Biomedical subjects

Y Iguchi

Publications and source records attributed to Y Iguchi.

At least 37 records · Page 2Linked to original sources

PubMed2000

Dynamic mediolateral activation of the pyramidal cell population in human somatosensory 3b area can be visualized by magnetic recordings.

Dynamic mediolateral activation in the pyramidal cell population of the human somatosensory 3b area was studied non-invasively. Somatosensory evoked fields (SEFs) were recorded over the hand area contralateral to the right median nerve stimulation at the wrist. Localization of an equivalent current dipole (ECD) for N20m primary cortical response was successively calculated for periods of 2.4 ms around N20m peak where the signal-to-noise ratio exceeded 100 and the spatial resolution was approximately 0.3 mm. The ECD moved toward the anterior, lateral and inferior direction for a distance of 8.7 mm at a propagation velocity of 3.6 m/s. This direction was orthogonal to the orientation of apical dendrites of the pyramidal neurons in area 3b and parallel to the surface of the posterior bank of the central sulcus. These findings suggest that the sequential mediolateral activation of the pyramidal cells in the somatosensory cortex is mediated by horizontal connections running parallel to the cortical surface.

Adult↗

PubMed2000

Sequential information processing during a mental arithmetic is reflected in the time course of event-related brain potentials.

OBJECTIVE: We hypothesized that mental arithmetic is a complex of sequential information processing. In order to test the hypothesis, event-related potentials (ERPs) were measured during 3 mental tasks. METHODS: Fifteen normal human subjects performed the following tasks; (1) subjects added up every digit delivered successively on a computer display, (2) subjects counted the number of presented digits, or (3) subjects counted the number of meaningless patterns. Spatiotemporal differences between ERP waveforms under the 3 tasks were studied within the period of 1200 ms post-stimulus. RESULTS: During the adding task, N120-P180-N220 complex advanced in latency in the left frontal, central and parietal regions. P300 increased in amplitude in the frontal and temporal regions during adding and counting digits, which was specific to the digit presentation. A positive slow potential depended on the adding task and showed two spatiotemporal distributions; one was a widespread brain activity over the frontal, central, temporal and parietal regions observed within 400-820 ms, and another was a brain activity restricted to the frontal region lasting up to 1150 ms. CONCLUSIONS: The results suggest that the early portion of ERPs reflects identification of physical attributes of stimuli and numeric meaning of digits, and that the positive slow potential reflects processes associated with calculation.

Adult↗

PubMed2000

Comparison of the depth of the desiccated zone with selected vaporizing-cutting electrodes: a basic study in animals.

OBJECTIVE: To evaluate in an animal model the haemostatic efficacy of vaporizing-cutting (VC) electrodes recently developed for use in high-energy transurethral resection of the prostate (TURP). MATERIALS AND METHODS: Four VC electrodes were assessed for their haemostatic efficacy in the muscle and liver of pigs (in vitro) and dogs (in vivo). The devices tested were the roller-cutting and Vapor Cut (Karl Storz GmbH, Germany); the Wedge (Boston Scientific Corp., Boston, USA); and the Uroloop (Endocare Inc., Irvine, CA). In each the depth of the desiccated zone was compared with that produced by a standard cutting loop electrode. Each electrode was attached to a scanning system (developed previously) that allowed the electrode pressure on the tissue surface (in 3% sorbitol solution) and the running speed to be adjusted. The same generator was used with all devices. The tissue (muscle or liver) was cut by running the electrode over the surface at 200, 250 or 300 W, with the loop electrode used as the reference. After completing the procedure, the surgical wound and the surrounding tissue were dissected out and the depth of the heat-affected zone (HAZ, defined as the desiccated zone) measured. RESULTS: In pig muscle (stroke speed 5 mm/s) there was no significant difference in the depth of the HAZ between the four VC electrodes and the loop, or among the VC electrodes at any of the power levels tested. In pig liver (stroke speed 5 mm/s), the roller cutting and Vapor Cut electrodes produced a thicker HAZ than the loop at all power levels tested (P < 0.01). The Wedge electrode produced a significantly thicker HAZ than the loop at 200 and 300 W (P < 0.01). There were no significant differences in HAZ among the VC electrodes at any power level. In dog muscle in vivo (stroke speed 10 mm/s), the roller cutting, Vapor Cut and Wedge electrodes produced a significantly thicker HAZ at 250 W than the loop at 150 W (the usual power for TURP) (P < 0.01). There was no significant difference among the VC electrodes. In dog liver in vivo (stroke speed 10 mm/s), the roller cutting electrode produced a significantly thicker HAZ at 250 W than the loop at 150 W (P < 0.01). CONCLUSIONS: The present VC electrodes produced a thicker desiccation zone at higher powers (200-300 W) than the standard loop at the usual power (150 W). The four VC electrodes produced a similar desiccation zone. With pig muscle and liver in vitro, regular loops used at a higher power created a desiccation zone that was 70-80% of the depth created by the VC electrodes.

