a-/- mice). Spontaneous apoptosis of peripheral blood neutrophils of A1-a-/- mice was enhanced compared with that of either wild-type mice or heterozygous mutants (A1-a+/- mice). Neutrophil apoptosis inhibition induced by lipopolysaccharide treatment in vitro or transendothelial migration in vivo observed in wild-type mice was abolished in both A1-a-/- and A1-a+/- animals. On the other hand, the extent of tumor necrosis factor alpha-induced acceleration of neutrophil apoptosis did not differ among A1-a-/-, A1-a+/-, and wild-type mice. The descending order of A1 mRNA expression was wild-type, A1-a+/-, and A1-a-/-. Taken together, these results suggest that A1 is involved in inhibition of certain types of neutrophil apoptosis.

Animals↗
PubMed1998

Multiple gene duplication and expression of mouse bcl-2-related genes, A1.

Here we report the genomic cloning and characterization of the murine A1 genes, which belong to the bcl-2 gene family. Southern analysis indicated the existence of at least four A1 genes in the murine genome and four different A1 genes, designated A1-a, -b, -c and -d, were cloned from the murine genomic library. The A1-a, -b and -d genes consisted of two exons, whereas the A1-c gene contained 1 bp insertion in the coding region which may result in an aberrant and truncated protein by frame-shift. With the exception of A1-c, the coding regions among A1 genes are highly conserved at >97% at the nucleotide level and at >96% at the amino acid level. A1-a, -b and -d genes appeared to be expressed specifically in organs containing many neutrophils. In neutrophils, A1-a, -b and -d transcripts were detected at a comparable level. Our data suggest that the multiple A1 genes in mice were generated by gene duplication and each of them may function as anti-apoptotic molecules in neutrophils.

Amino Acid Sequence↗
PubMed1997

[Simultaneous repair for funnel chest and intracardiac lesions in two pediatric patients].

Two successful cases underwent simultaneous repair for funnel chest using sternal turnover with rectus abdominal flap and intracardiac lesions were reported. A 7-year-old female (case 1) was diagnosed with funnel chest and annulo-aortic ectasia due to Marfan's syndrome. Second patient was a 12-year-old male (case 2) with funnel chest and ventricular septal defect (VSD). Both patients underwent sternal turnover and intracardiac repair (case 1: Bentall's operation, case 2: patch closure of VSD), simultaneously. Removing the cost-sterno complex before cardiac operation allowed an excellent surgical exposure. Bleeding was minimum, especially no homologous blood transfusion was needed in case 2. Simultaneous surgery consisted of intracardiac repair and sternal turnover is recommended even for pediatric patients.

Aortic Valve Insufficiency↗
PubMed1992

Actions of parathyroid hormone on cultured human dental pulp cells.

The responsiveness of human dental pulp (HDP) cells to parathyroid hormone (PTH) was investigated by measuring their cyclic AMP (cAMP) content, DNA synthesis, alkaline phosphatase activity, collagen synthesis, and glycosaminoglycan (GAG) synthesis. PTH dose-dependently increased the intracellular cAMP 1 min after the addition of PTH. Confluent HDP cells on day 14 expressed a high level of cAMP production after addition of 3 units/ml PTH. The hormone did not affect DNA synthesis by HDP cells. Alkaline phosphatase activity was suppressed by PTH to 81% of control (p < 0.01), and addition of dibutyryl cAMP to the medium mimicked the effect of PTH (79% of control, p < 0.01). The hormone inhibited collagen synthesis (15% decrease of [3H] proline incorporation, p < 0.01), and stimulated non-collagen protein synthesis (10% increase, p < 0.05). The increase of non-collagen protein by PTH was in accordance with the enhancement of GAG synthesis (17% increase of [35S]sulfate incorporation, p < 0.01). Dibutyryl cAMP caused further increase of GAG synthesis, to 155% of control (p < 0.01). Observations of the radiolabeled proteins on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis after metabolic labeling with [14C]proline and [35S]sulfate revealed a similar tendency to the quantitative determinations in which PTH inhibited collagen synthesis and stimulated GAG synthesis. These findings suggest that HDP cells have some osteoblastic characteristics in terms of PTH responsiveness, and that this culture system is a useful model for studies of human dental pulp.

