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Biomedical subjects

Satoshi Yamaguchi

Publications and source records attributed to Satoshi Yamaguchi.

At least 37 records · Page 2Linked to original sources
PubMed2005

Poly(ethylene glycol) hydrogels cross-linked by hydrolyzable polyrotaxane containing hydroxyapatite particles as scaffolds for bone regeneration.

Poly(ethylene glycol) (PEG) hydrogels cross-linked by a hydrolyzable polyrotaxane containing hydroxyapatite particles (PRX-HAp) were developed as scaffolds for bone regeneration. Five scaffolds with various composition of the polyrotaxane, PEG and HAp particles were prepared to examine cell adhesion in vitro using rat primary cultured osteoblast. Cells were observed to attach well on a PRX-HAp that have the same weight ratio of the polyrotaxane and HAp particles at 7 days after seeding. These results indicate that HAp particles are necessary for cell adhesion and survival, but a higher ratio of the particles is not suitable for cell adhesion. The composites of rat osteoblast and the PRX-HAp were implanted subcutaneously in syngeneic rats and harvested at 5 weeks after implantation. In histological analysis, osteoblast-like cells became arrayed along the surface of the PRX-HAp, and osteoid-like tissues were observed in the region between a queue of osteoblast-like cells and PRX-HAp. These images are similar to intramembranous ossification, and it is expected that bone regeneration occurs on the surface of the PRX-HAp. This study strongly suggests the great potential of the PRX-HAp as scaffolds for bone regeneration.

Animals↗
PubMed2005

Ligamentum flavum hematoma in the lumbar spine.

A 62-year-old male presented with a rare case of ligamentum flavum hematoma manifesting as low back pain and gait difficulty beginning 1 month before consulting our institute. He had no history of lumbar spine surgery or lumbar puncture. However, he might have suffered forgotten back injury while practicing martial arts. Magnetic resonance imaging showed a heterogeneous intensity mass lesion with a cystic component at the L3-4 levels. The lesion was totally removed through a hemilaminectomy. Intraoperative and histological findings confirmed the diagnosis of old hematoma with granulomatous change in the ligamentum flavum. Postoperatively, his low back pain and gait difficulty resolved within a few days.

Hematoma↗
PubMed2005

Simultaneous cranial and spinal subdural hematoma.

A 59-year-old male presented with spinal subdural hematoma (SDH) with concomitant cranial chronic SDH manifesting as mild paraparesis and numbness in both lower extremities. Magnetic resonance (MR) imaging showed simultaneous occurrence of cranial and spinal SDHs. The patient was treated conservatively because of poor medical condition and mild neurological symptoms, and recovered well within 1 month. Serial follow-up MR imaging revealed spontaneous resolution of both lesions, with signal intensity changes suggesting the degenerative process of subacute hematoma. The spinal hematoma may have migrated from the cranial lesion. Spinal SDH is a potential sequela of chronic SDH in the cranium.

Hematoma, Subdural, Intracranial↗
PubMed2005

[Utility of ureteral stent for stone street after extracorporeal shock wave lithotripsy].

We reviewed the records of the 530 patients with urinary stones (renal stones: 243; ureter stones 287) who received extracorporeal shock wave lithotripsy (ESWL) (MFL5000; Dornier), from January 1995 to July 2002, retrospectively and determined whether the ureteral stent affected the incidence rate of stone street (SS). We also assessed the effect of ureteral stent on the subsequent management for SS. Forty patients (7.5%) developed SS. Twenty patients were inserted a ureteral stent prior to ESWL (stent group), and 20 patients were performed ESWL without a ureteral stent (in situ group). In the stent group, the most common (80.0%) location for SS was in the upper third ureter, while in the in situ group, SS mostly developed in the distal third ureter (60.0%). The incidence of SS did not differ significantly between the two groups when the size of renal and ureter stones was below 30 and 20 mm, respectively. When the renal stones were larger than above 30 mm, the incidence of SS in the stent group was significantly higher than that in the in situ group. SS disappeared spontaneously with stone passage in 10 of the patients in in situ group, but in only 1 patient in the stent group. In the stent group, 15 patients were treated for SS by removal of ureteral stent regardless of stone diameter. We conclude that ESWL should be performed without a ureteral stent when the stone diameter is below 20 mm. When the ureteral stent is thought to interfere with the delivery of stone fragments, the decision to remove it should be made as soon as possible.

