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Biomedical subjects

Y Hamamoto

Publications and source records attributed to Y Hamamoto.

At least 19 recordsLinked to original sources
PubMed2006

Drugs share antidiabetic and antiatherosclerotic actions through "the common soil".

There have been increasing evidences that atherosclerosis is not the result of diabetes mellitus, but that both type 2 diabetes mellitus and atherosclerosis may share common pathogenesis, as Stern proposed as 'common soil' hypothesis in 1995. There are several candidates for 'common soil', such as insulin resistance, vascular inflammation and endothelial dysfunction. Recently many of clinical studies have indicated that some drugs can prevent or delay the development of cardiovascular diseases (CVD). Furthermore, many studies have suggested that some classes of drugs may prevent the development of type 2 diabetes. It is to be noted that most of the drugs may have both actions, i.e., to prevent development of new diabetes and to prevent CVD. Furthermore, they are reported to inhibit inflammation or endothelial dysfunction. Taken together, it is hypothesized that the drug which may have antiatherogenetic action may also have antidiabetic action, and vice versa. This hypothesis may provide the new insights into perspectives of drug development both to prevent type 2 diabetes and to prevent CVD.

Atherosclerosis↗
PubMed2006

Development of MBR with reduced operational and maintenance costs.

To reduce MBR O&M costs, a new MBR process that conducts efficient simultaneous biological nitrogen and phosphorus removal (BNR) was developed. In the development of this process, various approaches were taken, including reduction of power demand, chemical consumption and sludge disposal costs. To address power demand reductions, air supply requirements for membrane cleaning were reduced. The process adopted an improved membrane that requires less air for cleaning than conventional membranes. It also introduced cyclic aeration, which alternately supplies washing air to the two series of membrane units. Adoption of biological phosphorus removal eliminated chemical costs for phosphorus removal and contributed to the reduction of sludge disposal costs. By combining these technologies, compared to conventional MBR processes, an approximately 27% reduction in O&M costs was achieved.

Bioreactors↗
PubMed2005

A rare case of the cutaneous form of adult T-cell leukaemia/lymphoma: assessment of remission by PCR for clonal T-cell receptor gamma gene rearrangements in an electron beam-irradiated cutaneous lesion.

Adult T-cell leukaemia/lymphoma is a lymphoproliferative disorder aetiologically associated with human T-cell lymphotropic virus type I infection. A cutaneous lesion often develops in the disease, and in rare cases, is even the only manifestation. Here we report a rare case of 'cutaneous' adult T-cell leukaemia/lymphoma with neither atypical cells in the peripheral blood nor lymph node involvement. All nodular lesions were completely eliminated after local electron beam irradiation (20 Gy/nodule in total). To evaluate whether or not there were residual lymphoma cells in the skin, we performed PCR to detect clonal T cell receptor gamma gene rearrangements. The sample from the nodule before irradiation showed evidence of a rearranged band, which was not detected at the same site after treatment nor in any peripheral blood. The findings suggest that this procedure is useful for the evaluation of therapeutic effects and the early detection of lymphoma recurrence.

Female↗
PubMed2004

Narrow-band imaging in the diagnosis of colorectal mucosal lesions: a pilot study.

BACKGROUND AND STUDY AIMS: A newly developed narrow-band imaging (NBI) technique, in which modified optical filters were used in the light source of a video endoscope system, was applied during colonoscopy in a clinical setting. This pilot study evaluated the clinical feasibility of the NBI system for evaluating colorectal lesions. PATIENTS AND METHODS: A total of 43 colorectal lesions in 34 patients were included in the study. The quality of visualization of colorectal lesions and the accuracy of differentiation between neoplastic and non-neoplastic lesions using the NBI system were evaluated in comparison with results from conventional colonoscopy and with chromoendoscopy. RESULTS: For pit pattern delineation, NBI was superior to conventional endoscopy (P < 0.001), but inferior to chromoendoscopy (P < 0.05). NBI achieved better visualization of the mucosal vascular network and of the hue of lesions than conventional endoscopy (P < 0.05). However there was no significant difference between NBI and chromoendoscopy in differentiating neoplastic from non-neoplastic lesions (both techniques had a sensitivity of 100 % and a specificity 75 %). This was better than the results of conventional colonoscopy (sensitivity 83 %, specificity 44 %; P < 0.05 for specificity). CONCLUSIONS: These results suggest that in the examination of colonic lesions the NBI system provides imaging features additional to those of both conventional endoscopy and chromoendoscopy. For distinguishing neoplasms from non-neoplastic lesions, NBI was equivalent to chromoendoscopy.

