Biomedical subjects

Hiroki Yamada

Publications and source records attributed to Hiroki Yamada.

At least 19 recordsLinked to original sources

PubMed2006

Surgical treatment of blepharoptosis caused by chronic progressive external ophthalmoplegia.

UNLABELLED: Chronic progressive external ophthalmoplegia (CPEO) is a neuromyopathic disorder characterized by progressive weakness of the extraocular and levator muscles, which causes blepharoptosis and impairment of ocular motility. Because of the risk of worsening of lagophthalmos and exposure keratitis due to an associated poor Bell phenomenon or weak orbicularis function, surgical treatment of the blepharoptosis caused by CPEO is problematic. We present our experience with a case of blepharoptosis in CPEO. CASE: A 61-year-old woman presented with slowly progressive bilateral blepharoptosis. A muscle biopsy of the rectus femoris revealed mitochondrial abnormalities, which satisfied the definition of the diagnosis of CPEO as mitochondrial encephalomyopathy. The lid opening was 2 mm, with maximal frontalis contraction, the levator function was zero, and the eyeball movement was severely limited. The blow movement was about 6 mm. Combination of modest blepharoplasty and frontalis suspension using a monofilament suture was performed. The postoperative result was satisfactory, and the patient's quality of life was markedly improved.

Biopsy↗

PubMed2006

Percutaneous cryoablation of renal cell carcinoma guided by horizontal open magnetic resonance imaging.

BACKGROUND: Cryoablation is a treatment option for some patients with small exophytic lesions of the kidney. The purpose of this study is to determine the feasibility, safety, and intermediate-term treatment outcome of percutaneous cryoablation of renal cell carcinoma guided by horizontal open magnetic resonance imaging (MRI). METHODS: We prospectively used cryoablation to treat 13 patients with radiographically confirmed enhancing small, solid renal tumors (< or =4.8 cm). An argon gas-based cryoablation system was used. One to four cryoprobes with 2 or 3-mm diameters were placed percutaneously into the tumor under local anaesthesia and MRI guidance. Ice ball dimensions were monitored by 2-D MR images. Double freeze-thaw cycles were conducted throughout the procedure. After successful cryoablation, patients were followed on a regular basis to evaluate the treatment's clinical outcome. RESULTS: Median follow up from time of procedure is 35 months (range, 28-42). In all cases the entire procedure was accomplished without significant morbidity or complications. A mild retroperitoneal hematoma, which subsided spontaneously, was noted in one patient. Follow-up dynamic computed tomography (CT) at 3 months after operation confirmed the absence of enhancement in resolved tumor masses for 11 of 13 cases. None of these 11 patients had clinical evidence of recurrent disease at last follow up. The remaining two patients had lesions with some enhanced areas. Subsequent partial nephrectomy histologically confirmed the presence of vital tumor in, respectively, the center and the periphery of the residual masses. One of these patients developed multiple lung and ipsilateral adrenal metastases 13 months after surgical resection. CONCLUSIONS: Percutaneous cryoablation of small renal cell carcinomas under horizontal open MRI guidance appears to be safe and feasible. An intermediate-term follow up continues to demonstrate efficacy in most patients; however, a few patients experience incomplete ablation with risk of treatment failure. The ideal candidates for this procedure still need to be determined in longer follow up with diligent observation.

Adult↗

PubMed2005

Characterization of glial cell line-derived neurotrophic factor family receptor alpha-1 in peripheral nerve Schwann cells.

Glial cell line-derived neurotrophic factor (GDNF) family receptor alpha-1 (GFRalpha-1) is a receptor component of GDNF that associates with and activates the tyrosine kinase receptor Ret. To further understand GDNF and its receptor system in the PNS, we first characterized the expression of GFRalpha-1 in bovine peripheral nerve in vivo. GFRalpha-1 immunoreactivity was localized adjacent to the outermost layer of myelin sheath, as well as in the endoneurium and axoplasm. In a fractionation study, GFRalpha-1 was recovered mostly in the soluble fraction, although a small amount was recovered in the membrane fraction. A substantial amount of GFRalpha-1 in the membrane fraction was extractable by detergent and alkaline conditions. To further clarify the expression of GFRalpha-1 in Schwann cells, we examined cultured rat Schwann cells and the Schwannoma cell line RT4. Schwann cells expressed GFRalpha-1 in both the soluble/cytosolic and membrane fractions, and the membrane form of GFRalpha-1 was expressed at the outer surface of the Schwann cell plasma membrane. We also confirmed the secretion of the soluble form of GFRalpha-1 from Schwannoma cells in a metabolic labeling experiment. These data contribute to our knowledge of the production, expression and functions of GFRalpha-1 in the PNS.