Humans↗
PubMed2004

Ultrahigh-quality silicon carbide single crystals.

Silicon carbide (SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for next-generation electronic devices. Careful consideration of the thermal conditions in which SiC [0001] is grown has resulted in improvements in crystal diameter and quality: the quantity of macroscopic defects such as hollow core dislocations (micropipes), inclusions, small-angle boundaries and long-range lattice warp has been reduced. But some macroscopic defects (about 1-10 cm(-2)) and a large density of elementary dislocations (approximately 10(4) cm(-2)), such as edge, basal plane and screw dislocations, remain within the crystal, and have so far prevented the realization of high-efficiency, reliable electronic devices in SiC (refs 12-16). Here we report a method, inspired by the dislocation structure of SiC grown perpendicular to the c-axis (a-face growth), to reduce the number of dislocations in SiC single crystals by two to three orders of magnitude, rendering them virtually dislocation-free. These substrates will promote the development of high-power SiC devices and reduce energy losses of the resulting electrical systems.

Journal Article↗
PubMed2004

Water-soluble prodrugs of dipeptide HIV protease inhibitors based on O-->N intramolecular acyl migration: Design, synthesis and kinetic study.

To improve the low water-solubility of HIV protease inhibitors, we synthesized water-soluble prodrugs of KNI-727, a potent small-sized dipeptide-type HIV-1 protease inhibitor consisting of an Apns-Dmt core (Apns; allophenylnorstatine, Dmt; (R)-5,5-dimethyl-1,3-thiazolidine-4-carboxylic acid) as inhibitory machinery. These prodrugs contained an O-acyl peptidomimetic structure with an ionized amino group leading to an increase in water-solubility, and were designed to regenerate the corresponding parent drugs based on the O-->N intramolecular acyl migration reaction via a five-membered ring intermediate at the alpha-hydroxy-beta-amino acid residue, that is Apns. The synthetic prodrug 3a improved the water-solubility (13 mg/mL) more than 8000-fold in comparison with the parent compound, which is the practically acceptable value as water-soluble drug. Furthermore, to understand the structural effects of the O-acyl moiety on the migration rate, we evaluated several phenylacetyl-type and benzoyl-type prodrugs. These prodrugs were stable as an HCl salt and in a strongly acidic solution corresponding to gastric juice (pH 2.0), and could be converted to the parent compounds promptly under aqueous conditions from slightly acidic to basic pH at 37 degrees C.

Acylation↗
PubMed2004

Sarcomas of the oral and maxillofacial region: a review of 32 cases in 25 years.

Thirty-two cases of sarcomas involving the oral and maxillofacial region over a period of 25 years were reviewed. The age range was from 5 months to 77 years with a mean age of 42. The male to female ratio was 3:1. The sarcomas were located in the maxilla including the maxillary sinus (n= 13), mandible (n= 13), buccal mucosa (n= 3), temporomandibular fossa (n= 2), and submandibular region (n= 1). Histologically sarcomas were classified as osteosarcoma (n= 9), malignant fibrous histiocytoma (n= 7), rhabdomyosarcoma (n= 5), fibrosarcoma (n= 3), plasmacytoma (n= 2), leiomyosarcoma (n= 2), angiosarcoma (n= 2), liposarcoma (n= 1), and ameloblastic fibrosarcoma (n= 1). Surgical resection was performed in 29 cases. Local recurrence was found in 10 patients and metastasis in 11 patients. Metastases included five regional lymph node metastases and eight distant metastases. The survival of patients with local recurrence or metastasis was poor. Surgery is the most reliable treatment for sarcomas of the oral and maxillofacial region. Adequate excision with safety surgical margin as the initial therapy is important for better survival. The value of radiation therapy and/or chemotherapy is uncertain. The 5-year survival rate of primary cases was 61%.

Adult↗
PubMed2004

Solid-phase artificial chaperone-assisted refolding using insoluble beta-cyclodextrin-acrylamide copolymer beads.