Aged↗
PubMed2003

Beneficial effect of pretreatment of islets with fibronectin on glucose tolerance after islet transplantation.

The scarcity of available islets is an obstacle for clinically successful islet transplantation. One solution might be to increase the efficacy of the limited islets. Isolated islets are exposed to a variety of cellular stressors, and disruption of the cell-matrix connections damages islets. We examined the effect of fibronectin, a major component of the extracellular matrix, on islet viability, mass and function, and also examined whether fibronectin-treated islets improved the results of islet transplantation. Islets cultured with fibronectin for 48 hours maintained higher cell viability (0.146 +/- 0.010 vs. 0.173 +/- 0.007 by MTT assay), and also had a greater insulin and DNA content (86.8 +/- 3.6 vs. 72.8 +/- 3.2 ng/islet and 35.2 +/- 1.4 vs. 30.0 +/- 1.5 ng/islet, respectively) than islets cultured without fibronectin (control). Absolute values of insulin secretion were higher in fibronectin-treated islets than in controls; however, the ratio of stimulated insulin secretion to basal secretion was not significantly different (206.9 +/- 23.3 vs. 191.7 +/- 20.2% when the insulin response to 16.7 mmol/l glucose was compared to that of 3.3 mmol/l glucose); the higher insulin secretion was thus mainly due to larger islet cell mass. The rats transplanted with fibronectin-treated islets had lower plasma glucose and higher plasma insulin levels within 2 weeks after transplantation, and had more favorable glucose tolerance 9 weeks after transplantation. These results indicate that cultivation with fibronectin might preserve islet cell viability, mass and insulin secretory function, which could improve glucose tolerance following islet transplantation.

Animals↗
PubMed2002

MR and CT findings of craniopharyngioma during and after radiation therapy.

Long-term changes in craniopharyngioma treated with radiation therapy (RT) were investigated by computed tomography (CT) and/ or magnetic resonance (MR) imaging. Eight patients with craniopharyngioma were treated with incomplete resection or conservative surgical intervention followed by postoperative RT. The periods of tumor shrinkage were often long and varied (range: 6-68 months, mean: 29.1 months). Temporary enlargement of the solid component of a tumor usually occurs during RT and does not represent tumor progression. Cystic enlargement also occurs sometimes comparatively early after RT, and enlarged cysts often shrink with no treatment or with conservative treatment. These changes should be differentiated from tumor recurrence, with careful follow-up. After shrinkage, small solid or cystic nodules enhanced with contrast medium often remain. Long-term follow-up is necessary to differentiate uncontrolled tumors from controlled tumors with imaging modalities.

Adolescent↗
PubMed2001

Recovery of function and mass of endogenous beta-cells in streptozotocin-induced diabetic rats treated with islet transplantation.

Islet transplantation corrects chronic hyperglycemia by augmentation of insulin supply from the graft tissue, but the role of endogenous beta-cells after transplantation is not clear. In the present study, we examined endogenous beta-cell function after glucose homeostasis had been reestablished by islet graft in streptozotocin (STZ)-induced diabetic rats. Fed plasma glucose levels in diabetic rats transplanted with a large number of islets (2500 islets) into the left kidney capsule soon became lower (139.8 +/- 8.2 mg/dl) and close to the level in controls (129.7 +/- 11.3 mg/dl), and IPGTT exhibited a pattern of plasma glucose response almost identical to control. The insulin and DNA contents, islet area, and the distribution of beta-cells that were markedly deteriorated in islets of STZ rats were significantly restored in transplanted rats. The insulin release in response to glucose or alpha-ketoisocaproate was less in STZ rats, while in islets of transplanted rats the secretion recovered to levels similar to controls. On the other hand, arginine-induced insulin release was conversely hyperresponsive in STZ rats, but in transplanted rats, the response was decreased similar to controls. Thus, as the plasma glucose level normalizes, residual beta-cells show a recovery of function that cannot be accounted for by the increase in mass alone.

Animals↗
PubMed2001

Heat shock restores insulin secretion after injury by nitric oxide by maintaining glucokinase activity in rat islets.