Animals↗

PubMed2005

[Fundamental study of coronary angiography using gadolinium contrast agent].

To investigate the clinical usefulness of coronary arteriography using a gadolinium contrast medium (hereinafter referred to as Gd contrast medium) in patients with iodine allergy, images obtained using an iodinated contrast medium and a Gd contrast medium were compared using respective phantoms. Within the range of the effective energy (34.8 to 41.0 keV) in clinical use, the tube-voltage dependency of the Gd contrast medium was lower than that of the iodinated contrast medium. The contrast ratios were found to be comparable for the images obtained by a 4-fold-diluted iodinated contrast medium and the undiluted Gd contrast medium. Although the assessment of stenotic ratio was difficult to obtain by visual evaluation of the clinical images, due to unclear borders of the blood vessels, the presence or absence of significant stenosis was discriminative by arteriography using the Gd contrast medium. Based on these findings, it was considered necessary to make a confirmed diagnosis using a Gd contrast medium with concurrent diagnosis by intravascular echography. In conclusion, coronary arteriography and PCI using a Gd contrast medium are considered to offer benefit to the diagnosis and treatment of patients with iodine allergy.

Angioplasty, Balloon, Coronary↗

PubMed2005

Magnetic field strength increase yields significantly greater contrast-to-noise ratio increase: Measured using BOLD contrast in the primary visual area.

RATIONALE AND OBJECTIVE: The advantage of a higher static magnetic field for functional MRI has been advocated; however, the observed advantage varies. The aim of this study was to evaluate the effect of increasing static magnetic field strength on the task-related increase in blood oxygenation level-dependent (BOLD) signal and residual noise with visual stimuli of different frequencies, which may enable better comparisons of results of different MRI scanners. MATERIALS AND METHODS: Eight right-handed healthy volunteers were presented checkerboard stimuli flickering at 5 different frequencies up to 8 Hz. Field strengths of 3 T or 1.5 T were used to measure frequency-dependent signal changes in the primary visual area. Regression analysis was performed for the signal increase and the "noise," which was defined by the root mean of squares of the residual signal fluctuation. These values were compared and their relationship was analyzed. Imaging parameters were identical except for the use of a 25% shorter echo time using 3 T. RESULTS: The frequency-dependent increase in BOLD signal using 3 T was twice that using 1.5 T. In contrast, the ratio of noise values that reflect time-course signal fluctuation (3 T/1.5 T) was only 0.88. There was large individual variance in these values, but the slope and noise values were linearly related using either field strength. The contrast-to-noise ratio using 3 T was 2.3 times higher than that using 1.5 T. CONCLUSION: There was a greater-than-linear increase in the contrast-to-noise ratio compared with the increase of field strength, demonstrating an advantage of using higher field strengths in fMRI studies.

Adult↗

PubMed2005

Sarcomatoid renal cell carcinoma with a chromophobe component producing beta-human chorionic gonadotropin.