Solid-phase refolding methods are advantageous since they facilitate both separation of solid additives from the refolded protein and recycling of the additives. Beta-cyclodextrin-acrylamide copolymer hydrogel beads were used as a matrix for detergents in solid-phase artificial chaperone-assisted refolding and improved the yield of lysozyme (up to 65%) and carbonic anhydrase B (up to 80%), compared with conventional solid host matrices.

Acrylamide↗
PubMed2004

Spontaneous regression of Langerhans cell histiocytosis: a case report.

BACKGROUND: Spontaneous regression of Langerhans cell histiocytosis (LCH) has been reported in skin, bone, and pulmonary lesions. However, such phenomena in the central nervous system (CNS) have not been described previously. CASE DESCRIPTION: A case of LCH in the CNS with spontaneous regression is reported. A 2-year-old boy presented with general convulsion followed by frequent vomiting and diabetes insipidus. Magnetic resonance imaging (MRI) scan revealed numerous multifocal nodules predominantly in the left frontal lobe. The patient underwent surgery to remove part of the frontal lesion. Subsequent to surgery, residual lesions showed regression without any additional treatment, and clinical symptoms also subsided. The multiple lesions disappeared completely and did not relapse during 5-year observation. CONCLUSION: Surgical resection and/or adjuvant therapy such as radiation and chemotherapy has been performed for the treatment of LCH in the CNS. However, there may be a subgroup of patients with multifocal brain LCH that regress spontaneously. Further clinical study is required to establish the natural course and prognostic factors of this disease.

Brain Diseases↗
PubMed2004

Changes in urinary parameters after oral administration of potassium-sodium citrate and magnesium oxide to prevent urolithiasis.

OBJECTIVES: To examine urinary parameters among normal individuals and patients with calcium oxalate (CaOx) stones after oral administration of potassium-sodium citrate (KNa-Cit) and magnesium oxide (MgO). Urinary citrate and magnesium have been known as the inhibitors of CaOx stone formation. Supplementation with potassium-magnesium citrate prevents the recurrence of CaOx stones. METHODS: Twenty-five male volunteers aged 21 to 42 years without a history of urinary stones were given either KNa-Cit or MgO, or both. Fourteen patients with recurrent CaOx stones were also given both supplements, and 24-hour urine samples were collected to determine the urinary parameters. RESULTS: The administration of both KNa-Cit and MgO to the normal individuals increased the excretion of citrate, magnesium, and potassium by 70.0%, 44.2%, and 50.0%, respectively. These parameters increased less when KNa-Cit or MgO was administered individually. After administration of both supplements to the patients with stones, the citrate, magnesium, and potassium levels increased by 62.1%, 63.3%, and 25.3%, respectively, and oxalate decreased by 66.5%. In both normal individuals and patients, the ion activity product index of CaOx decreased significantly more after administration of the combination than with either compound alone or before administration. CONCLUSION: The combination of KNa-Cit and MgO is more effective than either supplement alone in inhibiting the crystallization of CaOx stones. The combination may improve the urinary parameters of patients with stones accompanied by hypocitraturia and/or hypomagnesuria.

Administration, Oral↗
PubMed2004

Evaluation of surface hydrophobicity of immobilized protein with a surface plasmon resonance sensor.

Immobilization is widely used to isolate agglutinative and associative proteins with large hydrophobic surfaces. Surface hydrophobicities of immobilized proteins were quantified by measuring the adsorption amounts of Triton X-100 as a hydrophobic probe with a biosensor that utilizes the phenomena of surface plasmon resonance (SPR). We measured SPR signal changes derived from adsorption of Triton X-100 to five kinds proteins and calculated the monolayer adsorption capacity using the Brunauer-Emmett-Teller equation, partly modified with a term for correcting an influence of the net charge of immobilized protein. SPR signal changes obtained by this method correlated with the values of surface hydrophobicities obtained by conventional assay using a hydrophobic probe. Thus this measuring method using an SPR sensor and Triton X-100 is expected to be a tool for quantifying surface hydrophobicities of immobilized proteins.

Octoxynol↗
PubMed2004

Executive dysfunction can explain word-list learning disability in very mild Alzheimer's disease: the Tajiri project.