Heat shock protein (hsp), including hsp70, has been reported to restore the glucose-induced insulin release suppressed by nitric oxide (NO). However, the mechanism underlying this recovery remains unclear. In the present study, we examine the effects, in rat islets, of heat shock on insulin secretion inhibited by a small amount of NO and also on glucose metabolism, the crucial factor in insulin release. Exposure to a higher dose (15 U/ml) of interleukin-1beta (IL-1beta) abolished the insulin release by stimulation of glucose or KCl in both control and heat shocked islets. In rat islets exposed to a lower dose (1.5 U/ml) of IL-1beta, insulin secretion in response to glucose, but not to glyceraldehydes (GA), ketoisocaproate (KIC), or KCl, was selectively impaired, concomitantly with lower ATP concentrations in the presence of 16.7 mM glucose, while such suppression of insulin secretion and ATP content was not observed in heat shock-treated islets. NO production in islets exposed to 1.5 U/ml IL-1beta was significantly, but only partly, decreased by heat shock treatment. The glucose utilization rate measurement using [5-3H]-glucose and [2-3H]-glucose and the glucokinase activity in vitro were reduced in islets treated with 1.5 U/ml IL-1beta. In heat shock-treated islets, glucose utilization and glucokinase activity were not affected by 1.5 U/ml IL-1beta. These data suggest that heat shock restores glucose-induced insulin release inhibited by NO by maintaining glucokinase activity and the glucose utilization rate in islets in addition to reducing endogenous NO production.

Animals↗
PubMed2001

Incidence of deep fascial space infection after surgical removal of the mandibular third molars.

Nine hundred and ninety-three patients who underwent surgical removal of the mandibular third molars with oral antibiotic prophylaxis were examined to determine the incidence of postoperative deep fascial space infection and its background factors. Postoperative deep fascial space infection was observed in 8 of the patients (0.8%; 4 males and 4 females), and submandibular spaces were involved in all infected patients. Only 1 of these 8 patients was an immune compromised host. Patients aged 30 years or more had a significantly higher incidence of deep fascial space infection than those aged under 30. Five patients had partial bony impactions and 3 had complete bony impactions. However, the incidence of infection according to the molar positions was not significantly different between partial bony impaction and complete bony impaction. The 8 patients had not had pericoronitis preoperatively. The clinical courses of all were favorable after antibiotics were administered intravenously. In conclusion, the incidence of deep fascial space infection after removal of the mandibular third molars was low, at 0.8%. However, it may be desirable to remove the molars, if applicable, at a younger age because of the higher incidence of infection in patients aged over 30. The results of this study also offer information that will be useful as a basis for obtaining informed consent from patients whose mandibular third molars are to be removed.

Adolescent↗
PubMed2001

Regressive effect of intralesional injection of a moderate dose of recombinant interleukin-2 on carcinoma erysipeloides from gastric carcinoma.

Cutaneous metastatic diseases remain nearly incurable and a major medical challenge. It has been shown that interleukin-2 (IL-2) has potential as a therapeutic agent for various neoplastic diseases such as melanoma, renal cell carcinoma and myeloid leukaemia. However, IL-2 therapy for metastatic skin lesions has not been established yet. In the present study, we investigated the effect of recombinant IL-2 in a 79-year-old Japanese man with carcinoma erysipeloides, a rare type of cutaneous metastasis from gastric cancer. He was treated with an intralesional injection of rIL-2 (200 000 JRU) daily. Ten days after treatment, an erythematous plaque was eliminated almost completely leaving light brown pigmentation. A skin biopsy from the pigmented area revealed the absence of obvious tumour cells. These findings suggest that this cytokine should be considered for the clinical treatment of several inoperative metastatic cutaneous diseases, including gastric cancer.

Adenocarcinoma↗
PubMed2001

Fixed drug eruption due to clarithromycin.

Clarithromycin is one of the macrolide antibiotics used for cutaneous and respiratory system infections. Only a few cases of adverse cutaneous reactions to this drug have been reported. Here we report a rare case of clarithromycin-induced fixed drug eruption which could be reproduced by a peroral provocation test, whereas patch tests on both unaffected and residual pigmented skin yielded negative results. All cutaneous lesions that recurred due to the challenge test developed the same pigmentation after a short course of intravenous corticosteroid.

Aged↗
PubMed2001

Pseudoankylosis of the mandible as a result of methyl methacrylate-induced inflammatory cicatricial contracture of the temporal muscle after cranioplasty.

Pseudoankylosis of the mandible after intracranial surgical procedure has been widely reported, and is usually caused by fibrosis of the temporal muscle as a result of injury during the operation. We present an unusual case of mandibular pseudoankylosis as a result of methyl methacrylate-induced aseptic inflammatory cicatricial contracture of the temporal muscle after cranioplasty.