We report a case of sarcomatoid renal cell carcinoma with a chromophobe component showing significant elevation of beta-human chorionic gonadotropin (beta-HCG) in the peripheral blood. A 35-year-old man was hospitalized because of a large tumor of the left kidney and elevated serum levels of beta-HCG. Extended nephrectomy was performed, after which the serum beta-HCG level decreased. However, 3 months later, masses were discovered in the left renal bed and in the lung in association with elevated serum levels of beta-HCG. The patient was rehospitalized and received combination therapy with interferon-alpha and doxorubicin-based multiple chemotherapy (cyclophosphamide, vincristine, doxorubicin, and dacarbazine). The recurrent mass responded extremely well to treatment, and beta-HCG normalized. However, the patient died 14 months after nephrectomy because of eventual resistance to chemotherapy. Sarcomatoid renal cell carcinoma containing beta-HCG positive cells were pathologically diagnosed with immunohistochemical staining in the left kidney. Sarcomatoid renal cell carcinoma is a variant of renal adenocarcinoma which has a poor prognosis. This patient had an extremely rare sarcomatoid renal cell carcinoma associated with serum levels of beta-HCG which were elevated and strongly correlated with morphologic cancer activity. beta-HCG might be a useful serum marker for detecting and monitoring this renal cell carcinoma.

Adult↗

PubMed2005

[Roles of BPH impact index in the evaluation of impaired urination in patients with BPH].

OBJECTIVE: To assess the significance and current status of the benign prostatic hyperplasia (BPH) impact index (BII) in the evaluation of subjective symptoms of impaired urination in so-called QOL disease, BPH. PATIENTS AND METHODS: Over the past 2 year-period, in 159 patients with the diagnosis of BPH were asked to reply to each of the international prostate symptom score (I-PSS), QOL index and BII questionnaires. The subjective symptom scores (a total of 246 points) were evaluated from the viewpoint of clinical statistics in the search for any these and to find which questions cover the BII, most. RESULTS: 1) Statistically significant but moderate correlations were observed among I-PSS total score, QOL index and BII. The correlations among Qmax, BII and QOL were very weak. 2) Out of the 11 domains in both IPSS and BII, 2 questions of BII ("bothersomeness caused by urinary problems" and "degree of worry about well-being") and 4 questions of IPSS ("residual sense," " pollakisuria," "weak urinary stream" and "nocturia") were shared as QOL indices. Patient satisfaction was affected also by the questions in the BII. 3) Of the 7 BPH symptoms assessed in IPSS, 4 symptoms ("residual sense," "pollakisuria," "weak urinary stream" and "nocturia") affected the QOL index, and 4 symptoms ("urgency on micturition," "residual sense," "nocturia" and "strain at urination") affected BII. 4) Of the 7 symptoms assessed by IPSS, different symptoms affected each of the 4 BII questions. CONCLUSION: It is needed to assess BPH symptoms not only by the IPSS and QOL index but also based on BII to provide the detailed therapeutic instructions and thorough patients consultation.

Aged↗

PubMed2004

Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study.

BACKGROUND: Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language. RESULTS: The sign-comprehension tasks activated the planum temporale of both early- and late-deaf subjects, but not that of hearing signers. In early-deaf subjects, the middle superior temporal sulcus was more prominently activated than in late-deaf subjects. CONCLUSIONS: As the middle superior temporal sulcus is known to respond selectively to human voices, our findings suggest that this subregion of the auditory-association cortex, when deprived of its proper input, might make a functional shift from human voice processing to visual processing in an age-dependent manner.

Adult↗

PubMed2004

[Clinical characteristics of 16 patients suspected preclinical Cushing's syndrome].

PURPOSE: In 1996, Japanese guidelines for the diagnosis of preclinical adrenal Cushing's syndrome were proposed. However, several patients with preclinical Cushing's syndrome (PCS) didn't clearly show that these diagnostic guidelines were universally applicable. The aim of the present study was to evaluate the validity of these diagnostic guidelines on the basis of our clinical experience. PATIENTS AND METHODS: We performed adrenalectomy for adrenal incidentaloma in 16 patients with suspected PCS at our university hospital from 1990 through 2002. Eight patients met the Japanese criteria for the diagnosis of PCS (PC group) and 8 did not (dexamethasone [DXM] suppression group). Clinical characteristics and pathology profiles were compared between the groups. RESULTS: No patients in the DXM suppression group showed responses of serum cortisol levels on a 1-mg overnight dexamethasone suppression test. Twenty-four-hour urinary levels of 17-hydroxycorticosteroids were significantly higher in the PC group than in the DXM suppression group. In all patients of both groups, adrenal scintigraphy showed marked accumulation of radioisotope in the adhesive, atrophic adrenal cortex. One patient of the DXM suppression group had severe adrenal symptoms after adrenalectomy. Several patients in the DMX suppression group showed clinical improvement after adrenalectomy, as well as did several patients in the PC group. CONCLUSION: Endocrine activity may have been higher in the PC group than in the DXM suppression group. However, because patients who failed a 1-mg DXM suppression test may in fact have autonomous cortisol secretion, adrenalectomy may still be indicated. Autonomous cortisol secretion might not be documented with the 1-mg overnight DXM suppression test; therefore, the results must be interpreted carefully.