Elderly people with questionable dementia (i.e. a Clinical Dementia Rating (CDR) of 0.5) have been focused on as representing the borderline zone condition between healthy people and dementia patients. Many of them are known to have pathologic traits of very mild Alzheimer's disease (AD). Although they present mild memory disorder, the underlying mechanism has not been fully investigated. Herein is reported the mechanism of learning disability in very mild AD. Eighty-six CDR 0.5 participants and 101 age- and education-matched healthy controls (CDR 0) were randomly selected from a community in the town of Tajiri, Miyagi Prefecture. The word-recall task of the Alzheimer Disease Assessment Scale-Japanese (i.e. learning and recall of 10 words) was administered. The numbers of words recalled in each trial and those never recalled throughout the trials were compared for the two CDR groups. The serial-position function was depicted for three parts (i.e. primary, middle, and recency). The CDR 0.5 group recalled significantly fewer words than the CDR 0 group. The number of never-recalled words was greater in the CDR 0.5 group. A remarkable difference was found in the middle part of the word list. The number of never-recalled words of the CDR 0.5 group was greater in the middle part. The large number of never-recalled words accounted for the poor learning performance of very mild AD participants. The results suggested that very mild AD participants have difficulty in learning and retaining words in the middle part of the word-list because of a functional decline of the central executive system.

Aged↗
PubMed2004

Comparative study of novel endoluminal ultrasonography and conventional transurethral ultrasonography in staging of bladder cancer.

BACKGROUND: Recent advances in ultrasonic techniques have improved the image quality and diagnostic accuracy for staging of bladder cancer. The aim of this study was to assess the feasibility and usefulness of endoluminal ultrasonography (ELUS) in staging of bladder cancer, and to compare them with those of conventional transurethral ultrasonography (TUUS). METHODS: From 2000 to 2002, 19 patients with bladder cancer were evaluated by ELUS and TUUS before transurethral resection or biopsy. Clinical staging using ELUS, TUUS, computed tomography (CT) and magnetic resonance imaging (MRI) was compared with the results of pathological staging. RESULTS: In 16 of 19 patients, both ELUS and TUUS were able to diagnose tumor stage. In the remaining three patients, both methods were unable to evaluate stage of tumor. In two of these patients, this inability to evaluate tumor state was caused by a difficulty in depicting the tumor base in rectangular scanning. In the remaining patient, the inability to evaluate tumor stage was caused by a difficulty in recognizing the normal muscularis because of edema around the tumor base. Both diagnostic accuracies of ELUS and TUUS were 84%, which were superior to those of CT (44%) and MRI (82%). CONCLUSIONS: Endoluminal ultrasonography and TUUS were equally useful for staging diagnosis of bladder cancer. Because the ELUS probe is very small in diameter and can be manipulated under direct vision, it is superior to the TUUS in safety and in fine visualization. However, the main limitations of ELUS include an inability to evaluate the depth of invasion of large tumors and an inability to visualize the tumor base in the position of the bladder neck.

Aged↗
PubMed2004

Neuropsychosocial features of very mild Alzheimer's disease (CDR 0.5) and progression to dementia in a community: the Tajiri project.

The borderline condition between normal aging and dementia should be detected to predict further deterioration. The authors cross-sectionally analyzed neuropsychological data, memory complaints, and social activities for community-dwelling older adults. The rate of decline from Clinical Dementia Rating (CDR) 0.5 to dementia during a 3-year interval was also analyzed. Short-term memory rather than long-term memory was found to be sensitive in distinguishing those with CDR 0 from those with CDR 0.5. Relatives' observations of memory decline rather than subjective memory complaints were significantly different. Participants with CDR 0.5 reported fewer problems with social activities than did their relatives. Ten of the 29 CDR 0.5 participants (34.5%) showed cognitive decline, the decliners showing lower scores on short-term memory and orientation at the baseline condition. The neuropsychological data showed CDR 0.5 to be similar to very mild Alzheimer's disease. It would be better if subjective complaints were excluded from the criteria of the borderline condition.

Aged↗
PubMed2004

[Postoperative hypoglycemia after resection of pheochromocytoma: a case report].