Animals↗

PubMed1999

Frequency representation in the human hand somatosensory cortex: a reappraisal.

Frequency organization in the human primary somatosensory cortex (SI) was re-examined. Somatosensory evoked magnetic fields (SEFs) were measured with a 37 channel first-order axial gradiometer system. Sensory stimuli comprising a 20ms vibration at frequencies of 50, 100, 200 and 400 Hz were delivered to the volar surface of the tip of the right index finger. Using a single dipole model, the sources of the first main peak (M50) of SEFs were estimated. All of the sources were located in the 3b area. There were no statistically significant differences between the locations of the dipoles evoked by different frequency stimulations. These results support our previous study using a 122 channel whole head planar gradiometer system that systematic frequency organization at the hand area of SI cortex may not be present in humans.

Adult↗

PubMed1999

Distal-proximal somatotopy in the human hand somatosensory cortex: a reappraisal.

The distal-proximal representation of the finger and palm in the first somatosensory cortex was reexamined. Somatosensory evoked magnetic fields (SEFs) were measured with a 37-channel first-order axial gradiometer system. Sensory stimulus comprising a 20-ms vibration at a frequency of 200 Hz was delivered to five successive sites in 3-cm increments along the distal-proximal direction over the volar surface of the right index finger and palm. Using a single dipole model, the sources and the signal strengths of the main peak (M50) of the SEFs were estimated. All of the sources were located in the 3b area. There were no statistically significant differences between the locations of dipoles evoked by stimulation of different sites. The results support those of our previous study using a 122-channel whole-head planar gradiometer system that orderly distal-proximal representation of the hand, as described in monkeys, is blurred in the adult human somatosensory cortex.

Adult↗

PubMed1999

Reciprocal modulation of somatosensory evoked N20m primary response and high-frequency oscillations by interference stimulation.

OBJECTIVES: We examined whether the inverse relation between somatic evoked N20m primary response and high-frequency oscillations during a wake-sleep cycle (Hashimoto, I., Mashiko, T., Imada, T., Somatic evoked high-frequency magnetic oscillations reflect activity of inhibitory interneurons in the human somatosensory cortex, Electroenceph clin Neurophysiol 1996;100:189-203) holds for interference stimulation. METHODS: Somatosensory evoked fields (SEFs) from 14 subjects were measured following electric median nerve stimulation at the wrist with, and without, concurrent brushing of the palm and fingers. SEFs were recorded with a wide bandpass (0.1-1200 Hz) and then N20m and high-frequency oscillations were separated by subsequent low-pass (< 300 Hz) and high-pass (> 300 Hz) filtering. RESULTS: The N20m decreased dramatically in amplitude during interference stimulation. In contrast, the high-frequency oscillations moderately increased in number of peaks. CONCLUSIONS: These results demonstrate the presence of an inverse relation between N20m and high-frequency oscillations for interference stimulation. We speculate that the high-frequency oscillations represent a localized activity of GABAergic inhibitory interneurons of layer 4, characterized by a high-frequency spike burst (200-1000 Hz) without adaptation, and that the continuous interference stimulation induces tonic excitation of the interneurons, leading to a facilitation of responses to the coherent afferent volley elicited by the median nerve stimulation (bottom-up mechanism). On the other hand, refractoriness of the pyramidal neurons caused directly by interference stimulation along with an enhanced feed-forward inhibition from the interneurons will lead to a decrease of N20m amplitude.

Adult↗

PubMed1999

[Renal angiomyolipoma with a tumor thrombus extending into the right atrium--a case report].