Adrenocorticotropic Hormone↗

PubMed2003

Association of dystroglycan and laminin-2 coexpression with myelinogenesis in peripheral nerves.

To provide clues to the biological functions of dystroglycan-laminin-2 complex in peripheral nerves, we investigated the expressions of beta-dystroglycan and laminin-alpha(2) chain in rat sciatic nerve during axonal degeneration and regeneration and during development, as well as in rat dorsal root ganglia. In normal conditions, immunoreactivity of the cytoplasmic domain of beta-dystroglycan was associated with the Schwann cell abaxonal membrane. The immunoreactivities of both beta-dystroglycan and the laminin-alpha(2) chain decreased in Schwann cells losing axons during axonal degeneration and progressively increased in remyelinating Schwann cells during axonal regeneration. Interestingly, during axonal degeneration, the abaxonal membrane losing contact with the basal lamina lost the association with beta-dystroglycan immunoreactivity. During development, expression of both beta-dystroglycan and laminin-alpha(2) chain strikingly increased during postnatal 7 days, which is a critical period when basal lamina assembly and myelin formation rapidly progress. These results suggest that coexpression of dystroglycan and laminin-2 is associated with myelinogenesis in peripheral nerves. These two proteins may function as an anchorage between the abaxonal membrane and the basal lamina, enabling myelin forma-tion to progress. Beta-dystroglycan and laminin-2 were also coexpressed in satellite cells in dorsal root ganglia, suggesting that interaction of these two proteins plays some role in physiological functions of these cells.

Animals↗

PubMed2003

Structure of the polysaccharide isolated from the sheath of Sphaerotilus natans.

A polysaccharide was isolated from the sheath of a sheathed bacterium, Sphaerotilus natans. The sheath polysaccharide (SPS) was composed of D-glucose and D-(N-acetyl)galactosamine in molar ratios of 1:4. Methylation linkage analysis revealed the presence of the residues of 4-linked glucose, 4-linked (N-acetyl)galactosamine, and 3-linked (N-acetyl)galactosamine in molar ratios of 1:3:1. The oligomer of SPS was prepared with an SPS-specific degrading enzyme from a sheath-degrading bacterium, Paenibacillus koleovorans. The oligomer was derivatized and subjected to fast atom bombardment-mass spectrometry to investigate the monosaccharide sequence of SPS. The structure of SPS was confirmed by nuclear magnetic resonance. The resulting data showed that SPS is a straight-chained basic polysaccharide constructed of a pentasaccharide repeating unit.

Acetylgalactosamine↗

PubMed2003

Disruption of dystroglycan axis by beta-dystroglycan processing in cardiomyopathic hamster muscle.

Alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix, while beta-dystroglycan is a type I integral membrane protein which anchors alpha-dystroglycan to the cell membrane via the N-terminal extracellular domain. The complex composed of alpha- and beta-dystroglycan is called the dystroglycan complex. Although defects of the dystroglycan gene have not been identified as the primary causes of hereditary diseases in humans, secondary but significant abnormalities of the dystroglycan complex have been revealed in severe muscular dystrophies, including sarcoglycanopathy (LGMD2C, D, E and F). In this study, we investigated proteolytic processing of beta-dystroglycan and its effect on the extracellular matrix-cell membrane linkage in cardiomyopathic hamsters, the model animals of LGMD2F. Compared to normal controls, proteolytic processing of beta-dystroglycan was activated in the skeletal, cardiac and smooth muscles of cardiomyopathic hamsters and this resulted in the partial disruption of the dystroglycan complex in these tissues. These phenomena were observed from the early phase of muscle degeneration process. Our results suggest that proteolytic processing of beta-dystroglycan disrupts the extracellular matrix-cell membrane linkage via the dystroglycan complex and this may play a role in the molecular pathogenesis of muscle degeneration in cardiomyopathic hamsters.