Adolescent↗
PubMed1991

Regulation of glycosaminoglycan synthesis by parathyroid hormone and prostaglandin E2 in cultured dental pulp cells.

The effects of parathyroid hormone (PTH) and prostaglandin E2 (PGE2) on glycosaminoglycan (GAG) synthesis in bovine dental pulp cells were studied. Dibutyryl cyclic adenosine 3',5'-monophosphate and isobutyl methylxanthine were used to assess whether their effects were mediated by intracellular cAMP. Glycosaminoglycan synthesis was assayed by measuring [35S]sulfate incorporation into the GAG fraction of dental pulp cells. Glycosaminoglycan synthesis was increased 1.3-fold by PTH (4 units per ml) alone, 1.6-fold by PTH in the presence of isobutyl methylxanthine, 1.2-fold by PGE2 (100 ng per ml) alone, and 1.5-fold by PGE2 in the presence of isobutyl methylxanthine. Dibutyryl cyclic adenosine 3',5'-monophosphate enhanced GAG synthesis in a concentration-dependent manner and mimicked the effects of PTH and PGE2. The effects of these hormones on pulp and gingival cells were compared; addition of PTH, PGE2, and dibutyryl cAMP had no effect on gingival cell GAG synthesis, whereas their addition induced significant increases of GAG in pulp cells. These results indicate that PTH and PGE2 are involved in the differentiation of dental pulp cells and that these effects are mediated by cAMP.

Animals↗
PubMed1991

Effects of parathyroid hormone, 1,25-dihydroxyvitamin D3, and prostaglandin E2 on alkaline phosphatase activity in cultured dental pulp and gingiva cells of bovine calf.

The effects of parathyroid hormone (PTH), 1,25-dihydroxyvitamin D3, and prostaglandin E2 (PGE2) on alkaline phosphatase activity on cultured dental pulp and gingiva cells of bovine calf were compared. In pulp cells, PTH, 1,25-dihydroxyvitamin D3, and PGE2 significantly increased alkaline phosphatase activity, but no increase in the enzyme activity by these factors was observed in gingiva cells. Dibutyryl cAMP also increased alkaline phosphatase activity in both types of cell, but the increase in pulp cells was greater than that in gingiva cells. Treatment of the cultured pulp cells with PTH or PGE2 significantly increased the intracellular cAMP content. These results suggest that calciotropic factors such as PTH, 1,25-dihydroxyvitamin D3, and PGE2 may be involved in the differentiation of dental pulp cells and that some of these effects (those of PTH and PGE2) are mediated by cAMP.

Alkaline Phosphatase↗
PubMed1991

Nifedipine-induced gingival hyperplasia: a clinical and in vitro study.

Two cases of gingival hyperplasia associated with long-term administration of nifedipine, a drug that dilates coronary arteries, are reported. The clinical and histopathological features of the gingival hyperplasia induced by nifedipine were similar to those induced by phenytoin, an anticonvulsant drug. In the present cases, gingival inflammation had developed before drug administration. In one case, extensive dental plaque control in addition to surgical removal of the overgrown gingival tissues resulted in satisfactory progress without the need to discontinue drug administration, suggesting that the preexisting gingival inflammation was involved in the development of this periodontal disease. In the other case, change from nifedipine to another drug resulted in spontaneous recovery, strongly suggesting that the drug had induced the gingival hyperplasia. Nifedipine had no direct effects in vitro on proliferation or collagen synthesis of gingival fibroblastic cells from one of the patients. Study of these two cases suggests that both local inflammatory factors and long-term administration of nifedipine were responsible for the gingival hyperplastic changes observed.

Cell Division↗