We present a case of spontaneous rupture of renal angiomyolipoma with a tumor thrombus extending from the right renal vein and inferior vena cava to the right atrium. A 41-year-old woman, previously in good health, was referred to our hospital with right flank pain. Computed tomography showed fat densities in both tumor and thrombus. Other imaging examinations also demonstrated a large right renal mass (18 cm in diameter), a long tumor thrombus (13 cm in length) and a small left renal tumor (1.5 cm in diameter). Right nephrectomy and en-bloc removal of the intra caval and intracardiac tumor thrombus were performed on cardiopulmonary bypass. It was pathologically diagnosed as an angiomyolipoma without tuberous sclerosis. At present, three years after surgery the patient is doing well, showing neither metastasis nor increase of the left renal angiomyolipoma. To our knowledge, our case seems to be the 3rd case report of renal angiomyolipoma with a tumor thrombus extending to the right atrium. We conclude that renal angiomyolipoma even with an intra cardiac tumor thrombus can be resected safely and successfully.

Adult↗

PubMed1999

Event-related potentials reflecting sequential information processing during a mental arithmetic task.

The sequence of brain activities was identified with respect to the behavioral output indicated by the reaction time. The early portion of ERPs suggests two automatic processes irrespective of the adding task; one is identification of physical attributes of digits and patterns and the other is recognition of the numeric meaning specific to digits. The elicitation of the subsequent positive slow potential depends on the adding task, suggesting mental processes associated with calculation and memorizing the result of the sum. These stages of information processing concatenate sequentially during the time course of performing the adding task.

Adult↗

PubMed1999

[A case of renal cell carcinoma associated with von Hippel-Lindau disease and the necessity for family genetic diagnosis].

We report a 47-year-old man who had bilateral renal cell carcinoma (RCC) associated with von Hippel-Lindau (VHL) disease. Surgical resection of hemangioblastomas and left nephrectomy for RCC had been done previously. This time, a small RCC was found in his right kidney and enucleation was performed to preserve renal function. His mother had retinal angioma, hemangioblastoma, and bilateral RCC. Hemangioblastoma was also found in his daughter. Genetic diagnosis was performed in his family and a germline VHL mutation was recognized. For improvement of the prognosis of VHL disease, genetic diagnosis and early clinical assessment are important.

Carcinoma, Renal Cell↗

PubMed1998

Benzodiazepine effects on human sleep EEG spectra: a comparison of triazolam and flunitrazepam.

The effects of 0.5 mg triazolam (TRI) and 4 mg flunitrazepam (FNZ) on the sleep electroencephalogram (EEG) were studied in eleven (six for TRI, and five for FNZ) healthy young male subjects. C3 EEG channel data of one baseline night, three drug nights and two withdrawal nights were recorded and their analyzed using a fast Fourier transformation (FFT) method. Changes in the 0.5 Hz to 40 Hz power spectrum showed that: 1) both TRI and FNZ increased higher frequency activity and reduced lower frequency activity on the drug nights; 2) on drug nights, NREM sigma frequency power was more strongly enhanced by TRI than FNZ, while the beta power of both NREM and REM was more strongly enhanced by FNZ than TRI; 3) NREM alpha power increased on the second night of withdrawal from both TRI and FNZ; 4) the power spectra for both NREM and REM sleep returned to baseline levels by the fourth night of withdrawal from either TRI or FNZ. These findings suggest that 0.5 mg TRI and 4 mg FNZ have both common and differing pharmacological effects on the central nervous system. Such differences could be caused by differences in the dose, half-life or systemic distribution of these two drugs.

Adult↗

PubMed1998

Autotransfusion supported by erythropoietin therapy in transurethral resection of the prostate.

We investigated the collection and transfusion of autologous blood after treatment with EPO in 68 BPH patients (including 10 controls) who were scheduled to undergo TUR-P. All patients received oral and/or intravenous iron supplements. Assessments were made based on the preoperative increase in blood hemoglobin levels including autologous blood predonation (deltaHb). The deltaHb in patients undergoing collection of 600 ml of blood were as follows: control group: -0.36 +/- 0.57 g/dl; EPO group, 9 x 3000 units intravenously: 1.15 +/- 0.83 g/dl; EPO group, 6 x 6000 units intravenously: 0.79 +/- 0.80 g/dl; EPO group, 3 x 12,000 units subcutaneously: 1.47 +/- 0.62 g/dl. In patients undergoing collection of 800 ml of blood, the results were as follows: EPO group, 3 x 12,000 units subcutaneously: 1.80 +/- 0.69 g/dl; EPO group, 3 x 24,000 units subcutaneously: 2.03 +/- 0.77 g/dl. All EPO-treated patients successfully underwent surgery using their own blood, and none of them required homologous transfusion. The increase of Hb was greater in the patients treated with EPO than in controls, allowing safe preoperative blood collection even in elderly patients. In patients with relatively severe BPH, homologous transfusion could be avoided and surgery was performed safely.