Adult↗
PubMed2001

[Primary squamous cell carcinoma of the prostate forming a rectourethral fistula: a case report].

Eleven cases of squamous cell carcinoma of the prostate have been previously reported in the Japanese medical literature. Patients with this type of carcinoma have dismal prognoses. Herein, we report a case in a 61-year-old man who was admitted to our hospital and whose chief complaints were dysuria and high fever. Pyuria, bacteriuria, and the results of a digital rectal examination suggested acute prostatitis. Despite the administration of antibiotics, the dysuria did not improve. A transrectal needle biopsy was performed, and histology of the tissue showed squamous cell carcinoma. After chemotherapy using methotrexate, pirarubicin, and cisplatin, total pelvic excentration was performed. At 12 months after the operation, the patient is alive with no evidence of the disease.

Antigens, Neoplasm↗
PubMed2001

[A case of ileal conduit stenosis 13 years after construction].

A 63-year-old male was admitted to our hospital with the complaint of bilateral hydronephroses. Total cystectomy and ileal conduit construction were performed because of bladder tumor (TCC, G2, pT2N0M0) in 1985. The patient remained asymptomatic, but bilateral hydronephroses was observed by ultrasonography in 1997. DTPA renogram showed the delayed excretion. Conduitgraphy and antegrade pyelography revealed that the conduit was narrow like a pinhole at 2 cm distal region from the anastomotic site of the urinary duct. The stenotic region was inflated by a 24 Fr inflation-balloon-catheter. Chronic inflammation, which was thought to be caused by infection, was detected at the stenotic conduit by biopsy. Hydronephroses disappeared after the operation and the postoperative course was uneventful.

Catheterization↗
PubMed2001

[Hyperdense renal cyst associated with papillary adenoma: a case report].

An abnormal shadow in the chest of a 57-year-old male was detected during a medical checkup and careful investigation revealed a left posterior mediastinal tumor (neurinoma) and a clearly demarcated homogenous mass with dimensions of 16 x 12 mm and computed tomographic (CT) value of 79 H.U. in the superior pole of the right kidney. The content solution was sticky and blackish-green. Neoplastic degenerations of 8 x 4 and 5 x 5 mm were seen in the cyst. Partial nephrectomy, which included the cystic section, was conducted and papillary adenoma was pathologically diagnosed. Nine years after the operation, the patient is alive and neither relapse nor other abnormalities were detected.

Adenoma↗
PubMed2000

The insulinotropic mechanism of the novel hypoglycaemic agent JTT-608: direct enhancement of Ca(2+) efficacy and increase of Ca(2+) influx by phosphodiesterase inhibition.

We examined the effects of the novel hypoglycaemic agent JTT-608 [trans-4-(4-methylcyclohexyl)-4-oxobutyric acid] on insulin secretion using rat pancreatic islets, and analysed the mechanism of its effect. JTT-608 augmented 8.3 mM glucose-induced insulin secretion dose-dependently, and there was a stimulatory effect of 100 microM JTT-608 at both moderate and high concentrations (8.3, 11. 1 and 16.7 mM) of glucose, but not at low concentrations (3.3 and 5. 5 mM). In perifusion experiments, both phases of insulin release were enhanced, and the effect was eliminated 10 min after withdrawal of the agent. In the presence of 200 microM diazoxide and a depolarizing concentration (30 mM) of K(+), there was an augmentation of insulin secretion by 100 microM JTT-608, not only under high levels of glucose but also under low levels, and the effects were abolished by 10 microM nitrendipine. JTT-608 augmented insulin secretion from electrically permeabilized islets in the presence of stimulatory concentrations (0.3 and 1.0 microM) of Ca(2+), and the intracellular Ca(2+) concentration ([Ca(2+)](i)) response under 16.7 mM glucose, 200 microM diazoxide, and 30 mM K(+) was also increased. The cyclic AMP content in the islets was increased by 100 microM JTT-608, and an additive effect to 1 microM forskolin was observed, but not to 50 microM 3-isobutyl-1-methylxanthine (IBMX). JTT-608 inhibited phosphodiesterase (PDE) activity dose-dependently. We conclude that JTT-608 augments insulin secretion by enhancing Ca(2+) efficacy and by increasing Ca(2+) influx. This appears to be a result of the increased intracellular cyclic AMP concentration due to PDE inhibition.

Animals↗