Animals↗

PubMed2003

[Clinical studies on TUR-P using clinical path: report of 50 cases and review of literature].

PURPOSE: This study was undertaken to clarify the usefulness and problems involved in the clinical path of transurethral prostatectomy (TUR-P) in hospital. PATIENTS AND METHODS: The subjects consisted of 50 patients, for whom the Department of Urology, Jikei Medical University Hospital introduced its own clinical path and performed TUR-P during a period of 9 months from July 1999 to March 2000. The mean length of hospital stay, rate of postoperative complications, and the medical insurance claims made by these patients were clarified and compared with those of 73 patients before introduction of the clinical path. RESULTS: With the introduction of the clinical path, the length of hospital stay decreased by an average of 3.4 days and the total medical insurance claims decreased by an average of 18.5%. The rate of postoperative complications before and after introduction was almost equal. CONCLUSION: Our clinical path for TUR-P was well accepted by both patients and comedicals. However, the present medical treatment system in Japan is not as yet prepared to promote the introduction of this clinical path, and it will take some time before this clinical path is introduced on a full scale.

Aged↗

PubMed2003

[Carcinoma of urachus: report of 15 cases and review of literature--is total cystectomy the treatment of choice for urachal carcinoma?].

PURPOSE: This study was undertaken to determine the most appropriate type of operation for the improvement of the radical cure rate and QOL of patients with urachal cancer. We assessed the association between the stage, type of operation, and prognosis of cases we experienced and those reported in Japan. PATIENTS AND METHOD: The subjects included 15 cases of urachal cancer we have experienced in the past 14 years. While clarifying the clinical patterns of these cases, the association between stage, type of operation, and prognosis was studied. Of the cases of urachal cancer reported in Japan in the recent 20 years, 75 cases in which the stage, type of operation, and prognosis were documented were selected, and the association between the stage and outcome in each type of operation was studied. RESULTS: In regard to stage, all the cases were rated as more than IIIA. As for prognosis, 9 cases (60%) are alive without cancer at the present time with a mean survival time of 7 years. Of the above patients, 3 underwent cystectomy and 6 underwent en bloc segmental resection (herein after referred to en bloc). Recurrence or cancer death was experienced in 5 patients, 2 of which were classified as stage IIIA and 3 as IIID. Of these patients, one underwent en bloc, 3 partial resection of the bladder, and one underwent exploratory laparotomy. As far as our study of the cases reported in Japan is concerned, the prognosis of the cases having undergone only partial resection of the bladder was poor, while of the cases having undergone en bloc or total cystectomy 88-100% were alive without cancer for more than 2 years if their stage was classified as IIIA or below. On the other hand, prognosis was very poor whatever the type of operation in the cases whose cancer was stage IIIC or above. CONCLUSIONS: It appears that the en bloc is most appropriate as the type of operation for the cases of urachal cancer and that the application of total cystectomy is limited to some cases. In performing the en bloc, an extensive resection of the peritoneum, resection of the posterior sheath of the rectus muscle of the abdomen, and dissection of the intrapelvic lymph nodes in addition to the conventional types of operation should be carried out positively.

Adenocarcinoma↗

PubMed2003

[Bilateral pyeloureteritis cystica: a case report].

We report here a case of bilateral pyeloureteritis cystica. A 67-year-old woman was admitted to our hospital with asymptomatic macrohematuria in September 1999. Drip infusion pyelography and enhanced computed tomography demonstrated multiple small, round filling defects in both renal pelvises and ureters. Ureteroscopy and cold punch biopsy were performed, and histological examination revealed pyeloureteritis cystica. This patient was not given adjuvant therapy but was carefully followed up for 3 years and 6 months postoperatively.

Aged↗

PubMed2003

[Retrospective analysis of uroepithelial malignancies detected in the renal pelvis and ureter over the past decade at the Jikei University Hospital].