Aged↗

PubMed1998

[The reaction of the nasal mucosa in allergic rhinitis to cold saline stimulus].

To clarify the nature of the reaction pattern of the nasal mucosa in allergic rhinitis, nasal lavage using a cold saline solution of 4 degrees C and a warm saline solution was attempted in 8 patients with nasal allergy to the pollen of the Japanese cedar and cypress in a non-scatter season, and the concentration of protein contents in the nasal washings was determined. The concentrations of total protein, albumin and 26 kD protein were higher in cold saline than in the warm saline lavage. In particular, the concentration of 26 kD protein was 5.3 times higher. However, the concentration was not very high compared with the value obtained by warm saline lavage in the scatter season. These findings indicate that the nasal mucosa of patients with allergic rhinitis is reactive to cold saline stimuli even in the non-scatter season.

Adult↗

PubMed1998

[Clinical and histopathological features of hemangiopericytoma-like tumor of the nasal cavity].

A 65-year-old woman consulted our hospital complaining of left nasal obstruction. On nasal examination, a reddish half round tumor arising from the left nasal septum was found. We removed the tumor together with normal septal mucosa. Histologically, the tumor was diagnosed as a hemangiopericytoma-like tumor. It has been reported that a hemangiopericytoma-like tumor is microscopically distinguished from similar type tumors arising from other sites of the body. The most notable microscopic features of intranasal hemangiopericytoma-like tumors are their uniformity of cells and the absence of nuclear or cytoplasmic pleomorphism with a sheetlike arrangement, and no evidence of varying growth phases or necrosis. This is the second case report of this type of tumor in Japan.

Aged↗

PubMed1998

[Percutaneous ethanol and acetic acid injection for liver metastasis from colon cancer--two case reports].

Two cases of liver metastasis from colon cancer were treated by percutaneous ethanol (PEI) and acetic acid (PAI) injection for the recurrent lesion after surgery. Case 1 was a 60-year-old female who received sigmoidectomy with partial hepatectomy, and intraarterial 5-FU infusion was done after surgery. One year later, recurrence of liver tumor was detected, and PEI and PAI were performed for the metastatic lesions of the liver. Tumor regression and histopathological examination revealed coagulative necrosis. The patient died of lung metastasis 2 years and 10 months after treatment. Case 2 was a 58-year-old-male with ascending colon cancer and liver metastasis, who received surgery, and chemotherapy with intraarterial 5-FU infusion was continued. Four months later, recurrence of liver metastasis with elevation of serum CEA was noted. The patient received PEI three times and CEA decreased. Re-operation of hepatectomy revealed complete necrosis at the site of PEI. The patient has been alive for 1 year and 6 months with a new recurrence in the liver and is receiving repeated PEI therapy. PEI and PAI seem to be useful for the treatment of unresectable liver metastasis.

Acetic Acid↗

PubMed1997

Plasmapheresis for prevention of recurrent focal segmental glomerulosclerosis of kidney allograft in adult recipients.

Nephrotic syndrome due to focal segmental glomerulosclerosis (FGS) frequently recurs even after renal transplantation and may cause renal allograft failure. From January 1983 though April 1995, 11 adult recipients with primary FGS received 11 kidney transplants at our institution, and 3 of them were treated with pretransplant plasma exchange (PE). Other patients did not receive any preoperative PE, and 4 patients lost their grafts due to recurrent FGS (50%). PE was completed 3 times before the transplantation to prevent posttransplant recurrence of FGS. Two recipients did not have any proteinuria or graft dysfunction without posttransplant PE. One patient had mild proteinuria immediately after transplantation, and histological examination showed recurrent FGS. The patient has been undergoing PE once a month (2 years posttransplant). Her renal function is excellent (sCr 1.2 mg/dl), and her FGS is being well controlled by PE. PE seems to be effective for the prevention of the recurrence of FGS following renal transplantation.

Adult↗

PubMed1997

Solitary cystic dilatation of the intrahepatic bile duct.