We report a case of severe hypoglycemia following resection of pheochromocytoma. A 39-year-old male was admitted to our hospital with a chief complaint of palpitation. Blood pressure and fasting blood glucose were within the normal range. Computed tomography and magnetic resonance imaging revealed a right adrenal tumor (7.5 x 5 x 7 cm) and 131I-MIBG scintigraphy showed marked tumor uptake of isotope. As plasma and urinary catecholamine levels were very high, a clinical diagnosis of pheochromocytoma was established. Doxazosin and propranolol were administered for 43 days prior to adrenalectomy. During intensive care monitoring 2 hours postoperatively, the patient became drowsy and began to sweat. Although blood pressure remained stable, severe hypoglycemia (38 mg/dl) and hyperinsulinism (63.67 microU/ml) were confirmed. Infusion of 50% glucose improved these symptoms and plasma glucose level and insulin secretion normalized within 15 days of surgery. We also reviewed 25 cases of hypoglycemia after resection of pheochromocytoma. We recommend close monitoring of blood glucose for at least 6 hours after adrenalectomy for pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed2004

[Epidemiological characteristics of urolithiasis in Okhotsk coast area in Hokkaido].

An epidemiological study of 422 stone-formers who visited our hospital from 1997 to 2001 was conducted. The mean annual prevalence and incidence of both upper and lower urinary tract stones were higher than what was found in a nationwide urolithiasis survey carried out in Japan in 1995. The incidence of upper and lower urinary tract stones was 90.8% and 9.2%, respectively. The frequency of lower urinary tract stones was higher than that found in the previously mentioned nationwide study. The male-to-female ratio of upper and lower urinary tract stones was 1.68:1 and 2.25:1, respectively. The frequency in females was higher in this study than that found in the nationwide survey. The peak age for incidence of upper urinary tract stones is 50s in males and females. In the treatment of upper urinary tract stones, ureteroscopic lithotripsy was carried out more often than shock wave lithotripsy (SWL), because our hospital had no SWL device. Many endoscopic lithotripsy procedures were performed to treat stones located in the lower urinary tract. Of the upper urinary tract stones 83.7% were composed of calcium, the incidence of uric acid stones was high (6.6%), whereas the incidence of infectious stones was low (1.9%). For lower urinary tract stones, the frequency of infectious stones was high (52.6%). In the present study, the epidemiological features were as follows: high annual prevalence and incidence, high frequency of lower urinary tract stones, high frequency in females, many endoscopic treatment procedures and high frequency of uric acid stones in the upper urinary tract.

Adult↗
PubMed2004

Efficacy of whole PTH assay and 1-84/non-(1-84) PTH ratio in patients on hemodialysis or undergoing parathyroidectomy.

For measurement of parathyroid hormone (PTH), the intact PTH (I-PTH) assay is generally used. However, I-PTH assay apparently detects PTH 7-84 fragments, in addition to PTH 1-84. The whole PTH (W-PTH) assay exhibits no cross-reactivity with PTH 7-84. Ratio of PTH 1-84 to non-(1-84) PTH has been proposed as a non-invasive indicator of bone turnover in patients with end-stage renal disease (ESRD). We evaluated the efficacy of W-PTH assay and 1-84/non-(1-84) PTH ratio in hemodialysis patients and patients who had undergone parathyroidectomy. PTH levels were measured using W-PTH and I-PTH assays in 138 hemodialysis patients, 27 healthy controls and 10 patients who were scheduled to undergo parathyroidectomy for secondary hyperparathyroidism. Alkaline phosphatase, bone alkaline phosphatase and intact osteocalcin were also measured for comparison with 1-84/non-(1-84) PTH ratio. W-PTH was strongly correlated with I-PTH in both groups, and with all three bone metabolic markers in hemodialysis patients. In hemodialysis patients, both PTH and bone metabolic markers were significantly lower in the subgroup with a PTH ratio < 1.0 than in the subgroup with a PTH ratio > or = 1.0. However, PTH ratio exhibited no significant correlation with bone metabolism markers. PTH ratio was higher after parathyroidectomy than before. W-PTH and I-PTH assays offer identical indicators of bone metabolism in ESRD patients. However, 1-84/non-(1-84) PTH ratio may be of limited diagnostic use regarding bone turnover if a cut-off value of 1.0 is used. PTH 1-84 may be secreted relatively more than non-(1-84) PTH after parathyroidectomy, due to decreases in serum calcium. As the W-PTH assay allows easy calculation of non-(1-84) PTH by subtracting the I-PTH value, this assay contributes to identification of the function of non-(1-84) PTH fragments in various conditions.

Biomarkers↗