The aim of this study was to investigate recent characteristics and alterations of upper urinary tract cancer based on experience at a single institution over the past decade. Ninety-nine patients with renal pelvic and ureteral cancer resected at the Jikei University Hospital from January 1991 through December 2000 were retrospectively analyzed. Cancer-specific survival by pathologic stage, grade, and various clinical parameters were calculated by the Kaplan-Meier method. Prognostic factors for survival were examined with univariate and multivariate analysis. Cox regression analysis was used for multivariate analysis. Twenty-eight percent of cancers had been detected incidentally without having caused any symptoms. The overall 3-year and 5-year cancer-specific survival rates were 78% and 70%, respectively. The 5-year survival rate was 100% in patients with G1 cancer and 38% in those with G3 cancer. The 5-year survival rate was significantly higher in patients with cancers of lower grade (p = 0.0089), and was also higher in patients with cancers of stage pT1 or lower than in patients with cancers of stage pT2 and higher (p = 0.0038). The survival of patients with recurrence in the bladder was significantly longer than that of patients with recurrence in other organs. Multivariate analysis indicated that patient age and pT were the most important prognostic factors, followed by the presence of symptoms at diagnosis. The incidence of asymptomatic upper urinary tract cancer is increasing at institutions in Japan. We conclude that the cancer grade and stage still have classical predictive value, but that the presence of symptoms at the time of diagnosis is also an important prognostic factor.

Aged↗

PubMed2002

Characterization of parkin in bovine peripheral nerve.

The autosomal recessive juvenile parkinsonism is caused by the mutations of the gene encoding a novel protein called parkin. It has been reported that parkin is expressed in the central nervous system and functions as a ubiquitin-protein ligase (E3) which suppresses neuronal cell degeneration by ubiquitinating misfolded proteins. Thus far, however, it remains unknown if parkin is expressed and functions in the peripheral nervous system. In order to begin to address to this question, we investigated the expression of parkin in bovine peripheral nerve. Reverse transcription polymerase chain reaction analysis demonstrated the presence of parkin transcript in bovine peripheral nerve. The obtained bovine parkin cDNA sequence was identical to that of human except a single nucleotide. Immunoblot analysis demonstrated the expression of parkin protein in bovine peripheral nerve. Immunohistochemical analysis demonstrated the localization of parkin in the axoplasm of myelinated nerve fibers, the Schwann cell cytoplasm and the Schwann cell outer membrane. Furthermore, fractionation analysis indicated the presence of two fractions of parkin in bovine peripheral nerve, the cytosolic fraction and the cell membrane-bound fraction. All together, these results point to diverse roles of parkin in not only the central but also the peripheral nervous system.

Animals↗

PubMed2002

Expression of dystroglycan and the laminin-alpha 2 chain in the rat peripheral nerve during development.

In Schwann cells, the transmembrane glycoprotein beta-dystroglycan comprises the dystroglycan complex, together with the extracellular glycoprotein alpha-dystroglycan, which binds laminin-2 (alpha 2/beta 1/gamma 1), a major component of the Schwann cell basal lamina. To provide clues to the biological functions of the interaction of the dystroglycan complex with laminin-2 in peripheral nerves, we investigated the expression of beta-dystroglycan and the laminin-alpha 2 chain in rat sciatic nerve during development by immunoblot, immunofluorescence, and immunoelectron microscopic studies. The expression of beta-dystroglycan and the laminin-alpha 2 chain in the rat sciatic nerve was low and not confined to the Schwann cell outer membrane from embryonic day 18 to birth, when there was only an immature basal lamina assembly and no compact myelin formation by Schwann cells. However, the expression of these proteins increased markedly and became clearly localized to the Schwann cell outer membrane between birth and postnatal day 7, when both basal lamina assembly and compact myelin formation by Schwann cells progressed rapidly. From postnatal day 7 to adult, there was no remarkable change in the expression of these proteins. Our results support the hypothesis that the dystroglycan complex functions as an adhesion apparatus, binding the Schwann cell outer membrane with the basal lamina, and suggest that the dystroglycan complex plays a role in Schwann cell myelination through its interaction with laminin-2.

Aging↗