A 31 year old man was hospitalised with general fatigue and epigastric pain. Abdominal ultrasonography, computed tomography, and magnetic resonance imaging showed a cystic lesion in the left lobe of the liver. Endoscopic retrograde cholangio-pancreatography and percutaneous trans-hepatic cholangiography revealed a localised dilatation of the intrahepatic bile duct without any obstruction. However, a large mass of mucinous material was noted in the saccular intrahepatic duct and the common bile duct. There was no evidence of a choledochal cyst, anomalous pancreaticobiliary ductal union, or congenital cystic change of the kidneys. A possible diagnosis of mucinous cystic neoplasm of the intrahepatic bile duct was made and a left hepatectomy performed. Cholangiography of the resected specimen showed a non-obstructive solitary cystic dilatation of the left hepatic duct. Histologically, the dilated duct was lined with columnar biliary epithelium without any papillary proliferation and/or atypia. Neither malignancy nor hepatic fibrosis was observed; the term "solitary cystic dilatation of the intrahepatic bile duct" perhaps is more descriptive and the concept easier to understand.

Adult↗

PubMed1997

Long-term outcome of renal transplantation in hepatitis B surface antigen-positive patients in cyclosporin era.

The impact of hepatitis B virus (HBV) infection on the outcome of renal transplantation (Tx) has been controversial. To determine the indication of renal Tx in patients infected by HBV, we investigated the long-term outcome of renal transplant patients with hepatitis B surface antigen (HBsAg). We analyzed 980 patients, including 18 HBsAg carriers, who underwent renal Tx and were immunosuppressed with cyclosporin in our institute. Fourteen out of 18 patients (77.8%) showed hepatic dysfunction after an average period of 17.8 months (range 1-65) after Tx. Four out of 14 patients (28.5%) with hepatic dysfunction died of liver failure due to fulminant hepatitis with functioning grafts between 15 and 71 months after Tx. The remaining 10 patients with hepatic dysfunction are alive up to the time of last follow-up; however, 5 of them lost their grafts because of rejection between 44 and 92 months after Tx. Their liver function improved after withdrawal of cyclosporin. Only 4 patients did not develop chronic liver disease and have had functioning grafts for between 44 and 147 months. One patient died of subarachnoid hemorrhage 22 months after Tx. HBe antigen, antibody and HCV antibody status were not related to the occurrence of liver dysfunction after Tx. Four HBV-DNA-positive patients showed deteriorated liver function. Three patients with chronic active hepatitis confirmed by the biopsy were treated with interferon. Interferon improved liver function in 2 patients, however, 1 patient died of liver failure despite interferon therapy. Our data suggested that the presence of HBsAg is often associated with chronic liver disease leading to liver failure regardless of HBe and HCV status after Tx. The indication of renal Tx in patients with HBsAg should be determined carefully giving consideration to these results.

Adolescent↗

PubMed1997

[A preliminary study on transurethral electrovaporization of the prostate (TVP) using VaporTrode].

BACKGROUND: Surgical therapy for Benign Prostatic Hypertrophy (B.P.H.) has mainly depended upon Transurethral Resection of the Prostate (TUR-P) using a cutting loop electrode. Recently, a new technique TVP was reported using the VaporTrode apparatus. We assessed the safety and efficacy of the VaporTrode in a preliminary study. METHODS: Histological changes of the muscle and liver of pigs were examined after vaporization using the VaporTrode and a cutting loop electrode. First, histological changes were investigated following vaporization after one stroke at a slow hand speed. Next, histological changes were assessed following vaporization at fixed stroke speed in an experimental model. RESULTS: At an electrical output of less than 275 W, the depth of the vaporized layer increased as the stroke speed became slower (4.0 cm/s-2.5 cm/s). When the electrical output was 300 W, the depth of vaporized layer increased even at a faster stroke speed (2.5 cm/s-3.0 cm/s.) The depth of the desiccated layer increased as the stroke speed became slower at any electrical output. However, when the stroke speed was 4.0 cm/s, the depth of this layer was less than 2.0 mm. With the cutting loop electrode, the depth of the desiccated layer increased at a higher electrical power, but the change was very small. CONCLUSION: To achieve deep enough vaporized and desiccated layers safely, the VaporTrode should be used at a stroke speed slower than 3.0 cm/s and a high electrical power of about 275 W.

Animals↗